context: Ablation: The removal or destruction of tissue. Advance Directive (living will): A document written in "good" health which informs your family and health care providers of your wishes for extended medical treatment in times of emergency. Aerobic Exercise: Exercise which raises your heart rate and can improve your functional ability and, in some cases, reduce symptoms of heart disease. It is repetitive in nature and involves the large muscle groups. Examples are walking, swimming, and cycling. Ambulatory Monitors: Small portable electrocardiogram machines that are able to record the heart's rhythm. Each type of monitor has unique features related to length of recording time and ability to send the recordings over the phone. They include: Holter Monitor, Loop recorder ( Event monitor), and Transtelephonic transmitter. Anemia: A condition characterized by a deficiency of red blood cells. Anemia reduces the amount of oxygen available to the body. Aneurysm: A sac formed by the bulging of a blood vessel wall or heart tissue. When aneurysms grow too large, they can rupture and the bleeding can be life threatening. Aneurysms that have grown too large should be removed. Angina (also called angina pectoris): Discomfort or pressure, usually in the chest, caused by a temporarily inadequate blood supply to the heart muscle. Discomfort may also be felt in the neck, jaw, or arms. Angiogenesis: The spontaneous or drug-induced growth of new blood vessels. The growth of these vessels may help to alleviate coronary artery disease by rerouting blood flow around clogged arteries. Angioplasty: An invasive procedure, during which a specially designed balloon catheter with a small balloon tip is guided to the point of narrowing in the artery. Once in place, the balloon is inflated to compress the fatty matter into the artery wall and stretch the artery open to increase blood flow to the heart. Angiotensin- Converting Enzyme Inhibitors ( ACE inhibitors): A group of drugs used to treat high blood pressure and heart failure. ACE inhibitors block a specific enzyme ( ACE or angiotensin-converting enzyme) that retains salt in the kidney and can cause heart and blood pressure problems. ACE inhibitors have been shown to decrease the risk of dying from a heart attack or heart failure. Angiotensin Receptor Neprilysin Inhibitors ( ARNIs): A new class of drugs, which combine a neprilysin inhibitor and an ARB, used to treat heart failure. ARNIs decrease the risk of death and hospitalization by reducing the strain on the failing heart. Angiotensin II Receptor Blockers ( ARBs): A group of drugs used to treat high blood pressure. For patients who have side effects from ACE inhibitors, these are often used in the treatment of heart failure. Annulus: A ring of tough fibrous tissue that is attached to and supports the leaflets of the heart valve. Anomalous Coronary Artery: The normal anatomy for the coronary arteries involves their origin from the aorta at each of two separate sites. Sometimes people can be born with the origin of a coronary artery that comes from an abnormal site. In rare cases, the anomaly can lead to problems of coronary ischemia which can subsequently lead to a heart attack. If this type of anomaly is present, then it may require surgery. Antiarrhythmic: A drug that is used to treat abnormal heart rhythms. Anticoagulant ("blood thinner"): A drug that prevents blood from clotting; used for people at risk for stroke or blood clots. Antihypertensive: A drug used to treat high blood pressure. Antioxidant: Vitamins ( A, C, and E) that may help to limit the cellular damage caused by free radicals (which are released when tissue is being injured, such as during the progression of heart disease.) Aorta: The large artery leaving the heart that carries blood to other parts of the body. Aortic Insufficiency: Aortic insufficiency refers specifically to the aortic valve, which is the valve the blood passes through as it leaves the heart and enters the aorta. When blood leaks back through the valve it is known as aortic insufficiency. Small amounts of aortic insufficiency may be inconsequential, but larger amounts require repair or replacement of the aortic valve. Aortic Valve: The aortic valve is the last valve through which the blood passes before it enters the aorta or main blood vessel of the body. The valve's role is to prevent blood from leaking back into the left ventricle from the aorta after it has been ejected from the heart. Aortic Valve Replacement: When the aortic valve is diseased, it can become either stenotic (too narrow) or insufficient (leaky). In such cases, the aortic valve may need to be replaced with either a prosthetic or human valve. Aortic Valve Homograft: When replacement of an aortic valve is necessary it is possible to replace the valve with another human valve known as an aortic valve homograft. This operation involves cardiopulmonary bypass. Aortic Valve Repair: The aortic valve is the last valve in the heart through which the blood travels prior to circulating in the body. When this valve is leaking or too tight, a surgeon may be able to repair the valve rather than replace it. Arrhythmia: An irregular heartbeat. Arterial Grafting: In patients who require coronary artery bypass graft surgery, arteries from other parts of the body can be used to provide the bypass grafts. This is known as arterial grafting. The alternative is to use vein grafts for coronary bypass surgery. Arteries: Blood vessels that carry blood away from the heart. Atherectomy ( Directional Coronary Atherectomy or DCA): This procedure is used to clean out clogged heart arteries. A DCA catheter has a hollow cylinder on the tip with an open window on one side and a balloon on the other. When the catheter is inserted into the narrowed artery, the balloon is inflated, pushing the window against the fatty matter clogging the vessel. A blade (cutter) within the cylinder rotates and shaves off any fat, which protruded into the window. The shavings are caught in a chamber within the catheter and removed. This process is repeated as needed to allow better blood flow. Atherosclerosis ("hardening of the arteries"): The process whereby abnormal deposits of lipids, cholesterol, and plaque build up, leading to coronary artery disease and other cardiovascular problems. Atria: The upper chambers of the heart. ( Atrium refers to one chamber of the heart). Atrial Fibrillation ( AF): Atrial fibrillation is an irregular heart rhythm in which many impulses begin and spread through the atria. The resulting rhythm is disorganized, rapid, and irregular and the atria are not able to fully empty their contents into the ventricles. This condition can lead to a stroke. Atrial Flutter: Atrial flutter is a regular heart rhythm in which many impulses begin and spread through the atria. The resulting rhythm is organized, but so rapid that the atria are not able to fully empty their contents into the ventricles. Atrial Myxoma: A myxoma is a benign tumor of the heart. It resides in the atrial chamber and causes symptoms when its growth produces a tumor so large it obstructs blood flow through the heart chambers. Treatment of atrial myxoma is surgical removal of the tumor. Atrial Septal Defect: An abnormal hole located in the walls between the two atria. Tiny defects called patent foramen ovale are present in up to 30% of people and are of no consequence except in unusual circumstances. Moderate size to larger size defects should be corrected and may require heart surgery, though there are now devices that can close the hole without open heart surgery. Atrioventricular ( AV) Node: A group of special cells located near the center of the heart that helps to regulate the heart rhythm. Here, the electrical current slows for a moment before going on to the ventricles. Atrium: The top chamber of the heart. There are two atria -- the left and the right, divided by a muscular wall, called the septum. The atrium contracts before the ventricle to allow optimal filling of the ventricle. Balloon Angioplasty ( Percutaneous Transluminal Coronary Angioplasty or PTCA): A procedure used to clean out clogged heart arteries. A specially designed balloon catheter with a small balloon tip is guided to the point of narrowing in the artery. Once in place, the balloon is inflated to compress the fatty matter into the artery wall and stretch the artery open to increase blood flow to the heart. Batista Procedure: During this surgical procedure to treat heart failure, the surgeon cuts out a piece of the patient's enlarged left ventricular muscle. The intent is to reduce the size of the left ventricular cavity, improve left ventricular function, and reverse congestive heart failure. Studies have shown that this procedure is ineffective. Beta- Blocker: A drug that slows heart rate, lowers blood pressure, controls angina, and protects patients with prior heart attacks from future heart attacks. Bicuspid Valve: A valve with two leaflets (cusps) instead of three. Biopsy: Removal and analysis of a tissue sample. Blood Pressure: The force exerted in the arteries by blood as it circulates. It is divided into systolic (when the heart contracts) and diastolic (when the heart is filling) pressures. Body Mass Index ( BMI): A number that reflects body weight adjusted for height. Normal values are 18.5-24.9. Values of 25-29.9 are considered overweight. Values of 30 or higher are considered obese. Bradycardia: A slow heart rate. Bundle Branch: Part of the electrical pathway of the heart that delivers electrical impulses to the ventricles of the heart. Bundle Branch Block: Normally, the electrical impulse travels down both the right and left bundle branches at the same speed and the ventricles contract at the same time. If there is a block in one of the branches, it's called a bundle branch block. A bundle branch block causes one ventricle to contract just after the other ventricle, reducing the overall efficiency of contraction. Calcium- Channel Blocker: A drug that reduces spasm of the blood vessels, lowers blood pressure, and controls angina; it acts by selectively blocking the uptake of calcium by the cells. Capillaries: Tiny blood vessels connecting arteries to veins. These blood vessels carry oxygen and nutrients to individual cells throughout the body. Carbohydrate: An organic compound, found in food substances such as sugar, cereal and other grain products, fruits, and vegetables, which provides fuel for the body. Carbon Dioxide: A gas created during metabolism, when the cells use oxygen to burn fat and release energy. The lungs release carbon dioxide when you breathe out. Cardiac Arrest: When the heart stops beating suddenly and respiration (breathing) and other body functions stop as a result. Without immediate treatment the affected person will die. Cardiac Catheterization: A heart procedure used to diagnose heart disease. During the procedure, a catheter (inserted into an artery in your arm or leg) is guided to your heart, contrast dye is injected, and X-rays of the coronary arteries, heart chambers, and valves are taken. Cardiac Output: The amount of blood pumped by the heart each minute. Cardiac Rehabilitation: A structured program of education and activity guided toward lifestyle modification, increasing functional capabilities and peer support. Cardiologist: Doctor specializing in the diagnosis and treatment of heart disease. Cardiomyopathy: An abnormal heart condition in which the heart is dilated (poor pumping power), restrictive (impaired ability of the heart to fill) and hypertrophic (thickened). Cardiopulmonary Resusitation ( CPR): A technique designed to temporarily circulate oxygenated blood through the body of a person whose heart has stopped. It involves assessing the airway; if necessary breathing for the person; determining if the person is without a pulse; and if necessary, applying pressure to the chest to circulate blood. Cardiovascular: Relates to the heart and blood vessels. Cardioversion: A procedure used to convert an irregular heart rhythm to a normal heart rhythm by applying electric shock or using certain medications. Carotid Artery: A vessel that supplies the brain with oxygenated blood. Carotid Artery Disease: A progressive disease that involves the buildup of fatty material and plaque in the carotid arteries; can lead to a stroke. Catheter: A slender, hollow, flexible tube. Chest X-ray ( CXR, chest film): A very small amount of radiation is used to produce an image of the structures of the chest (heart, lungs, and bones) on film. Cholesterol: A fatty substance made by the body and found in some foods. Cholesterol is deposited in the arteries in coronary artery disease. Chordae Tendinae: Thin chords that provide support to the tricuspid and mitral valves of the heart helping them to open and shut properly. Clubbing: An abnormality where the ends of the fingers and toes enlarge and the nails curve; often it is related to an inadequate oxygen-rich blood supply, however it can be hereditary and completely normal. Often seen with congenital heart defects, but also seen in other conditions. Coarctation of the Aorta: A severe narrowing of the aorta, causing a decrease in blood flow to the lower part of the body. This narrowing is a congenital defect and can be corrected with surgery and sometimes with balloon dilation. Collateral Blood Vessels: Small capillary-like branches of an artery that form over time in response to narrowed coronary arteries. The collaterals "bypass" the area of narrowing and help to restore blood flow. However, during times of increased exertion, the collaterals may not be able to supply enough oxygen-rich blood to the heart muscle. Commissurotomy: A surgical procedure that helps to open blocked or defective heart valves. In some patients, specifically those with rheumatic heart disease, the edges of the valve leaflets (also called the commissures) can become fused together, preventing the valve leaflets from opening and allowing blood to flow through easily. In this surgery, the commissures are cut open to allow for valve opening. Complex Carbohydrates: Starchy foods that are good sources of energy and nutrients, such as whole grain breads, rice, and pasta. Congenital Heart Defects: Heart defects present at birth. Congestive Heart Failure ( CHF or heart failure): A condition where the heart muscle weakens and can't pump blood efficiently throughout the body, causing the body to hold onto salt and fluids. Constrictive Pericarditis: The pericardium is the sac around the heart. In people with constrictive pericarditis, this sac becomes inflamed and scarred leading to shrinkage of the pericardium. This can prevent the heart from filling to its full extent. Coronary Arteries: Network of blood vessels that branch off the aorta to supply the heart muscle with oxygen-rich blood. There are two main coronary arteries: the right and the left. The left splits into two arteries called the circumflex and the left anterior descending ( LAD) arteries. Coronary Artery Disease (atherosclerosis): A build-up of fatty material, also called plaques, in the wall of the coronary artery that causes narrowing of the artery. Coronary Spasm: Repeated contractions and dilations of the coronary arteries, causing a lack of blood supply to the heart muscle. It may occur at rest and can even occur in people without significant coronary artery disease. Cyanosis: A blue tint to the skin, indicating the body is not receiving enough oxygen-rich blood. Defibrillator: A machine that is used to administer an electric shock to the heart in order to re-establish normal heart rhythm. Diabetes: A condition in which the body does not produce or respond to insulin (a hormone produced by your body, which allows blood sugar or glucose into your body's cells for energy). Diastolic Pressure: The pressure of the blood in the arteries when the heart is filling. It is the lower of two blood pressure measurements; for example, if the blood pressure is 120/80, then 80 is the diastolic pressure. Dilated Cardiomyopathy: A disease of the myocardium (heart muscle) that causes the heart cavity to become stretched and enlarged, and the pumping capacity of the heart is reduced. Dilatation: The increase in size of a blood vessel. Dipyridamole Stress Test: If you are unable to exercise on a treadmill or stationary bicycle for a stress test, a drug called dipyridamole ( Persantine) is used instead of exercise to test the heart's blood flow. Diuretic: A drug that enables the kidneys to rid the body of excess fluid. It may also be referred to as a "water pill." Dobutamine Stress Echocardiogram ( Dobutamine echo): A procedure that involves infusing a medication (dobutamine) through an intravenous ( IV) line while you are closely monitored. This drug stimulates your heart allowing evaluation of heart and valve function at rest and with exertion, when you are unable to exercise on a treadmill or stationary cycle. An echocardiogram is then performed repeatedly during a stress test to evaluate the pumping chambers of the heart. Dyspnea: Difficulty breathing. Echocardiogram (echo): An imaging procedure that creates a moving picture outline of the heart's valves and chambers using high-frequency sound waves that come from a hand held wand placed on your chest or passed down your throat. Echo is often combined with Doppler ultrasound and color Doppler to evaluate blood flow across the heart's valves. Doppler senses the speed of sound and can pick up abnormal leakage or blockage of valves. ECMO( Extra corporeal Membrane Oxygenation): In people who are unable to provide oxygen for their own blood or enough blood circulation, they can be put on life support known as extra corporeal membrane oxygenation. The blood is withdrawn from a large vein in the body and passes through a pumping mechanism, and then through a device that puts oxygen into the blood and removes carbon dioxide from the blood. The blood is then returned to the body and circulated in such a way as to sustain life. Edema: Swelling; the accumulation of fluids, usually in the hands, feet, or abdomen. Ejection Fraction ( EF): The amount of blood -- given as a percentage -- pumped out of a ventricle during each heartbeat. The ejection fraction evaluates how well the heart is pumping. Normal ejection fractions range from 55% to 65%. Electrocardiogram ( ECG, EKG): The ECG records on graph paper the electrical activity of the heart using small electrode patches attached to the skin. Electrolyte: One of the substances in the blood that helps to regulate the proper balance of body fluids. Examples of electrolytes include sodium and potassium. Electrophysiology ( EP) Study: An EP study is a test that evaluates the electrical activity within your heart. This test is used to help your doctor find out the cause of your rhythm disturbance and the best treatment for you. During the test, your doctor may safely reproduce your abnormal heart rhythm, then give you medications to see which one controls it best. Embolus: A blood clot that moves through the blood stream. Endocarditis: An infection of the inner lining of the heart or its valves. It is usually caused by bacteria and is more likely to occur in people who have heart valve defects or have had heart surgery to treat valve disease. Enhanced External Counterpulsation ( EECP): A treatment for those with symptomatic coronary artery disease (also called refractory angina), not eligible for standard treatments of revascularization (such as bypass surgery.) During EECP, cuffs wrapped around the calves, thighs, and buttocks are inflated and deflated, gently but firmly compressing the blood vessels in the lower limbs, increasing blood flow to the heart. EECP may stimulate the openings or formation of collateral vessels to create a "natural bypass" around narrowed or blocked arteries. Event Monitor ( Loop recorder): A small recorder (monitor) that monitors your heartbeat and is used to record potential abnormalities. It is attached to electrodes on your chest and is worn continuously for a period of time, or it can be implanted just under the skin. If symptoms, such as palpitations, are felt, an event button can be depressed and the heart's rhythm is recorded and saved in the recorder. The rhythm can be saved and transmitted over the phone line. Recordings can also be taken automatically without the patient knowing. Exercise Stress Echocardiogram ( Stress Echo): A procedure that combines echocardiography with exercise to evaluate the heart's function at rest and with exertion. Echocardiography is an imaging procedure that creates a picture of the heart's movement, valves, and chambers using high-frequency sound waves that come from a hand held wand placed on your chest. Echo may be combined with Doppler ultrasound and color Doppler to evaluate blood flow across the heart's valves. Exercise Stress Test: A test used to provide information about how the heart responds to stress. It usually involves walking on a treadmill or pedaling a stationary bike at increasing levels of difficulty, while the electrocardiogram, heart rate, and blood pressure are monitored. Fat: A high-energy fuel source. Fiber: An indigestible carbohydrate found in foods such as fruits and vegetables; aids in digestion and may lower LDL cholesterol. Fibrillation: Abnormally rapid, inefficient contractions of the atria or ventricles. Ventricular fibrillation is life-threatening. Flutter: One form of rapid heartbeat, often involving the top part of the heart, called the atria. Free Mammary Artery Graft: When the surgeon removes the mammary artery from its origin to use it as a bypass graft. Free Radical: A destructive fragment of oxygen produced as a by-product. Increased free radicals are thought to trigger atherosclerosis. Glucose: Blood sugar. Head Upright Tilt Test ( HUT, tilt table test, head-up tilt test): A test used to determine the cause of fainting spells. The test involves being tilted at different angles for a period of time. Heart rhythm, blood pressure, and other measurements are evaluated with changes in position. Heart Attack (myocardial infarction): Permanent damage to the heart muscle caused by a lack of blood supply to the heart for an extended time period due to a blockage in a coronary artery. Heart Block: An arrhythmia where the electrical current is slowed between the atria and ventricles. In more severe cases, conduction is blocked completely and a pacemaker is usually required.. Heart Failure (congestive heart failure, CHF): A condition where the heart muscle weakens and cannot pump blood efficiently, causing the body to retain salt and fluids. Fluid accumulates in the lungs, hands, ankles, or other parts of the body. Heart Lung Bypass Machine: A machine that oxygenates the blood and circulates it throughout the body during surgery. Heart Surgery: Heart surgery is any surgery that involves the heart or heart valves. Heart Valves: There are four valves in the heart: the tricuspid and the mitral valve, which lie between the atria and ventricles, and the pulmonic and aortic valves, which lie between the ventricles and the blood vessels leaving the heart. The heart valves help to maintain one-way blood flow through the heart. Hemoglobin: A protein in red blood cells that transports oxygen and carbon dioxide and gives blood its red color. Hibernating Myocardium: Hibernating myocardium is heart muscle that does not pump normally due to decreased blood flow, usually from a coronary artery blockage or heart attack. If normal blood flow is restored (for example, by angioplasty of a coronary blockage), then the myocardium may be able to return to normal function. High- Density Lipoprotein ( HDL): Lipoprotein particle in the blood. HDL is known as "good" cholesterol because it removes cholesterol from the bloodstream and deposits it in the liver where it is excreted by the body. High HDL is thought to protect against coronary artery disease. Holter Monitor: A small recorder (monitor) that monitors for abnormal heartbeats. It is attached to electrodes on your chest. It records the heart's rhythm continuously for 24 to 48 hours. After the monitor is removed, the heart's beats are counted and analyzed by a technician with the aid of a computer. Your doctor can learn if you are having irregular heartbeats, what kind they are, how long they last, as well as what may cause them. Homocysteine: An amino acid. High levels of homocysteine are a risk factor for coronary artery disease. Hydrogenation: A process used to harden unsaturated liquid vegetable oils into saturated fats. Hyperlipidemia: High levels of fat in the blood, such as cholesterol and triglycerides. Hypertension: High blood pressure. Hypertrophic Obstructive Cardiomyopathy ( HOCM): See IHSS below. Hypertrophy: An abnormal enlargement of an organ or thickening of its tissue. Ventricular hypertrophy is the name given to a thickened ventricle. Hypotension: Low blood pressure. Idiopathic: When the cause of a disease or process is not known. IHSS: Idiopathic Hypertrophic Subaortic Stenosis is another term used synonymously with hypertrophic obstructive cardiomyopathy ( HOCM). It is an inherited disease of the heart that causes thickening of the heart muscle and other changes to the heart that significantly impair its function. Although the disease is rare, IHSS is the most common cause of sudden cardiac arrest in young people. The term that is most frequently used now is HOCM. Immunosuppressants: Drugs that are used to keep the body's immune system from rejecting a transplanted organ, such as the heart, or to slow down the destructive processes of autoimmune disease (where the body's immune system goes awry and kills normal cells and tissue.) Implantable Cardioverter Defibrillator ( ICD): A surgically inserted electronic device that constantly monitors your heart rate and rhythm. When it detects a very fast, abnormal heart rhythm, it can deliver an electrical shock to the heart muscle to help the heart beat in a normal rhythm again. Infarction: Tissue death due to lack of oxygen-rich blood. Inotropic Medication: A drug used to strengthen the heart's contractions and improve blood circulation. Insulin: A hormone produced by the pancreas that helps the body digest sugar. Intra-aortic Balloon Pump Assist Device ( IABP): A machine that can help the pumping function of the heart. It is usually inserted through an artery in the groin area and threaded into the descending thoracic aorta in the chest. In this location the balloon inflates and deflates in synchrony with the heart in order to aid the blood pumping function of the heart in people with cardiac disease. Intracardiac Tumor: An intracardiac tumor can be any tumor of the heart, either malignant or benign. The most common tumor of the heart is a benign atrial myxoma. Intravascular: Inside a blood vessel. Intravascular Ultrasound ( IVUS): An invasive procedure, performed along with cardiac catheterization. A miniature sound probe (transducer) on the tip of a catheter is threaded through the coronary arteries and, using high-frequency sound waves, produces detailed images of the interior walls of the arteries. Ischemia: Condition in which there is not enough oxygen-rich blood supplied to the heart muscle to meet the heart's needs. Lead Extraction: A lead is a special wire that delivers energy from a pacemaker or implantable cardioverter defibrillator ( ICD) to the heart muscle. A lead extraction is the removal of one or more leads from inside the heart. Leaflets: Thin pieces of tissue or flaps that make up a valve. Left Ventricular Assist Device ( LVAD): A mechanical device placed in people with end-stage heart failure. The device aids in the pumping function of the blood. Lipid: Fat circulating in the blood. Lipoprotein: A combination of fat and protein that transports lipids (fats) in the blood. Loop Recorder ( Event monitor): See Event monitor (above) Low- Density Lipoprotein ( LDL): A lipoprotein particle in the blood responsible for depositing cholesterol into the lining of the artery. Known as "bad" cholesterol because high LDL is one of the factors that contribute to coronary artery disease. Magnetic Resonance Imaging ( MRI): A test that produces high-quality still and moving pictures of the heart and large blood vessels. MRI uses large magnets and radio-frequency waves to produce pictures of the body's internal structures. No X-ray exposure is involved. MRI acquires information about the heart as it is beating, creating moving images of the heart throughout its pumping cycle. Mammary Artery (also called internal thoracic artery): Artery located in the chest wall and used for coronary artery bypass surgery. Most commonly kept intact at its origin, and sewn to the coronary artery beyond the site of blockage. If the surgeon removes the mammary artery from its origin to use as a bypass graft, it is then called a "free" mammary artery bypass graft. Maze Procedure: A surgical treatment for chronic atrial fibrillation. The surgeon makes multiple incisions in the atrium to block the path of the atrial fibrillation rhythm, thus allowing the normal heartbeat to occur. Mechanical Valve: A mechanical valve replaces a diseased heart valve. It is made of artificial parts and functions similarly to a normal heart valve. People who have a mechanical valve implanted must take blood thinners lifelong to prevent blood clots from forming on the mechanical valve. Metabolic Exercise Stress Test (also called metabolic stress test): A test used to measure the performance of the heart and lungs while they are under physical stress. The test involves walking on a treadmill or pedaling a stationary bike at increasing levels of difficulty, while being closely monitored. Minimally Invasive Heart Surgery: Minimally invasive heart surgery is a technique where small incisions are made on the side of the chest, rather than in the middle of the chest. In addition, the breastbone is left intact, rather than cut open. The smaller incision that is used may allow the patient to heal more rapidly and decrease the time to recovery and full activity. It also helps to reduce the pain and discomfort associated with heart surgery. Mitral Insufficiency: A condition where the mitral valve does not fully close during heart contraction, allowing blood from the left ventricle to leak back into the left atrium. Mitral Stenosis: A condition where the mitral valve becomes narrowed or stenotic preventing the easy flow of blood from the left atrium into the left ventricle. Mitral Valve: The valve that lies between the left atrium and left ventricle (main pumping chamber of the heart). This valve allows blood to flow from the left atrium into the left ventricle. Morbidity Rate: The percentage of people who have complications from a medical condition or after a procedure or treatment. Mortality Rate: The percentage of deaths associated with a disease or medical treatment. Multigated Acquisition Scan ( MUGA scan): A nuclear scan that evaluates the pumping function of the ventricles. Murmur: Turbulent blood flow across a heart valve creating a "swishing" sound heard by a stethoscope. Myocardial Biopsy ( Cardiac biopsy): An invasive procedure to obtain a small piece of heart muscle tissue for analysis. Myocardial Infarction ( Heart attack): See heart attack (above). Myocarditis: Inflammation of the myocardium (heart muscle). Myocardium: Heart muscle. Myomectomy: A surgical procedure to remove abnormally thickened heart muscle. Used to treat people with idiopathic hypertrophic subaortic stenosis ( IHSS) or HOCM to relieve the obstruction to blood flow in the left ventricle during contraction. Nitroglycerin: A drug used to relax and dilate the blood vessels (vasodilator), improving blood flow. It is the most common vasodilator used to treat angina. Nuclear Scan: Nuclear imaging is a method of producing images by detecting radiation from different parts of the body after the administration of a radioactive tracer material. Obesity: Excess fat due to eating more calories than used. It is usually defined having a body mass index ( BMI -- see above) of 30 or higher. Occlusion: Blockage. Off Pump Heart Surgery: Heart surgery done without the use of the cardiopulmonary bypass machine. Pacemaker: A small electronic device is implanted under the skin and sends electrical impulses to the heart muscle to maintain a suitable heart rate and to prevent slow heart rates. Palpitation: A fluttering sensation in the chest that is often related to a missed heart beat or rapid heartbeat. Papillary Muscles: Small muscles that are part of the inside walls of the ventricles and attach to the chordae tendineae. Patency Rate: The likelihood that a vessel will remain open. Pericardiocentesis (pericardial tap): An invasive procedure that involves using a needle and catheter to remove fluid from the sac around the heart. The fluid may then be sent to a lab for tests to look for signs of infection or cancer. Pericardium: The sac that surrounds the heart. Pericarditis: Pericarditis is an inflammation of the pericardium. The pericardium is the sac around the heart. Plaque: Deposits of fats, inflammatory cells, proteins, and calcium material along the lining of arteries seen in atherosclerosis. The plaque builds up and narrows the artery Platelets: Components of blood that aid in clotting. Positron Emission Tomography ( PET or cardiac viability study): An imaging procedure that uses radioactive tracers to create 3-dimensional pictures of the tissues inside of the body and can monitor metabolic processes. Premature Ventricular Contractions ( PVCs): An irregular heartbeat in which the lower chambers of the heart (the ventricles) beat before they are supposed to. Prophylaxis: The prevention of disease. Pulmonary Edema: An abnormal swelling of tissue in the lungs due to fluid build-up. This condition often causes shortness of breath. Pulmonary Hypertension: Pulmonary hypertension is high blood pressure of the pulmonary arteries. Pulmonic Valve: The last valve through which the blood passes before it enters pulmonary artery from the right ventricle. Pulse Rate: The number of heartbeats per minute. The resting pulse rate for an average adult is between 60 and 80 beats per minute. Radial Artery: The radial artery is a blood vessel that carries oxygen-rich blood in the forearm. You can feel the pulse of the radial artery by feeling the inside of the wrist underneath the base of the thumb. Radionuclide Study ( MUGA): See MUGA above. Regurgitation: Leaking or backward flow. Restenosis: The closing or narrowing of an artery that was previously opened by a cardiac procedure such as angioplasty. Rheumatic Fever: Rheumatic fever is an inflammatory reaction that can involve the heart as a consequence of streptococcal infection. Rheumatic Heart Disease: Rheumatic fever can lead to a condition known as rheumatic heart disease. This is usually a thickening and stenosis of one or more of the heart valves and often requires surgery to repair or replace the involved valve(s). Rheumatic Valve Disease: Rheumatic valve disease is a consequence of rheumatic fever. Rheumatic valve disease is a thickening and stenosis of one or more of the heart valves and often requires surgery to repair or replace the affected valve(s). The valve could become leaky instead of stenotic as well. Right Ventricular Biopsy: The removal of a small piece of heart tissue from your right ventricle. This tissue sample is studied under a microscope to help your doctor assess your heart muscle. Risk Factor (for heart disease): Traits people have that are linked to the development and progression of coronary artery disease. There are modifiable risk factors -- related to lifestyle and may be changed or controlled -- and non-modifiable risk factors -- related to aging and genetics and cannot be changed. Rotoblation ( Percutaneous Transluminal Rotational Atherectomy or PCRA): A special catheter, with an acorn-shaped diamond-coated tip, is guided to the point of narrowing in the coronary artery. The tip spins around at a high speed and grinds away the plaque on the artery walls. The microscopic particles are washed safely away in your blood stream and filtered out by the liver and spleen. This process is repeated as needed to allow better blood flow. PCRA is rarely performed now. Saphenous Vein: Vein located in the leg(s) and used for coronary artery bypass surgery. It is surgically removed from the leg and sewn from the aorta to the coronary artery beyond the site of blockage. Selective sinus node inhibitors. - A class of drug which targets a specific area of the heart, the sinoatrial pacemaker, making it easier to control the heart rate. Septum: The muscular wall separating the right and left sides of the heart. Sestamibi Exercise Stress Test ( Sestamibi stress test, stress perfusion scan, stress Sestamibi): A diagnostic study, which uses a small amount of radioactive tracer, injected into the body, and a special camera, which detects the radiation, released by the substance to produce a computer image of the heart. Combined with exercise, the study can help determine if there is adequate blood flow to the heart at rest, as compared with activity. Silent Ischemia: Inadequate supply of oxygen-rich blood to the heart that does not cause symptoms such as chest pain. Sinoatrial Node ( SA or sinus node): A specialized cluster of cells in the heart that initiates the heartbeat. Known as the heart's natural pacemaker. Sodium (salt): A mineral found in most of the foods we eat. The largest source of dietary sodium comes from sodium chloride or table salt. Intake of sodium tends to increase the retention of water. Sphygmomanometer: A device for measuring blood pressure. Stenosis: Narrowing or restriction of a blood vessel or valve that reduces blood flow. Stent: A small tube, inserted during an angioplasty, that acts as a scaffold to provide support inside the coronary artery. More permanent stents are made of metal mesh, while others are made of dissolvable material. Sternum (breastbone): Bone in chest separated during open heart surgery. Stress Test: See Exercise Stress Test. Stroke: A sudden loss of brain function due to decreased blood flow to an area of the brain. This can be caused by either a blood clot in the brain or bleeding into the brain. Stunned Myocardium: If blood flow is returned to an area of heart muscle after a period of ischemia (lack of blood supply), the heart muscle may not pump normally for a period of days following the event. This is called "stunned" heart muscle or myocardium. Subvalvular Aortic Stenosis: A narrowing of the flow of blood below the aortic valve in the left ventricle. It is usually caused by a membrane or thickening in the muscle in this area. Syncope: Fainting. Systole: The portion of the cardiac cycle in which the heart muscle contracts, forcing the blood into the main blood vessels. Systolic Pressure: The pressure of the blood in the arteries when the heart pumps. It is the higher of two blood pressure measurements; for example, if the blood pressure is 120/80, then 120 is the systolic pressure. Tachycardia: Rapid heartbeat. A heart rate above 100 beats per minute. Thallium Exercise Stress Test ( Stress thallium test, Perfusion scan): A type of nuclear scanning technique that uses the radioactive substance thallium. A thallium stress test combines nuclear scanning with exercise on a treadmill or stationary bicycle to assess heart function and determine if there is adequate blood flow to the myocardium. Sestamibi has mostly replaced thallium as the tracer for nuclear stress tests. Thrombolytic Medication (clot-buster drug): Medication used to dissolve any clots that may be blocking blood flow in arteries and veins. Thrombus: A blood clot. Total Cholesterol: The total amount of cholesterol in the blood. Transesophageal Echocardiogram ( TEE): An invasive imaging procedure that creates a picture of the heart's movement, valves, and chambers using high frequency sound waves that come from a small transducer passed down your throat. TEE provides clear images of the heart's movement because the transducer is close to the heart and limits interference from air in the lungs. Echo is often combined with Doppler ultrasound and color Doppler to evaluate blood flow across the heart's valves. Transient Ischemic Attack ( TIA): A stroke-like event lasting minutes, or hours, that occurs when the brain is deprived of oxygen-rich blood but in which the effects wear off completely after resumption of blood-flow. Trans- Myocardial Revascularization ( TMR): A procedure used in people with severe heart disease who are not candidates for bypass surgery. In this procedure, an incision is made in the chest. The heart is exposed and small holes are drilled through the wall of the heart with a laser. Transtelephonic Monitor: A small monitor is attached to electrode leads (usually on your finger or wrist) and measures your heart beat and rhythm. This information is then transmitted over the phone line with the aid of this device to your doctor's office. Tricuspid Valve: The tricuspid valve is the valve that separates the right atrium from the right ventricle and prevents blood from flowing back into the right atrium during contraction of the ventricle. Triglyceride: A fat found in the blood. Most fat found in the diet and body is in the form of triglycerides. Unstable Angina: This type of angina is considered an acute coronary syndrome. It may be a new symptom or a change from stable angina. It may come more often, occur at rest, or feel more severe. Although this angina can be relieved with oral medications, it is unstable and may progress to a heart attack. Usually medical treatment or a procedure such as a coronary catheterization is required to address it. Valve: Structures that maintain the proper direction of blood flow and divide the chambers of the heart. There are four valves in the heart: the tricuspid and the mitral valve, which lie between the atria and ventricles and the pulmonic and aortic valves which lie between the ventricles and the blood vessels leaving the heart. Valvuloplasty: A procedure to improve valve function. Balloon valvuloplasty is when a balloon is used to at the time of cardiac catheterization to increase the area of a narrowed valve. Variant Angina: A type of angina that occurs at rest most often due to coronary spasm. Vasodilator: A type of drug that relaxes and dilates the blood vessels, allowing increased blood flow. Veins: Blood vessels that carry blood toward the heart. Ventricles: The lower, pumping chambers of the heart. The heart has two ventricles -- the right and left ventricle. Ventricular Fibrillation: An erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and are unable to contract or pump blood to the body. This is a medical emergency that must be treated with cardiopulmonary resuscitation ( CPR) and defibrillation as soon as possible. Ventricular Rupture: An area of the muscular wall of the heart that weakens and ruptures, usually due to a heart attack. If this happens, then blood from within the heart can leak into the pericardium. This is a medical emergency and usually requires urgent surgery. Ventricular Septal Defect: The right and left ventricles lie next to each other in the heart. The septum is the membranous wall that separates them. A ventricular septal defect is a hole in the septum. Ventricular Tachycardia: A rapid life-threatening rhythm originating from the lower chambers of the heart. The rapid rate prevents the heart from filling adequately with blood, and less blood is able to pump through the body. Wolff Parkinson White Syndrome ( WPW): WPW is an abnormal conduction pathway that can sometimes cause an arrhythmia. People with WPW have more than one electrical conduction pathway in their heart (accessory pathways). These electrical impulses set up a short circuit causing the heart to beat rapidly and conduct impulses in both directions. The impulses travel through the extra pathway (short cut) as well as the normal AV- HIS Purkinje system. The impulses can travel around the heart very quickly, in a circular pattern, causing the heart to beat unusually fast. This is called a re-entrant tachycardia.