Glossary of Cardiomyopathy Terms

Cardiomyopathy Glossary

Navigating technical medical terminology can help you better understand the world of HCM and DCM. Take a look at our cheat sheet below:

Select a letter to display all entries in the Glossary which begin with that letter.

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Ablation The removal or destruction of tissue. Also refers to a procedure that eliminates extra electrical pathways within the heart that cause fast or irregular heart rhythms.

Actin A cellular protein that forms microfilaments and is active in muscular contraction, cellular movement, and maintenance of cell shape.

Angiogram A medical test used to see the structure of arteries and veins. When the test is used for blood vessels into or out of the heart is it generally referred to as a coronary angiogram. The test is done using a catheter (long flexible tube inserted into a blood vessel in the neck or groin) to inject dye into the vessel and having an x-ray to image that area.

Anonymized Unidentified so as to preserve anonymity.

Antiarrhythmic A drug used to treat abnormal heart rhythms.

Aorta The largest artery in the body and the primary blood vessel which carries oxygenated blood out of the heart.

Aortic regurgitation or Aortic insufficiancy Backwards leakage of blood from the aorta, through a weakened aortic valve and into the left ventricle.

Aortic stenosis Narrowing of the opening of the aortic valve.

Aortic valve The valve that lies between the the left ventricle and the aorta.

Arrhythmia An irregular heartbeat.

Asymmetric Septal Hypertrophy (ASH) An asymmetric thickening of the septum. Found in approximately two thirds of patients with HCM. Known more commonly today as HCM with obstruction.

Atrial fibrillation An irregular beating of the atria (the upper two chambers of the heart). It is the most common cardiac arrhythmia.

Atrial flutter A very fast but organized beating of the atria (the upper two chambers of the heart).

Atrial septum The wall between the right and left atria.

Atrioventricular (AV) Node A group of specialized cells located near the center of the heart that helps to regulate the heart rhythm.

Atrium (atria plural) The top two chambers of the heart.

Autosomal Dominant This relates to how a genetic disease if passed down from generation to generation.  If a disease is autosomal dominant only one of the parents needs to carry a mutation to pass it on in a family, and children have a 50-50 chance of inheriting that affected gene. 


Beta blocker A medication that slows the heart rate and lowers blood pressure.

Bicuspid valve Another name for the mitral valve

Bradycardia An abnormally slow heartbeat.


Calcium channel blocker A medication that lowers blood pressure and reduces spasms of the blood vessels by selectively blocking the uptake of calcium by the cells.

Cardiac Catheterization a procedure used to diagnose and treat cardiovascular conditions. During this test, a long thin tube (catheter) is inserted into an artery or vein in the patients groin, neck or arm and threaded through a blood vessels into the heart.

Catheterization (Left Heart) The catheter is inserted across the aortic valve into the left side of your heart (left ventricle). This is done to evaluate hemodynamics (force of blood) into and out of the left ventricle.

Catheterization (Right Heart) The catheter is inserted into the right side of the heart (right atrium and right ventricle) and on into the pulmonary artery. This is done primarily to asses the blood flow through the heart and measure the pressures inside the heart and lungs.

Cardiac output The amount of blood pumped by the heart in one minute. Cardiomyopathy An abnormal heart condition that weakens and enlarges the heart muscle. There are three main types of cardiomyopathy — dilated, hypertrophic and restrictive.

Congestive heart failure(CHF or heart failure) A condition where the heart muscle weakens and cannot pump out all of the blood that enters it, which leads to an accumulation of blood in the vessels leading to the heart and fluid in the body tissues.


Defibrillator An electronic device used to re-establish normal heartbeat.

Dilated Cardiomyopathy A disease of the myocardium (heart muscle) that causes the heart cavity to become stretched and enlarged, reducing the hearts pumping capacity.

Diuretic A medication that helps the kidneys to remove excess fluids from the body.


Echocardiogram (echo) A procedure that evaluates the structure and function of the heart by using sound waves recorded through a hand held wand placed on your chest or down your throat. It produces a moving picture of the heart and heart valves.

Edema The accumulation of fluids, usually in the hands, feet, or abdomen.

Ejection fraction The measurement of the amount of blood pumped out of the ventricles each time the heart beats. Normal ejection fractions are 55% and higher.

Electrocardiogram (ECG or EKG) A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle stress through small electrode patches attached to your skin.

Electrophysiological study (EPS) A cardiac catheterization to study the electrical conduction system of the heart.

Event Monitor (Loop recorder) A small recorder (monitor) that is attached to electrodes on your chest. It is worn continuously for a period of time. If symptoms are felt, an event button is pressed, thereby saving the heart rhythm in the recorder.

Exercise Stress Echocardiogram (Stress Echo) A procedure that combines echocardiography with exercise to evaluate the heart's function during exertion and while at rest.


Fibrillation Abnormally rapid and inefficient contractions of the heart muscles.


Hemodynamics The pressure and flow of blood throughout the heart and blood vessels

Heritable A condition that can be passed on, or inherited, from one generation to the next

Holter monitor A portable EKG machine worn for a 24-hour period to record irregular, fast, or slow heart rhythms while engaging in normal activities.

Hypertrophic Cardiomyopathy (HCM) An inherited disease of the heart that causes thickening of the muscle and other changes to the heart that significantly impair its function.

Hypertrophic Obstructive Cardiomyopathy (HOCM) More commonly known as HCM with obstruction. Generally a patient is diagnosed with HOCM if their septal thickening causes obstruction of blood flow. This definition is at times also known as Asymmetric Septal Hypertrophy (ASH). Patients with obstruction generally display Systolic Anterior Motion (SAM). See definition below.


Implantable Cardioverter Defibrillator (ICD) A surgically inserted electronic device that continuously monitors your heart rate and rhythm. When it detects a very fast, abnormal heart rhythm, it delivers electrical shock to the heart muscle to help re-establish a normal rhythm.

Infarction Tissue death caused by the lack of oxygen-rich blood.

Ischemia Condition in which the supply of oxygen-rich blood to the heart muscle is insufficient to meet the heart's needs.


Left Ventricular Assist Device (LVAD) A mechanical device placed in people whose hearts do not pump a sufficient amount of blood to keep the body healthy (heart failure). The device takes blood from a lower chamber of the heart and helps pump it to the body and vital organs.


Magnetic resonance imaging (MRI) A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed still and moving images of organs and structures within the body.

Mitral valve The valve that controls blood flow between the two left chambers of the heart.

Mitral valve prolapse An abnormality of the valve between the left upper and left lower chambers of the heart that causes blood to leak backwards from the left ventricle into the left atrium.

Murmur A blowing or swishing sound heard while listening to the heart that may or may not indicate problems within the heart or circulatory system.

Myomectomy or Myectomy A surgical procedure for people with HCM to remove abnormally thickened heart muscle. The surgery relieves the obstruction to blood flow in the left ventricle during contraction.

Myosin  The prototype of a protein that converts chemical energy to mechanical energy, thus generating force and movement. Acts in conjunction with Actin to create muscle contraction.


Pacemaker An electronic device that is surgically placed in the patient's body and connected to the heart to maintain a regular heart rate and prevent a slow heart rate.

Palpitation A fluttering sensation in the chest caused by an irregular heartbeat.

Positron Emission Tomography (PET or cardiac viability study) An nuclear medical imaging procedure that uses radioactive tracers to create 3-dimensional images of the tissues inside the body.

Premature Ventricular Contractions (PVCs) An irregular heartbeat in which the the ventricles beat before they are supposed to.

Prophylaxis A medication or other treatment delivered to prevent of disease.


Regurgitation Leaking or backward flow of blood caused by a defective heart valve.


Sarcomere The basic muscle filaments that are composed of long, fibrous proteins that slide past each other when the muscles contract and relax.

Stenosis Narrowing or restriction of a blood vessel or valve in the heart thereby reducing blood flow.

Systolic Anterior Motion (SAM) Abnormal movement of the anterior leaflet of the mitral valve.


Tachycardia A rapid heartbeat of over 100 beats per minute.

Transesophageal echocardiography (TEE) An imaging procedure that uses a long tube guided into the mouth, throat, and esophagus to evaluate the structures inside the heart with sound waves.

Tricuspid valve The valve between the right atrium and left ventricle of the heart that functions to prevent back flow of blood into the right atrium.


Valves The structures between the chambers of the heart that maintain the proper direction of blood flow. The 4 heart valves are the tricuspid, pulmonic, mitral, and aortic.

Vasodilator A medication that relaxes and widens the opening in a blood vessel, allowing better circulation.

Ventricle One of the two lower pumping chambers of the heart.

Ventricular fibrillation A condition in which the ventricles contract in rapid and uncoordinated rhythms and cannot pump blood into the body.

Ventricular tachycardia A fast heart rhythm that begins in one of the ventricles.

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