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Illustrated Glossary

Look up the meaning of heart-related terms that you might have seen or heard. Some terms also include detailed illustrations.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A
	Abdominal aortic aneurysm (AAA) A balloon-like enlargement of the aorta that weakens the wall of the artery. If untreated, this enlargement can lead to aortic rupture, which results in death in nearly 80% of cases.
	ABI (ankle brachial index) A noninvasive test that expresses the ratio of blood pressure measurements in ankles to arms to screen for the presence of peripheral vascular disease.
	Ablation (cardiac) The removal, isolation, or destruction of heart muscle cells that cause electrical conduction problems; a procedure to destroy abnormal cells by using radiofrequency (RF) energy and catheters.
	Ablation catheter A special catheter that allows energy to pass through it. The catheter is used to treat a disease state. Also known as a therapeutic catheter.
	Accelerometer A device for measuring acceleration. In pacing, used as a sensor in adaptive-rate pacemakers to measure body motion or movement.
	Active-fixation lead A pacemaker or defibrillator lead with a screw-like mechanism at the tip that attaches the lead to the inner surface of heart. See also passive-fixation lead >>
	Aneurysm A swelling or enlargement of a blood vessel.
	Angina (angina pectoris) Chest pain caused by an inadequate supply of blood to the heart.
	Angiogram An X-ray image of blood vessels or of chambers of the heart that shows the course of a special fluid, called a contrast medium or dye, injected into the bloodstream.
	Angiography A diagnostic procedure in which catheters are passed through blood vessels to take pictures of the vessels or chambers of the heart.
	Angioplasty A minimally invasive procedure whereby a balloon dilatation catheter is passed through to the blocked area of an artery. Once inflated, the catheter compresses the plaque against the blood vessel wall, re-establishing blood flow. An angioplasty can also be performed with a stent or atherectomy. Also called percutaneous transluminal coronary angioplasty, or PTCA.
	Antiarrhythmic (medicine) A drug that prevents an abnormal heart rhythm from occurring. These drugs help the heart beat more regularly.
	Anticoagulant A substance that slows the clotting of blood.
	Antitachycardia pacing A method of treating ventricular tachycardia (an abnormally fast heartbeat) by stimulating the heart with a preset rapid series of electrical pulses, re-establishing a normal heartbeat.
	Aorta The largest artery in the body, which delivers oxygenated blood from the left ventricle of the heart to the tissues of the body.
	Aortic valve The heart valve between the left ventricle and the aorta.
	Apex Pointed part of the heart's left lower chamber (ventricle).
	Arrest (cardiac) Sudden cessation or stopping of the heart’s pumping function due to a rhythm dysfunction call ventricular fibrillation; sudden cardiac arrest (SCA) can cause death within minutes after onset of symptoms.
	Arrhythmia An abnormal rhythm of the heart with respect to rate, regularity, or site of impulse origin. Types of arrhythmias include tachycardia (fast heart rhythm) and bradycardia (slow heart rhythm).
	Arteriogram A diagnostic test that uses X-rays and contrast medium or dye to show blood flow through arteries.
	Artery A blood vessel that carries blood away from the heart to various parts of the body. Arteries usually carry oxygenated blood — except for the pulmonary artery, which carries unoxygenated blood from the heart to the lungs for oxygenation.
	Asynchrony A condition in which the heart fails to maintain a normal time sequence between atrial and ventricular contractions or between the ventricles when they contract.
	Asystole Absence of ventricular contractions of the heart.
	Atherectomy A minimally invasive coronary artery disease (CAD) intervention procedure that involves the excision and removal of blockages by catheters with miniature cutting systems.
	Atherosclerosis Narrowing or blockage of arteries caused by a build-up of fat (cholesterol) within the artery wall. This build-up is sometimes referred to as plaque.
	Atria The upper two chambers of the heart muscle that collect blood as it enters the heart and fill the lower chambers (ventricles) with blood. The atria are separated by a membranous wall known as the atrial septum. Singular: atrium.
	Atrial asystole Absence of atrial contractions.
	Atrial fibrillation (AF or AFib) An arrhythmia in the atrium caused by many disorganized electrical impulses originating and spreading through the heart muscle. Atrial fibrillation can cause an irregular and rapid heartbeat ranging from 100 to 400 beats per minute (as much as 4x faster than a normal heart). The fastest growing patient population and most common arrhythmia.
	Atrial flutter (AFL) A type of tachycardia which causes the atria (upper chambers) to beat faster than the ventricles (lower chambers). The range can be anywhere from 100-450 bpm. Type 1 Atrial Flutter is the most common form of atrial flutter. Originates in the right atrium. Involves a counterclockwise circuit that repeats itself, causing the heart to flutter.
	Atrial lead A lead designed for use in the atrium; it may be endocardial (within the heart) or epicardial (attached outside the heart).
	Atrial tachycardia A rapid heartbeat that originates in the atria.
	Atrioventricular (A-V) block A partial or total disruption of the conduction of electrical impulses from the atria to the ventricles.
	Atrioventricular (A-V) node A cluster of cells located in the wall between the right and left atria, just above the ventricles. This part of the heart's electrical pathway helps carry signals from the atria to the ventricles.
	Atrioventricular nodal re-entrant tachycardia (AVNRT) A type of supraventricular tachycardias (SVT). Accounts for about 60% of all fast heart rates that start in the upper part of the heart. AVNRT occurs when the A-V node has an extra electrical pathway in the heart linking the right atrium to the A-V node, a kind of "short circuit." The paths are different and unique; one is fast and the other slow. Symptoms include attacks of palpitations, dizziness, and syncope; heart rates can achieve 150-230 beats per minute. These attacks start and stop suddenly.
	Atrioventricular (A-V) synchrony The normal time sequence for an atrial contraction followed, after a fraction of a second, by a ventricular contraction.
	Atrioventricular (A-V) valves The two valves, one in each side of the heart, between the atria and ventricles. The tricuspid valve is located on the right side of the heart, and the mitral value is located on the left side.
	Atrium One of the upper two chambers of the heart (plural: atria). The right atrium collects deoxygenated blood and the left atrium collects oxygenated blood before it is passed to the ventricles.
	Automatic implantable cardioverter defibrillator (AICD) A surgically implanted device that monitors the heartbeat and delivers electrical impulses to correct an abnormally fast rhythm and restore a regular heartbeat. The AICD system usually consists of an implanted pulse generator and one or more leads. The system is adjusted using an external programming device. Also known as an implantable cardioverter defibrillator (ICD).
	A-V node See atrioventricular (A-V) node >>

B
	Bacterial endocarditis A bacterial infection of the heart lining or valves. People with abnormal heart valves or congenital heart defects are at increased risk of developing this disease.
	Balloon dilatation catheter An inflatable device used for stretching and compressing plaque against blood vessel walls during angioplasty.
	Battery The power source of implantable pulse generators. Lithium-iodine batteries are used most often in modern pacemakers.
	Biomarker (biochemistry marker) A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease. A biomarker may be used to see how well the body responds to a treatment for a disease or condition. Also called molecular marker and signature molecule.
	Blood clot A jelly-like mass of blood tissue formed by clotting factors in the blood, which can stop the flow of blood. Blood clots can cause a heart attack or stroke when they form inside an artery whose walls are damaged by atherosclerosis.
	Blood pressure The force exerted by the heart in pumping blood; the pressure of blood in the arteries.
	Blood volume The amount of blood circulating throughout the body, typically about 5 liters for an adult.
	bpm (beats per minute) Usually refers to an intrinsic heart rate that is not being paced. For adults, the typical heart rate is about 70 bpm.
	Brachial Pertaining to the arm.
	Bradycardia (bradyarrhythmia) A slow heartbeat, typically less than 60 beats per minute. It may be caused by the sinoatrial (SA) node not working properly, or by a condition called heart block. Can be considered normal or abnormal.
	Bradycardia pacing A method of treating a slow or irregular heartbeat by periodically stimulating the heart with small electrical pulses.
	Brady-Tachy Syndrome An arrhythmia characterized by alternating periods of bradycardia (slow rhythms) and supraventricular tachycardias (rapid rhythms) in patients with S-A node dysfunction.
	Bruise An injury to tissue. A pooling of blood cells under the tissue.
	Bundle branches The nerve pathways that supply the electrical stimulation to the left and right sides of the heart.
	Bundle of His A group of conduction fibers that descend from the atrioventricular (AV) node to the bundle branches.
	Bypass See coronary artery bypass graft (CABG) >>

C
	Capillaries Tiny blood vessels whose walls are so thin that oxygen, nutrients, and waste products flow through them.
	Cardiac Pertaining to the heart.
	Cardiac ablation A procedure that neutralizes (or ablates) the specific cells in the heart that cause an arrhythmia. Also called cardiac catheterization.
	Cardiac arrest An electrical problem of the heart. "Sudden" cardiac arrest (SCA) is not the same as a heart attack. SCA can lead to sudden cardiac death.
	Cardiac arrhythmia An abnormal heartbeat. Types of arrhythmias include tachycardias (fast heartbeats) and bradycardias (slow heartbeats).
	Cardiac catheterization A test in which a small tube (catheter) is inserted through the veins or arteries and into the heart to measure pressure, take blood samples, and test for abnormalities in the heart.
	Cardiac catheterization laboratory (cath lab) A sterile X-ray procedure room in which heart catheterization is performed.
	Cardiac conduction system The specialized network of cells in the heart that initiates an electrical signal in the heart and carries it throughout the heart, causing it to beat.
	Cardiac Output Volume of blood ejected by the heart per minute. Cardiac output = heart rate x stroke volume, usually measured in liters per minute.
	Cardiac rhythm management (CRM) The field of cardiovascular disease therapy that relates to the detection and treatment of abnormally fast (tachycardia) and abnormally slow (bradycardia) heart rhythms (electrical patterns in the heart).
	Cardiologist A physician trained in the prevention, diagnosis, and treatment of heart disease.
	Cardiomyopathy A chronic disorder that causes the muscle of the heart to become weakened and not work as efficiently as it should.
	Cardiopulmonary bypass (CPB) Often referred to as the "heart-lung machine," a circulatory support system that works in place of a patient's heart and lungs, providing blood flow to the whole body during open-heart surgery.
	Cardiothoracic surgeon A surgeon who specializes in surgery of the heart and lungs.
	Cardioversion The use of electrical shock to correct a fast, irregular heart rhythm.
	Cardioverter A device that delivers an electrical shock to the heart to restore its normal rhythm. Can be external or implanted in the body.
	Carotid arteries Arteries in your neck that supply blood to the brain.
	Carotid artery disease A condition that reduces the blood flow through the carotid arteries to the brain.
	Carotid endarterectomy A surgical procedure in which the fatty plaque causing the blockage of the carotid artery is removed.
	Catheter A long, thin, flexible tube with wires and metal bands or electrodes that is inserted into the groin vein and threaded up through the blood vessel and into the heart under X-ray guidance. Mapping/diagnostic catheters are used to identify the location of the abnormality, and ablation catheters are used to destroy the tissue in the affected location.
	Catheter Ablation A procedure in which abnormal cells are destroyed by radiofrequency (RF) energy. The energy is transferred to the tissue via a catheter.
	Catheterization Use or insertion of a tubular device into a duct, blood vessel, hollow organ, or body cavity. During catheterization, fluids are injected or withdrawn for diagnostic or therapeutic purposes. See cardiac catheterization >>
	Cerebral embolism A blood clot formed in one part of the body and then carried by the bloodstream to the brain, where it blocks an artery.
	Cerebral hemorrhage Bleeding from an artery in the brain, caused by a head injury or a burst aneurysm.
	Cerebral thrombosis A blood clot (thrombus) that forms and blocks blood flow in an artery that supplies blood to part of the brain. It is the most common cause of stroke.
	Cerebrovascular accident A sudden, severe attack of paralysis, loss of vision, sensation, or speech resulting from brain cell damage caused by insufficient blood supply to the brain or from injury to the brain or spinal cord. Also called cerebral vascular accident, apoplexy, or stroke.
	Chamber An area of the heart through which blood passes.
	Cholesterol A waxy substance found only in food that comes from animals.
	Chronotropic Incompetence Inability of the heart to give a heart rate that matches the needs of the body.
	Circulation The movement of blood through the vessels. Circulation is induced by the pumping action of the heart, enabling the flow of nutrients and oxygen through the body.
	Circulatory System The circulatory system is composed of the heart, arteries, capillaries and veins. It transports blood low in oxygen from the body to the lungs and heart via the veins. Oxygenated blood from the lungs and heart are sent throughout the body via the arteries.
	Claudication Pain in the legs that occurs with work or exercise.
	Clinical Trial Research study conducted with patients. Clinical trials evaluate a new treatment or drug. Each trial is designed to answer scientific questions. The goal of a clinical trial is to find better ways to treat people with a specific disease.
	Computerized tomography (CT) scan A diagnostic test that uses special X-rays and contrast dye to show different areas in the body.
	Congenital Refers to conditions that are present at birth, regardless of their cause. Congenital heart defects are malformations of the heart or of its major blood vessels that are present at birth.
	Congestive heart failure (CHF) A condition in which the heart cannot pump enough blood to meet the needs of the other organs. Congestion offers refers to symptoms associated with the lungs. Also known as heart failure.
	Constriction Narrowing of a vessel or structure.
	Contraction The rhythmic squeezing of the heart muscle that causes blood to be pumped out of the heart chambers and into the body. Each contraction produces a heartbeat.
	Coronary Of, relating to, or being the vessels of the heart.
	Coronary arteries The blood vessels that carry oxygenated blood from the aorta to the heart muscle. There are three major coronary arteries: the right coronary artery, the left anterior descending artery, and the circumflex artery.
	Coronary artery bypass graft (CABG) An operation performed to circumvent blocked coronary arteries and deliver/redirect blood to areas of the heart receiving insufficient blood flow. More than 350,000 Americans undergo coronary bypass each year. Also referred to as coronary bypass surgery.
	Coronary artery disease (CAD) A progressive disease of the heart caused by narrowing of the coronary arteries from plaque in the blood. This results in a decreased blood supply to the heart muscle. Also called ischemic heart disease and coronary heart disease.
	Coronary atherectomy See atherectomy >>
	Coronary bypass surgery See coronary artery bypass graft (CABG) >>
	Coronary occlusion An obstruction of one of the coronary arteries that hinders blood flow to some part of the heart muscle. Also called coronary thrombosis.

D
	Defibrillation The termination of a fast, erratic, and often fatal heart rate by delivering a high-energy electrical shock to restore the heart's normal rhythm. A shock is administered through electrodes placed on the chest (external defibrillation) or in the heart (internal defibrillation).
	Defibrillator A device that delivers an electric shock to stop extremely rapid and irregular heartbeats and return the heart to normal rhythm. Can be external or implanted in the body.
	Deoxygenated blood Blood low in oxygen returning from the body tissues to the heart for circulation through the lungs, where it becomes oxygenated.
	Diabetes A disease in which the body doesn't produce or properly use insulin. Insulin is needed to convert sugar and starch into the energy needed in daily life. The full name for this condition is diabetes mellitus.
	Diagnostics Information gathered by an Implantable Cardioverter Defibrillator (ICD) or pacemaker to evaluate a patient's rhythm status, verify system operation, or assure delivery of appropriate system therapies.
	Diaphragmatic Stimulation Simulation of the phrenic nerve or diaphragm by a pacing output pulse, causing a hiccough-like reaction.
	Diastolic blood pressure The lowest blood pressure, measured in the arteries when the heart muscle is relaxed between beats. Diastole is the phase of the cardiac system where the heart rests.
	Dilation The gradual opening of a narrowed artery by cracking and compressing the obstructive plaque.
	Doppler ultrasound A noninvasive test using sound waves to evaluate blood flow in the heart or blood vessels.
	Dual-chamber pacing To pace and/or sense in both the right atrium and the right ventricle. See also pacemaker, dual-chamber >>
	Dysrhythmia See arrhythmia >>

E
	Echocardiogram (echo) A non-invasive test that records a sound wave picture of the heart and gives information about the heart valves and the function of the heart's muscular walls. An echo test can also measure ejection fraction (how efficiently the heart is pumping with each contraction).
	Edema Swelling in body tissues due to excessive tissue fluid.
	Ejection fraction (EF) A measurement of how well the heart is pumping. People with healthy hearts usually have an ejection fraction of 50% or greater. Ejection fraction can be measured by an echocardiogram (ECG) or with other diagnostic tests.
	Elective Replacement Time (ERT) When the battery voltage in a pulse generator declines to a point at which replacement is indicated.
	Electrocardiogram (ECG or EKG) A printout from an electrocardiography machine used to record the electrical activity of the heart, as sensed from the surface of the skin.
	Electrocautery The application of electrical currents to stop bleeding during surgery.
	Electrode A metal chip used to transmit or receive electrical impulses from one point to another.
	Electrogram (EGM) A picture of the electrical activity of the heart as detected from within the heart. An EGM is different from an ECG, which is a picture of the heart's electrical activity detected from the surface of the skin.
	Electromagnetic field Invisible lines of force that are created from the flow of electricity, such as when using an electrical device that is plugged into an outlet or operated by a battery.
	Electromagnetic interference (EMI) The temporary interference in the normal operation of an implanted device due to the presence of an electromagnetic field.
	Electrophysiologist (EP) A cardiologist specializing in the prevention, diagnosis, and treatment of heart rhythm (electrical system) disorders.
	Electrophysiology (EP) Lab Specially equipped lab located in a hospital or medical facility that contains equipment used to treat heart rhythm disorders.
	Electrophysiology (EP) test or study A test performed to record and measure the electrical impulses running through the heart during a heartbeat. Catheters containing electrodes are introduced into the heart through veins or arteries to “map” the heart signals. The test can also help a physician evaluate abnormal heart rhythms, determine their origin, and assess how well medicines are working to control them. The test also may be used to check how an implantable cardioverter defibrillator (ICD) functions during an abnormal heart rhythm.
	Embolic protection device A device used during the carotid artery stent procedure to capture and remove plaque and other particles that may be released during the procedure.
	Embolism Obstruction or occlusion of a blood vessel by an embolus.
	Embolus A plug composed of a detached thrombus or mass of bacteria that occludes a blood vessel.
	Endoarterectomy Surgical removal of plaque deposits or blood clots in an artery.
	Endocardial The inside surface of the heart. Endocardial leads are placed inside the heart through the veins.
	Endocardial lead A long, thin insulated wire that runs from a pulse generator through a vein into the heart. The lead is positioned in the atrium or ventricle, where it transmits signals from the heart to the pulse generator and/or delivers therapy from the pulse generator to the heart.
	Endocardium The inner layer of heart tissue that lines the chambers.
	Endothelium The cells that make up the smooth inner lining of many body structures, including the heart (endocardium) and blood vessels.
	Endovascular Within the blood vessels.
	EP study See electrophysiology (EP) test or study >>
	Epicardium The outside surface of the heart. Epicardial leads are sometimes placed outside the heart during open-chest surgery.
	Event recorder A portable monitor worn by a patient for an extended period that records the patient's ECG. The event recorder assists physicians in diagnosing events where individuals have unexplained symptoms, such as losing consciousness or becoming lightheaded.
	External defibrillator A portable device used to shock a life-threatening arrhythmia to a normal rhythm by using strong electric shocks delivered between paddle electrodes placed on a patient's chest.

F
	Femoral Pertaining to the thigh.
	Fibrillation An erratic, chaotic quivering of the myocardium during which the heart cannot effectively pump blood. Fibrillation of the atrium is called atrial fibrillation (AF); in the ventricle, it is called ventricular fibrillation (VF). Ventricular fibrillation is typically fatal if not corrected within several minutes.
	Fibrin A protein in the blood that enmeshes blood cells and other substances during blood clotting.
	Fibrosis The formation of fibrous/scar tissue.
	Fibrotic capsule Scar tissue that can form around the lead electrode tip or the pulse generator and is part of the body's normal protective reaction to any foreign material.
	Fixation Attachment of a lead to the heart. Active fixation uses a mechanism such as a screw-in tip and passive fixation uses tines or fins.
	Fluoroscope An X-ray monitor that provides a continuous x-ray image of the heart and vessels during invasive procedures.
	Flutter A condition in which the contractions in the upper or lower chambers of the heart become extremely rapid (but regular). A patient may or may not feel the flutter.

G
	Gangrene Necrosis or tissue death, usually due to inadequate or absent blood supply.
	Graft A procedure where portions of artery or vein from one area of the patient's body are used to reroute blood around a blockage in another area.
	Guide wire A specially designed wire used to guide the placement of a catheter or lead into a vessel.
	Guiding catheter A tube through which fluids or objects can be introduced into or removed from the body.

H
	Heart attack A condition in which a blocked artery prevents blood flow to the heart muscle, causing the tissue to die. Symptoms may include nausea, shortness of breath, and pain in the chest, arm, or neck. Also called myocardial infarction. It can result in cardiac arrest.
	Heart block A condition that stops the conduction of electrical impulses through the heart. May be caused by damage to cardiac tissue or by the disease process within the electrical impulse system. Condition may be intermittent or permanent. First-Degree Heart Block - Delay in the conduction of an atrial impulse to the ventricle through the AV-node characterized by a prolonged P-R interval on an ECG. Second-Degree Block - Intermittent blockage of atrial impulses at the A-V node. Conduction ratios are represented by the number of P-waves versus the number of ventricular responses in an ECG. Mobitz I is a type of second-degree heart block, also known as the Wenckebach phenomenon, in which the time between the atrial and ventricular contractions (P-R interval) becomes progressively longer until a P-wave is not conducted through the A-V node. Mobitz II is a type of second-degree heart block in which the time between the atrial and ventricular contractions is a consistent P-R interval, but an occasional P-wave is not conducted through the A-V node. Complete Heart Block - A pathologic condition in which intrinsic conduction is blocked at any level in the A-V junction. Also referred to as third-degree heart block.
	Heart rate (rhythm) Another term for a heartbeat. The number of times the heart beats (completes a cardiac cycle of contraction and relaxation) in a minute. A normal heart rate typically ranges from 60 to 100 beats per minute at rest.
	Heart valves Valves within the heart that open and close automatically to control blood flow into, through, and out of the heart.
	His-Purkinje Network A group of fibers that continue the electrical impulses to the ventricles that trigger contraction.
	Holter monitor A diagnostic monitor worn by a patient that utilizes a continuous electrocardiogram (ECG) to detect abnormal changes in the heart's rhythm.
	Hypertension High blood pressure usually ranging from 140/90 mm Hg to 200/110 mm Hg.
	Hypertrophy Enlargement of an organ or part of an organ.
	Hypertrophic cardiomyopathy A disorder of the heart muscle caused by an enlarged heart resulting from the increase in the size of muscle tissue. In some people the disease is transmitted genetically and its cause is unknown.
	Hypotension Abnormally low blood pressure.

I
	ICD See implantable cardioverter defibrillator (ICD or AICD) >>
	Iliac arteries The two main arteries coming from the aorta, going into the legs.
	Implantable cardioverter defibrillator (ICD) A surgically implanted device that monitors the heartbeat and delivers electrical impulses to correct an abnormally fast rhythm and restore a regular heartbeat. The ICD system usually consists of an implanted pulse generator and one or more leads. The system is adjusted using an external programming device. Also known as an automatic implantable cardioverter defibrillator (AICD).
	Implantable cardioverter defibrillator (ICD), dual-chamber An implantable cardioverter defibrillator (ICD) that includes the functions of a dual-chamber pacemaker.
	Implantable pulse generator A small device implanted in the body that senses the heart's electrical activity and delivers electrical impulses to regulate the heart when its own rhythm is abnormal.
	Implanted Placed inside the body. Automatic implantable cardioverter defibrillator (AICDs), pacemakers and stents are implanted systems.
	Incision A surgical cut or wound produced in order to perform surgery. The incision becomes a scar after surgery.
	Infarct See infarction >>
	Infarction An area of deadened tissue resulting from the obstruction of blood circulation that normally nourishes tissue. A myocardial infarction refers to myocardial tissue damage due to interrupted blood flow through a coronary artery. A myocardial infarction is frequently referred to as a heart attack.
	Inferior vena cava The largest vein in the body. It returns blood from the lower half of the body to the right atrium of the heart.
	Interrogation A device evaluation performed during a follow-up visit of a device patient; session with the device to assess the pacemaker lead wires, the battery level, and evaluate heart rhythms detected by the pacemaker.
	Introducer Sheaths A hollow tubular device used for the introduction of catheters or needles.
	Ischemia Insufficient blood flow to and oxygen deprivation of tissue, usually due to constriction or obstruction of an artery.
	Ischemic heart disease A heart condition caused by narrowing of the coronary arteries and characterized by a decreased blood supply to the heart. Also called coronary artery disease (CAD) and coronary heart disease.

L
	Laparoscopy A form of minimally invasive surgery in which viewing endoscopes and small diameter surgical instruments are inserted into the abdominal cavity through small incisions instead of through large abdominal incisions.
	Lead An insulated wire that carries the heart signal to the pulse generator and energy from the pulse generator to the heart. Leads are attached to the surface of the heart or passed into the heart through the veins.
	Left coronary artery (LCA) One of the three main coronary arteries that supplies blood to the heart. The LCA supplies about 65% of the heart's blood.
	Local anesthetic A substance used to temporarily block nerve sensation in the area to which it is applied.
	Lumen The inner channel or cavity of a blood vessel or tube.

M
	Magnetic resonance imaging (MRI) A diagnostic test that uses a strong magnet to reveal and create pictures of different areas of the body, including blood vessels.
	Minimally Invasive Procedural techniques that use small incisions to gain access to the surgical site.
	Minute Ventilation The total respiratory volume over one minute. In some adaptive-rate pacemakers, sensors detect changes in minute ventilation to indicate changes in metabolic need that result in an increase or decrease in the paced rate.
	Mitral valve The heart valve between the left atrium and the left ventricle.
	Morbidity The frequency of complications following a surgical procedure or treatment. Also, a disease state that requires hospitalization.
	Mortality rate Deaths from a given disease over a period of time, usually a year.
	Myocardial infarction Death of an area of heart tissue due to a blockage of blood flow to the heart muscle (myocardium). Symptoms may include nausea, shortness of breath, and pain in the chest, arm, or neck. Also called a heart attack.
	Myocardial ischemia Oxygen deprivation of the heart muscle caused by a blockage in the blood vessels serving a particular region of the heart.
	Myocardial lead A lead designed to attach to the outside of the heart (epicardium). Sometimes called an epicardial lead.
	Myocarditis An inflammation of the middle layer of the heart (the myocardium). Often begins as an infection by bacteria, viruses or other microbes. May result in enlarged ventricle.
	Myocardium The middle and thickest layer of the heart. It contracts to pump blood out of the heart and then relaxes as the heart refills with returning blood.

Noninvasive

Medical instruments or procedures that do not require cutting the skin.

O
	Open-heart surgery Surgery performed on the opened heart while the bloodstream is diverted through a heart-lung machine to sustain normal oxygenation and circulation.
	Over-the-wire (OTW) catheter Balloon dilatation catheter that is delivered over a separate guide wire to position the catheter in a specific place.
	Oxygenated Carrying oxygen with it. Blood that carries oxygen from the lungs to all body tissue is oxygenated blood.

P
	Pacemaker/pacing system An implantable system that includes a pulse generator (pacemaker) and one or two leads. The system delivers pacing pulses to the heart when the patient's own rate is too slow to pump enough blood to the body.
	Pacemaker/pacing lead An electrically insulated conductor that carries signals between the pulse generator (pacemaker) and the heart. Some leads enter the heart through a vein, and other leads attach to the outer surface of the heart.
	Pacemaker, adaptive-rate A pulse generator with one or two special sensors designed to recognize changes in the body, such as motion or respiratory patterns. The adaptive-rate pacemaker monitors these body changes and alters the pacing rate accordingly.
	Pacemaker, dual-chamber A pacemaker with two leads that can pace and/or sense in two chambers to correct slow heart rhythms. One lead is placed in the right atrium; the other is placed in the right ventricle.
	Pacemaker, natural The heart's natural pacemaker, called the sinoatrial or S-A node, which is located in heart's upper right chamber, the right atrium. Electrical impulses originate in the S-A node, which causes the atria to contract, forcing blood into the heart's lower chambers, the ventricles.
	Pacemaker, single-chamber A pulse generator that paces and senses a single heart chamber, either the right atrium or right ventricle.
	Pacemaker Syndrome A set of symptoms related to the adverse impact of a loss of A-V synchrony, commonly associated with ventricular pacing. Symptoms include dizziness, faintness or syncope, tightness in the chest, shortness of breath, and neck pulsations known as Cannon waves.
	Pacing Stimulating the heart to increase its rate.
	Pacing system analyzer (PSA) An external testing and measuring device used during pacemaker implantation to pace the heart and take various measurements from the leads to ensure they are in the correct location and functioning properly.
	Palpitations Irregular, rapid beating or pulsation of the heart not necessarily an indication that you have an arrhythmia.
	Paroxysmal atrial tachycardia (PAT) An atrial tachycardia that starts and stops suddenly. The atrial rate may be as fast as 160-220 bpm.
	Passive-fixation lead Pacing leads that use appendages of insulation material, such as tines, at the lead tip. The tines are designed to lodge in the ridges or fibers of muscle that line the inner wall of the heart and secure the lead. See also active-fixation lead.
	Pectoral The area near the shoulder or upper chest.
	Percutaneous Through the skin.
	Percutaneous introducer A thin, hollow tube used to ease insertion of the endocardial lead through the skin into a vein, then to advance the lead into the heart.
	Percutaneous method Insertion of a lead or catheter into a vein by means of an introducer. A small needle puncture is made in the vein to gain entry for the lead or catheter.
	Percutaneous transluminal coronary angioplasty (PTCA) A minimally invasive procedure whereby a balloon dilatation catheter is passed through to the blocked area of an artery. Once inflated, the catheter compresses the plaque against the blood vessel wall, re-establishing blood flow. PTCA also can be performed with a stent or atherectomy. Also called angioplasty.
	Pericarditis Inflammation of the pericardium, the membranous sac that surrounds the heart.
	Pericardium A fibrous sac surrounding the heart and roots of the great blood vessels.
	Peripheral vascular disease (PVD) Vascular disease that affects the blood vessels of the extremities.
	Plaque An accumulation or build-up of fatty deposits, calcium, and/or cell debris in an artery that leads to narrowing of the blood vessel.
	Platelet One of three kinds of formed elements found in blood that aids in the clotting of the blood.
	Premature contraction A spontaneous, early contraction of heart muscle caused by an electrical impulse outside the normal conduction path. Premature Atrial Contractions (PAC) occurs in the atria. Premature Ventricular Contraction (PVC) occur in the ventricle.
	Programmer Microcomputer-based equipment that is used to communicate with an implanted pulse generator and provide information during testing and follow-up exams. A programmer is also used to adjust a pulse generator so that it senses and treats arrhythmias appropriately.
	Pulmonary Pertaining to the lungs.
	Pulmonary artery The artery leading from the right ventricle of the heart to the lungs.
	Pulmonary embolism An embolism that lodges in the pulmonary artery or its branches.
	Pulmonary valve The heart valve between the right ventricle and the pulmonary artery.
	Pulmonary veins The four veins that drain oxygenated blood from the lungs and deliver it to the left atrium.
	Pulse A pressure wave transmitted to arteries by contraction of the left ventricle. Felt at the radial artery in the wrist. Can be counted to determine the number of heartbeats per minute (rate). The pulse also gives information about the regularity or rhythm for the heartbeat.
	Pulse generator The part of the pacemaker or defibrillator system that contains the electronics and the battery. It is implanted in the abdominal or pectoral area.

Quality of Life

The level of function, comfort, enjoyment, a person is able to achieve during daily activities. A high quality of life means one is able to perform all or most expected or desired activities in their daily life.

QRS

The electrocardiogram (ECG) waveform that represents ventricular depolarization. If all components are present, the complex is made up of Q-, R- and S-waves. The duration of a normal QRS complex is approximately 80-120 ms.

R
	Rapid exchange (RX) A feature available on catheters that allows for easy exchange of the catheter without the removal of the original guide wire.
	Radiofrequency Energy (RF) Radiant energy (light waves) of a certain frequency range. Used to generate resistive heat during cardiac ablation procedures.
	Rate-responsive pacing Pacing in which the heart rate is altered in response to changes in activity levels of the body to meet the demand for increased blood circulation.
	Renal arteries Arteries that provide blood to the kidneys.
	Restenosis A recurring blockage caused by excessive cell proliferation inside the artery following an interventional procedure such as angioplasty or stenting.

S
	S-A node See sinoatrial node >>
	Scar An area of tissue that has healed after tissue destruction has occurred. It is electrically inactive. Electrically inactive tissue cannot transmit electrical signals.
	Sensing The monitoring function of an implanted pacemaker or defibrillator system that allows the device to detect the heart's natural electrical activity.
	Sensor The part of an implanted system that detects the body's need for a different heart rate. The system uses sensor information to provide the proper heart rate.
	Septum The muscular wall that separates the left and right sides of the heart.
	Sick sinus syndrome A term used to describe abnormalities of the S-A node, the heart's natural pacemaker. These abnormalities may result in slow, fast, and/or irregular heart rates or sinus arrest.
	Silent heart attack Episodes of heart damage by a blocked coronary artery, but is so subtle that is goes unnoticed. Silent heart attacks, or silent ischemia, can be detected by ECG and other lab techniques.
	Sinoatrial (S-A) node The small area in the right atrium that starts the electrical impulse that is transmitted through the heart, causing it to beat. The S-A node is often called the natural pacemaker of the heart.
	Sinus rhythm The normal rhythm of the heart, initiated in the S-A node.
	Special procedures room A sterile room much like the cardiac catheterization room where specific procedures are performed, such as angiograms and angioplasty.
	Stent A tiny, latticed metal tube that is implanted into an artery during an angioplasty. The stent provides scaffolding necessary to hold the artery open and ensure blood flow through the artery.
	Sternotomy A lengthwise incision through the breastbone (sternum) that may be made when open-heart surgery is performed.
	Stress test A diagnostic test using an ECG machine and a stationary bicycle or treadmill to monitor or assess areas of the heart that may have a decreased blood supply.
	Stroke Tissue damage in the brain caused by lack of oxygen. Damage depends on the location and extent of brain tissue affected.
	Subcutaneous Beneath the skin.
	Sudden cardiac death (SCD) A death due to electrical problems in the heart. SCD is usually caused by ventricular tachycardia or fibrillation. SCD is different from a heart attack, which results from heart muscle damage from blood flow blockage, rather than an electrical problem. SCD commonly results from sudden cardiac arrest (SCA).
	Superior vena cava The second largest vein in the body. It returns blood from the upper half of the body to the right atrium of the heart.
	Support group A group of patients and their family members coordinated by medical professionals. The group provides an opportunity for members to share their experiences with therapy and to discuss any concerns.
	Supraventricular tachycardia (SVT) A tachycardia originating from an impulse arising in any portion of the atrium, the A-V node, or the bundle of His.
	Syncope A brief period of unconsciousness caused by insufficient blood supply to the brain.
	Systolic blood pressure The highest blood pressure, measured in the arteries when the heart muscle is contracting. Systole is the phase of the cardiac system where the heart contracts and ejects blood from the ventricles.

T
	Tachycardia (tachyarrhythmia) Rapid beating of the heart, usually more than 100 beats per minute.
	Thoracic Pertaining to the chest (thorax).
	Thoracotomy An incision into the chest that may be made when heart or lung surgery is performed.
	Thrombectomy An operation to remove a blood clot from a blood vessel.
	Thrombolysis The use of drugs called thrombolytic agents to dissolve (lyse) a blood clot (thrombus).
	Thrombus A blood clot that forms inside a blood vessel or cavity of the heart. If the blood clot breaks away, it becomes an embolus. Both a thrombus and an embolus can lead to paralysis, blindness, stroke or death.
	Transient ischemic attack (TIA) Temporary symptoms of stroke. A patient who has a TIA may be at higher risk for stroke.
	Transluminal Passing across or performed by way of a lumen.
	Transradial Through the radial artery near the wrist.
	Transvenous Passed into the heart through a vein. See endocardial >>
	Tricuspid valve The portal which controls flow of blood between the right atrium and right ventricle.

Ultrasound

A diagnostic test that uses sound waves read by a probe that moves along the outside of the body.

V
	Valve Flap-like structures within the heart that open and close to control the flow of blood through and out of the heart.
	Vascular Pertaining to the blood vessels.
	Vein A blood vessel that carries blood from the body toward the heart.
	Vena cava Either of two large veins that return blood to the right atrium of the heart. The superior vena cava returns blood from the head, neck and chest; the inferior vena cava returns blood from the legs and abdomen.
	Ventricle One of the two lower chambers of the heart. The right ventricle sends unoxygenated blood to the lungs, and the left ventricle passes blood carrying oxygen to the rest of the body. The ventricles are the main pumping chambers of the heart and they contract at the same time.
	Ventricular fibrillation (VF) A very fast, irregular heartbeat that is caused by abnormal impulses coming from several areas of the heart. These abnormal impulses take over the natural pacemaker function of the S-A node. The heartbeat is so fast that the heart does not have time to pump enough blood to the brain and body tissue, which may cause unconsciousness, cardiac arrest, and death.
	Ventricular lead An implantable lead designed for use in or on the ventricle.
	Ventricular tachycardia (VT) A fast heartbeat caused by abnormal impulses coming from a single area of the heart. These abnormal impulses take over the "pacemaker" function of the S-A node. The rapid heartbeat can produce symptoms of fainting, dizziness, weakness, blind spots, and potentially, unconsciousness and cardiac arrest.

Wolff-Parkinson-White Syndrome (WPW)

A type of supraventricular tachycardia (SVT) caused by extra electrical pathways that conduct electrical impulses faster than normal or conduct impulses in both directions. Named after Wolff, Parkinson & White. They were the first physicians to describe this SVT in 1930, but it was not officially a confirmed/documented disease until 1944.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

CRM9-3960-1010

Illustrated Glossary

Abdominal aortic aneurysm (AAA)

ABI (ankle brachial index)

Ablation (cardiac)

Ablation catheter

Accelerometer

Active-fixation lead

Aneurysm

Angina (angina pectoris)

Angiogram

Angiography

Angioplasty

Antiarrhythmic (medicine)

Anticoagulant

Antitachycardia pacing

Aorta

Aortic valve

Apex

Arrest (cardiac)

Arrhythmia

Arteriogram

Artery

Asynchrony

Asystole

Atherectomy

Atherosclerosis

Atria

Atrial asystole

Atrial fibrillation (AF or AFib)

Atrial flutter (AFL)

Atrial lead

Atrial tachycardia

Atrioventricular (A-V) block

Atrioventricular (A-V) node

Atrioventricular nodal re-entrant tachycardia (AVNRT)

Atrioventricular (A-V) synchrony

Atrioventricular (A-V) valves

Atrium

Automatic implantable cardioverter defibrillator (AICD)

A-V node

Bacterial endocarditis

Balloon dilatation catheter

Battery

Biomarker (biochemistry marker)

Blood clot

Blood pressure

Blood volume

bpm (beats per minute)

Brachial

Bradycardia (bradyarrhythmia)

Bradycardia pacing

Brady-Tachy Syndrome

Bruise

Bundle branches

Bundle of His

Bypass

Capillaries

Cardiac

Cardiac ablation

Cardiac arrest

Cardiac arrhythmia

Cardiac catheterization

Cardiac catheterization laboratory (cath lab)

Cardiac conduction system

Cardiac Output

Cardiac rhythm management (CRM)

Cardiologist

Cardiomyopathy

Cardiopulmonary bypass (CPB)

Cardiothoracic surgeon

Cardioversion

Cardioverter

Carotid arteries

Carotid artery disease

Carotid endarterectomy

Catheter

Catheter Ablation

Catheterization

Cerebral embolism

Cerebral hemorrhage