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AICD - Automatic Implantable Cardioverter Defibrillator. Currently called an ICD.

Angina - Chest discomfort, a term used almost exclusively to denote angina pectoris, which is chest pain that often radiates to the arms, particularly the left.

Aorta - The main artery that carries blood away from the heart.

Aortic Valve - A cardiac membrane that controls the flow of blood out of the heart and into the aorta.

Apnea - The absence of breathing.

Arteries - Vessels through which the blood passes away from the heart to the various parts of the body.

Artifact - In Electrophysiology, this refers to any electrical signal seen on the EKG or by an implanted device which did not come from heart tissue.

Arrhythmia - Irregular or rapid heartbeat.

Asystole - The complete absence of heart rhythm. Cardiac standstill.

Atherosclerosis - A build-up of cholesterol or other fatty deposits called plaque that can occur on the inner wall of arteries, which in advanced stages causes restriction or blockage of the blood flow to the heart or brain.

Atrial Fibrillation - An irregular heartbeat that causes a fluttering sensation of the heart.

Atrial Natriuretic Peptide (ANP) - A cardiac hormone secreted by atrial tissue in the response to stretch. It is sometimes measured in the bloodstream as an indicator of heart failure.

AV Block - A partial or total interruption of the conducted impulse from the atria to the ventricles via the AV node.

AV Node (Atrio-ventricular node) - Part of a normal heart consisting of electrically active tissue which conducts impulses from the upper chambers (atria) to the lower chambers (ventricles).

AVNRT - AV Nodal Re-entry Tachycardia. A type of supra ventricular tachycardia caused by re-entry of electrical impulses within the AV node and characterized by a sudden increase in heart rate.

AVRT - Atrio Ventricular Re-entry Tachycardia. A type of tachycardia caused by re-entry in a cardiac circuit which includes the atria, ventricle, AV node and
accessory pathway.

Atrium - (plural of atria) One of a pair of smaller cavities in the heart from which blood passes to the ventricles.

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Bradycardia - Slowness of the heartbeat, as evidenced by slowing of the pulse rate to less than 50 beats per minute in an adult.

Bundle Branch - A delay in the conduction of the electrical impulse of the heart to the ventricle.

Baroreceptor - A sensory nerve ending, located in the heart, arteries and veins which transmit pressure levels to the central nervous system.

BOL - Beginning of life. A term used to describe battery voltage at the time of implantation of a pacemaker or defibrillator.

Beta Blocker - A group of drugs that blocks the effects of adrenaline.

Bi-Ventricular Pacing - A type of lower chamber pacing using a lead in the right ventricle and another on the left ventricle.

Bigeminy - A cardiac arrhythmia in which every other beat is abnormal.

Biphasic - A description of an electrical impulse which has both a positive and a negative component.

Bipolar - Used to describe pacing or defibrillation lead which paces and/or senses from two electrodes on that lead.

Bradycardia-Tachycardia Syndrome - A description of arrhythmias which result in both periods of rapid heart rhythm (tachycardia) and slow heart rhythm (bradycardia) in the same patient. it is a subset of sick sinus syndrome and is also called brady-tachy syndrome and tachy-brady syndrome.

Burst Pacing - A technique consisting of multiple paced impulses delivered to the heart in an attempt to either induce or terminate an arrhythmia.

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CABG - Coronary Artery Bypass Grafting

Capacitor - A device that can store an electrical charge. It is used in both pacemakers and defibrillators.

Capture - The successful depolarization of a cardiac chamber by the delivery of an electrical pulse by a pacemaker or during electrophysiology studies.

Capture Threshold - The lowest amount of pacing energy delivered to the heart that results in capture.

Cardiac Arrest - The sudden loss of cardiac pumping function. This can occur when there is complete loss of rhythm (asystole) or when circulation stops due to rapid rhythms like ventricular tachycardia or ventricular fibrillation.

Cardiac Catheterization - An invasive diagnostic procedure involving placement of a catheter at the origin of the coronary arteries, injection of contrast liquid (dye) and x-ray imaging of the arteries. Mainly performed to diagnose coronary atherosclerosis (CAD).

Cardiac Conduction System - All of the electrically active cardiac tissue that provides for a normal heart rate and contraction sequence within the heart.

Cardiac Dyssynchrony - An abnormal contraction sequence within the ventricles due to prolonged or otherwise abnormal electrical activation of the heart.

Cardiac Mapping - A technique used during electrophysiology studies to determine the sequence of electrical activation of the heart correlated to anatomy in order to locate the origin or circuit of an arrhythmia.

Cardiac Murmur - A sound heard, usually through a stethoscope, coming from the heart due to turbulent flow of blood due to a heart valve problem.

Cardiac Resynchronization Therapy (CRT) - A pacing therapy for some heart failure patients to improve pumping function.

Cardiac Tamponade - The compression of the heart by the accumulation of blood or other fluid within the pericardial sac resulting in decreased heart function.

Cardiomegaly - Enlargement of the heart.

Cardiomyopathy - Any disease that weakens heart muscle.

Cardioversion - The delivery of a therapy to restore normal rhythm in the setting of a sustained tachycardia. This can be accomplished by medications (chemical cardioversion) or by electrical shocking of the heart (electrical or DC Cardioversion).

Cardiomyopathy - Disease of the heart muscle that causes decreased functioning of the heart.

Catheter - A tubular device designed to be passed into a blood vessel, orifice, duct or body cavity. There are many different types of catheters. Catheters with electrodes on them are used in electrophysiology studies and ablations.

Catheter Ablation - A procedure using a catheter to destroy cardiac tissue to correct an arrhythmia.

Cauterization - The destruction of tissue by heat, electricity or drugs.

Chambers - An enclosed space. The heart is divided into four chambers. The upper chambers are called the right and left atrium, and the lower chambers are called the right and left ventricle.

Chordae Tendinae - Fibrous strands of tissue extending from the papillary muscles to edges of the leaflets of the mitral and tricuspid valves.

Chronic - of long duration.

Chronic Obstructive Pulmonary Disease (COPD) - A group of lung diseases resulting from loss of normal pulmonary tissue and inflammation of the lungs.

Chronotropic Incompetence - The inability of the heart to regulate its rate appropriately for the level of stress or exertion.

Circumflex Coronary Artery - One of the three main coronary arteries.

Clavicle - The collar bone

Compensated Heart Failure - The condition when the heart and body adapt to heart damage, resulting in diminished symptoms of heart failure.

Complete Blood Count (CBC) - A common blood test measuring white blood cells, red blood cells and hemoglobin.

Complete Heart Block (CHB) - An arrhythmia in which the AV node fails to conduct any impulses to the ventricles. Also called third degree heart block.

Concentric Hypertrophy - Thickening of the walls of the heart.

Congestive Heart Failure (CHF) - The failure of the heart to pump an adequate amount of blood to the tissues of the body. It can be associated with an increased risk of sudden cardiac death.

Coronary Artery Disease (CAD) - Atherosclerosis of the arteries of the heart that provide oxygen and nutrients to the heart muscle.

Coronary Sinus - The outlet of the coronary venous blood into the right atrium. The veins of the left ventricle drain into this vascular structure. It is used as an access point to place leads on the outer surface of the left ventricle.

Coronary Thrombosis - A blood clot in a coronary artery. Total occlusion of the coronary artery results in a heart attack (myocardial infarction).

Creatinine - A normal chemical found in the blood and urine. When blood levels are increased, this usually indicates kidney failure.

CRT - Cardiac Resynchronization Therapy. A pacing therapy used to improve or prevent deterioration of ventricular function. Also called bi-ventricular pacing.

CVA - Cerebro-Vascular Accident. Long-lasting damage to the brain due to interruption of normal blood flow. A stroke.

Cyanosis - A blueish discoloration of the skin associated with decreased levels of oxygen in the blood.

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Decompensated Heart Failure - Any worsening of the heart’s ability to maintain an adequate circulation to the body’s tissues.

Defibrillation - The termination of either atrial fibrillation or ventricular fibrillation by delivering a high voltage shock to the heart. This can be performed by paddles of pads on the chest, at the time of open heart surgery with sterile paddles or with the use of an implanted defibrillator.

Defibrillation Leads - The highly specialized insulated wires that are placed in or around the heart used by an implanted defibrillator to deliver high voltage shocks to the heart.

Defibrillation Threshold (DFT) - The lowest energy which reliably terminates fibrillation.

Delta Wave - An abnormality seen on the EKG in patients with Wolf-Parkinson White Syndrome or ventricular pre-excitation.

Demand - A word used to describe a type of pacing mode that delivers an electric impulse only when needed.

Depolarization - An increase in the voltage inside electrically active cells. If long enough, it results in electrical activation of the nerve or cardiac cell to conduct or contract, respectively.

Diaphragmatic Stimulation - Electrical activation of the phrenic nerve, usually by a pacing lead, which results in contraction of the diaphragm (hiccup).

Diastole - The time period of the cardiac cycle when the chambers relax and fill with blood.

Diastolic Dysfunction - A type of heart failure produced by inadequate relaxation of cardiac muscle.

Diastolic Pressure - The lowest pressure measured in the arteries during diastole.

Dilated Cardiomyopathy - A weakening of heart muscle resulting in enlargement of the heart.

Dislodgment - The displacement or migration of a lead that was placed inside the heart.

Diuretic - A type of medication that increases urination. The loss of excess water can be helpful in patients with congestive heart failure or hypertension.

Dual-Chamber Pacing - A type of pacing which involves pacing in both an atrium and a ventricle.

Dyspnea - Shortness of breath.

Dysrhythmia - An abnormal heart rhythm which can make the heart beat too slow, too fast or irregularly. Some arrhythmias are benign and others can be life threatening.

DVT - Deep Vein Thrombosis (blood clot)

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ECG - Electrocardiogram. Same as EKG.

Echocardiogram - A test of heart anatomy and function using ultrasound. The ultrasound probe can be placed on the chest wall (Transthoracic Echocardiogram [TTE]), down the throat (Transesophogeal Echocardiogram [TEE]) or within a cavity of the heart (Intra-Cardiac Echocardiogram [ICE]). Also called an echo test.

Edema - An excessive accumulation of fluid inside tissues of the body.

EGM - Electrogram. A direct recording of heart tissue electrical activity.

Ejection Fraction (EF) - The percentage of blood pumped out of the ventricular chamber per beat. This number decreases when there is damage to the heart. A low EF has been associated with an increased risk of sudden cardiac death. A normal EF is higher than 40%.

Electrocardiogram (EKG or ECG) - EKG or ECG. A recording of the heart’s electrical activity using electrodes places on the skin. Also called a surface electrocardiogram.

Electrogram (EGM) - A recorded electrical signal from a specific location in the heart, usually obtained using an intracardiac catheter or from a pacemaker or defibrillator lead.

Electrode - An adhesive patch that adheres to the skin and serves as the medium between the heart and an EKG recorder.

Electromagnetic Interference (EMI) - Electrical signals of non-cardiac origin such as radio waves or from high voltage electrical wires or generators. It sometimes is detected by pacemakers and defibrillators and coul result in abnormal device function.

Electrophysiologist -

Electrophysiology Laboratory - The clinical environment where Electrophysiology studies are performed in addition to implanting pacemakers and defibrillators. The EP lab has x-ray equipment, anesthesia equipment and advanced computer equipment required to safely perform these procedures.

Electrophysiology Study (EPS) - An invasive diagnostic procedure which involves placing catheters with eletrodes in various locations within the heart in order to record electrograms, stimulate cardiac tissue and to induce arrhythmias.

Embolus - A plug which occludes a blood vessel. An embolus is usually a blood clot, but can be a foreign object, a mass of bacteria or platelettes, or a piece of tissue.

Encapsulation - The result of an inflammatory tissue response to the presence of a foreign body. Fibrous or scar tissue forms around the foreign body, usually a pacemaker or defibrillator pulse generator and leads.

Endocardium - The innermost surface of the heart.

End of Life (EOL) - A term used to describe end of useful battery life of a pacemaker or defibrillator.

Epicardium - The outer surface of the heart.

Erosion - The deterioration of tissue around a pacemaker or defibrillator pulse generator or lead which then allows this foreign body to move outside the skin layer, blood vessel or heart.

Esophageal Lead - A catheter used to pace and record electrograms of the left atrium via the esophagus.

Esophagus - The passageway that connects the mouth with the stomach.

Event Recorder (or Monitor) - A portable battery-powered device with an internal memory for recording EKG information. It is used to capture a patient's EKG rhythm during symptoms.

Explantation - The removal of a previously implanted device, usually this term is used to describe the surgical procedure of removal of an implanted pacemaker, defibrillator, loop recorder or leads.

External Counterpulsation - A therapy for congestive heart failure or refractory angina that uses an inflatable suit surrounding the legs that inflates with air to compress the veins and help the heart pump more efficiently.

External Pacemaker - A battery-powered pacemaker which is kept outside the body and used to temporarily pace the heart.

Extrusionn - See "erosion."

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Fast Pathway - One of the condutcing pathways in AV node (re-entry tachycardia which is characterized by more rapid conduction but more easily blocked. Also called the beta pathway.

FDA (Food and Drug Administration) - A regulatory agency of the United States government which is responsible for approving market-release of medical devices as well as many other activities.

Fibrillation - A type of cardiac arrhythmia which is characterized by very rapid and irregular, uncoordinated electrical activity of either the atria or ventricles.

Fibrosis - The build-up of scar tissue, typically seen around implanted leads and pulse generators, usually after about one year.

First Degree AV block - One of the types of artrio-ventricular block, characterized by abnormally prolonged conduction time from the artrium to the ventricles via the AV node.

Fixation - A term describing the attachment of a lead to the heart. Active fixation involves an attachment mechanism (usually a screw-in tip) and passive fixation involves the use of soft tines or fins to hold the lead tip in place.

Fluoroscopy - A type of x-ray device used during EP studies, ablation and pacemaker/ICD implantation which allows the electrophysiologist to watch the motion and location of tissues and leads in real-time.

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Heart attack - A critical medical situation that occurs when the blood supply to the heart is blocked and there is death of heart muscle.

Heart block - Impairment of the conduction system of the heart that blocks its electrical pathways.

Hemodynamic monitoring - A diagnostic study that evaluates the movement of blood circulation.

Hypertension - High blood pressure that is exerted against the walls of your blood vessels as blood is pumped through the body.

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Myocardial Infarction - Irreversible damage to the heart muscle due to a blocked coronary artery. This is sometimes referred to as an "infarct." myocarditis - inflammation of the muscular walls of the heart.

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Pericarditis - Inflammation of the pericardium, which is the sac that surrounds the heart.

Plaque - A combination of cholesterol, fatty deposits, cellular debris and calcium that form deposits on the inner lining of the coronary arteries, which results in Coronary Artery Disease.

Prosthesis - An artificial substitute for a missing body part.

Pulse - The rhythmic expansion of an artery that can be felt with the finger on your wrists, neck and temple. Your pulse reflects the number of times your heart beats each minute.

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Sheath - A small, plastic tube used to enter a vein or artery.

Sinus Node - The heart's natural pacemaker that produces electrical impulses to keep it beating at a healthy pace. These impulses cause the heart to contract and pump blood at regular intervals.

Stent - An expandable mesh tube (about one-half inch long) that is placed in an artery to maintain the free flow of blood through the vessel following an angioplasty or atherectomy.

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Tachycardia - Excessive rapidity in the action of the heart; the term is usually applied to a heart rate above 100 beats per minute in an adult.

Telemetry Monitor - A method for measuring a patient's vital signs from a distance, transmitted through radio signals or other means and displayed onto a monitor.

Transducer - A device that translates one form of energy to another, such as during an ultrasound when high frequency sound waves are transmitted through a transducer and then converted into electrical impulses. An echocardiograph machine converts the electrical impulses into images that are displayed onto a monitor and recorded.

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Ultrasound - An imaging modality that visualizes the body's internal structures by recording the pulsating "echoes" of sound waves that are directed into the tissues.

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Valve - Membrane in a passage that prevents the reflux of the contents flowing through it. Cardiac valves control the flow of blood through and from the heart.

Valvular Stenosis - Narrowing of the heart valves. The specific valve that is affected is often preceded by the word stenosis, i.e., aortic stenosis, mitral stenosis, pulmonary stenosis and tricuspid stenosis.

- a small cavity. The right and left ventricles of the heart have thick muscular walls that make up the bulk of the heart and propel blood through and from the heart.

- any channel for carrying a fluid, such as blood vessels, which include arteries, arterioles, capillaries, venules and veins.

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