The abdominal aorta is the section of the aorta located below the diaphragm.
ALVEOLUS (pl. Alveoli)
Alveoli are tiny air sacs in the lungs that exchange oxygen and carbon dioxide with the blood carried past them in capillaries. Adults have roughly 300 million microscopic alveoli in their lungs.
An aneurysm is a weakening in the muscular walls of a part of an artery which results in an enlargement or sagging of the damaged section. Aneurysms may be caused by a congenital defect, a degenerative disease, or a syphilitic infection. An aortic aneurysm may occur anywhere in the aorta. Aneurysms located in the ascending aorta or the aortic arch are frequently treated surgically. Aneurysms located in the descending aorta are usually treated medically and are only operated on if medical treatment fails. If an aneurysm ruptures, massive bleeding can result in hypotension, coma, and death.
Angina pectoris occurs when the heart does not get enough oxygen-rich blood from the coronary arteries (often caused by a coronary atheroma). The pain associated with angina pectoris often begins as a suffocating feeling in the center of the chest and may spread out to the arms and jaw. If drug therapy does not increase the blood flow, a coronary angioplasty or coronary bypass grafting may be necessary.
An angioplasty is a procedure in which a small deflated balloon is guided into a section of clogged artery or vein through an X-Ray guided catheter (hollow tube). Once the balloon reaches the selected section it is inflated, thereby expanding the clogged area and permitting an increased blood flow (see also stent).
Annuloaortic ectasia is the weakening or dilation of the annulus, the ring that surrounds the aortic valve.
Annuloplasty refers to the repair of a regurgitant valve — a valve that is loose, or torn, permitting reverse blood flow. In an annuloplasty, the diameter of the valve is carefully measured and the defect in the valve is surgically repaired. The valve is thereby secured to prevent further leakage.
The artery through which blood leaves the left ventricle of the heart, the aorta is the main artery of the body. All other arteries in the body stem from the aorta.
The aortic arch is the section of the aorta that travels (arches) over the heart before heading to the lower body. It originates from the ascending aorta (which is directly connected to the left ventricle of the heart) and gives off the main arterial branches to the head and arms: the brachiocephalic (innominate) artery; the left common carotid artery; and the left subclavian artery. The aortic arch later becomes the descending aorta (which travels down along the spinal column). The aortic arch helps to monitor blood pressure in the body through stretch receptors located in its outer wall.
An aortic dissection is a tear or rip in one or several layers of the wall of the aorta. An aortic dissection is not a complete tear, or rupture, of the aortic wall, which is a lethal condition. When a dissection occurs, blood flows through the tear, filling the space between the layers of the aorta and becoming trapped. An aortic dissection usually causes severe pain. Dissection in the ascending aorta or the aortic arch are generally treated surgically. Dissections in the descending aorta are only operated upon if medical treatment fails.
Aortic regurgitation occurs when some blood flows back into the left ventricle of the heart from the aorta after a heart beat. Aortic regurgitation is caused by a damaged aortic valve. When open, the aortic valve allows blood to flow from the left ventricle of the heart into the aorta. When closed, the aortic valve forms a strong seal, separating the ventricle from the aorta. If the aortic valve is damaged, a reverse in the blood flow, or aortic regurgitation, may be possible. Symptoms and signs of this condition include breathlessness, angina pectoris, enlargement of the heart, and a diastolic murmur (a murmur or slight noise heard when the heart is not contracting). While mild cases may have no symptoms, in severe cases the valve may have to be either repaired or replaced surgically.
The aortic root is the thick base of the aorta where the aorta connects with the aortic valve.
Aortic stenosis occurs when two of the three flaps that comprise the aortic valve fuse together. This fusion narrows the opening to the aorta, thus restricting the blood flow out of the left ventricle into the aorta. Symptoms and signs of this condition include breathlessness, fainting, angina pectoris, and a systolic murmur (a murmur or slight noise heard when the heart contracts). There is no good non-surgical medical treatment for severe aortic stenosis. The valve should be replaced or repaired surgically.
The aortic valve separates the left ventricle of the heart from the aorta (the main artery of the body). The aortic valve is comprised of three leaflets that, when open, permit blood to flow in only one direction – from the left ventricle into the aorta.
Aortitis is an inflammation of the aorta. Possible complications of aortitis include the formation of an aneurysm or other obstruction in the ascending aorta and aortic regurgitation. Pressure from the inflammation or from a reduced blood supply may cause chest pain. In severe cases the aortic valve and sections of the aorta may have to be either repaired or replaced surgically.
An aortogram is an X-ray examination of the aorta which is used to help to determine the extent and location of disease including aneurysms and aortic dissections. In order to take the X-rays, a radiopaque contrast medium is injected into the aorta.
An aortography is an X-Ray examination of the aorta, using intravenous contrast dye to outline the aorta.
An arrhythmia occurs any time the heart beats differently than normal. (For specific types of arrhythmia see: ectopic beats (extrasystole); ectopic tachycardias; fibrillation; and heart block.) Arrhythmias may cause breathlessness, chest pain, heart palpitations, and – in severe cases — cardiac arrest.
ARTERIOVENOUS FISTULA (ARTERIOVENOUS ANEURYSM)
An arteriovenous fistula is a direct connection between an artery (which carries oxygen-rich blood from the heart to the body) and a vein (which carries oxygen-poor blood back to the heart) which short-circuits the normal blood pathway in the body. They may occur in the systemic circulation or the pulmonary circulation. Surgery may be needed for a large connection in order to prevent heart failure (or cyanosis).
Arteries are the blood vessels that carry oxygen-rich blood away from the heart to the body. Artery walls have muscles that help to maintain blood pressure and pump blood through the body. The pulmonary artery from the right ventricle to the lungs is the only artery that does not carry oxygen-rich blood.
The ascending aorta begins at the aortic valve, which connects the aorta to the left ventricle, and extends upward until transforming into aortic arch.
Asystole is when the heart does not beat.
Atheroma is the substance that causes clogged arteries. Fatty plaques and scar tissue can build-up on artery walls, forming an atheroma. Common causes of atheroma are a high fat diet, smoking, obesity, and/or physical inactivity. These arterial build-ups limit blood circulation and often cause thrombus (blood clots). Symptoms and signs include angina pectoris, heart attacks (cardiac arrest), and strokes. Treatments range from prevention, to drug therapy, and coronary bypass surgery.
Atherosclerosis is the blockage of arteries from a build-up of fatty plaques on the inner artery walls (see Atheroma).
ATRIOVENTRICULAR BUNDLE (AV BUNDLE; BUNDLE OF HIS)
The AV bundle is a group of specialized heart muscles that connects the sinoatrial node to the AV Node, travels down through the septum — the division between the right and left sides of the heart — and splits off into a right bundle for the right ventricle and a left bundle for the left ventricle. These specialized muscles carry the electrical stimuli which cause the heart muscle to contract. Once the AV Node receives the message to contract, it passes it on to the AV bundle which in turn transmits the message to the muscles in both ventricles.
ATRIOVENTRICULAR NODE (AV NODE)
The AV Node is a group of specialized heart muscle in the lower-middle of the right atrium that serves as an electrical relay station for the heart. The sinoatrial node sends one electrical signal telling the atrium to contract and another signal to the AV Node. The AV Node then delays the signal before sending the message to the Atrioventricular Bundle. Finally, the AV Bundle passes the signal on to both ventricles, and they contract.
The atrioventricular septum is the physical wall that separates the atria from the ventricles.
ATRIUM (pl. atria)
The atria are the upper chambers of the heart that collect blood before passing it on to the larger, more muscular ventricles. Oxygen-poor blood enters the right atrium through the venae cavae. Oxygen-rich blood enters the left atrium through the pulmonary veins.
AUTOMATIC IMPLANTABLE CARDIAC DEFIBRILLATORS, AICD AICDs
are devices which are placed inside the body and connected to the heart. These devices sense when the heart is beating chaotically and give strong shocks to cardiovert or defibrillate it back into a healthy heart rhythm. Some AICDs also function as pacemakers, giving little shocks to treat a too slow heart rate.
AUTONOMIC NERVOUS SYSTEM
The autonomic nervous system controls many of those systemic functions that the mind does not consciously govern, such as the beating of the heart. The autonomic nervous system is divided into two different sub-systems, the sympathetic nervous system, and the parasympathetic nervous system. These two systems govern many of the same parts of the body, but are responsible for giving opposing signals. A sympathetic signal will speed the heart rate and heart’s strength of contraction. A parasympathetic signal slows the heart rate.
BEATING HEART SURGERY
See Minimally Invasive Surgery.
Blood pressure is the pressure of blood traveling through the main arteries of the body. Blood pressure is measured both when the ventricles of the heart are contracting (systolic pressure), and when the ventricles are at rest (diastolic pressure). The autonomic nervous system regulates the body’s blood pressure. Healthy blood pressure levels vary with age. For a young adult a healthy pressure averages 120 systolic and 80 diastolic (recorded as 120/80). Blood pressure also varies temporarily with physical or emotional stress and exercise. Hypertension is when the blood pressure is too high and hypotension is when it is too low.
BRACHIOCEPHALIC (INNOMINATE) ARTERY
The brachiocephalic artery is an extremely short artery that is the first artery to stem directly from the aortic arch. At the neck, the brachiocephalic artery divides into the right common carotid artery and the right subclavian artery.
BRACHIOCEPHALIC (INNOMINATE) VEIN
The two brachiocephalic veins are formed at the base of the neck by the joining of the jugular veins in the neck and the subclavan veins from the arms. These two veins in turn combine in the chest to form the superior vena cava.
Capillaries are the smallest blood vessel in the body, with walls only one cell thick. Capillaries run throughout the body, passing oxygen, nutrients, and other substances through their walls to the tissue beds and taking carbon dioxide and other waste products from the tissue beds back into the blood stream.
Cardiac arrest, or a heart attack, is when the heart stops pumping blood through the body. This can occur because the ventricles are beating too erratically to effectively pump any blood (ventricular fibrillation), or because the heart stops beating at all (asystole). Heart attack victims quickly lose consciousness, their pulse disappears, and they stop breathing. Emergency measures include CPR (cardiopulmonary resuscitation) and defibrillation.
In cardiac catheterization a catheter (a flexible tube) with a tiny camera on the end is inserted into a major vein in the arms or the legs and then worked through into the chambers of the heart and coronary arteries. This method allows the physicians to see blockages in the coronary arteries, abnormal sections of heart muscle, and leaky valves.
Cardiac muscle (see also myocardium) comprises most of the walls of the heart, making the powerful contractions that pump blood throughout the body. It is a special form of muscle which can work continuously.
The walls of the heart contain sensory fibers that alert the brain when the heart is beating faster than normal. The brain then sends a message through the vagus nerve which tells the heart to beat more slowly. This process of self-monitoring is referred to as the cardiac reflex.
Cardiogenic shock occurs when the heart cannot pump enough blood to maintain a normal body blood pressure. Results from this severe condition include fainting, organ failure, coma, and death.
Cardiomyopathy is any chronic disorder affecting the heart muscle. Possible conditions caused by cardiomyopathy include enlargement of the heart, heart failure, arrhythmias, and embolisms.
Cardioplegia is a potassium-salt solution used to intentionally stop the heart in order to perform bypass surgery or a transplant. Other methods of stopping the heart include cooling the heart and using an electrical shock.
During cardiopulmonary bypass, the function of the heart and lungs are taken over temporarily by a machine. This heart-lung machine maintains circulation throughout the body during open-heart surgery. Blood is taken out of the body from the superior and inferior venae cavae, pumped through the machine and oxygenated and then circulated back into the body through a major artery.
Cardiotocography is the monitoring of a fetal heart rate.
CARDIOTOMY SYNDROME (DRESSLER’S SYNDROME)
A possible complication of heart surgery, cardiotomy syndrome is an autoimmune condition that results in fever, pericarditis, and possibly pneumonia. Treatment includes anti-inflammatory drugs.
The cardiovascular system refers to the heart and all the blood vessels.
Cardioversion is a controlled electrical shock (from a machine called a defibrillator) applied to the chest wall of a patient. It is used to return to normal the heart beat of a patient suffering from arrhythmia. Recently, implantable devices (automatic implantable cardiac defibrillators, AICD) that automatically shock the heart in case of distress have been placed into patients who have been previously saved by cardioversion.
The carotid artery supplies blood to the head and neck. The left common carotid artery branches directly off the aortic arch. The right common carotid artery branches off the brachiocephalic artery.
Cholesterol is a waxy, fat related compound in the body tissues and organs of man and animal, cholesterol plays a vital role in metabolism. However, cholesterol is a key part in the creation of fatty deposits in the arterial walls and an increased blood cholesterol is a risk factor in coronary artery disease. Cholesterol is found only in foods of animal origin. It is recommended that the daily intake of dietary cholesterol be no more than 200 – 300 mg. per day.
A congenital defect is a defect in any organ present at birth.
CONGESTIVE HEART FAILURE, CHF
Congestive heart failure refers to a global failing of the heart muscle. After the heart muscle ceases to work, fluid accumulates in the lungs and body. Among the possible consequences of CHF are an inability to breathe, liver failure, hypotension, myocardial infarction, and death. CHF is treated with diuretics or, in severe cases, a heart transplant.
A coronary angioplasty is a procedure in which a deflated balloon is guided into a section of clogged artery through an X-Ray guided cardiac catheter. Once the balloon reaches the selected section it is inflated, thereby expanding the clogged area and permitting an increased blood flow. If a coronary angioplasty does not work, a coronary bypass graft may be necessary. (See also stent.)
The coronary arteries are the arteries that wrap around the heart, providing the heart with its own blood supply. There are two coronary arteries, the right and left, which both branch off from the aorta.
CORONARY ARTERY BYPASS GRAFT (CABG)
A coronary artery bypass graft is a surgical procedure whereby a blocked section of artery is literally “bypassed” by attaching a healthy segment of blood vessel around the diseased area. Both arteries and veins (which are converted into arteries) may be used to “bypass” the blocked coronary segments. Arteries and veins are taken from elsewhere in the patient’s body, most commonly the internal mammary arteries from the inside of the front of the chest or the saphenous veins from the legs. (To learn about the surgical procedure for CABGs, please see the Procedures section).
Revascularization refers to the medical process of restoring healthy blood flow to the heart muscle. Traditionally revascularization has fallen into two distinctive categories: Coronary Artery Bypass Graft and Angioplasty. Recently a new revascularization technique, Minimally Invasive Direct Coronary Artery Bypass, MIDCAB, surgery has been developed. Both CABG and MIDCAB are surgical procedures in which the blocked segment of artery is “bypassed” with a segment of healthy artery or vein. Angioplasty is an interventional, non-surgical, procedure that opens the clogged section of artery instead of bypassing it surgically.
Oxygen-poor blood pools in the coronary sinus before flowing into the right atrium. This blood originates in the coronary arteries, where the heart muscle consumes its oxygen.
A coronary thrombus is a blood clot (thrombus) that forms in the coronary artery, usually at the site of an atheroma, blocking the supply of blood to a section of the heart. This lack of blood may cause a myocardial infarction, or the death of that section of the heart muscle.
CT SCAN/COMPUTED TOMOGRAPHY
Computed Tomography, commonly referred to as a CT scan, takes X-ray “slice” images of the human body and the uses a computer to create a composite cross-sectional image.
Cyanosis occurs when oxygen-poor blood is introduced into the arteries, which normally only carry oxygen-rich blood. Its name comes from the blue tint that appears in the patient’s skin when this condition occurs. (Oxygen-poor blood is blue in color. Cyan is from the Greek word for blue.)
Defibrillation is the use of strong but controlled electric shocks to return the heart to a normal rhythm of contractions. Defibrillation is used when the ventricles of patient’s heart are beating too quickly or erratically to effectively pump blood (ventricular fibrillation). The electrical shocks are applied by a machine called a defibrillator either through electrodes on the chest wall of a patient, or directly to the patient’s heart. See also Automatic Implantable Cardiac Defibrillators, AICDs.
The descending aorta begins after the aorta arches over the heart. The descending aorta travels down along the spine. The section of the descending aorta from the aortic arch to the diaphragm is also called the thoracic aorta. The section of the descending aorta below the diaphragm is also called the abdominal aorta.
The period of diastole is when the ventricle relaxes between contractions. When a patient’s blood pressure is taken, the diastolic pressure, or the measurement of this resting period, is the second figure given. An average diastole lasts roughly 0.5 seconds for a heart rate of 70 beats per minute.
DIRECTIONAL CORONARY ATHERECTOMY (DCA)
A directional coronary atherectomy is similar to an angioplasty except that the blockage is decreased by mechanically removing the plaque.
See cardiotomy syndrome.
An echocardiogram is a picture of the heart taken using sound waves. This image gives information about the structure and function of the heart.
ECTOPIC BEAT (EXTRASYSTOLE)
An ectopic beat is a premature heartbeat due to a contraction impulse from an abnormal source. Normally the sinoatrial node starts the contraction process. With an ectopic beat, however, either a source in the atria (supraventricular) or a source in the ventricles (ventricular) may initiate the contraction. Among the causes of ectopic beats are heart disease, smoking, and caffeine.
Edema is swelling caused by excess fluid accumulated in body tissues. (Edema was formerly known as dropsy.) Possible results range from swollen limbs to heart failure, depending on the extent and location of the swelling. Edema in the lungs is known as pulmonary edema and is life threatening.
An electrocardiogram is a recording of the electrical activity of the heart taken by a machine called an electrocardiograph.
Electrophysiology studies are done to determine the focus or focii of arrhythmias in the heart. During cardiac catheterization, small electrodes are placed in the heart and the electrical potential of the heart can be measured internally. This allows the physician to find an area of abnormal electrical conductance responsible for an arrhythmia and ablate it (kill off the abnormal cells).
An embolism is when an embolus – a traveling clot of blood, fat, air, or other substance – lodges in an artery and blocks the blood flow. Pulmonary embolisms (clots in the pulmonary artery) are the most common. An embolus which goes to the brain can cause a stroke.
An embolus is a clot of blood, fat, air, or some other substance that travels through the bloodstream, lodging in small vessels.
Endocarditis is an inflammation of the endocardium (the lining of the heart) and valves. Frequently caused by a bacterial infection or rheumatic fever, symptoms include fever, embolism, changing heart murmurs, and heart failure.
The endocardium is the delicate inner lining of the heart, which also covers the arteries, veins and valves. The cusps of the valves are formed from folds of this linings.
Endomyocarditis is an inflammation of the muscle and lining membrane of the heart, frequently caused by a viral infection or rheumatic fever. Symptoms include arrhythmias, enlargement of the heart, murmurs, and embolisms. (If the pericardium, the sac surrounding the heart, is also inflamed then the diagnosis is pancarditis.)
The epicardium is both the outer layer of the heart and the inner layer of the pericardium (the sac surrounding the heart).
Fat is an essential nutrient used by the body for many functions including energy, thermal insulation, vital organ protection, cell structure, and function. It is recommended that less than 30% of food calories come from dietary fats, which are present in foods of both animal and vegetable origin. (See also Saturated Fat; Monounsaturated Fat; Polyunsaturated Fat; and Omega-3 Fatty Acids.)
The femoral artery starts at the top of the thigh, runs along the front, before passing to the back of the thigh, and running behind the knee.
Fibrillation is when the heart beats so quickly and chaotically that it cannot effectively pump blood. Atrial fibrillation is a frequent cause of arrhythmia and often stems from hypertensive heart disease or pericarditis. It can usually be treated with drug therapy. Ventricular fibrillation is a much more serious condition, which can lead to cardiac arrest or death of heart muscle (myocardial infarction).
GRADED EXERCISE STRESS TEST
A graded exercise stress test involves exercising on a treadmill or bike at increased degrees of difficulty while the heart’s response is recorded on an electrocardiogram (EKG). The level of exercise tolerance is measured by changes on the EKG, reported symptoms, as well as blood pressure and heart rate response. It also allows the physician to evaluate the effectiveness of your medical treatment. Patients recovering from a heart attack are usually given a low level exercise stress test prior to discharge.
The heart is a muscular cone-shaped organ responsible for pumping blood throughout the body. It lies between the two lungs and is divided vertically into a right and left side. Both sides are also divided horizontally into an atrium and a ventricle. Oxygen-poor blood enters the right atrium and then flows through the tricuspid valve into the right ventricle. From the right ventricle the blood is pumped through the pulmonic valve to the lungs where it absorbs oxygen. Freshly oxygenated blood then travels from the lungs into left atrium. The blood collects in the left atrium before flowing through the mitral valve into the left ventricle. From the left ventricle the blood is then pumped out the aortic valve through the aorta to the body. Once the oxygen and other nutrients have been absorbed from the bloodstream, the blood returns to the right atrium and the process repeats. The walls of the heart are composed of three layers: (1) the endocardium, the delicate inner lining of the heart that also covers the arteries and forms the folds of the valves; (2) the myocardium, the thick muscular middle layer of the heart responsible for pumping; and (3) the epicardium, the outer layer of the heart that also forms the inner layer of the pericardium, the sac in which the heart rests.
A heart attack is a common term which applies to both cardiac arrest and myocardial infarction, or death of heart muscle.
Heart block is when the heart beats too slowly because of a problem with the conduction of electrical impulses (from the sinoatrial node) that tell the heart when to contract. There are varying degrees of heart block. In complete heart block (or third degree heart block) the electrical impulses stop completely and the ventricles beat at their slow base rate of 20-40 beats per minute (versus a healthy average of 70 beats per minute). Causes of heart block include congenital heart disease, death of heart muscle (myocardial infarction), myocarditis, diseased valves, and scarring of the electrical conductive tissue of the heart. An artificial pacemaker can restore the heart’s rhythm.
In heart failure, the ventricle cannot pump the blood hard enough, so blood begins to stagnate in the tissues, causing back pressure (blood flow in the wrong direction). This back pressure results in breathlessness, swelling of the tissues (edema), congestion in the lungs and the liver, and the swelling of veins in the neck. In severe cases, not enough blood may reach the vital organs of the body (cardiogenic shock). Causes of heart failure include multiple myocardial infarctions, hypertension, coronary thrombosis, diseased valves, and arrhythmias.
See Cardiopulmonary Bypass.
HIGH DENSITY LIPOPROTEINS (HDL)
High Density Lipoprotein (HDL) is a type of cholesterol carrier which helps remove cholesterol from the bloodstream. (See also Low Density Lipoprotein)
Holter monitoring is 24-hour monitoring of heart rhythms on an ambulatory basis. The patient’s heart is monitored during their normal activities of daily living in order to discover arrhythmias. The information is stored by the Holter monitor and analyzed at a later date.
Hypertension is when an individual’s blood pressure is above their healthy range. Causes of hypertension range from diseased or clogged arteries, to kidney disease and unknown causes (essential hypertension). Severe cases of hypertension can lead to heart failure. Normally hypertension can be controlled with careful monitoring of diet and drug therapy. Other forms of hypertension, such as the narrowing of the descending aorta or narrowing of the arteries to the kidneys require more serious treatments, such as surgery.
Hypotension is when an individual’s blood pressure is below their healthy range. Symptoms include lightheadedness, fainting, sweats, a weak pulse, and loss of circulation in the limbs. It can be caused by a severe, sudden loss of blood, death of heart muscle (myocardial infarction), pulmonary embolism, arrhythmias, and a severe infection or allergic reaction. Treatments include oxygen, medicines, intravenous fluids and blood.
The iliac arteries branch off the abdominal aorta and supply most of the blood to the pelvic region and the lower limbs.
INTERNAL MAMMARY ARTERIES
The internal mammary arteries originate from the subclavian artery (that run beneath the shoulders and provide blood to the arms). The mammary arteries run parallel down each side of the front of the chest and connect with small arteries under each rib. They may be taken for use in coronary artery bypass grafting and minimally invasive direct coronary artery bypass procedures since the small arteries beneath the ribs provide a secondary source of blood for the area.
Isotonic exercise is accomplished by an alternate contraction and relaxation of large muscles. This form of exercise promotes cardiovascular fitness by strengthening the heart muscle. Excellent examples of this form of exercise are walking, biking, cross-country skiing, and swimming.
Isometric exercise is a sustained contraction of large muscles, such as weight lifting. This places a disproportional workload on the heart and limits the amount of oxygen delivered to the heart.
LOW DENSITY LIPOPROTEINS (LDL)
Low Density Lipoprotein (LDL) is a type of cholesterol carrier which deposits cholesterol on the walls of blood vessels. (See also High Density Lipoprotein.)
Marfan’s syndrome is an inherited disease characterized by aneurysms in the aorta, excessive height, abnormally long fingers and toes, and problems with the eyes. (For more information on Marfan’s Syndrome, please see http://www.marfan.org/; http://www.crtelco.com/~ckbryant/marfan.html; or http://www.aorn.org/JOURNAL/1296/HOMESTUD/article.htm)
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS SURGERY (MIDCAB)
Minimally invasive direct coronary artery bypass, MIDCAB, surgery refers to open heart bypass surgery performed through a small incision in the chest wall. The purpose of the smaller incision is to reduce pain and recovery time. MIDCAB surgery follows the same basic premise as traditional coronary artery bypass graft, CABG surgery. The blocked section of artery is bypassed surgically through the attachment of a healthy section of artery, usually an internal mammary artery. In a MIDCAB procedure the surgeon operates through a 12 cm incision. (A full sternotomy used in a conventional CABG requires, on average, a 30 cm incision.) The heart is not stopped or placed on cardiopulmonary bypass (the heart-lung machine) for a MIDCAB operation. New heart stabilizers limit motion in the operation field to within 1 millimeter, permitting the surgeon to operate while the heart continues to beat. Because the patient is not placed on the heart-lung machine and because of the smaller incision size, the average post-operative length of stay for MIDCAB patients is only 2-3 days — versus an average of 5 days for conventional CABG patients.
MINIMALLY INVASIVE SURGERY
Minimally invasive surgery, also known as beating heart surgery, refers to the last advancement in open heart surgery. Minimally invasive procedures are performed through a small incision in the chest wall to reduce pain and recovery time. (In conventional open heart surgery a full sternotomy is performed — the full length of the breast bone, 30 cm long on average, is opened. The average length of a minimally invasive incision ranges from 9-12 cm long.) There are three major types of minimally invasive procedures: (1) minimally invasive direct coronary artery bypass, MIDCAB; (2) minimally invasive valve repair and replacement; and (3) minimally invasive port-access. Originally developed in the early 1960s by a Russian surgeon, minimally invasive techniques have been perfected in the last few years with the development of new medical technologies.
Mitral incompetence is a problem with the mitral valve that connects the left atrium to the left ventricle. The valve does not create a complete seal when closed, permitting some blood to flow back into the left atrium when the ventricle contracts — normally all blood flows out through the aorta. The damage to the valve can be congenital, a result of scarring from an infection, or caused by a myocardial infarction (death of some heart muscle). Symptoms and signs of mitral incompetence include breathlessness, atrial fibrillation (rapid, irregular, ineffective heartbeats), embolisms, enlargement of the left ventricle, and a murmur (systolic). In severe cases the valve should either be repaired or replaced surgically.
A stenotic mitral valve has a narrowed valve opening. Mitral stenosis is often caused by rheumatic fever. Symptoms are the same as for mitral incompetence (except that the heart murmur is diastolic instead of systolic). In severe cases the valve should either be repaired or replaced surgically.
The mitral valve connects left atrium to the left ventricle. It has two cusps that, when open, lets blood flow in one direction, from the left atrium into the left ventricle.
Monounsaturated fat helps to lower blood cholesterol when used in place of saturated fat in the diet. (See also Saturated Fat; Polyunsaturated Fat; and Omega-3 Fatty Acids.)
MRI/MAGNETIC RESONANCE IMAGING (MRI)
Magnetic Resonance Imaging uses magnets and computer technology to take detailed pictures inside the body.
A MUGA scan uses low dose radioactive material given intravenously to visualize the heart’s pumping action (ejection fraction).
A murmur is a abnormal sound made by blood that is flowing irregularly, or turbulently in the heart or arteries. It may be caused by a narrowed vessel or valve, a leaking valve, or too much blood flow through a normal vessel. The presence of a murmur may not mean a significant heart problems, but usually requires further evaluation. Systolic murmurs occur when the heart is contracting. Diastolic murmurs occur when the heart is relaxing. Continuous murmurs usually indicate abnormal communications between arteries and veins or between the aorta and other parts of the heart.
Myocardial infarction is the death of a section of heart muscle caused by a loss of blood flow from a coronary artery. Most myocardial infarctions occur in the left ventricle and cause sharp pain in the chest, which can spread to the arms and throat. Other complications include ventricular fibrillation, heart failure, embolisms, mitral incompetence, and shock.
Myocarditis is any inflammation of the heart muscle.
The myocardium is the muscular middle layer of the heart, responsible for making the heart contract.
NUCLEAR STRESS TESTING
Nuclear stress testing is a test done in order to find areas of decreased blood flow to the heart at times when the heart is stressed. A radioactive isotope is injected into the blood stream prior to having a patient exercise. Once the patient has reached his/her target heart rate, a nuclear scan is performed which looks at the concentration of the isotope in various parts of the heart. Areas which appear light in color on the scan do not receive enough blood flow during exercise are likely to be served by a stenotic vessel. Testing is repeated after several hours while the patient is at rest, to determine extent of disease. This test is also known as a stress thalium test.
OMEGA-3 FATTY ACIDS
Omega-3 fatty acids are fats found in fish sources which help to lower Low Density Lipoprotein (LDL) cholesterol. (See also Saturated Fat; Polyunsaturated Fat; and Monounsaturated Fat.)
A pacemaker is an electrical device that can be implanted in the body and connected to the heart. The pacemaker gives small shocks to the atrium and/or ventricle when the heart fails to beat quickly enough. Pacemakers contain batteries and special computer chips that simulate the heart’s normal electrical function (see sinoatrial node and heart block).
PARASYMPATHEIC NERVOUS SYSTEM
The parasympathetic nervous system helps regulate those parts of the body, like the heart and the blood vessels, that the brain does not consciously control. Nerves for the parasympathetic nervous system originate in the brain and in the lower spinal cord. As one of the two parts that compose the autonomic nervous system, the parasympathetic nervous system is often responsible for giving the opposite message as its counterpart, the sympathetic nervous system. The parasympathetic nervous system usually has a calming or slowing effect on the systems it enervates.
The pericardium is a thin lubricated sac in which the heart rests, protecting the heart from friction.
Pericarditis is the inflammation of the pericardium, the lubricated sac in which the heart rests. Among the causes of pericarditis are viral infection and cancer. Results include fever, chest pain, and the build-up of too much fluid in the sac (pericardial effusions). Rarely, the pericardium thickens (chronic constrictive pericarditis), interfering with the functioning of the heart.
PERSANTINE STRESS TEST
A persantine stress test is similar to the graded exercise stress test except that a medication called persantine is used to elevate the heart rate instead of exercise.
Phlebothrombosis occurs when a vein is blocked by a blood clot. Phlebothromboses are most commonly found in the leg.
Polyunsaturated fat comes primarily from vegetable sources which are generally liquid at room temperature. When used in moderation, they tend not to effect blood cholesterol levels. (See also Saturated Fat; Monounsaturated Fat; and Omega-3 Fatty Acids.)
POST INFARCTION VENTRICULAR SEPTAL DEFECT
A post infarction ventricular septal defect is a hole that forms in the ventricular septum (wall) due to a weakening of the septum from a myocardial infarction (the death of a section of heart muscle). In other words, a section of the heart muscle in the septum dies from a myocardial infarction. As a result that section of septum is abnormally weak. Continued pressure on the weakened section leads to the formation of a hole in the septum. Congestive heart failure, heart murmurs, and endocarditis are some of the possible complications of a ventricular septal defect.
The pulmonary artery carries oxygen-poor blood from the right ventricle to the lungs. After it leaves the right ventricle, the pulmonary artery splits into two branches, one for each lung. The pulmonary artery is the only artery in the body that carries oxygen-poor blood.
The pulmonary circulation refers to all the blood vessels connecting the heart and the lungs. See pulmonary veins and pulmonary artery.
Pulmonary edema occurs when too much fluid accumulates in the lungs. The fluid blocks the transport of oxygen from the lungs into the blood. Emergency treatment with medicines and mechanical ventilation may be necessary.
Pulmonary hypertension occurs when the blood pressure in the blood vessels supplying the lungs is too high. This increased pressure causes the right ventricle of the heart to become enlarged, and may result in fainting, chest pain, and heart failure. Other possible complications include, embolisms, septal defects, mitral valve diseases, and chronic lung diseases.
The pulmonary veins carry oxygenated blood from the lung to the left atrium. They are the only veins in the body that carry oxygen-rich blood.
The pulmonic valve separates the right ventricle from the pulmonary artery. The pulmonic valve is comprised of three leaflets that, when open, permit blood to flow in only one direction – from the right ventricle into the pulmonary artery.
Revascularization (in open heart surgery) refers to the medical process of restoring healthy blood flow to the heart muscle. Traditionally revascularization has fallen into two distinctive categories:Coronary Artery Bypass Graft and Angioplasty. Recently a new revascularization technique, Minimally Invasive Direct Coronary Artery Bypass, MIDCAB, surgery has been developed. Both CABG and MIDCAB are surgical procedures in which the blocked segment of artery is “bypassed” with a segment of healthy artery or vein. Angioplasty is an interventional, non-surgical, procedure that opens the clogged section of artery instead of bypassing it surgically.
A rotoblator is a small blade located on the end of a catheter (hollow tube). When the catheter is guided down a coronary artery, the rotoblator can be turned to shave atheroma (plaque build-up) off the artery wall. Blood flow through the artery increases once the atheroma is cut away.
The saphenous veins are large veins that run beneath the skin in the legs. Their function is to cool the body when it is overheated. There is a second deep system of veins in the legs. The saphenous veins, therefore, can be taken for use in the coronary bypass grafting.
Saturated fat is a type of fat that is usually solid or semi-solid at room temperature and can be found in animal as well as vegetable sources. A diet high in saturated fat frequently increases blood cholesterol and Low Density Lipoprotein (LDL). (See also Polyunsaturated Fat; Monounsaturated Fat; and Omega-3 Fatty Acids.)
A septal defect is a congenital birth defect that results in a hole in the partition between the right and left sides of the heart (the septum). For both an atrial septal defect (between the left and right atrium) and a ventricular septal defect (the left and right ventricle) the blood flows through the hole from the high pressure left side of the heart to the lower pressure right side. The excess of blood in the right side of the heart can cause too much blood to flow through the lungs and may result in pulmonary hypertension or heart failure. Large holes, and some small holes, should be closed surgically.
Signs are objective findings discovered by a clinician/physician, e.g. heart murmur. See also: symptoms.
SINOATRIAL NODE (SA NODE)
The SA Node is the heart’s natural pacemaker. Located in the right atrium near the entry of vena cava, the SA Node is composed of a group of specialized heart muscles that contract rhythmically at about 70 times per minute. Every time the SA node contracts it sends an impulse through the atrial muscle to contract. The atrial muscle in turn forwards the contraction message to the atrioventricular node (AV Node). The normal mode of the SA node can be sped up or slowed down by impulses sent to it from autonomic nervous system.
Stenosis is a segmental narrowing of an artery, leading to a decreased blood flow. Stenosis is usually caused by atheroma, fatty plaques and scar tissue that build-up on artery walls.
A stenotic valve has been narrowed, thereby restricting the blood flow. Common causes of a stenotic valve include calcification as a result of the natural aging process, damage due to infection, and congenital narrowing.
A tubular mesh stent is used during an angioplasty to keep the coronary artery open. The stent initially rests on the deflated balloon of the catheter. Once the balloon is inflated in an area of stenosis the stent lodges in the artery wall and holds the artery open. After the balloon is deflated, the stent remains in place.
A sternotomy is the surgical division of the breastbone used in open heart surgery to give the surgeon access to the heart. The average length of a sternotomy is 30 cm long.
A stress echocardiogram is similar to a graded exercise stress test, except that an echocardiogram is performed prior to the stress test and immediately following the stress test. A stress echocardiogram allows the physician to visualize changes in the pumping action of the heart between rest and exercise.
The subclavian arteries deliver blood to the neck and the arms. The left subclavian artery stems directly from the aortic arch. The right subclavian artery branches off the brachiocephalic (innominate) artery.
SYMPATHETIC NERVOUS SYSTEM
The sympathetic nervous system regulates those parts of the body, like the heart and the blood vessels, that the brain does not consciously control. Nerves for the sympathetic nervous system originate in the middle section of the spinal cord. As one of the two parts that compose the autonomic nervous system, the sympathetic nervous system is often responsible for giving the opposite message as its counterpart, the parasympathetic nervous system. The sympathetic nervous system usually functions to excite or speed up the systems it enervates.
Symptoms are subjective indications experienced by the patient, e.g. chest pain. See also signs.
The systemic circulation refers to all of the blood vessels in the body except those that supply the lungs.
Systole is the period during a ventricular contraction. When a patient’s blood pressure is taken the systolic pressure, or the measurement of this contraction period, is the first figure given. An average systole lasts roughly 0.3 seconds for a heart rate of 70 beats per minute.
Tachycardia is an increase of the heart rate above the normal level. Among its many possible causes are arrhythmias, illness, exercise, stress, or excitement.
Telemetry is a method of placing a patient on an electrocardiogram (EKG) monitor without having wires limiting activity. The EKGs are transmitted via radio waves to a central monitoring point. Patients can therefore walk around while still being monitored.
THALLIUM STRESS TEST
A thallium stress test may be done at rest, or follow the same procedure as a graded exercise test, with an intravenous injection of a low dose of radioactive material at peak exercise. This is immediately followed by a scan of the heart to visualize areas of the heart that do not receive sufficient blood supply. A comparative scan will be done four hours later to note any changes at rest.
Thrombolytic agents are intravenous drugs which are administered during a heart attack. These drugs are intended to break up a thrombus, thereby allowing blood to reach the heart muscle.
In thrombolytic therapy, medication is given intravenously to dissolve the blood clot causing the heart attack. Once the blood clot is dissolved, blood flow can be restored to the affected area of the heart. Activase (t-PA) or Streptokinase are the most common medications used for dissolving a blood clot.
A thrombus is when a blood clot is formed in a diseased blood vessel. When a thrombus blocks the blood supply to an organ it can cause death to all or part of that organ. A thrombus in the heart (coronary thrombosis) can cause a heart attack (cardiac arrest), while a thrombus in the brain can cause a stroke. (For thrombus in a vein see phlebothrombosis.) If a thrombus breaks free and joins the bloodstream it is called an embolism.
A transesophageal echocardiogram is the same as a standard echocardiogram, except a miniaturized transducer (the probe) is passed down the esophagus by means of a flexible scope to visualize the heart. Sound waves are used to image/take pictures of vital structures such as the heart and aorta.
The tricuspid valve separates the right atrium from the right ventricle. The tricuspid valve is comprised of three leaflets that, when open, permit blood to flow in only one direction – from the right atrium into the right ventricle.
Triglyceride is a type of fat made up of glycerol and three fatty-acid molecules. The body makes triglycerides from the products of digestion of dietary fat. Fat is then stored in the body as triglycerides.
The vagus nerves are paired nerves on each side of the body which carry parasympathetic impulses to the heart and other body organs. These impulses slow the heart when it is beating too quickly.
Valvuloplasty is a procedure usually performed to treat a stenotic valve. During this procedure the surgeon opens up the narrowed valve. This can be done with an incision, while on cardiopulmonary bypass, or in certain cases by closed heart techniques. In a balloon valvuloplasty, a small deflated balloon is guided into a valve opening via a catheter (hollow tube). Once inside the valve opening, the balloon is inflated. These procedures help to widen the valve, thereby permitting an increased blood flow.
A vein is a blood vessel that carries oxygen-poor blood to the heart. (The only exception is the pulmonary vein.) Blood from the veins enter the right atrium of the heart through the vena cava.
(pl. venae cavae) The superior and the inferior vena cava both deliver oxygen-poor blood into the right atrium of the heart. The superior vena cava draws blood from above the diaphragm, while the inferior vena cava draws blood from below.
The right and left ventricles are the two muscular lower chambers of the heart. The right ventricle pumps oxygen-poor blood received from the right atrium out to the lungs through the pulmonary artery. The left ventricle pumps oxygen-rich blood received from the left atrium out to the body through the aorta.