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Ablation — Cardiac ablation is a therapeutic method in which a form of energy is used to physically destroy a small section of heart tissue that is a source of abnormal electrical activity causing or contributing to some types of tachycardia (fast heartbeat). Most often, cardiac ablation is used to treat rapid heartbeats that begin in the upper chambers (atria) or in the atrioventricular (AV) node. Less often, ablation is used to treat heart rhythm disorders of the lower heart chambers (ventricles). It may be done through surgery or using a transcatheter approach with an electrode catheter (catheter ablation). Electrodes at the catheter tip are used to help identify the site of abnormal activity. The electrode then delivers either radiofrequency energy (RF ablation) or intense cold (cryoablation) to destroy the small section of tissue.

Adenosine — A naturally occurring substance produced in many sites in the body that plays a role in important biochemical processes. It can cause dilation (widening) of coronary arteries as well as many other effects throughout the body such as regulating heart rhythm, toning blood vessels, maintaining wakefulness and producing urine. As a drug, adenosine is used to treat some types of arrhythmias (abnormal heart rhythms), specifically those that cause a fast heartbeat.

Aldosterone — A hormone released by the adrenal glands that works on the kidneys to help the body retain sodium and excrete potassium. It is the main regulator of the salt and water balance in the body. It also acts on the central nervous system to increase a person’s appetite for salt and to make them feel thirsty. These effects directly act to increase the amount of fluid in the blood and to increase blood pressure.

Aldosterone Antagonist (Aldosterone Receptor Blocker), (Diuretic) — Drugs that act as diuretics (water pills) by blocking the body’s response to the hormone aldosterone. Aldosterone promotes the retention of sodium and the excretion of potassium. Aldosterone antagonists increase urination, reducing water and salt while retaining potassium. They help lower blood pressure, increase the heart’s pumping ability and help protect the heart in heart failure.

  Alpha Blockers — A group of drugs used to lower blood pressure. They do this by blocking the effects of certain chemicals or hormones (specifically adrenaline or adrenaline-like substances) on alpha receptors (parts of cells that trigger physiological changes in the body). These changes can speed the heart, strengthen the heartbeat and constrict the blood vessels. These reactions cannot be triggered if the alpha blockers block the chemicals. (Also known as alpha-adrenergic antagonists, alpha-adrenergic blocking agents, and alpha-adrenergic blockers.)

Amiodarone — A Class III antiarrhythmic drug (potassium channel blocker) used to slow the heart rate and help keep it in a regular rhythm. It is used to treat fast and/or irregular heart rates from the heart’s upper and lower chambers including atrial fibrillation, ventricular tachycardia and ventricular fibrillation. Side effects are usually dose-related and regular follow-up is necessary to determine kidney, liver and lung function.

Aneurysm — An abnormal widening or ballooning-out of the wall of an artery, a vein or the heart due to weakening of the wall by disease, injury or an abnormality present at birth. Some common locations for aneurysms include the aorta (the major artery leading away from the heart), brain (cerebral aneurysm), leg, intestine and splenic artery.

Angina Pectoris (Angina) — Medical term for chest pain or discomfort due to coronary heart disease. Angina is a symptom of a condition called myocardial ischemia. It occurs when the heart muscle (myocardium) doesn't get as much blood (hence as much oxygen) as it needs for a given level of work. Insufficient blood supply is called ischemia. Stable angina (or chronic stable angina) refers to “predictable” chest discomfort such as that associated with physical exertion or mental or emotional stress. Rest and/or nitroglycerin usually relieve stable angina. Unstable angina refers to unexpected chest pain and usually occurs at rest. It is typically more severe and prolonged and is due to a reduced blood flow to the heart caused by the narrowing of the coronary arteries in atherosclerosis. Unstable angina is an acute coronary syndrome and should be treated as an emergency.

Angiogenesis — The creation of blood vessels. The body creates small blood vessels called “collaterals” to help compensate for reduced blood flow.

Angiography — An X-ray test used to detect and diagnose diseases of the blood vessels, such as weakening of the vessel walls and the narrowing or blocking of vessels, and to examine the chambers of the heart. The X-ray is taken after the vessels have been injected with a substance (dye) that allows them to be seen on film. The pictures that are obtained are called angiograms. Coronary angiography is done during a cardiac catheterization. (Also known as Angiocardiography, Angiogram and Arteriography.)

Angioplasty — A medical procedure in which a balloon is used to open narrowed or blocked blood vessels of the heart (coronary arteries). It is not considered to be a type of surgery. A catheter with a deflated balloon on its tip is passed into the narrowed artery segment, the balloon is inflated and the narrowed segment widened. Then the balloon is deflated and the catheter is removed. (Also known as  Percutaneous Coronary Intervention (PCI), Balloon Angioplasty, and Coronary Artery Balloon Dilation.)

Angiotensin — A chemical produced by the body that acts as a vasoconstrictor, causing the muscles around the blood vessels to contract, thus narrowing the blood vessels. This can cause high blood pressure. Angiotensin also stimulates aldosterone secretion.

Angiotensin-Converting Enzyme (ACE) Inhibitors — A class of drugs used to treat high blood pressure and heart failure. ACE inhibitors stop the body’s production of angiotensin, which lowers blood pressure, increases blood flow to the heart and reduces the heart’s workload.

  Angiotensin II Receptor Blockers (or Inhibitors) (ARBs) — A class of drugs used to treat high blood pressure and heart failure. They do not interfere with the body’s production of angiotensin. They block the effects of angiotensin, preventing it from constricting the muscles around the blood vessels and narrowing the blood vessels. In this way they keep the coronary arteries open, which lowers blood pressure, increases blood flow to the heart and reduces the heart’s workload. Often used in patients who cannot tolerate ACE inhibitors.  (Also known as Angiotensin-2 Receptor Antagonists).

  Ankle-brachial Index (ABI) Test— A painless exam that compares the blood pressure in the feet to the blood pressure in the arms to determine how well the blood is flowing. This test is used to diagnose peripheral artery disease (PAD). It takes only a few minutes and can be performed by a healthcare professional as part of a routine exam.

  Antiarrhythmic Medication — A group of drugs that helps control and slow heart rate. They do this by either suppressing (slowing) the activity of tissue that is initiating electrical impulses too quickly in the heart’s natural pacemaker (the sinoatrial or SA node) or by slowing the transmission of fast electrical impulses inside the heart. Antiarrhythmics include several classes of drugs such as sodium channel blockers, beta-blockers, potassium channel blockers, calcium channel blockers, adenosine and digitalis (also called digoxin and digitoxin). The type of arrhythmia you have determines which medication will be prescribed.

  Anticoagulant (Blood Thinners) — A group of drugs that decrease the ability of the blood to clot, or coagulate. They are sometimes called blood thinners, although they do not actually thin the blood. They are used to treat certain blood vessel, heart and lung conditions. They are also given to certain people at high risk for forming blood clots, such as those with artificial heart valves or who have atrial fibrillation. Anticoagulants do not dissolve clots but may prevent existing clots from becoming larger and causing more serious problems, and are often prescribed to prevent first or recurrent heart attack or stroke. Common anticoagulant drugs are heparin and warfarin.

  Antihypertensive Drugs — A group of drugs commonly prescribed to help lower blood pressure when appropriate diet and regular physical activity alone have not succeeded. They include diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blocker (ARBs), vasodilators, alpha-blockers, beta-blockers, calcium channel blockers and central alpha-agonists. Many patients with high blood pressure may require more than one drug to achieve control. Some of these drugs may also be prescribed for heart failure and arrhythmia patients.

Antiplatelet Agents — A group of drugs used to keep blood clots from forming by preventing blood platelets from sticking together. They help prevent clotting in patients who have had a heart attack, unstable angina, ischemic strokes, transient ischemic attacks (TIA) and other forms of cardiovascular disease. They are usually prescribed preventively, when plaque buildup is evident in the arteries but there is not yet a large obstruction. Aspirin and clopidogrel are examples.

Aorta — The large artery that receives blood from the heart’s left ventricle and distributes it to the body.

Aortic Stenosis (AS) — A congenital heart defect in which the aortic valve, between the left ventricle and the aorta, is narrowed. It occurs when the aortic valve didn't form properly. Sometimes stenosis is severe and symptoms occur in infancy. Otherwise, most children with aortic stenosis have no symptoms. In some children, chest pain, unusual tiring, dizziness or fainting may occur. The need for surgery depends on how severe the stenosis is. A procedure called balloon valvuloplasty has been used in some children. Children with aortic stenosis need lifelong medical follow-up.

Aortic Valve — The heart valve between the left ventricle and the aorta. It has three flaps (cusps).

Aphasia — A total or partial loss of the ability to use words. It may be caused by brain injury or disease. It's most often caused by a stroke that injures the brain's language center. Some people with aphasia recover quickly and completely after a stroke. Others may have permanent speech and language problems.

Arrhythmia (Dysrhythmia) — An abnormal heartrhythm caused by a disruption of the normal functioning of the heart’s electrical conduction system. Normally, the atria and ventricles contract in a coordinated manner. Arrhythmias result in ineffective and uncoordinated contractions of the heart muscle and may cause a slow, rapid or irregular pulse. Arrhythmias may cause decreased cardiac output and failure to pump enough blood to meet the body’s needs. Some causes of arrhythmias are coronary artery disease, rheumatic heart disease, hypertension and acute myocardial infarction. Hyperthyroidism and some medications may also cause arrhythmia.

Arterial Switch Operation (ASO) — An open-heart procedure used to correct many forms of transposition of the great arteries (TGA). In TGA, a congenital heart defect, the aorta and pulmonary artery are reversed. The aorta receives the oxygen-poor blood from the right ventricle, but this blood is carried back to the body without receiving more oxygen. Likewise, the pulmonary artery receives the oxygen-rich blood from the left ventricle but carries this blood back to the lungs. In ASO, the aorta and pulmonary artery are switched back to their normal positions so the aorta is connected to the left ventricle, and the pulmonary artery is connected to the right ventricle. The coronary arteries, which carry the oxygen-rich blood that nourishes the heart muscle, also need to be re-attached to the new aorta.

Arteriography — A testing procedure in which a dye visible to X-rays is injected into the bloodstream. Then X-ray pictures are taken and studied to see if the arteries are damaged, narrowed or blocked. Arteriography is done during cardiac catheterization. (Also known as Angiocardiography, Angiogram and Angiography.)

Arterioles — Small, muscular branches of arteries. When they contract, they increase resistance to blood flow, and blood pressure in the arteries increases.

Arteriosclerosis — Commonly called hardening of the arteries, this includes a variety of conditions that cause artery walls to thicken and lose elasticity. Arteriosclerosis can occur because of fatty deposits on the inner lining of arteries (atherosclerosis), calcification of the wall of the arteries, or thickening of the muscular wall of the arteries from chronically elevated blood pressure. It also is associated with aging. Atherosclerosis is a form of arteriosclerosis

Artery — One of a series of vessels that carry oxygenated blood from the heart to the various parts of the body. Their thick elastic walls expand as blood flows through the arteries.

Artificial Heart — A prosthetic device that is implanted into the body to replace the original biological heart. (The American Heart Association currently considers the artificial heart to be an experimental device. We monitor experimental clinical use of the artificial heart as part of our key commitment to reduce disability and death from cardiovascular diseases.)

Asystole — An abnormal heart rhythm characterized by an absence of electrical activity. Because there is no electrical activity, there is no heartbeat. This condition is followed by death if not treated and reversed immediately.

Atherectomy — A procedure to remove plaque from arteries. An ultra-thin wire is threaded through a special catheter into the blocked artery. Several devices may then be used. One is a high-speed rotating “burr” that grinds the plaque into very tiny pieces. Another is a small rotating cutter that “shaves off” pieces of the blockage. Still another is a laser catheter that vaporizes the plaque. (See Laser Angioplasty.)

  Atherosclerosis — A form of arteriosclerosis in which the inner layers of artery walls become thick and irregular due to deposits of fat, cholesterol and other substances. This buildup is called “plaque.” As the interior walls of arteries become lined with these deposits, the arteries become narrowed, reducing the blood flow through them. Eventually the plaque can erode the wall of the artery and diminish its elasticity. Plaque deposits can also rupture, causing blood clots to form that can block blood flow or break off and travel to another part of the body. This is a common cause of heart attack and stroke. If a clot blocks the blood supply to the arms or legs, it can cause difficulty walking and eventually gangrene if not treated.

Atria (singular of Atrium) — The heart’s two upper chambers that receive and pump blood into the ventricles, the lower chamber of the heart. There are two atria, one on the right side of the heart and one on the left side.

Atrial Fibrillation — A disorder of heart rate and rhythm in which the heart’s two small, upper chambers (atria) quiver rapidly like a bowl of gelatin and empty blood into the heart’s lower chambers (ventricles) in a disorganized manner instead of beating effectively. Blood that isn’t pumped completely out of the atria when the heart beats may pool and clot. If a piece of a clot enters the bloodstream, it may lodge in the brain causing a stroke (ischemic stroke). Causes of atrial fibrillation include dysfunction of the sinus node (the heart’s pacemaking area in the right atrium), coronary artery disease, rheumatic heart disease, hypertension and hyperthyroidism. Since 15 percent of strokes occur in people with atrial fibrillation, its treatment is important to stroke prevention.

Atrial Flutter — Very rapid beating of the heart's upper chambers (atria). This rhythm occurs most often in people with heart diseases such as pericarditis, coronary artery disease and cardiomyopathy. Atrial flutter is typically not a stable rhythm and often degenerates into atrial fibrillation. It may persist for months or even years.

Atrioventricular (AV) Node — The AV node is one of the major elements in the cardiac conduction system, which controls the heart rate and rhythm. This system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. Electrical impulses begin in the sinoatrial node (sinus node or SA node), known as the heart's natural pacemaker and located in the upper part of the wall of the right atrium (the heart’s right upper chamber). The electrical signal generated by the SA node moves from cell to cell down through the heart until it reaches the AV node, a cluster of cells at the bottom of the right atrium. The AV node serves as a gate (an "electrical relay station") that slows the electrical current before the signal is permitted to pass to the ventricles. This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated and prevents rapid conduction to the ventricle in cases of atrial fibrillation or atrial flutter. After passing the AV node, the electrical current travels to the ventricles along special fibers embedded in the walls of the lower part of the heart. In certain types of supraventricular tachycardia, a person could have two AV nodes; this will cause a loop in electrical current and uncontrollably rapid heartbeat.

Atrium — Either of the heart’s two upper chambers in which blood collects before being passed to the ventricles (the heart’s lower chambers).

B-type Natriuretic Peptide (BNP) — A chemical that is gaining attention as a possible marker for heart failure. Higher BNP levels seem to correlate with worse degrees of heart failure.

Bacterial Endocarditis — (See Endocarditis)

Balloon Angioplasty — (See Angioplasty)

Balloon Valvuloplasty — A non-surgical procedure performed in the cardiac catheterization laboratory to treat mitral stenosis. Long, slender tubes called catheters are placed into blood vessels in the groin and guided into the chambers of the heart. A tiny hole is created in the wall between the upper two chambers of the heart. This hole provides an opening to access the left atrium with a special catheter that has a balloon at the tip. The catheter is positioned so the balloon tip is directly inside the narrowed valve. The balloon is inflated and deflated several times to widen the valve opening. Once the opening of the valve has been widened enough, the balloon is deflated and removed. During the procedure, an echocardiogram (ultrasound of the heart) may be performed to get a better picture of the mitral valve. (Also used to treat Aortic Stenosis)

Beta-Blockers (Beta-Adrenergic Blocking Agents) — A class of drugs that slow the heartbeat, lessen the force with which the heart muscle contracts and reduce blood vessel contraction in the heart, brain and throughout the body. They do this by blocking the action of beta-adrenergic substances such as adrenaline (epinephrine) in the “sympathetic” portion of the autonomic (involuntary) nervous system at the beta receptor. By blocking the action of the sympathetic nervous system on the heart, beta-blockers relieve stress on the heart. They may be used to treat abnormal heart rhythms (arrhythmias) and prevent abnormally fast heart rates (tachycardias) or irregular rhythms such as premature ventricular beats. Since they reduce the demand of the heart muscle for oxygen, they may be useful in treating angina (chest pain), which occurs when the oxygen demand of the heart exceeds the supply. They have become an important drug in improving survival after a person has had a heart attack. Beta-blockers are also used to treat high blood pressure and other heart conditions by reducing the heart rate and the heart’s output of blood.

Bicuspid Aortic Valve — A congenital heart defect in which the aortic valve (valve between the left ventricle and the aorta) has only two flaps (cusps or leaflets) instead of the normal three. Because of this, patients with a bicuspid valve may develop a narrowed or leaking aortic valve. Narrowing or leakage do not necessarily develop in childhood, but may occur in adulthood. This sometimes requires surgical repair.

Blood Clot  — A jelly-like mass of blood tissue formed by clotting (coagulating) factors in the blood. A blood clot is a normal reaction of the body that occurs if a blood vessel is injured. This is desirable if it occurs to stop the bleeding caused by an injury. However, blood clots can become very dangerous if they occur within the bloodstream. This can happen when plaque deposits in the blood vessel walls rupture and a blood clot forms. If a piece of the blood clot breaks away and gets into the bloodstream, it can block the flow of blood to the heart or brain and cause a heart attack or stroke. A blood clot in an artery is called an arterial thrombosis. A blood clot in the vein is called a venous thrombosis. When an arterial or venous thrombosis breaks loose and travels through the bloodstream, it is called an embolus. Blood clots also can form inside the atria if blood isn’t pumped out completely and pools due to atrial fibrillation or flutter.

 Blood Pressure — The force or pressure exerted by the heart against the walls of the arteries. When the arterioles (smaller arteries) constrict (narrow), the blood must flow through a smaller “pipe” and the pressure rises. High blood pressure can result, adding to the workload of the heart and arteries. Optimal blood pressure is less than 120/80 mm Hg. High blood pressure, or hypertension, is a condition in which blood pressure levels are above the normal range. Blood pressures of 120–139 / 80–89 mm Hg are considered prehypertension. Blood pressure is considered high if it is 140/90 mm Hg or higher. High blood pressure increases the risk for heart attack, angina, stroke, kidney failure and peripheral artery disease (PAD). High blood pressure may also increase the risk of developing fatty deposit in arteries (atherosclerosis). The risk of heart failure also increases due to the increased workload that high blood pressure places on the heart.

Blood Vessels — Hollow tubes that carry blood from the heart and lungs to every cell in the body and back to the heart and lungs. These tubes are flexible and respond to circumstances and hormonal changes in the body by dilating, (becoming larger) or constricting (becoming smaller). Arteries are blood vessels that carry blood from the heart. Veins are blood vessels that carry blood back to the heart.

Blood Vessel Dilators (Vasodilators) — Drugs that cause the blood vessels (especially the arterioles) to expand by relaxing their muscular walls. This lowers blood pressure and reduces the heart's workload. ACE inhibitors and nitroglycerine are examples of vasodilators.

Body Mass Index (BMI) — A formula to assess a person’s body weight relative to height. BMI is determined by weight in kilograms divided by height in meters squared (kg/m²). It is a useful, indirect measure of body composition and in most people it correlates highly with body fat. In studies by the National Center for Health Statistics, BMI values less than 18.5 are considered underweight. Those from 18.5 to 24.9 are healthy. Overweight is defined as a body mass index of 25.0 to 29.9. A BMI of about 25 kg/m² corresponds to about 10 percent over ideal body weight. People with a BMI in this range have a moderate risk of heart and blood vessel disease. Obesity is defined as a BMI of 30.0 or greater (based on criteria of the World Health Organization), or about 30 pounds overweight. People with a BMI of 30 or more are at high risk of cardiovascular disease. Extreme obesity is defined as a BMI of 40 or greater.

Bradycardia — Slowness of the heart rate (less than 60 beats per minute). Bradycardia can be present in otherwise normal individuals and is common in well-trained athletes and in most persons during deep sleep. It can also be related to heart metabolic abnormalities and heart disease. If it presents no symptoms, it usually doesn’t require treatment. However, with symptoms such as fainting (syncope), chest pain (angina), heart failure and high blood pressure, it should be treated.

Bypass Surgery — (See Coronary Artery Bypass Graft.)

C-Reactive Protein (CRP) Test — Blood test that measures the concentration of C-reactive protein (CRP), a plasma protein known as acute phase protein, that rises in the blood with inflammation from certain conditions. Since inflammation is believed to play a role in the development of coronary artery disease (atherosclerosis), a highly sensitive assay (hs-CRP) test may be added to the screening battery of cholesterol and other lipid tests to help detect people at risk for a heart attack.

Calcium Channel Blockers (Calcium Antagonists) — A class of drugs that blocks the movement of calcium into the heart and blood vessel muscle cells. This causes the muscles to relax, lowering blood pressure, slowing the heart rate and decreasing oxygen demands of the heart. These medications lower blood pressure in patients with hypertension, but have little effect on normal blood pressure. Since they decrease the heart’s pumping strength, slow the heart rate and relax blood vessels, they are also used to treat other heart conditions, such as chest pain (angina) and abnormal heart rhythms (arrhythmias).

 Capillaries — Microscopically small blood vessels between arteries and veins that distribute oxygenated blood to the body’s tissues.

Cardiac — Pertaining to the heart.

Cardiac Arrest — Cardiac arrest is the sudden, abrupt loss of heart function. It's also called sudden cardiac arrest or unexpected cardiac arrest. Most cardiac arrests occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation) or both. This irregular heart rhythm (arrhythmia) causes the heart to suddenly stop beating. Cardiac arrest can be reversed if it's treated within a few minutes with cardiopulmonary resuscitation (CPR) and an electric shock (defibrillation) to the heart to restore a normal heartbeat. Sudden cardiac death (SCD) occurs within minutes after symptoms appear unless cardiac arrest is reversed. The term "massive heart attack" is often wrongly used in the media to describe sudden death from cardiac arrest. The term "heart attack" refers to death of heart muscle tissue due to the loss of blood supply, not necessarily resulting in a cardiac arrest or the death of the heart attack victim. A heart attack may cause cardiac arrest and sudden cardiac death, but the terms aren't synonymous. (See Sudden Cardiac Death)

Cardiac Catheterization — The process of examining the heart by guiding a thin tube (catheter) into a vein or artery and passing it into the heart and into the coronary arteries. Coronary Arteriography (angiography) and angioplasty (PCI, Balloon Angioplasty) are done during a cardiac catheterization.

Cardiac Computed Tomography (CT Scan), Computerized Axial Tomographic Scan (CAT scan) — An X-ray imaging technique that uses a computer to produce tomographic, or cross-sectional, images of the chest (including the heart and great vessels) or the brain. It’s used to diagnosis and evaluate heart diseases such as aortic diseases, cardiac masses and pericardial disease and to define the areas in the brain affected by stroke.

Cardiac Enzymes — Enzymes in the body that are sometimes called heart damage markers because they are released into the bloodstream when heart muscle cells are damaged. There has been an increased emphasis on developing blood tests that detect injury in the heart muscle as early as possible. These blood tests can confirm or refute suspicions raised early in the evaluation of heart disease, especially in the emergency setting.

Cardiac Positron Emission Tomography (PET) — A non-invasive nuclear imaging technique that uses tomographic (cross-sectional) images and radioactive tracers to study and quantify how the heart tissue works. Cardiac PET scans are used to diagnose coronary artery disease (CAD) and can be used to identify injured but viable (living) myocardium (heart muscle).

Cardiac (Cardiovascular) Rehabilitation — Cardiovascular rehabilitation is a medically supervised program to help heart patients recover quickly and improve their overall physical and mental functioning. The goal is to reduce the risk of another cardiac event or to keep an existing heart condition from getting worse. Cardiac rehabilitation programs allow patients to have medically supervised counseling, exercise, vocational guidance and assistance with making the lifestyle changes necessary for a healthy heart. Research has shown that patients who participate in rehabilitation programs have a higher survival rate and a better quality of life.

Cardiac Resynchronization (Biventricular Pacing) — A treatment for heart failure that uses a three-lead biventricular pacemaker implanted in the chest. The pacemaker sends tiny electrical impulses to the heart muscle to coordinate (resynchronize) the pumping of the chambers of the heart, improving the heart’s pumping efficiency. Both ventricles are paced to contract at the same time. This can reduce the symptoms of heart failure.

Cardiologist — A doctor who diagnoses and treats heart problems.

Cardiology — The study of the heart and its functions in health and disease.

Cardiomyopathy (Myocarditis) — A serious disease affecting the heart. It involves an inflammation and reduced function in heart muscle. There are multiple causes including viral infections. In cardiomyopathy, the heart muscle becomes inflamed and weakened, causing symptoms of heart failure, which can mimic a heart attack. Cardiomyopathy can be classified as primary or secondary. Primary cardiomyopathy can't be attributed to a specific cause, such as high blood pressure, heart valve disease, artery diseases or congenital heart defects. Secondary cardiomyopathy is due to specific causes. It's often associated with diseases involving other organs as well as the heart. There are three main types of cardiomyopathy — dilated, hypertrophic and restrictive. Treatment includes evaluation and treating the underlying cause.

Cardiomyoplasty — An investigational procedure in which skeletal muscles are taken from a patient's back or abdomen and wrapped around an ailing heart. This added muscle, aided by ongoing stimulation from a device similar to a pacemaker, may boost the heart's pumping motion. This procedure is experimental, and is performed in limited numbers. Recent research suggests that it may not be as effective as originally hoped.

Cardiopulmonary Bypass (Heart/Lung Machine) — A procedure to circulate and oxygenate the blood while surgery is performed on the heart. It involves diverting blood from the heart and lungs through a heart/lung machine and the return of oxygenated blood to the aorta.

Cardiopulmonary Resuscitation (CPR) — An emergency lifesaving procedure that is performed when a person’s own breathing or heartbeat have stopped. It uses a combination of chest compressions and mouth-to-mouth breathing (rescue breathing). The chest compressions keep oxygenated blood circulating and the breathing provides oxygen to the lungs until an effective heartbeat and breathing can be restored or the patient can be put on advanced cardiac life support.

Cardiovascular — Pertaining to the heart and blood vessels. (“Cardio” means heart; “vascular” means blood vessels.) The circulatory system of the heart and blood vessels is the cardiovascular system.

Cardioversion — Delivering an electrical shock to a person’s heart to rapidly restore an abnormal heart rhythm (arrhythmia) back to normal. External cardioversion is performed with a defibrillator, either in an emergency situation or as a scheduled treatment for arrhythmia. Internal cardioversion is delivered by a device similar to a pacemaker, called an implantable cardioverter defibrillator (ICD). ICDs are used to treat arrhythmias in the lower heart chamber (ventricle) such as ventricular tachyarrhythmia or fibrillation. These arrhythmias can cause sudden cardiac death (SCD) because of the dangerously fast heart rate. Internal cardioversion is also used to treat arrhythmias of the upper heart chamber (atrium) in some cases. The device used in this case is called an atrial defibrillator.

Carotid Artery — One type of major artery in the neck carrying blood from the heart to the brain. The other type is vertebral artery.

Carotid Artery Disease (Carotid Artery Stenosis) — A carotid artery narrowed by a buildup of plaque. Carotid artery disease, a type of atherosclerosis, is a major risk factor for ischemic stroke.

Carotid Artery Stent — The carotid artery is a major artery in the neck that carries blood to the brain. Carotid angioplasty is used to open a narrowed artery to allow more blood to flow through to help prevent stroke. Stents are used to prop an artery open after angioplasty. A stent is a wire mesh tube that is collapsed into a small diameter, put over a balloon catheter and moved into the area of blockage. When the balloon is inflated, the stent expands and locks in place, holding the artery open. The stent stays in the artery permanently to prop it open and improve blood flow.

Carotid Bruit — An abnormal sound in the neck of a person with carotid artery disease, created by the blood as it flows through the diseased artery.

Carotid Phonoangiography — A test using a sensitive microphone placed on the neck, very close to the carotid artery. It records sounds and detects blockages, such as those caused by carotid artery disease.

Catheterization  — (See Cardiac Catheterization)

Central Agonists (Central Alpha-Agonists) — Drugs that lower heart rate and reduce blood pressure. They work by preventing the brain from sending signals to the nervous system to speed up the heart rate and narrow the blood vessels. As a result, the heart doesn’t pump as hard and blood flows more easily through blood vessels.

Cerebral — Pertaining to the brain.

Cerebral Angiography — A procedure used most frequently to confirm cases of stroke, tumor, bulging of the artery walls (aneurysm), a clot or narrowing of the arteries and to evaluate the arteries of the head and neck before surgery. It is used to get more exact information after something abnormal, such as bleeding within the brain, has been detected by an MRI or CT scan of the head. The arteries are not normally seen in an X-ray, so a contrast dye is injected into one or more arteries to make them visible. For the cerebral angiography, the dye is injected into one or both of the carotid, or vertebral, arteries in the neck (leading to the brain). (Also known as carotid angiography, vertebral angiogram and head angiography.)

Cerebral Aneurysm (Brain Aneurysm) — A brain aneurysm is a ballooning-out of the wall of an artery in the brain. Often this wall is weakened by disease, injury or an abnormality present at birth. Aneurysms are often caused or made worse by high blood pressure. They aren't always life‑threatening, but serious consequences, such as stroke, can result if one bursts in the brain. This is called a hemorrhagic (or bleeding) stroke. When a blood vessel on the brain's surface ruptures and bleeds into the space between the brain and the skull (but not into the brain itself), it's called a subarachnoid hemorrhage. When an artery in the brain bursts, flooding the surrounding tissue with blood, it's called a cerebral hemorrhage.

Cerebral Embolism — An embolism occurs when foreign material, such as a broken-off piece of plaque or a blood clot travels through the bloodstream and becomes lodged in a blood vessel blocking the flow of blood. When an embolism blocks the flow of blood to the brain, it is called a cerebral embolism. A type of stroke.

Cerebral Hemorrhage — Bleeding within the brain, resulting from a ruptured aneurysm or a head injury. It results in a hemorrhagic stroke.

Cerebral Thrombosis — Formation of a blood clot inside a blood vessel or artery that supplies part of the brain, blocking the flow of blood. A type of stroke.

Cerebrovascular — Pertaining to the brain and its major blood vessels.

Cerebrovascular Accident (CVA) — The medical term for a stroke (apoplexy). Strokes can be either ischemic (loss of blood supply) or hemorrhagic (bleeding into the brain). (See Stroke)

Cerebrovascular Occlusion — The obstruction or closing of a blood vessel leading to or within the brain, resulting in a stroke.

Cholesterol — A soft, waxy substance found among the lipids (fats) in the bloodstream and in all the body's cells. It's an important part of a healthy body because it's used to form cell membranes, some hormones and is needed for other functions. Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. There are several kinds, but the most important are low-density lipoprotein (LDL or “bad”) and high-density lipoprotein (HDL or “good”). (See LDL Cholesterol and HDL Cholesterol.)

Cholesterol Classifications — Total blood cholesterol is the most common measurement of blood cholesterol. Cholesterol is measured in milligrams per deciliter (mg/dL) of blood. Total cholesterol is composed of high-density lipoprotein (HDL or "good") cholesterol, low-density lipoprotein (LDL or "bad") cholesterol and very-low density lipoprotein (VLDL), which carries triglycerides. Triglycerides, a common type of blood fat, can also affect cardiac risk. Blood cholesterol and triglycerides are classified by levels that relate to the risk for heart disease. The numbers are interpreted based on all risk factors including age, family history, smoking status, blood pressure, physical activity level, weight, and diabetes status.

Cholesterol-Lowering Drugs — Cholesterol-lowering drugs reduce LDL (“bad”) cholesterol, increase HDL (“good”) cholesterol and reduce triglycerides (a blood fat) depending on the class of drugs. Several classes of drugs are used to treat cholesterol including statins. People may be prescribed a “combination” therapy of drugs depending on their specific situations. Cholesterol-lowering drugs have been proven to reduce risks for heart disease. Due to potential side effects, patients who are taking most cholesterol-lowering drugs may need to have periodic liver function tests.

Circulatory System — Pertaining to the heart, blood vessels and the blood’s circulation.

Clinical Nurse Specialist (CNS) — An advanced practice nurse with special expertise in-patient care, family education and staff support.

Closed-Heart Surgery — An operation on the heart (or more typically the great vessels) without the need for cardiopulmonary bypass. Examples of closed-heart surgery include repairs of coarctation of the aorta and patent ductus arteriosus.

Coarctation of the Aorta (“Coarct”) — A congenital heart defect (birth defect) in which the major artery from the heart (aorta) is narrowed (constricted) somewhere along its length. This obstructs blood flow to the lower part of the body and increases blood pressure above the constriction.

Collateral Circulation — The process in which a system of small, normally closed arteries opens up and starts to carry blood to part of the heart when a coronary artery is blocked, or to part of the brain when a cerebral artery is blocked. They can serve as alternate routes of blood supply.

Congenital Heart Disease (CHD) — A broad term for a number of different abnormalities present at birth (congenital) affecting the heart. Though present at birth, the effects of these abnormalities may not be obvious immediately. In some cases, the defects may not be evident for years, may never cause any problems and are compatible with normal physical activity and a normal life span. Congenital heart disease is responsible for more deaths in the first year of life than any other birth defects. Many of these defects need to be followed carefully. Though some heal over time, others will require treatment. Congenital heart disease is often divided into two types: those with cyanosis (blue discoloration caused by a relative lack of oxygen) and those without cyanosis.

Congestive Heart Failure (Heart Failure) — Because not all patients with heart failure have problems with excess fluid, such as in the lungs or extremities, the term "heart failure" is preferred over "congestive heart failure." Heart failure is the inability of the heart to pump out all the blood that returns to it. This results in blood backing up in the veins that lead to the heart and sometimes in fluid accumulating in various parts of the body. (See Heart Failure.) Congestive heart failure is a sub category of heart failure.

  Coronary Arteries — Two arteries arising from the aorta that arch down over the top of the heart and branch out in additional arteries that provide blood to the heart muscle.

 Coronary Artery Disease (CAD) — Conditions that cause narrowing of the coronary arteries, reducing blood flow to the heart muscle. A type of atherosclerosis. Severe cases can result in heart attack.

  Coronary Artery Bypass Graft (Bypass Surgery) — Surgery that reroutes (bypasses) blood around clogged coronary arteries and improves the supply of blood and oxygen to the heart muscle. It’s sometimes called open-heart surgery or CABG (for coronary artery bypass graft) or “cabbage.”

Coronary Care Unit (CCU) — A specialized facility in a hospital or emergency mobile unit that’s equipped with monitoring devices and staffed with trained personnel. It’s designed specifically to treat heart patients.

Coronary Heart Disease (CHD) — Disease of the heart caused by atherosclerotic narrowing of the coronary arteries likely to produce chest pain (angina pectoris) or heart attack.

Coronary Occlusion (or Coronary Thrombosis) — An obstruction of a coronary artery that hinders blood flow to some part of the heart muscle. A cause of heart attack.

Creatinine — Creatinine is a breakdown product of creatine phosphate generated from muscle metabolism. Creatinine is usually filtered out by the kidneys and leaves the body. If a patient's kidneys are not working well, creatinine will build up in the blood and can serve as a warning sign for lack of kidney function and cardiovascular disease (CVD). Normal creatinine levels are less then 1.2 mg/dL. Kidney problems can be a complication of heart failure. In heart failure the kidneys are less able to dispose of sodium and water, causing fluid retention in the tissues.

Creatine Kinase (CK), (Creatine phosphokinase CPK) — A blood enzyme. Tests for CK and the fraction CK-MB are used to confirm the existence of heart muscle damage as rapid detection of a heart attack.

Cyanosis — A bluish discoloration of the skin or mucous membranes caused by lack of oxygen in the blood. This is caused when much of the blood circulating through the body is “blue” (or oxygen‑poor) rather than “red” (or oxygen‑rich).



This content is reviewed regularly. Last updated 04/28/08.