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Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. In medicine, ablation is the same as removal of a part of biological tissue, usually by surgery, and more recently using other modalities such as radiofrequency ablation and cryoablation.
Ablation therapy using radiofrequency waves on the heart is used to cure a variety of cardiac arrhythmias such as supraventricular tachycardia, Wolff-Parkinson-White syndrome, ventricular tachycardia and more recently atrial fibrillation.
Rotoablation is a type of arterial cleansing that consists of inserting a tiny, diamond-tipped, drill-like device into the affected artery to remove fatty deposits or plaque. The procedure is used in the treatment of coronary heart disease to restore blood flow.
Angiotensin Converting Enzyme (ACE) Inhibitors
Angiotensin II is a very potent chemical that causes the muscles surrounding blood vessels to contract and thereby narrows the blood vessels. The narrowing of the vessels increases the pressure within the vessels and can cause high blood pressure (hypertension). Angiotensin II is formed from angiotensin I in the blood by the enzyme, angiotensin converting enzyme (ACE). ACE inhibitors are medications that slow (inhibit) the activity of the enzyme, which decreases the production of angiotensin II. As a result, the blood vessels enlarge or dilate, and the blood pressure is reduced. This lower blood pressure makes it easier for the heart to pump blood and can improve the function of a failing heart. In addition, the progression of kidney disease due to high blood pressure or diabetes is slowed. ACE inhibitors are used for controlling blood pressure, treating heart failure and preventing kidney damage in people with hypertension or diabetes.
Angiotensin is an oligopeptide in the blood that causes vasoconstriction, increased blood pressure, and release of aldosterone from the adrenal cortex.
Acetycholine. (Muscle Relaxants)
The chemical compound acetylcholine, abbreviated as ACh, is a chemical transmitter in both the peripheral nervous system (PNS) and central nervous system (CNS). Acetylcholine is the neurotransmitter in all autonomic ganglia. Acetylcholine binds to acetylcholine receptors on skeletal muscle fibers, it opens ligand gated sodium channels in the membrane. Sodium ions then enter the muscle cell, stimulating muscle contraction. Acetylcholine, while inducing contraction of skeletal muscles, instead induces decreased contraction in cardiac muscle fibers. This distinction is attributed to differences in receptor structure between skeletal and cardiac fibers. Acetylcholine also cause excitatory actions in the brain.
Increased hydrogen ion concentration when arterial pH falls below 7.35, while its counterpart (alkalosis) occurs at a pH over 7.45. Arterial blood gas analysis and other tests are required to separate the main causes.
An action potential is a "spike" of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal life, rapidly carrying information within and between tissues.
A disease with either or both of: 1.a rapid onset; 2.a short course (as opposed to a chronic (long-lasting or recurrent) course).
Acute coronary syndrome.
ACS is a set of signs and symptoms, usually a combination of chest pain and other features, interpreted as being the result of abruptly decreased blood flow to the heart (cardiac ischemia); the most common cause for this is the disruption of atherosclerotic plaque in an epicardial coronary artery. The subtypes of acute coronary syndrome include unstable angina (UA), not associated with heart muscle damage, and two forms of myocardial infarction, in which heart muscle is damaged. These types are named according to the appearance of the electrocardiogram (ECG) as non-ST segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI). ACS should be distinguished from stable angina, which develops during exertion and resolves at rest. In contrast with stable angina, unstable angina occurs suddenly, often at rest or with minimal exertion, or at lesser degrees of exertion than the individual's previous angina ("crescendo angina"). New onset angina is also considered unstable angina, since it suggests a new problem in a coronary artery.
Acute Myocardial infarction.
Acute myocardial infarction (AMI or MI): (Heart attack) is a disease state that occurs when the blood supply to a part of the heart is interrupted. The resulting ischemia or oxygen shortage causes damage and potential death of heart tissue. It is a medical emergency, and the leading cause of death for both men and women all over the world. The term myocardial infarction is derived from myocardium (the heart muscle) and infarction (tissue death due to oxygen starvation). The phrase "heart attack" is sometimes used incorrectly to describe sudden cardiac death, which may or may not be the result of acute myocardial infarction. Classical symptoms of acute myocardial infarction include chest pain, shortness of breath, nausea, vomiting, palpitations, sweating, and anxiety or a feeling of impending doom.
In cardiac physiology, afterload is used to mean the tension produced by a chamber of the heart in order to contract. If the chamber is not mentioned, it is usually assumed to be the left ventricle. However, the strict definition of the term relates to the properties of a single cardiac myocyte. It is therefore only of direct relevance in the laboratory; in the clinic, the term end-systolic pressure is usually more appropriate, although not equivalent. Afterload can also be described as the pressure that the chamber of the heart has to generate in order to eject blood out of the chamber. Everything else held equal, as afterload increases, cardiac output decreases. In the case of the left ventricle, the afterload is a consequence of the blood pressure, since the pressure in the ventricle must be greater than the peripheral blood pressure in order to open the aortic valve.
Alkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma (is the liquid component of blood, in which the blood cells are suspended). (alkalemia). Generally alkalosis is said to occur when arterial pH exceeds 7.45. The opposite condition is acidosis. More specifically, alkalosis can refer to:
• Respiratory alkalosis.
• Metabolic alkalosis.
Alpha blockers (also called alpha-adrenergic blocking agents) constitute a variety of drugs which block α1-adrenergic receptors in arteries and smooth muscles,e.g. Phentolamine (Rogitine).
Angina is chest pain or discomfort that occurs when your heart isn’t getting enough oxygen because of reduced blood flow to the heart. It is usually a symptom of coronary heart disease.
Stable angina usually results from atherosclerotic plaques in the coronary arteries, whereas unstable angina is usually due to plaque rupture and may occur either in patients with a history of stable angina or in those with previously silent coronary artery disease. It is important to distinguish unstable from stable angina; unstable angina is usually characterised by new onset severe angina or sudden worsening of previously stable angina.
A severe local swelling of the skin, particularly around the eyes, lips, nose, tongue, larynx or hands. Angio-oedema is caused by an abnormal reaction by the body's immune system ( disease fighting system ). An attack is usually caused by an allergy.
Angiography or arteriography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. Its name comes from the Greek words angeion, "vessel", and graphien, "to write or record". The X-ray film or image of the blood vessels is called an angiograph, or more commonly, an angiogram.
Angiograms require the insertion of a catheter into a peripheral artery, e.g. the femoral artery. As blood has the same radiodensity as the surrounding tissues, a radiocontrast agent (which absorbs X-rays) is added to the blood to make angiography visualization possible. The angiographic X-Ray image shows shadows of the openings within the cardiovascular structures carrying blood (actually the radiocontrast agent within). The blood vessels or heart chambers themselves remain largely to totally invisible on the X-Ray image.
Angioplasty is the mechanical widening of a narrowed or totally-obstructed blood vessel. These obstructions are often caused by atherosclerosis. The term "angioplasty" is a portmanteau of the words "angio" (from the Latin/Greek word meaning vessel) and "plasticos" (Greek: fit for moulding). Angioplasty has come to include all manner of vascular interventions typically performed in a minimally-invasive or "percutaneous"-(via needle-puncture of the skin) method.
Anti, against; opposing; counteracting. Arrhythmia is any variation from the normal rhythm in the heartbeat.
Anticholinergic: The action of certain medications that inhibit the transmission of parasympathetic nerve impulses and thereby reduce spasms of smooth muscle (such as that, for example, in the bladder).
An acetylcholinesterase inhibitor or anti-cholinesterase is a chemical that inhibits the cholinesterase enzyme from breaking down acetylcholine, so increasing both the level and duration of action of the neurotransmitter acetylcholine.
• occur naturally as venoms and poisons.
• are used as weapons in the form of nerve agents .
• are used medicinally:
o to treat myasthenia gravis-(from the Greek myastheneia, lit. 'condition of no strength in the muscle', and Latin gravis, 'serious').In myasthenia gravis, they are used to increase neuromuscular transmission.
o to treat Alzheimer's disease.
o as an antidote to anticholinergic poisoning.
Examples: Compounds which function as reversible competitive or noncompetitive inhibitors of cholinesterase are those most likely to have therapeutic uses. These include: neostigmine, physostigmine.
An aortic cross-clamp is a surgical instrument used in cardiac surgery to clamp the aorta and separate the systemic circulation from the outflow of the heart.
Aortic dissection is a tear in the wall of the aorta that causes blood to flow between the layers of the wall of the aorta and force the layers apart. Aortic dissection is a medical emergency and can quickly lead to death, even with optimal treatment. If the dissection tears the aorta completely open (through all three layers) massive and rapid blood loss occurs. Aortic dissections resulting in rupture have a 90% mortality rate even if intervention is timely.
Blood penetrates the intima and enters the media layer.
As with all other arteries, the aorta is made up of three layers. The layer that is in direct contact with the flow of blood is the tunica intima, commonly called the intima. This layer is made up of mainly endothelial- (a thin layer of cells that line the interior surface of blood vessels) cells. Just deep to this layer is the tunica media, known as the media. This "middle layer" is made up of smooth muscle cells and elastic tissue. The outermost layer (furthest from the flow of blood) is known as the tunica adventitia or the adventitia. This layer is composed of connective tissue. In an aortic dissection, blood penetrates the intima and enters the media layer. The high pressure rips the tissue of the media apart, allowing more blood to enter. This can propagate along the length of the aorta for a variable distance, dissecting either towards or away from the heart or both. The initial tear is usually within 100 mm of the aortic valve .The risk in aortic dissection is that the aorta may rupture, leading to massive blood loss resulting in death.
Aortic Aneurysm Thoracic.
The aorta is the largest artery in your body, and it carries blood away from your heart to all the parts of your body. The part of your aorta that runs through your chest is called the thoracic aorta and, when your aorta reaches your abdomen, it is called the abdominal aorta. When a weak area of your thoracic aorta expands or bulges, it is called a thoracic aortic aneurysm (TAA). Approximately 25 percent of aortic aneurysms occur in the chest, and the rest involve the abdominal aorta.
A special type of thoracic aneurysm is called an aortic dissection – (see above), and is usually associated with high blood pressure. Sometimes, blood flow forces the layers of the wall of your aorta apart, and it weakens your aorta. This process is called aortic dissection and can cause TAA. The separation can extend from your thoracic aorta through your entire aorta and block arteries to your legs, arms, kidneys, brain, spinal cord, and other areas. Another problem associated with aortic dissection is that over time, the pressure of blood flow can cause the weakened area of your aorta to bulge like a balloon. Much like an over-inflated balloon, an aneurysm can stretch the aorta beyond its safety margin.
Thoracic aortic aneurysms are a serious health risk because they can burst or rupture. A ruptured aneurysm can cause severe internal bleeding, which can rapidly lead to shock or death.
Aortic Valve Replacement ( A.V.R ).
Aortic valve replacement is a cardiac surgery procedure in which a patient's aortic valve is replaced by a different valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky (aortic insufficiency / regurgitation) or partially blocked (aortic stenosis ). Aortic valve replacement currently requires open heart surgery. As of 2006, percutaneous aortic valve replacement is being researched, which allows the implantion of valves using a catheter without open heart surgery.
Types of Heart Valves: There are two basic types of artificial heart valve, mechanical valves and tissue valves.
Tissue valves: Tissue heart valves are usually made from animal tissues, either animal heart valve tissue or animal pericardial tissue. The tissue is treated to prevent rejection and to prevent calcification.
There are alternatives to animal tissue valves. In some cases a homograft - a human aortic valve - can be implanted. Homograft valves are donated by patients and harvested after the patient dies. The durability of homograft valves is probably the same for porcine tissue valves. Another procedure for aortic valve replacement is the Ross procedure (or pulmonary autograft). The Ross procedure is surgery where the aortic valve is removed and replaced with the patient's own pulmonary valve. A pulmonary homograft (pulmonary valve taken from a cadaver) is then used to replace the patients own pulmonary valve. This procedure was first used in 1967 and is used primarily in children.
Mechanical valves: Mechanical valves are designed to outlast the patient, and have typically been stress-tested to last several hundred years. Although mechanical valves are long-lasting and generally only one surgery is needed, there is an increased risk of blood clots forming with mechanical valves. As a result, mechanical valve recipients must generally take anti-coagulant drugs such as warfarin for the rest of their lives, which effectively makes them borderline haemophiliacs. ( .Haemophilia is the name of several hereditary genetic illnesses that impair the body's ability to control coagulation ).
Valve selection: Tissue valves tend to wear out faster with increased flow demands - such as with a more active (typically younger person). Tissue valves typically last 10-15 years in less active (typically elderly) patients, but wear out faster in younger patients. When a tissue valve wears out and needs replacement, the person must undergo another valve replacement surgery. For this reason, younger patients are often recommended mechanical valves to prevent the increased risk (and inconvenience) of another valve replacement.
Arrhythmia is any variation from the normal rhythm in the heartbeat.
Cardiac arrhythmia is any of a group of conditions in which the electrical activity of the heart is irregular or is faster or slower than normal. Some arrhythmiae are life-threatening medical emergencies that can cause cardiac arrest and sudden death. Others cause aggravating symptoms, such as an awareness of a different heart beat, or palpitation, which can be annoying. Some are quite small and normal. Sinus arrhythmia is the mild acceleration followed by slowing of the normal rhythm that occurs with breathing. In adults the normal resting heart rate ranges from 60 beats per minute to 100 beats per minute. The normal heart beat is controlled by a small area in the upper chamber of the heart called the sinoatrial node or sinus node. The sinus node contains specialized cells that have spontaneous electrical activity that starts each normal heart beat.
Producing or promoting arrhythmia.
Arterial blood gas analysis
An arterial blood gas (ABG) test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood. This test is used to check how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood. As blood passes through your lungs, oxygen moves into the blood while carbon dioxide moves out of the blood into the lungs. An ABG test uses blood drawn from an artery, where the oxygen and carbon dioxide levels can be measured before they enter body tissues. An ABG measures:
Partial pressure of oxygen (PaO2).
This measures the pressure of oxygen dissolved in the blood and how well oxygen is able to move from the airspace of the lungs into the blood.
Partial pressure of carbon dioxide (PaCO2).
This measures how much carbon dioxide is dissolved in the blood and how well carbon dioxide is able to move out of the body.
The pH measures hydrogen ions (H+) in blood. The pH of blood is usually between 7.35 and 7.45. A pH of less than 7.35 is called acid and a pH greater than 7.45 is called basic (alkaline).
Bicarbonate is a chemical that keeps the pH of blood from becoming too acid. If the pH level drops, HCO3 is absorbed by the kidneys and returned to the blood instead of passing out of the body in the urine.
Oxygen content (O2CT) and oxygen saturation (O2Sat) values.
O2 content measures the amount of oxygen in the blood. Oxygen saturation measures how much of the haemoglobin in the red blood cells is carrying oxygen (O2).
Blood for an ABG test is taken from an artery. Most other blood tests are done on a sample of blood taken from a vein, after the blood has already passed through the body's tissues where the oxygen is used up and carbon dioxide is produced.
Partial pressure of oxygen (PaO2): 75–100 mm Hg
Partial pressure of carbon dioxide (PaCO2): 35–45 mm Hg
Bicarbonate (HCO3): 20–29 mEq/L or 20–29 mmol/L
Oxygen content (O2CT): 15%–22% (15–22 mL per 100 mL of blood)
Oxygen saturation (O2Sat): 95%–100% (95–100 mL per 100 mL of blood)
Arterial Line monitoring.
The systolic arterial pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle; the diastolic arterial pressure is the lowest pressure (at the resting phase of the cardiac cycle). The average pressure throughout the cardiac cycle is reported as mean arterial pressure; the pulse pressure reflects the difference between the maximum and minimum pressures measured. Arterial pressures can be measured invasively (by penetrating the skin and measuring inside the blood vessels) or non-invasively-( see Blood Pressure).
Arterial blood pressure (BP) is most accurately measured invasively. Invasive arterial pressure measurement with intravascular cannulae involves direct measurement of arterial pressure by placing a cannula needle in an artery (usually radial, femoral, dorsalis pedis or brachial). This is usually done by an anaesthetist, surgeon or physician. The cannula must be connected to a sterile, fluid-filled system, which is connected to an electronic pressure transducer. The advantage of this system is that pressure is constantly monitored beat-by-beat, and a waveform (a graph of pressure against time) can be displayed. This invasive technique is regularly employed in intensive care medicine, anaesthetics, and for research purposes.
Cannulation for invasive vascular pressure monitoring is infrequently associated with complications such as thrombosis, infection, and bleeding. Patients with invasive arterial monitoring require very close supervision, as there is a danger of severe bleeding if the line becomes disconnected. It is generally reserved for patients where rapid variations in arterial pressure are anticipated.
Invasive vascular pressure monitors are pressure monitoring systems designed to acquire pressure information for display and processing. There are a variety of invasive vascular pressure monitors for trauma, critical care, and operating room applications. These include single pressure, dual pressure, and multi-parameter (i.e. pressure / temperature). The monitors can be used for measurement and follow-up of arterial, central venous, pulmonary arterial, left atrial, right atrial, femoral arterial, umbilical venous, umbilical arterial, and intracranial pressures.
Vascular pressure parameters are derived in the monitor's microcomputer system. Usually, systolic, diastolic and mean pressures are displayed simultaneously for pulsatile waveforms (i.e. arterial and pulmonary arterial). Some monitors also calculate and display CPP (cerebral perfusion pressure). Normally, a zero key on the front of the monitor makes pressure zeroing extremely fast and easy. Alarm limits may be set to assist the medical professional responsible for observing the patient. High and low alarms may be set on displayed temperature parameters.
• Systolic: less than 120 mmHg (2.32 psi or 15 kPa)
• Diastolic: less than 80 mmHg (1.55 psi or 10 kPa)
The mean arterial pressure (MAP) is the average pressure measured over one complete cardiac cycle. The up and down fluctuation of the arterial pressure results from the pulsatile nature of the cardiac output. The pulse pressure is determined by the interaction of the stroke volume versus the resistance to flow in the arterial tree.
The cause of coronary artery disease, in which the walls of the coronary arteries thicken due to the accumulation of plaque in the blood vessels.
In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow. Asystole is one of the conditions required for a medical practitioner to certify death. In asystole, the heart will not respond to defibrillation because it is already depolarized ( to partially or completely eliminate or counteract the polarization of) (polarise -to separate or accumulate positive and negative electric charges in two distinct regions ) however some emergency physicians advocate a trial of defibrillation in case the rhythm is actually fine ventricular fibrillation, although little evidence exists to support the practice. Asystole is usually a confirmation of death as opposed to a heart rhythm to be treated, although a small minority of patients are successfully resuscitated, if the underlying cause is identified and treated immediately.
Atrio-ventricular node.( A- V node ).
Pertaining to the atrium and ventricle,a node of neurogenic ( derived from or caused by nerve stimulation ) tissue. The A-V node serves as a gate (an "electrical relay station ") that slows the electrical current before the signal is permitted to pass down through to the ventricles, allowing the atria to fully contract before the ventricles are stimulated.
A cavity or passage. One of two upper chambers of the heart,( Formerly called auricle ).
Atrial fibrillation ( AF or afib ) is an abnormal rhythm which involves the two upper chambers of the heart. In a normal heart rhythm, the impulse generated by the sinoatrial node(SA node)spreads through the heart and causes causes contraction of the heart muscle and pumping of blood. In AF, the regular electrical impulses of the SA node are replaced by disorganised, rapid electrical impulses which result in irregular heart beats. AF is the most common cardiac arrhythmia, is often asymptomatic, but can lead to palpitations, fainting, chest pain, or even heart failure. It is also a leading cause of stroke as the erratic motion of the atria leads to blood stagnation which increases the risk of blood clots. AF may be treated with medications which either slow the heart or revert the heart rhythm back to
normal, synchronised electrical cardioversion may also be used to convert AF to a normal heart rhythm.
• there are no P waves present
• instead of P waves, fibrillarory "F" waves with a rate higher than 350 per minute are present
• the interval between QRS complexes is variable and there is no apparent rule in the rhythm of the QRS complexes (absolute arrhythmia)
• depending on the frequency of the QRS complexes we distinguish atrial fibrillation with bradycardic (less than 60 per minute), normocardic ( 60 to 100 per minute) and tachycardic (over 100 per minute) response of the ventricles .
Atrial flutter is a rapid heart rhythm caused by an extra electrical pathway in the heart that begins the upper chambers of the heart, called the atria. This causes a very fast, steady heartbeat. It occurs when rapidly fired signals cause the muscles in the atria to contract quickly. In AF the heart cannot fill completely with blood, preventing the body from receiving the blood volume it needs to function properly. Symptoms can include; palpitations, fatigue, chest pressure or pain, shortness of breath, fainting, light-headedness and dizziness.
There are two types of atrial flutter, the common type I and rarer type II.1 Most individuals with atrial flutter will manifest only one of these. Rarely someone may manifest both types; however, they can only manifest one type at a time.
A supraventricular tachycardia (SVT) is a tachycardia or rapid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node. These rhythms require the atria or the AV node for either initiation or maintenance. This is in contrast to ventricular tachycardias, which are rapid rhythms that originate from the ventricles of the heart, that is, below the atria or AV node.
• P waves are present, but they may be hidden within the T wave
• each P wave is followed by a QRS complex at an interval between 0,12 and 0,2 s
• the PR interval can be shorter at a higher heart rate
• the intervals between QRS complexes are equal
• heart rate is between 100 and 260 beats per minute
The Intra-aortic balloon pump (IABP) is a mechanical device that is used to decrease myocardial oxygen demand while at the same time increasing cardiac output. By increasing cardiac output it also increases coronary blood flow and therefore myocardial oxygen delivery. It consists of a cylindrical balloon that sits in the aorta and counter-pulsates. That is, it actively deflates in systole increasing forward blood flow by reducing afterload, and actively inflates in diastole increasing blood flow to the coronary arteries. The balloon is inflated during diastole by a computer controlled, ECG linked mechanism. This controls the flow of helium from a cylinder into and out of the balloon. Helium is used because it’s low viscosity-(a measure of the resistance of a fluid to deform under shear stress) allows it to travel quickly through the long connecting tubes.
Beating Heart Bypass Surgery, "Off-Pump".
Recent advances in surgery and medical devices allow doctors to have less invasive options in the treatment of coronary artery disease (CAD), such as Beating Heart or "Off-Pump" Bypass Surgery. Now individuals who have medical conditions such as diabetes, history of stroke, or poor physical health, can undergo cardiac surgery with lower risk for developing complications.
Beating Heart vs. Traditional Bypass Surgery:
Beating Heart Bypass Surgery is different from traditional bypass surgery because it is performed while the heart is still beating.The surgeon does not use the heart-lung machine to bypass your heart during the procedure.In some cases, the surgeon may still need to use the heart-lung machine during the operation. A perfusionist (a specialist trained to operate the heart-lung machine) may remain on standby – (coffee room) during the operation.
Clinical Benefits of Beating Heart Bypass Surgery:
The surgeon may choose the beating heart bypass procedure because of benefits such as: decreased length of hospital stay, less trauma due to the elimination of the heart-lung machine, reduction in need for blood transfusions,, fewer cognitive - (of, relating to, or being conscious intellectual activity) and neurological consequences such as stroke.
Beating Heart Bypass Surgery, "Off-Pump"(cont).
In addition, a recent study presented in the New England Journal of Medicine showed that patients who are treated with traditional bypass surgery may suffer from lapses in mental acuity - (sharpness; acuteness; keenness) that result from brain damage caused by the stopped heart bypass surgery.
Out of 261 patients whose mental acuity diminished after bypass surgery:
• 53% had diminished mental acuity at discharge.
• 36% had diminished mental acuity after 6 weeks.
• 24% had diminished mental acuity after 6 months.
• 42% had diminished mental acuity after 5 years.
Potential benefits of Beating Heart Bypass vs. Traditional Bypass surgery?:
When compared to traditional coronary artery bypass procedures that stop the patient's heart and utilize a heart-lung machine, beating heart bypass procedures reduced:
• Transfusion rates by 48%.
• Length of post-operative hospital stay by 40%.
• Hospital costs by 24%.
• Post-operative cognitive dysfunction by 36% at 5 days and 90% at 3 months..
There are three known types of beta receptor, designated β1, β2 and β3. β1-Adrenergic receptors are located mainly in the heart and in the kidneys. β2-Adrenergic receptors are located mainly in the lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle. β3-receptors are located in fat cells. β-adrenergic receptors are part of the sympathetic nervous system which mediates the "fight or flight" response ( see also Alpha adrenoceptors ).
Beta blockers (sometimes written as β-blockers ) are a class of drugs used for various indications, but particularly for the management of cardiac arrhythmias and cardio-protection after myocardial infarction. Beta blockers block the action of endogenous catecholamines,( adrenaline and noradrenaline in particular), on β-adrenergic receptors, part of the sympathetic nervous system which mediates the "fight or flight" response. There are three known types of beta receptor, designated β1, β2 and β3. β1-Adrenergic receptors are located mainly in the heart and in the kidneys. β2-Adrenergic receptors are located mainly in the lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle. β3-receptors are located in fat cells.
Bradycardia, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. Trained athletes tend to have slow resting heart rates, and resting bradycardia in athletes should not be considered abnormal if the individual has no symptoms associated with it. The term relative bradycardia is used to explain a heart rate that, while not technically below 60 beats per minute, is considered too slow for the individual's current medical condition. This cardiac arrhythmia can be underlied by several causes, which are best divided into cardiac and non-cardiac causes. Non-cardiac causes are usually secondary, and can involve drug use or abuse; metabolic or endocrine issues, especially in the thyroid; an electrolyte imbalance; neurological factors; autonomic reflexes; situational factors such as prolonged bed rest; and autoimmunity. Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease.
A bronchodilator is a substance that dilates the bronchi and bronchioles, increasing airflow.
Bronchodilators may be endogenous- (originating naturally within the body), or they may be
medications administered for the treatment of breathing difficulties. Bronchial asthma is the
most common application of these drugs. They are also intended to help improve the breathing
capacity of patients with emphysema, pneumonia and bronchitis.
Bronchi / Bronchus.
A bronchus (plural bronchi, adjective bronchial) is a caliber of airway in the
respiratory tract that conducts air into the lungs. No gas exchange takes place
in this part of the lungs.
Bronchioles / Bronchial.
Air entering the lungs goes through the main airway (bronchus ) and then into the smaller airways
(bronchioles ), to the air sacs (alveoli ) where it enriches the blood with oxygen.
Bronchitis is inflammation of the bronchi (medium-size airways) in the lungs. Acute bronchitis is usually caused by viruses or bacteria and may last several days or weeks. Chronic bronchitis is not necessarily caused by infection and is generally part of a syndrome called COPD (chronic obstructive pulmonary disease); it is defined clinically as a persistent cough that produces sputum (phlegm), for at least three months in two consecutive years.
Bronchoscopy is a medical procedure where a tube is inserted into the airways, usually through the nose or mouth. This allows the practitioner to examine inside a patient's airway for abnormalities such as foreign bodies, bleeding, tumours, or inflammation. The practitioner often takes samples from inside the lungs: biopsies, fluid bronchoalveolar lavage –(fluid is squirted into a small part of the lung and then recollected for examination), or endo-bronchial brushing. The practitioner may use either a rigid bronchoscope or flexible bronchoscope.
A rigid bronchoscope is a straight, hollow, metal tube. Doctors perform rigid bronchoscopy less often today, but it remains the procedure of choice for removing foreign material. Rigid bronchoscopy also becomes useful when bleeding interferes with viewing the examining area.
A flexible bronchoscope is a long thin tube that contains small clear fibers that transmit light images as the tube bends. Its flexibility allows this instrument to reach the farthest points in an airway. The procedure can be performed easily and safely under local anaesthesia.
• To view abnormalities of the airway.
• To obtain samples of an abnormality or specimens in undiagnosed infections.
• To obtain tissue specimens of the lung in a variety of disorders.
• To evaluate a person who has bleeding in the lungs, possible lung cancer, a chronic cough, or a collapsed lung.
• To remove foreign objects lodged in the airway.
• Electro-cauterization-(diathermy) of tumours, granulation tissue-(is the perfused, fibrous connective tissue that replaces a fibrin clot in healing wounds), or benign lesions such as papilloma-(refers to a benign epithelial tumour), hamartoma-(a focal malformation that resembles a neoplasm in the tissue of its origin), lipoma-(benign tumor composed of fatty tissue), and adenoma-(a collection of growths (-oma) of glandular origin).
• Laser resection of benign tracheal and bronchial strictures.
• Stent insertion to palliate-( reducing the severity of disease symptoms, rather than providing a cure) extrinsic compression of the tracheo-bronchial lumen from either malignant-(a severe and progressively worsening disease)or benign-(a mild and non-progressive disease) disease processes.
Although the rigid bronchoscope can scratch or tear airway or damage the vocal cords, the risk for bronchoscopy is limited. The conditions for which doctors use it are ongoing, life-threatening cardiac problems or severely low oxygen. Complications from bronchoscopy remain extremely low. Common complications include either heart and blood vessel problems or excessive bleeding following biopsy. A lung biopsy also may cause leakage of air called pneumothorax. Pneumothorax occurs in less than 1% of cases requiring lung biopsy.
Bronchospasm is a difficulty in breathing caused by a sudden constriction of the muscles in the walls of the bronchioles. It is caused by the release degranulation –( releases antimicrobial cytotoxic molecules ) of substances from mast cells -( rich in histamine ) or basophils- (contain large cytoplasmic- a gelatinous, semi-transparent fluid that "fills" most cells, granules ) under the influence of anaphylatoxins -( important part of the immune system ). Bronchospasm appears as the feature of asthma, chronic bronchitis, anaphylaxis, and as a possible side-effect of certain drugs. The over-activity of the bronchioles' muscle is a result of exposure to a stimulus which under normal
circumstances would cause little or no response. The resulting constriction and inflammation causes a narrowing of the airways and an increase in mucous production; this reduces the amount of oxygen that is available to the individual causing breathlessness, coughing and hypoxia (that can cause cyanosis).
Bullectomy is the surgical removal of bullae from the lung.
Bullae: More than one bulla, a bulla being a blister more than 5 mm (about 3/16 inch) in diameter with thin walls that is full of fluid. Blisters on the skin are called bullae. Bullae on the pleura (the membrane covering the lung) are also called blebs. In Latin a bulla (plural: bullae) was a "bubble, stud or knob." It referred to any rounded protrusion, particularly one that was hollow or cystic.
Bundle Branch Block.
The heart’s electrical impulse originates in the in the sinus node in the upper right atrium, then spreads across both atria, then travels through the AV node.
Leaving the AV node, the electrical impulse penetrates into the ventricles via the His bundle. From the His bundle, the electrical impulse enters the two “bundle branches” (the right and the left). The right and left bundle branches send the electrical impulse to the right and left ventricle, respectively. When the bundle branches are functioning normally, the right and left ventricles contract nearly simultaneously.
Bundle branch block (an example of an intraventricular conduction delay )
• the QRS complex is wide and/or has an altered shape.
• there can be any atrial rhythm present (e.g., sinus rhythm, atrial fibrillation or undulation, junctional rhythm)
Right bundle branch block (RBBB)
In RBBB, the right bundle branch no longer conducts electricity. Therefore, as the electrical impulse leaves the His bundle, it enters left bundle branch only, and is carried to the left ventricle. Then, from the left ventricle, the electrical impulse finally makes its way to the right ventricle. As a result, the two ventricles no longer receive the electrical impulse simultaneously. First the left ventricle receives the electrical impulse, then the right
ECG characteristics of a typical RBBB showing wide QRS complexes with a terminal R wave in lead V1 and slurred S
Left Bundle Branch Block (LBBB)
In LBBB, the opposite occurs. Here, the left bundle branch no longer conducts electricity. The electrical impulse thus enters right bundle branch, and is carried to the right ventricle. From there, it finally spreads to the left ventricle (second panel). Once again, the two ventricles no longer receive the electrical impulse simultaneously. First the right ventricle receives the electrical impulse, then the left. With either type of BBB, therefore, the electrical signal spreads across the ventricles sequentially, as opposed to simultaneously. This sequential spread of the impulse (i.e., first the right ventricle, then the left – or vice versa) means that it takes longer for the impulse to reach throughout the ventricles.
ECG characteristics of a typical LBBB showing wide QRS complexes with abnormal morphology in leads V1 and V6.
Bigeminy (Latin: Bi-Two Gemini-twins) is a descriptor for a heart arrhythmia in which abnormal heart beats occur every other concurrent beat. A typical example is with bigeminal premature ventricular beats, also known as a premature ventricular contractions/complexes (PVC). Following the PVC there is a pause and then the normal beat returns - only to be followed by another PVC. The continuation of this pairing of beats is an example of bigeminy.
These descriptors can increase depending on the number of beats involved in the abnormal system. If every other beat is abnormal, you can describe it as bigeminal. If every third beat is aberrant, it is trigeminal; every fourth would be quadrigeminal. Typically, if every fifth or more beat is abnormal, the aberrant beat would be termed occasional.
Bigeminy is contrasted with couplets, which are paired abnormal beats. If these concurrent beats number three, they are called triplets and are considered as a brief run of non-sustained Ventricular tachycardia or NS-VT.
PVC's are not the only aberrant beat that makes use of these adjectives; others are premature atrial contractions, parasystole, and escape complexes.
Capillaries are the smallest of a body's blood vessels, measuring 5-10 μm, which connect arterioles and venules, and are important for the interchange of oxygen, carbon dioxide, and other substances between blood and tissue cells.
Pertaining to the heart. The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδία, kardia, for "heart."
A cardiac arrest, also known as cardiorespiratory arrest, cardiopulmonary arrest or circulatory arrest, is the abrupt cessation of normal circulation of the blood due to failure of the heart to contract effectively during systole. "Arrested" blood circulation prevents delivery of oxygen to all parts of the body. Cerebral ( brain ) hypoxia, or lack of oxygen supply to the brain, causes victims to lose consciousness and to stop normal breathing.
Cardiac cycle is the term referring to all or any of the events related to the flow of blood that occur from the beginning of one heartbeat to the beginning of the next. The frequency of the cardiac cycle is the heart rate. Every single 'beat' of the heart involves three major stages: atrial systole, ventricular systole and complete cardiac diastole. The term diastole is synonymous with relaxation of a muscle. Throughout the cardiac cycle, the blood pressure increases and decreases.
Medical tests that are often referred to as cardiac markers include:
• Cardiac Troponin - troponin is a complex of three proteins that is integral to muscle contraction in skeletal and cardiac muscle, but not smooth muscle (the most sensitive and specific test for myocardial damage)
• Creatine kinase - creatine kinase (CK), also known as phosphocreatine kinase or creatine phosphokinase (CPK) is an enzyme expressed by various tissue types. It catalyses the conversion of creatine-(see creatinine) to phosphocreatine, consuming adenosine-(see adenosine) triphosphate (ATP) and generating adenosine diphosphate (ADP).In tissues that consume ATP rapidly, especially skeletal muscle, but also brain and smooth muscle, phosphocreatine serves as an energy reservoir for the rapid regeneration of ATP. Thus Creatine Kinase is an important enzyme in such tissues. Clinically, creatine kinase is assayed in blood tests as a marker of myocardial infarction rhabdomyolysis- (severe muscle breakdown) and in acute renal failure.
• Aspartate transaminase- (AST) also called serum glutamic oxaloacetic transaminase (SGOT) or aspartate aminotransferase (ASAT/AAT) is similar to alanine transaminase (ALT) in that it is another enzyme associated with liver parenchymal cells-(the functional parts of an organ in the body ).
• Lactate dehydrogenase -(LDH) is an enzyme present in a wide variety oforganisms. It catalyses the interconversion of lactate-( a chemical compound ) and pyruvate-( pyruvate is an important chemical compound in biochemistry. It is the output of the metabolism of glucose known as glycolysis- (for carbohydrate catabolism)
• Myoglobin- (Mb) has low specificify for myocardial infarction and is usedless than the other markers. Myoglobin is released from damaged muscle tissue rhabdomyolysis- (severe muscle breakdown), which has very high concentrations of myoglobin. The released myoglobin is filtered by the kidneys but is toxic to the renal tubular epithelium and so may cause acute renal failure. Myoglobin is a sensitive marker for muscle injury, making it a potential marker for heart attack in patients with chest pain. Its lack of specificity and the cost of the analysis has prevented its widespread use.
Cardiac markers are substances released from heart muscle when it is damaged as a result of myocardial infarction. Depending on the marker, it can take between 2 to 24 hours for the level to increase in the blood. Additionally, determining the levels of cardiac markers in the laboratory - like many other lab measurements - takes substantial time. Cardiac markers are therefore not useful in diagnosing a myocardial infarction in the acute phase. The clinical presentation and results from an ECG are more appropriate in the acute situation.
'Cardiac muscle' is a type of involuntary striated muscle found within the heart. Its function is to "pump" blood through the circulatory system by contracting. Unlike skeletal muscle, which contracts in response to nerve stimulation, cardiac muscle is myogenic, meaning that it is self-excitable stimulating contraction without a requisite electrical impulse coming from the central nervous system. A single cardiac muscle cell, if left without input, will contract rhythmically at a steady rate; if two cardiac muscle cells are in contact, whichever one contracts first will stimulate the other to contract, and so on. This inherent contractile activity is heavily regulated by the autonomic nervous system. If synchronization of cardiac muscle contraction is disrupted for some reason (for example, in a heart attack), uncoordinated contraction known as fibrillation can result. This transmission of impulses makes cardiac muscle tissue similar to nerve tissue, although cardiac muscle cells are notably connected to each other by intercalated discs-(undulating double membrane separating adjacent cells in cardiac muscle fibers). Intercalated discs conduct electrochemical potentials directly between the cytoplasms of adjacent cells via gap junctions. In contrast to the chemical synapses used by neurons, electrical synapses, in the case of cardiac muscle, are created by ions flowing from cell to cell, known as an action potential.
Cardiogenic shock is based upon an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectively. Since this is a category of shock there is insufficient perfusion of tissue (i.e. the heart) to meet the required demand for oxygen and nutrients. This leads to cell death from oxygen starvation, hypoxia. Because of this it may lead to cardiac arrest (or circulatory arrest) which is an acute cessation of cardiac pump function.
Definition: Cardiogenic shock is defined by sustained hypotension with tissue hypoperfusion despite adequate left ventricular filling pressure. Signs of tissue hypoperfusion include oliguria-(production of an abnormally small amount of urine), (<30 mL/h), cool extremities, and altered mentation -(the process of using your mind).
Etiology-(cause and effect): Cardiogenic shock is caused by the failure of the heart to pump effectively. It can be due to damage to the heart muscle, most often from a large myocardial infarction. Other causes include arrhythmia, cardiomyopathy, cardiac valve problems, ventricular outflow obstruction (i.e. aortic valve stenosis, aortic dissection, systolic anterior motion (SAM) in hypertrophic cardiomyopathy), ventriculoseptal defects (V.S.D)or medical error.
Signs and symptoms:
• Anxiety, restlessness, altered mental state due to decreased cerebral perfusion and subsequent hypoxia.
• Hypotension due to decrease in cardiac output.
• A rapid, weak, thready pulse due to decreased circulation combined with tachycardia.
• Cool, clammy, and mottled skin (cutis marmorata), due to vasoconstriction and subsequent hypoperfusion of the skin.
• Distended jugular veins due to increased jugular venous pressure.
• Oliguria (low urine output) due insufficient renal perfusion if condition persists.
• Rapid and deep respirations (hyperventilation) due to sympathetic nervous system stimulation and acidosis.
• Fatigue due to hyperventilation and hypoxia.
• Absent pulse in tachyarrhythmia.
Cardiogenic Shock (cont).
An Electrocardiogram helps establishing the exact diagnosis and guides treatment, it may reveal:
• Cardiac arrhythmias.
• Signs of cardiomyopathy.
Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a Heart-Lung Machine. Cardiopulmonary bypass pumps are operated by allied health professionals known as Perfusionists in association with surgeons who connect the pump to the patient's body.
Cardiopulmonary resuscitation (CPR) (Cardiac compressions ).
Cardiopulmonary resuscitation (CPR) is an emergency medical procedure for a victim of cardiac arrest or, in some circumstances, respiratory arrest. CPR is performed in hospitals, or in the community by laypersons or by emergency response professionals. CPR consists of artificial blood circulation and artificial respiration, (i.e. chest compressions and lung ventilation). CPR is generally continued, usually in the presence of advanced life support, until the patient regains a heart beat (called "return of spontaneous circulation" or "ROSC") or is declared dead. CPR is unlikely to restart the heart, but rather its purpose is to maintain a flow of oxygenated blood to the brain and the heart, thereby delaying tissue death and extending the brief window of opportunity for a successful resuscitation without permanent brain damage. Defibrillation and advanced life support are usually needed to restart the heart.
Cardiac output is the volume of blood being pumped by the heart, in particular a ventricle in a minute. It is equal to the heart rate multiplied by the stroke volume. Therefore, if there are 70 beats per minute, and 70 ml blood is ejected with each beat of the heart, the cardiac output is 4900 ml/minute. This value is typical for an average adult at rest, although cardiac output may reach up to 30 liters/minute during extreme exercise.
Cardiology is the branch of medicine pertaining to the heart.
Cardiomyopathy, which literally means "heart muscle disease", is the deterioration of the function of the myocardium (i.e., the actual heart muscle) for any reason. People with cardiomyopathy are often at risk of arrhythmia and/or sudden cardiac death.
Cardiomyopathies can generally be categorized into two groups, extrinsic cardiomyopathies and intrinsic cardiomyopathies.
These are cardiomyopathies where the primary pathology is outside the myocardium itself. Most cardiomyopathies are extrinsic, because by far the most common cause of a cardiomyopathy is ischemia. The World Health Organization calls these specific cardiomyopathies:
• Coronary Artery Disease.
• Congenital Heart Disease-(is heart disease in the newborn, and includes structural defects, congenital arrythmias, and cardiomyopathies).
• Nutritional Diseases-(relating to diet and health).
• Ischaemic cardiomyopathy.
• Hypertensive cardiomyopathy.
• Valvular cardiomyopathy.
• Inflammatory cardiomyopathy.
• Cardiomyopathy secondary to a systemic metabolic disease-(disorders that increase one's risk for cardiovascular disease and diabetes).
• Alcoholic cardiomyopathy-(a disease in which alcohol use damages the heart muscle causing heart failure).
Cardiac surgery is surgery on the heart and/or great vessels performed by a cardiac surgeon. Frequently, it is done to treat complications of ischemic heart disease (for example, coronary artery bypass grafting,correct congenital heart disease, or treat valvular heart disease created by various causes including endocarditis. It also includes heart transplantation.
The earliest operations on the pericardium (the sac that surrounds the heart) took place in the 19th century and were performed by, among others, Francisco Romero, Dominique Jean Larrey, Henry Dalton, and Daniel Hale Williams. The first successful surgery on the heart itself, performed without any
complications, was by Dr. Ludwig Rehn of Frankfurt, Germany, who repaired a stab wound to the right ventricle on September 7, 1896.
Surgery on the great vessels (aortic coarctation repair, Blalock-Taussig shunt creation, closure of patent ductus arteriosus), became common after the turn of the century and falls in the domain of cardiac surgery, but technically cannot be considered heart surgery.
Closed heart surgery:
Surgery on the great vessels was followed by the development of closed heart surgery, where the surgeon blindly worked on the beating heart. It left a great deal to be desired, but had much to offer for great risk. Palliation-( reducing the severity of disease symptoms, rather than providing a cure) of severe mitral valve stenosis, which was common in the past due to rheumatic fever - (is an inflammatory disease which may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain, could be accomplished by poking a finger into the (mitral) valve through an incision in the left atrium. If a finger didn't do, a knife was passed through the incision to cut-out tissue. Following successful treatment of mitral stenosis, a special cutter for aortic valve stenosis was developed, that manoeuvered through an incision in the left atrium, accomplished much the same thing as the surgeon's finger in a stenosed mitral valve.
Operations under hypothermia:
It was soon discovered that the repair of intracardiac pathologies - (refers to the study of disease) required a bloodless and motionless environment, which means that the heart should be stopped and drained of blood. The first successful intracardiac correction of a congenital heart defect using hypothermia was performed by Dr. C. Walton Lillehei and Dr. F. John Lewis at the University of Minnesota on September 2, 1952. The following year, Soviet surgeon Aleksandr Aleksandrovich Vishnevskiy conducted the first cardiac surgery under local anaesthesia.
Operations on the open heart:
Surgeons realized the limitations of hypothermia - complex intracardiac repairs take more time and the patient needs blood flow to the body (and particularly the brain); the patient needs the function of the heart and lungs provided by an artificial method, hence the term cardiopulmonary bypass. Dr. John Heysham Gibbon at Jefferson Medical School in Philadelphia reported in 1953 the first successful use of extracorporeal circulation by means of an oxygenator, but he abandoned the method, disappointed by subsequent failures. In 1954 Dr. Lillehei realized a successful series of operations with the controlled cross-circulation technique in which the patient's mother or father was used as a 'heart-lung machine'. Dr. John W. Kirklin at the Mayo Clinic in Rochester, Minnesota started using a Gibbon type pump-oxygenator in a series of successful operations, and was soon followed by surgeons in various parts of the world.
Modern beating-heart surgery:
Since the 1990s, surgeons have begun to perform "off-pump bypass surgery" - coronary artery bypass surgery without the aforementioned cardiopulmonary bypass. In these operations, the heart is beating during surgery, but is stabilised to provide a (almost) still work area. Some researchers believe this approach results in fewer post-operative complications such as postperfusion syndrome – (also known as pumphead, is a controversial condition that describes a constellation of neurocognitive- (of, relating to, or being conscious intellectual activity) impairments attributed to
cardiopulmonary bypass (CPB) during cardiac surgery) and better overall results (studies results are controversial as of 2007, surgeon's preference and hospital results still play a major role).
Minimally invasive surgery:
A new form of heart surgery that has grown in popularity is robotic heart surgery. This is where a machine (today by far and away the most popular is the da Vinci surgical system by Intuitive Surgical) is used to perform surgery while being controlled by the heart surgeon. The main advantage to this is the size of the incision made in the patient. Instead of a incision being at least big enough for the doctor to put his hands inside, it does not have to be bigger than 3 small holes for the robot's much smaller hands to get through. Also, a major advantage to the robot is the recovery time of a patient, instead of 6 months of recovery time, some patients have recovered and resumed playing athletics in a matter of weeks.
The development of cardiac surgery and cardiopulmonary bypass techniques has reduced the mortality rates of these surgeries to relatively low levels. For instance, repairs of congenital heart defects are currently estimated to have 4-6% mortality rates.
A major concern with cardiac surgery is the incidence of neurological - (of the nervous system) damage. Stroke occurs in 2-3% of all people undergoing cardiac surgery, and is higher in patients at risk for stroke. A more subtle constellation of neurocognitive deficits attributed to cardiopulmonary bypass is known as postperfusion syndrome (sometimes called 'pumphead'). The symptoms of postperfusion syndrome were initially felt to be permanent, but were shown to be transient with no permanent neurological impairment.
The term cardiovascular refers to the heart (cardio) and the blood vessels (vascular). The cardiovascular system includes arteries, veins, arterioles, venules, and capillaries.The main components of the circulatory system are the heart, the blood, and the blood vessels. Arteries bring oxygenated blood to the tissues (except pulmonary arteries), and veins bring deoxygenated blood back to the heart (except pulmonary and portal veins). Blood passes from arteries to veins through capillaries, which are the thinnest and most numerous of the blood vessels and these capillaries help to join tissue with arterioles for transportation of nutrition to the cells. The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products.
A method of terminating abnormal heart rhythm as in atrial fibrillation by means of an electrical shock.
Synchronized electrical cardio-version is the process by which an abnormally fast heart rate or cardiac arrhythmia is terminated by the delivery of a therapeutic dose of electrical current to the heart at a specific moment in the cardiac cycle.
Pharmacologic cardio-version uses medication instead of an electrical shock to convert the cardiac arrhythmia.
The carina is a cartilaginous ridge within the trachea that runs anteroposteriorly between the two primary bronchi at the site of the tracheal bifurcation at the inferior end of the trachea.
Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy.
Chemical that functions as a neurotransmitter or a hormone. Dopamine, adrenaline and noradrenaline are catecholamines.
In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction.
A catalyst provides an alternative route of reaction where the activation energy is lower than the original chemical reaction. Catalysts participate in reactions but are neither reactants nor products of the reaction they catalyze.
Cell / Cellular.
The cell is the structural and functional unit of all known living organisms. It is the simplest unit of an organism that is classified as living, and is sometimes called the "building block of life." Some organisms, such as bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular.
Intra-operative blood salvage, also known as autologous blood salvage, is a medical procedure involving recovering blood lost during surgery and re-infusing it into the patient. It has been used for many years and gained greater attention over time as risks associated with allogenic blood transfusion-( genetically different although belonging to or obtained from the same species) have seen greater publicity and more fully appreciated. Several medical devices have been developed to assist in salvaging the patient's own blood in the peri-operative setting. These are used frequently in cardiothoracic and vascular surgery, in which blood usage has traditionally been high. With a greater effort to avoid adverse events due to transfusion there as also been an emphasis on blood conservation. Regardless of manufacturer, there are many types of cell processors. Cell processors are red cell washing devices that collect anti-coagulated shed or recovered blood, wash and separate the red blood cells (RBCs) by centrifugation, and re-infuse the RBCs.
Central line (neck line).
In medicine, a central venous catheter (CVC or central venous line) is a catheter placed into a large vein in the neck, chest or groin, this is inserted by a physician when the patient needs more intensive cardiovascular monitoring, for assessment of fluid status, and for increased viability of intravenous drugs/fluids. The most commonly used veins are the internal jugular vein, the subclavian vein and the femoral vein. This is in contrast to a peripheral line which is usually placed in the arms or hands.
Central line (neck line (cont).
The Seldinger technique is generally employed to gain central venous access. Dependent on its use, the catheter is mono-luminal, bi-luminal or tri-luminal, dependent on the actual number of tubes or lumens (1, 2 and 3 respectively,). Some catheters have 4,quad-luminal or 5 quin-luminal, depending on the reason for their use. The catheter is usually held in place by a suture or staple and an occlusive dressing. Regular flushing with saline or a heparin-containing solution keeps the line patent and prevents infection. Indications for the use of central lines include:
• Monitoring of the central venous pressure (CVP) in acutely ill patients to quantify fluid balance. Normal CVP is 2-6 mm Hg.
• Parenteral nutrition
• Drugs that are prone to cause phlebitis in peripheral veins (caustic), such as:
o Calcium chloride
o Potassium chloride
• Need for intravenous therapy when peripheral venous access is impossible
Potential complications include:
Pneumothorax: Pneumothorax (for central lines placed in the chest) - this is why doctors routinely order a chest X-ray (CXR) after insertion of a subclavian or internal jugular line. The incidence is thought to be higher with subclavian vein catheterization. In catheterization of the internal jugular vein, the risk of pneumothorax can be minimized by the use of ultrasound guidance. For experienced clinicians, the incidence of pneumothorax is about 1%.
Infection: All catheters can introduce bacteria into the bloodstream, but CVCs are known for occasionally causing Staphylococcus aureus and Staphylococcus epidermidis sepsis.
Central venous pressure (CVP) monitoring:
Central venous pressure (CVP) describes the pressure of blood in the thoracic vena cava, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. It is a good approximation of right atrial pressure, which is a major determinant of right ventricular end diastolic volume. CVP can be measured by connecting the patient's central venous catheter to a special infusion set which is connected to a transducer-( an electronic pressure transducer ).
Factors which increase CVP include:
• Hypervolaemia-( see Hypervolaemia)
• forced exhalation
• Tension pneumothorax –(see pneumothorax)
• Heart failure- (see Heart failure)
• Pleural effusion-(see Pleural effusion)
• Decreased cardiac output –(cardiac output)
Factors which decrease CVP include:
• Hypovolaemia-(see Hypovolaemia)
• Deep inhalation
Central Nervous System( C.N.S ).
The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior. The CNS is contained within the dorsal cavity, with the brain within the cranial sub-cavity, and the spinal cord in the spinal cavity. The CNS is covered by the meninges, the brain is protected by the skull and the spinal cord by the vertebrae. The meninges (singular meninx) is the system of membranes which envelop the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.
Chronic obstructive pulmonary / airway disease.
Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive airway disease (COAD), is a group of diseases characterized by the pathological limitation of airflow in the airway that is not fully reversible. COPD is the umbrella term for chronic bronchitis, emphysema and a range of other lung disorders. It is most often due to tobacco smoking, but can be due to other airborne irritants such as coal dust, asbestos or solvents, as well as congenital -(is any medical condition that is present at birth) conditions such as alpha-1-antitrypsin deficiency-( a genetic disorder caused by defective production of alpha 1-antitrypsin, deficient activity in the blood and lungs, and deposition of excessive amounts of abnormal A1AT protein in liver cells.
The main symptoms of COPD include dyspnoea- (shortness of breath) lasting for months or perhaps years, possibly accompanied by wheezing, and a persistent cough with sputum production. It is possible the sputum may contain blood - (haemoptysis), usually due to damage of the blood vessels of the airways. Severe COPD could lead to cyanosis-(bluish decolorization usually in the lips and fingers) caused by a lack of oxygen in the blood. In extreme cases it could lead to cor pulmonale due the extra work required by the heart to get blood to flow through the lungs.
Chronotropic effects (from chrono-, meaning time) are those that change the heart rate. Chronotropic drugs may change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node.
Coagulation is a complex process by which blood forms solid clots. It is an important part of haemostasis (the cessation of blood loss from a damaged vessel) whereby a damaged blood vessel wall is covered by a platelet - and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. Disorders of coagulation can lead to an increased risk of bleeding and/or clotting and embolism.
Electro-coagulation ( diathermy )- Diathermy is the use of high frequency electric current to produce heat; Used to either cut or destroy tissue or to produce coagulation .by sealing the lumen of a vessel.
Collagen is the main protein of connective tissue(one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue.), in animals and the most abundant protein in mammals, making up about 25% of the total protein content.
A Colloid or colloidal dispersion is a type of homogenous mixture-(a mixture of a substance made by combining two or more different materials in such a way that no chemical reaction occurs). A colloid consists of two separate phases: a dispersed phase and a continuous phase. In a colloid, the dispersed phase is made of tiny particles or droplets that are distributed evenly throughout the continuous phase. The size of the dispersed phase particles are between 1 nm and 1000 nm in at least one dimension. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions or hydrosols. The dispersed phase particles or droplets are largely affected by the surface chemistry present in the colloid.
Because the size of the dispersed phase may be hard to measure, and because colloids look like solutions, colloids are sometimes characterized by their properties. For example, if a colloid has a solid phase dispersed in a liquid, the solid particles will not pass through a membrane, whereas the dissolved ions or molecules of a solution will pass through a membrane. In other words, dissolved components will diffuse through a membrane through which dispersed colloidal particles will not.
Conduits used for bypass (see Mammary artery).
Congestive Heart Failure.
Congestive heart failure (CHF), also called congestive cardiac failure (CCF) or just heart failure, is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood through the body. It is not to be confused with "cessation of heartbeat", which is known as asystole, or with cardiac arrest, which is the cessation of normal cardiac function with subsequent haemodynamic collapse leading to death. Because not all patients have volume overload at the time of initial or subsequent evaluation, the term "heart failure" is preferred over the older term "congestive heart failure".
Muscle contraction, one that occurs when a muscle fiber lengthens or shortens.
Muscle is contractile tissue of the body.
Cor pulmonale, also known as right heart failure, is a medical term used to describe a change in structure and function of the right ventricle of the heart as a result of a respiratory disorder. Right ventricular hypertrophy or RVH is the predominant change in chronic cor pulmonale although in acute cases dilation dominates. Both hypertrophy and dilation are the result of increased right ventricular pressure.
Dilation is essentially a stretching of the ventricle, the immediate result of increasing the pressure in an elastic container. Ventricular hypertrophy is an adaptive response to a long-term increase in pressure. Additional muscle grows to allow for the increased contractile force required to move the blood against greater resistance.
To be classified as cor pulmonale, the cause must originate in the pulmonary circulation system. Two major causes are vascular changes as a result of tissue damage (e.g. disease, hypoxic injury, chemical agents etc.), and chronic hypoxic pulmonary vasoconstriction. RVH due to a systemic defect is not classified as cor pulmonale. Left untreated, cor pulmonale can lead to right-heart failure and death.
Coronary Artery Bypass Graft ( C.A.B.G ) (see Coronary Heart Desease).
Coronary artery bypass surgery, also coronary artery bypass graft surgery, and colloquially heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease. Arteries or veins from elsewhere in the patient's body are grafted from the aorta to the coronary arteries to bypass atherosclerotic narrowings ( commonly referred to as a "hardening" or "furring" of the arteries ).. It is caused by the formation of multiple plaques, and improve the blood supply to the coronary circulation supplying the myocardium (heart muscle).The technique was pioneered by Argentine cardiac surgeon René Favaloro at the Cleveland Clinic in the late 1960s.
The terms single bypass, double bypass, triple bypass, quadruple bypass and quintuple bypass refer to the number of coronary arteries bypassed in the procedure. In other words, a double bypass means two coronary arteries are bypassed (e.g. the left anterior descending (LAD) coronary artery and right coronary artery (RCA)); a triple bypass means three vessels are bypassed (e.g. LAD, RCA, left circumflex artery (LCX)); a quadruple bypass means four vessels are bypassed (e.g. LAD, RCA, LCX, first diagnonal artery of the LAD) while quintuple means five(see coronary heart desease). Less commonly more than four coronary arteries may be bypassed. A greater number of bypasses does not imply a person is "sicker," nor does a lesser number imply a person is "healthier." A person with a large amount of coronary artery disease (CAD) may receive fewer bypass grafts due to the lack of suitable "target" vessels. A coronary artery may be unsuitable for bypass grafting it if it is small (< 1 mm or < 1.5 mm depending on surgeon preference), heavily calcified (meaning the artery does not have a section free of CAD) or intra-myocardial (the coronary artery is located within the heart muscle rather than on the surface of the heart). Similarly, a person with a single stenosis ("narrowing") of the left main coronary artery requires only two bypasses (to the LAD and the LCX). However, a left main lesion places a person at the highest risk for death from a cardiac cause. The surgeon reviews the coronary angiogram prior to surgery and identifies the lesions (or "blockages") in the coronary arteries. The surgeon will estimate of the number of bypass grafts prior to surgery, but the final decision is made in the operating room upon examination of the heart.
Conduits used for bypass: The choice of conduits is highly surgeon and institution dependent. Typically, the left internal mammary artery (LIMA) is grafted to the Left Anterior Descending artery and a combination of other arteries and veins is used for other coronary arteries. The right internal mammary artery (RIMA), the long saphenous vein from the leg and the radial artery from the forearm are frequently used.
A coronary catheterization is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and interventional (treatment) purposes.
A coronary angiogram (an X-ray with radio-opaque contrast in the coronary arteries) that shows the left coronary circulation. The distal left main coronary artery (LMCA) is in the left upper quadrant of the image. Its main branches (also visible) are the left circumflex artery (LCX), which courses top-to-bottom initially and then toward the centre/bottom, and the left anterior descending (LAD) artery, which courses from left-to-right on the image and then courses down the middle of the image to project underneath of the distal LCX. The LAD, as is usual, has two large diagonal branches, which arise at the centre-top of the image and course toward the centre/right of the image –(see coronary bypass graft).
Coronary catheterization is one of the several cardiology diagnostic tests and procedures. Specifically, coronary catheterization is a visually interpreted test performed to recognize occlusion, stenosis, restenosis – (literally means the reoccurrence of stenosis), thrombosis or aneurysmal - (a permanent cardiac or arterial dilatation usually caused by weakening of the vessel wall) enlargement the coronary artery lumens, heart chamber size, heart muscle contraction performance and some aspects of heart valve function. Important internal heart and lung blood pressures, not measurable from outside the body, can be accurately measured during the test. The relevant problems that the test deals with most commonly occur as a result of advanced atherosclerosis, atheroma – (a mass of yellowish fatty and cellular material that forms in and beneath the inner lining of the arterial walls) activity within the wall of the coronary arteries. Less frequently, other issues, valvular, heart muscle or arrhythmia issues are the primary focus of the test.
Coronary artery luminal – (the inner open space or cavity of a tubular organ, as of a blood vessel or an intestine) narrowing reduces the flow reserve for oxygenated blood to the heart, typically producing intermittent angina if very advanced; luminal occlusion usually produces a heart attack. However, it has been increasingly recognized, since the late 1980s, that coronary catheterization does not allow the recognition of the presence or absence of coronary atherosclerosis itself, only significant luminal changes which have occurred as a result of end stage complications of the atherosclerotic process.
Coronary Heart Disease
The heart is a strong muscular pump. It is responsible for pumping about 3,000 gallons of blood throughout your body every day. Like other muscles in the body, the heart itself needs to receive a good supply of blood at all times to function properly. The heart muscle gets the blood it needs to do its job from your coronary arteries.
Coronary artery disease is atherosclerosis of the coronary arteries. Atherosclerosis occurs when the arteries become clogged and narrowed, restricting blood flow to the heart. Without adequate blood, the heart becomes starved of oxygen and vital nutrients it needs to work properly. When the blood flow is slowed the heart doesn't get enough oxygen and nutrients. This can cause chest pain called angina. When one or more of the coronary arteries are completely blocked, the result is a heart attack (injury to the heart muscle).The coronary arteries are shaped like hollow tubes through which blood can flow freely. The "walls" of the coronary arteries are normally smooth and elastic. Coronary artery disease starts when you are very young. Before your teen years, the blood vessel walls begin to show streaks of fat. As you get older, the fat builds up, causing slight injury to your blood vessel walls. In an attempt to heal itself, the cells release chemicals that make the walls stickier. Other substances travelling through your blood stream, such as inflammatory cells, proteins and calcium begin to stick to the vessel walls. The fat and other substances combine to form a material called plaque. The plaque builds up and narrows the artery, called atherosclerosis (atha-row-skla-row-sis), also known as "hardening of the arteries.
Vasospasm refers to a condition in which blood vessels spasm, leading to vasoconstriction. This can lead to tissue ischemia and death (necrosis).
Normal range=0.6 - 1.2 mg/dL. Creatinine is a breakdown product of Creatine ( Creatine is nitrogenous organic acid that naturally occurs in vertebrates and helps to supply energy to muscle and nerve cells ) phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass). Measuring serum creatinine is a simple test and it is the most commonly used indicator of renal( see Kidneys ) function. A rise in blood creatinine levels is observed only with marked damage to functioning nephrons( see Kidneys ). Therefore, this test is not suitable for detecting early stage kidney disease. Therefore, this test is not suitable for detecting early stage kidney disease. A better estimation of kidney function is given by the creatinine clearance test. Creatinine clearance can be accurately calculated using serum creatinine concentration and some or all of the following variables: sex, age, weight, and race without a 24 hour urine collection.
Conventional crystalloids are fluids that contain a combination of water and electrolytes. They are divided into "balanced" salt solutions (e.g. Ringer's lactate) and hypotonic-(a cell environment has a lower concentration of solutes) solutions. Either their electrolyte composition approximates that of plasma, or they have a total calculated osmolality-(the concentration of an osmotic solution, usually expressed in terms of osmoles) that is similar to that of plasma.
n. A substance that in solution can pass through a semipermeable membrane and be crystallized, as distinguished from a colloid.
adj. Resembling or having properties of a crystal or crystalloid.
Cytoplasm is a gelatinous, semi-transparent fluid that "fills" most cells. The cytoplasm is the site where most cellular activities are done. All the functions for cell expansion, growth and replication are carried out in the cytoplasm of the cell.
Cyanosis is a bluish coloration of the skin due to the presence of deoxygenated haemoglobin in blood vessels near the skin surface. It occurs when the oxygen saturation of arterial blood falls below 85%-(see Arterial blood gases). The elementary principle behind cyanosis is that deoxygenated haemoglobin produces the bluish discoloration, and also produces vasoconstriction that makes it more evident. Thus oxygen deficiency - hypoxia - leads to blue discoloration of the lips and other mucus membranes. The name is derived from the colour cyan, the Greek word for blue.
Decortication is a medical procedure involving the surgical removal of the surface layer, membrane, or fibrous cover of an organ. The procedure is usually performed when the lung is covered by a thick, inelastic pleural peel restricting lung expansion. In a non-medical aspect, decortication is the removal of the bark, husk, or outer layer, or peel of an object. Decortication is performed under general anaesthesia. It is a major thoracic operation requiring a full thoracotomy. All fibrous tissue is removed from the visceral pleural peel and pus is subsequently drained from the pleural space.
Defibrillation is the definitive treatment for the life-threatening cardiac arrhythmias, ventricular fibrillation and pulseless ventricular tachycardia. Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator. This depolarizes a critical mass of the heart muscle, terminates the arrhythmia, and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart.Until recently, the way in which electrical therapy was delivered by trans-thoracic defibrillators was essentially the same for all manufacturers. Most commonly, the defibrillation waveforms used were monophasic. Monophasic technology was constrained by the electronics components available during the era it originated (1960s), remained largely unchanged over time, and never had substantive research to support its performance. Further, the waveforms used energy inefficiently and were not able to adjust effectively to a patient’s chest impedance.
Without effective defibrillator impedance compensation, high patient impedance degrades the waveform, a key factor in the relatively poor performance of traditional uncompensated monophasic technologies. Low impedance imposes a different set of potential problems. Low impedance patients may be more likely to shunt current away from the heart. Today, modern electronics permit much greater control of therapy generation and delivery, including the ability to compensate for the untoward effects of high and low patient impedance.
Defibrillators can be external, trans-venous, or implanted, depending on the type of device used. Some external units, known as automated external defibrillators (AEDs), automate the diagnosis of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully with little, or in some cases no, training. A defibrillator waveform should compensate for both high and low chest impedance. Patient impedance in humans has been shown to vary anywhere from 25 to 180 ohms. According to Ohm’s Law (I = V/R), a high impedance patient resists the flow of current and, therefore, the peak current is less; the peak current in a low impedance patient is comparatively higher. Through research, the "sweet spot" for waveform shape and duration was determined for the Biphasic waveform using a fixed, 150J adult defibrillation protocol. Based on this research, the Biphasic waveform is designed to perform across a wide range of anticipated patient impedance values. In the case of high impedance patients, the waveform lengthens to deliver adequate energy. For low impedance patients, the defibrillator delivers somewhat higher peak currents to compensate for the possible effects of shunting.
The process or act of neutralising polarity, depriving of polarity, or the result of such action; reduction to an un-polarised condition.
Diabetetes / Diabetic.
Diabetes is a chronic systemic disease due to a relative or absolute insulin lack. Both acute hyper- or hypo- glycaemia and long-term complications are of anaesthetic relevance. The aim for diabetic patients during anaesthesia is to avoid hypoglycaemia - (especially intra-operatively), provide glucose delivery to the tissues, and avoid hyperglycaemia and ketosis - (a process in which your body converts fats into energy). Blood glucose usually falls during the preoperative fast and rises during and after surgery. Insulin is also used in non- diabetic patients for all sorts of other medical treatments, insulin increases the vascularization of areas adjacent to the injection, insulin at any physiological dosage improves glucose tolerance, increases cellular permeability. Increased vascularization and increased cellular permeability allows for faster exchange of toxins, nutrients and metabolic waste products. The most dramatic and the most beneficial use of small doses of insulin are to accentuate healing.
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia (high blood sugar) and other signs, as distinct from a single illness or condition. The three main forms of diabetes: type 1, type 2, and gestational diabetes (occurring during pregnancy), which have similar signs, symptoms, and consequences, but different causes and population distributions. Ultimately, all forms are due to the beta cells of the pancreas being unable to produce sufficient insulin to prevent hyperglycemia. Type 1 is usually due to autoimmune destruction of the pancreatic beta cells which produce insulin. Type 2 is characterized by tissue-wide insulin resistance and varies widely; it sometimes progresses to loss of beta cell function. Gestational diabetes is similar to type 2 diabetes, in that it involves insulin resistance; the hormones of pregnancy cause insulin resistance in those women genetically predisposed to developing this condition.
Types 1 and 2 are incurable chronic conditions, but have been treatable since insulin became medically available in 1921, and today are usually managed with a combination of dietary treatment, tablets (in type 2) and, frequently, insulin supplementation. Gestational diabetes typically resolves with delivery.
Diabetes can cause many complications. Acute complications (hypoglycemia, (ketoacidosis a type of metabolic acidosis) or nonketotic hyperosmolar coma( a type of diabetic coma), may occur if the disease is not adequately controlled. Serious long-term complications include cardiovascular disease (doubled risk), chronic renal failure (diabetic nephropathy is the main cause of dialysis in developed world adults), retinal damage (which can lead to blindness and is the most significant cause of adult blindness in the non-elderly in the developed world), nerve damage (of several kinds), and micro-vascular damage, which may cause erectile dysfunction (impotence) and poor healing. Poor healing of wounds, particularly of the feet, can lead to gangrene which can require amputation — the leading cause of non-traumatic amputation in adults in the developed world. Adequate treatment of diabetes, as well as increased emphasis on blood pressure control and lifestyle factors (such as not smoking and keeping a healthy body weight), may improve the risk profile of most aforementioned complications.
Diabetes insipidus (DI) is a disease characterized by excretion of large amounts of severely diluted urine, which cannot be reduced when fluid intake is reduced. It denotes inability of the kidney to concentrate urine. DI is caused by a deficiency of anti-diuretic hormone (ADH), also known as vasopressin, or by an insensitivity of the kidneys to that hormone.
In medicine, dialysis is a type of renal replacement therapy which is used to provide an artificial replacement for lost kidney function due to renal failure. It is a life support treatment and does not treat any kidney diseases. Dialysis may be used for very sick patients who have suddenly lost their kidney function (acute renal failure) or for quite stable patients who have permanently lost their kidney function (end stage renal failure). When healthy, the kidneys remove waste products (for example potassium, acid and urea) from the blood and also remove excess fluid in the form of urine. Dialysis treatments have to duplicate both of these functions as dialysis (waste removal) and ultrafiltration (fluid removal).
Diastole is the period of time when the heart relaxes after contraction. Ventricular diastole is when the ventricles are relaxing, while atrial diastole is when the atria are relaxing.
• Diathermy is the use of high frequency electric current to produce heat.
• Used to either cut or destroy tissue or to produce coagulation.
• Mains electricity is 50 Hz and produces intense muscle and nerve activation.
• Electrical frequency used by diathermy is in the range of 300 kHz to 3 MHz.
• Patient’s body forms part of the electrical circuit.
• Current has no effect on muscles.
• Electrical plate is placed on patient and acts as indifferent electrode.
• Current passes between instrument and indifferent electrode.
• As surface area of instrument is an order of magnitude less than that of the plate.
• Localised heating is produced at tip of instrument.
• Minimal heating effect produced at indifferent electrode.
• Two electrodes are combined in the instrument (e.g. forceps).
• Current passes between tips and not through patient.
Effects of diathermy:
• The effects of diathermy depends on the current intensity and wave-form used
o Produced by interrupted pulses of current (50-100 per second).
o Square wave-form.
o Produced by continuous current.
o Sinus wave-form.
Risk and complications:
• Can interfere with pacemaker function.
• Arcing can occur with metal instruments and implants.
• Superficial burns if use spirit based skin preparation.
• Diathermy burns under indifferent electrode if plate improperly applied.
• Channeling effects if used on viscus with narrow pedicle (e.g. penis or testis).
A disease is an abnormal condition of an organism that impairs bodily functions. In human beings, "disease" is often used more broadly to refer to any condition that causes discomfort, dysfunction, distress, social problems, and/or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical-( not typical; not conforming to the type; irregular; abnormal) variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. While many diseases are biological processes with observable alterations of organ function or structure, others primarily involve alterations of behavior.
Many different factors intrinsic or extrinsic to a person (or plant or animal) can cause disease. Examples of intrinsic factors are genetic defects or nutritional deficiencies. An environmental exposure, such as second-hand smoke is an example of an extrinsic factor. Many diseases result from a combination of intrinsic and extrinsic factors. For many diseases a cause cannot be identified.
Digitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that was traditionally placed in the figwort family Scrophulariaceae. Due to new genetic research, it has now been placed in the much enlarged family Plantaginaceae. The genus is native to Europe, western and central Asia, and northwestern Africa. The term digitalis is also used for preparations containing cardiac glycosides, particularly digoxin, extracted from plants of this genus. The members of this genus are known in English as foxgloves. The scientific name means "finger-like" and refers to the ease with which a flower of Digitalis purpurea can be fitted over a human fingertip.
Digitalis Toxicity, Depending on the species, the digitalis plant may contains
several deadly physiological and chemically related cardiac and steroidal glycosides.
Thus, the digitalis has earned several more sinister monikers: Dead Man’s Bells, and
Witches’ Gloves. The entire plant is a poison (including the roots and seeds), although
the leaves of the upper stem are particularly potent, with just a nibble being enough to
potentially cause death.
Dissecting aortic aneurysm (see Aortic aneurysm).
1. Anatomically located far from a point of reference, such as an origin or a point of attachment.
2. Situated farthest from point of attachment or origin, as of a limb or bone.
A diuretic is a medicine which increases the amount of water that you pass out from your kidneys.
(A diuretic causes a 'diuresis' - an increase in urine.) So, they are sometimes called 'water tablets'.
Double Lumen Tubes.
Endobronchial tubes are used in thoracic surgery. Double lumen tubes all have cuffed endobronchial portions and tracheal cuffs. The endobronchial parts are curved to the left or right. They are passed blindly and their position should be confirmed bronchoscopically. The main disadvantage of right sided tubes concerns the short length of the right main bronchus before giving off the upper lobe bronchus (risk of occlusion). Thus, left-sided tubes are usually preferred, even for right-sided surgery, because of the risk of inadequate ventilation of the right upper lobe if incorrectly positioned.
Indications for one-lung ventilation:
The indications for one-lung ventilation (OLV) are divided into two groups: absolute and relative. The decision to use an endobronchial blocker is clinical and should be based on a consideration of risk versus benefit. Double-lumen tubes and endobronchial blockers function differently. Double-lumen endotracheal tubes isolate ventilation, separating the right and left pulmonary units using two separate endotracheal tubes. An endobronchial blocker blocks ventilation to a pulmonary segment. Endobronchial blockers are balloon tipped catheters that are placed in the portion of the trachea that is to be blocked (usually the right or left main stem bronchus). Ventilation to the pulmonary unit is blocked when the balloon is inflated. Endobronchial blockers are a preferable choice for patients optimally managed with single-lumen endotracheal tubes rather than conventional double-lumen tubes.
Risk of soilage
Control of ventilation
Surgical exposure - high priority
Thoracoabdominal aneurysm repair
Surgical exposure - low priority
Middle and lower lobe resection
Thoracic spine surgery
Insertion of endobronchial tubes
The tube is held with the bronchial curve concave anteriorly (as with normal endotracheal tubes). As the tip is passed through the larynx, the tube is rotated 90 degrees to direct the endobronchial part to the intended side. The tube is then connected to the breathing circuit via a double catheter mount.
Checking the tube position
Manual ventilation is commenced with the tracheal cuff inflated. Air entry should be equal on both sides and there should be no leak around the tracheal cuff.
The tracheal side of the adapter is then clamped and the tracheal port is opened distal to the clamp. The bronchial cuff is inflated so as to just eliminate air leak from the tracheal lumen. Breath sounds should be heard only on the side of endobronchial intubation.
The tracheal limb is then unclamped, the tracheal port closed and the bronchial limb of the adapter is clamped and the bronchial port opened to air. Breath sounds should only be heard on the contralateral side.
Fibreoptic bronchoscopy down the tracheal lumen should reveal the carina and the top edge of the blue bronchial cuff should be just visible in the intended main stem bronchus. When a right-sided tube is used, the fibrescope should be used to visualise the orifice of the right upper lobe bronchus.
The double lumen tube with final position in the left main bronchus with the bronchial and tracheal cuffs inflated.
Management of hypoxia under OLV
Manoeuvres are directed at minimising atelectasis - (a state in which the lung, in whole or in part, is collapsed or without air) in the ventilated lung and shunt in the non-ventilated lung. Set initial tidal volume at 10 ml/kg and adjust respiratory rate to maintain normocapnia. Use a fraction of oxygen in the inspired air (FIO2) of 0.5 initially and increase to 1.0 if required.
Ensure proper tube position auscultate - (listening to the internal sounds of the body, usually using a stethoscope), bronchoscopy; suction at regular intervals.
Apply continuous positive airway pressure (C.P.A.P) to the non-ventilated lung to expand it just enough so as not to interfere with the surgery, thus reduce shunt - (is a hole or passage which moves, or allows movement of, fluid or air from one part of the body to another).
Application of positive end-expiratory pressure (P.E.E.P) to the ventilated lung may reduce atelectasis- (a state in which the lung, in whole or in part, is collapsed or without air) but oxygenation may deteriorate due to increase in shunt ( see above) through the other lung.
Oxygenation can be insufflated into the non-ventilated lung via a suction catheter. Alternatively, the non-ventilated lung can be inflated briefly with 100% oxygen at intervals.
Persistent hypoxia that does not respond to the above manoeuvres must be treated with resumption of two-lung ventilation with 100% O2. Failing this, clamping of the pulmonary artery (of the surgical lung) should improve oxygenation.
A dromotropic agent is one which affects the conduction velocity of the AV node, and subsequently the rate of electrical impulses in the heart. Agents that are dromotropic are often (but not always) inotropic and chronotropic. For example, parasympathetic stimulation is usually negatively dromotropic, inotropic, and chronotropic.
Of or relating to a heartbeat that has its origin elsewhere than in the sinoatrial node.
An effector is a molecule (originally referring to small molecules but now encompassing any regulatory molecule, includes proteins) that binds to a protein and thereby alters the activity of that protein.
Ejection fraction: The portion of blood that is pumped out of a filled ventricle as a result of a heartbeat. The heart does not eject all of the blood that is in the ventricle. Only about two-thirds of the blood is normally pumped out with each beat. That fraction is referred to the ejection fraction. The ejection fraction is an indicator of the heart's health. If the heart is diseased from a heart attack or another cardiac condition, the ejection fraction may fall, for example, to a third. Only a third of the blood in the ventricle (half the normal two-thirds) is pumped out. The heart is essentially half-normal (in this respect).
Electrocardiogram (ECG) ( in USA: EKG):
An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. Analysis of the various waves and normal vectors of depolarization and repolarization yields important diagnostic information:
• It is the gold standard for the diagnosis of cardiac arrhythmias.
• It guides therapy and risk stratification for patients with suspected acute myocardial infarction.
• It helps detect electrolyte disturbances (e.g. hyperkalemia and hypokalemia).
• It allows for the detection of conduction abnormalities (e.g. right and left bundle branch block).
• It is used as a screening tool for ischemic heart disease during a cardiac stress test.
• It is occasionally helpful with non-cardiac diseases (e.g. pulmonary embolism or hypothermia)
ECG: Reading the Waves
An electrocardiogram (ECG) represents the electrical current moving through the heart during a heartbeat. The current's movement is divided into parts, and each part is given an alphabetic designation in the ECG.
Each heartbeat begins with an impulse from the heart's pacemaker (sinus or sinoatrial node). This impulse activates the upper chambers of the heart (atria). The P wave represents activation of the atria.
Next, the electrical current flows down to the lower chambers of the heart (ventricles). The QRS complex represents activation of the ventricles.
The electrical current then spreads back over the ventricles in the opposite direction. This activity is called the recovery wave, which is represented by the T wave.
An embolism can happen when something solid, semi-solid or gaseous is travelling in your bloodstream and gets stuck. The particle causing the blockage is called an embolus and is usually caused by a blood clot, fat particle or bubble of air. The embolus is carried in the blood stream until it gets stuck in a place where it forms a blockage.
The process by which a vessel is occluded with a circulating material mass (for example blood clot).
Embolization is a non-surgical, minimally-invasive procedure performed by an interventional radiologist and interventional neuro-radiologists. It involves the selective occlusion of blood vessels, by purposely introducing emboli.
Emphysema is a type of chronic obstructive lung disease. It is often caused by exposure to toxic chemicals or long-term exposure to tobacco smoke.
Emphysema is caused by loss of elasticity (increased compliance) of the lung tissue, from destruction of structures supporting the alveoli, and destruction of capillaries feeding the alveoli. The result is that the small airways collapse during exhalation (although alveolar collapsability has increased), leading to an obstructive form of lung disease (airflow is impeded and air is generally "trapped" in the lungs in obstructive lung diseases). Symptoms include shortness of breath on exertion (typically
when climbing stairs or inclines, and later at rest), hypoventilation, and an expanded chest. Emphysema patients are sometimes referred to as "pink puffers". This is because emphysema sufferers may hyperventilate to maintain adequate blood oxygen levels.
An empyema, also known as a pyothorax, is a collection of pus within the pleural cavity. It must be differentiated from an abscess, which is a collection of pus in a newly formed cavity. Most empyemas arise from an infection within the lung (pneumonia), often associated with parapneumonic effusions-( a type of pleural effusion that arises as a result of a pneumonia ).
There are 3 stages: exudative-( is any fluid that filters from the circulatory system into lesions or areas of inflammation), fibrino-purulent and organizing. In the exudative stage, the pus accumulates. This is followed by the fibrinopurulent stage in which there is loculation of the pleural fluid (the creation of grapelike pus pockets). In the final organizing stage, scarring of the pleural space may lead to lung entrapment.
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. The most common structures involved are the heart valves. Endocarditis can be classified by etiology as either infective or non-infective, depending on whether a microorganism is the source of the problem.
As the valves of the heart do not actually receive any blood supply of their own, which may be surprising given their location, defense mechanisms (such as white blood cells) cannot enter. So if an organism (such as bacteria) establishes a hold on the valves, the body cannot get rid of them. Normally, blood flows smoothly through these valves. If they have been damaged (for instance in rheumatic fever) bacteria can have a chance to take hold.
Non-infective or marantic endocarditis-(the deposition of small sterile vegetations on valve leaflets) is rare. A form of sterile endocarditis is termed Libman-Sacks endocarditis-(a form of nonbacterial endocarditis that is seen in systemic lupus erythematosus); this form occurs more often in patients with lupus erythematosus-(a chronic autoimmune disease) and the antiphospholipid syndrome-(a disorder of coagulation, which causes blood clots (thrombosis). Non-infective endocarditis may also occur in patients with cancers, particularly mucinous adenocarcinoma-(carcinoma that originates in glandular tissue).
The Endocardium is the inner layer of the heart. It consists of epithelial tissue and connective tissue- (one of the four types of tissue in traditional classifications, the others being epithelial, muscle, and nervous tissue.).Endocardium lines the inner cavities of the heart, covers heart valves, and is continuous with the inner lining of blood vessels.
The word endogenous means "arising from within", the opposite of exogenous.
Endothelial: Relating to the endothelium, the layer of flat cells lining the closed spaces of the body such as the inside of blood vessels, lymphatic vessels, the heart, and body cavities.
In medicine, intubation refers to the placement of a tube into an external or internal orifice of the body. Although the term can refer to endoscopic procedures, it is most often used to denote tracheal intubation. Tracheal intubation is the placement of a flexible plastic tube into the trachea to protect the patient's airway and provide a means of mechanical ventilation. The most common tracheal intubation is oro-tracheal intubation where, with the assistance of a laryngoscope, an endotracheal tube is passed through the mouth, larynx, and vocal cords, into the trachea. A bulb is then inflated near the distal tip of the tube to help secure it in place and protect the airway from blood, vomit, and secretions. Another possibility is naso-tracheal intubation where a tube is passed through the nose, larynx, vocal cords, and trachea.
Laryngoscope: Historically, the most common device used for intubation has been the laryngoscope. Although it has proven sufficient throughout history, many serious problems can arise from its misuse (ex. dental trauma). Newer technologies have fared better in reducing problematic incidence.
Fiber Optics: Another common technology used for intubation has been fiber optics. Although this system provides better visibility, it still has drawback such as inadequate controls and sporadic visibility failure. It is also considered very slow relative to the laryngoscope.
Enteric nervous system.
The enteric nervous system (ENS) is the part of the nervous system that directly controls the gastrointestinal (digestive tract) system. It is capable of autonomous functions such as the coordination of reflexes, although it receives considerable innervation from the autonomic nervous system and thus is often considered a part of it. Its study is the focus of neuro-gastroenterology. It has as many as one billion neurons, one hundredth of the number of neurons in the brain, and considerably more than the number of neurons in the spinal cord.
Enzymes are biological catalysts, or chemicals that speed up the rate of reaction between substances without themselves being consumed in the reaction. As such, they are vital to such bodily functions as digestion, and they make possible processes that normally could not occur except at temperatures so high they would threaten the well-being of the body. A type of protein, enzymes sometimes work in tandem with non-proteins called coenzymes. Among the processes in which enzymes play a vital role is fermentation, which takes place in the production of alcohol or the baking of bread and also plays a part in numerous other natural phenomena, such as the purification of wastewater.
Epicardium describes the outer layer of heart tissue (from Greek; epi- outer, cardium heart). When considered as a part of the pericardium, it is the inner layer, or visceral pericardium. Its largest constituent is connective tissue and functions as a protective layer. The visceral pericardium apparently produces the pericardial fluid, which lubricates motion between the inner and outer layers of the pericardium. During ventricular contraction, the wave of depolarization moves from endocardial to epicardial surface.
The term epidural is often short for epidural anesthesia, a form of regional anesthesia involving injection of drugs through a catheter placed into the epidural space. The injection can cause both a loss of sensation (anaesthesia) and a loss of pain (analgesia), by blocking the transmission of pain signals through nerves in or near the spinal cord. The epidural space (sometimes called the extra-dural space or peri-dural space) is a part of the human spine inside the spinal canal separated from the spinal cord and its surrounding cerebrospinal fluid by the dura mater. Injecting medication into the epidural space is primarily performed for analgesia. This may be performed using a number of different techniques and for a variety of reasons. Additionally, some of the side-effects of epidural analgesia may be beneficial in some circumstances (e.g. vasodilation may be beneficial if the patient has peripheral vascular disease). When a catheter is placed into the epidural space the effects of the analgesia may be prolonged for several days, if required. Epidurals may be used:
• For analgesia alone, where surgery is not contemplated. An epidural for pain relief (e.g. in childbirth).
• As an adjunct to general anaesthesia. The anaesthetist may use epidural analgesia in addition to general anaesthesia. This may reduce the patient's requirement for opioid analgesics. This is suitable for a wide variety of surgery, for example gynaecological surgery (e.g. hysterectomy), orthopaedic surgery (e.g. hip replacement), general surgery (e.g. laparotomy) and vascular surgery (e.g. open aortic aneurysm repair).
• As a sole technique for surgical anaesthesia. Some operations, most frequently Caesarean section, may be performed using an epidural anaesthetic as the sole technique. Typically the patient would remain awake during the operation. The dose required for anaesthesia is much higher than that required for analgesia.
• For post-operative analgesia, in either of the two situations above. Analgesics are given into the epidural space for a few days after surgery, provided a catheter has been inserted. Through the use of a patient-controlled analgesia (PCA) infusion pump, a patient may be given the ability to control post-surgical pain medications administered through the epidural.
• For the treatment of back pain. Injection of analgesics and steroids into the epidural space may improve some forms of back pain.
• For the treatment of chronic pain or palliation of symptoms in terminal care, usually in the short or medium term.
A patient getting a modern epidural for pain relief generally receives a combination of local anesthetics and opioids. Common local anesthetics include lidocaine, bupivicaineand chirocaine.Common opioids are morphine, fentanyl, and pethidine. These are then injected in relatively small doses.
Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen from the lungs to body tissues via the blood. Red blood cells are also known as RBCs, or erythrocytes (from Greek erythros for "red" and kytos for "hollow", with cyte nowadays translated as "cell"). Erythrocytes consist mainly of haemoglobin, a complex molecule
containing haeme groups whose iron atoms temporarily link to oxygen molecules in the lungs and release them throughout the body. Oxygen can easily diffuse through the red blood cell's cell membrane. Hemoglobin also carries some of the waste product carbon dioxide back from the tissues. (In humans, less than 2% of the total oxygen, and most of the carbon dioxide, is held in solution in the blood plasma).
Exsanguination (also known colloquially as bleeding out) is the fatal process of total hypovolemia (blood loss). It is most commonly known as "bleeding to death."
Exocrine (see gland ).
Extracorporeal: Outside the body, in the anatomic sense. As in extra-corporeal circulation, extracorporeal dialysis. From extra- + (corpus, meaning body).