Glossary

These definitions are provided by Arrhythmia Alliance whose mission is to promote better understanding, diagnosis, treatment and quality of life for individuals with cardiac arrhythmia. Used with permission.

AED
Automated External Defibrillator; a portable device used to shock the heart if it is needed

Antiarrhythmics
An action which stops or prevents arrhythmia

Arrhythmia
Irregular heart rhythm; the heartbeat can be irregular, too fast or too slow

Atria
The two upper chambers of the heart that receive blood from around the body and from the lungs

Atrial Fibrillation (AF)
Irregular heart rhythm

Atrial Flutter
An irregular heartbeat that begins in the upper chambers of the heart

Bradycardia
A slow heart rate, normally less than 60 beats per minute

Cardiac Arrest
When the heart stops beating

Cardiac Physiologist
A medical expert skilled in interpreting and providing information on your heart rhythm

Cardiologist
A doctor specializing in the diagnosis and treatment of patients with heart conditions

Cardioversion
A therapy to treat atrial fibrillation which involves changing or “converting” the atrial fibrillation into a normal rhythm

Concomitant 
Something that occurs with something else

CHD
Coronary Heart Disease

Coronary Artery Injuries
An injury to a coronary artery

CPR
Cardiopulmonary Resuscitation; a temporary measure used to continue supplying oxygen to the brain and other organs

CRT
Cardiac Resynchronization Therapy is the use of either a pacemaker or implantable defibrillator helping to treat heart failure

Defibrillation
The use of an unsynchronized (not specifically timed) shock to stop fast heart rhythms

Diagnostic Procedures
Tests that are conducted to diagnose a heart rhythm disorder

Echocardiogram (or Echo)
An image of the heart using echocardiography or sound wave-based technology. An echocardiogram shows a three-dimensional image of the heart

Electrocardiogram (ECG)
Records the electrical activity within the heart

Electrophysiologist
A cardiologist who has specialized in the electrical activity of the heart, meaning the heart’s rhythm and disorders

Electrophysiology Testing
Reproducing arrhythmias in a controlled setting to determine where in the heart they begin

Esophageal Perforation
An opening or hole in the esophagus that is caused by trauma, injury, or pathological process

Event Monitor
Monitor to record heartbeats

Fluroscopy 
An X-ray procedure that makes it possible to see internal organs in motion

Heart Attack
Occurs when one of the coronary arteries becomes blocked by a blood clot; the blood supply to part of the heart muscle is blocked, causing part of the heart muscle to die

Heart Block
Electrical impulses are slowed or blocked as they travel from the top to the bottom chambers of the heart

Heart Failure
A failure of the heart to pump blood to the body’s organ systems and maintain their function

Holter Monitor
A portable electrocardiogram used to show a change in heart rhythm during daily activities

Implantable Cardioverter Defibrillator (ICD)
a small device inserted under the skin and connected to the heart that makes the heart’s chambers pump at the same time; the device which functions like an AED, but is small enough to be implanted in a patient to allow automatic defibrillation at any time

Invasive Procedure
A procedure that enters the body usually by cutting or puncturing the skin or inserting instruments into the body

Less Invasive Procedure
A procedure that is performed using a small incision and specialized equipment

Long QT Syndrome (LQTS)
A disturbance of the heart’s electrical system (the QT in the name refers to the measure of time between the start of the Q wave and the end of the T wave in the heart's electrical cycle)

Pacemaker
A small metal device implanted under the skin, which produces electrical impulses to treat an abnormal heart rhythm

Phrenic Nerve Paralysis
Paralysis of the motor nerve of the diaphragm

Premature Ventricular Contractions
Early heart contractions that occur when the ventricles contract out of sequence with normal heart rhythm

Pulse Generator
Part of the ICD which contains the battery and electric circuits

Recorder
Evaluates a heart rate based on symptoms over an extended period of time

Sick Sinus Syndrome
Occurs when the heart’s electrical signal moves too slowly through the sinus node or there are pauses in the delivery of the electrical signal

Sino-Atrial Node (or Sinus Node)
The natural pacemaker of the heart, which is situated in the right atrium

Sinus Rhythm
The heart’s normal rhythm

Stress Test
Involves exercising on a treadmill or stationary bike while an electrocardiogram monitors heart activity

Stroke
A medical condition where the brain is deprived of oxygen; blockage of blood flow can be created when a blood clot breaks free, travels through the circulatory system and gets lodged in blood vessel long enough to cause a section of the brain to die

Sudden Cardiac Arrest (SCA)
When the heart stops beating suddenly and unexpectedly

Supraventricular Tachycardia (SVT)
A fast rhythm that starts in the upper chambers of the heart

Tachycardia
An abnormally fast heart rate

Tilt Table Test
A table that allows a patient to lie flat and then be tilted as if standing up to monitor the heart and nervous systems’ response to the change in angle

Ventricles
The two lower chambers of the heart; the right ventricle pumps blood into the lungs and the left ventricle pumps blood around the body

Ventricular Fibrillation (VF)
A fast, dangerous heart rhythm which causes the heart to stop pumping, which needs a shock to stop it and return the heart back to a normal rhythm; a cardiac arrest can soon follow if the rhythm is not treated quickly with a shock

Ventricular Tachycardia (VT)
A fast, potentially dangerous, heart rhythm which causes the heart to pump less efficiently, and may lead to dizziness, fainting and unconsciousness; if not treated with medication, pacing or an electric shock, the rhythm may lead to ventricular fibrillation

Last Reviewed: March 11, 2010 900245