Definitions of Heart Rhythm Abnormalities

Atrial Fibrillation
An abnormally fast heart rhythm in which the atria (upper chambers of the heart) quiver due to chaotic, uncoordinated electrical activity. Atrial fibrillation may be continuous or may start and stop spontaneously.

Atrial Flutter
A condition in which the contractions in the atria (upper chambers of the heart) become extremely rapid.

The heartbeat is too slow, or slows enough to cause symptoms.

Sick Sinus Syndrome (SSS)
A broad term to describe abnormalities in the SA node (the heart's natural pacemaker). This may result in a slow, fast or irregular heart rate, or intermittent cessation of the SA node activity.

Supraventricular Tachycardia (SVT)
A category of heart rhythm disorder characterized by an abnormal rapid or irregular heart rhythm in the atria (upper chambers) of the heart.

Ventricular Fibrillation (VF)
A heart rhythm disorder that originates in the ventricles (lower chambers of the heart), VF is an abnormally rapid heart rhythm that is highly unstable and irregular. During VF, electrical signals move chaotically through the heart, preventing it from pumping blood and beating properly.

Ventricular Tachycardia (VT)
A heart rhythm that originates in the ventricles (lower chambers of the heart). VT is a rapid rhythm during which patients may feel faint or dizzy, or even pass out. During VT, the heart does not pump blood as efficiently as it does during a normal rhythm because rapid contractions prevent it from filling adequately with blood between beats.

A chronic disorder that causes the muscle of the heart to become weakened and not work as efficiently as it should.

Congestive Heart Failure
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 causing fluid to accumulate in various parts of the body. This may occur due to heart attack, hypertension, heart muscle or heart valve disease.

Heart Failure
A syndrome or clinical condition resulting from failure of the heart to maintain adequate circulation of blood. It may result from failure of the right or left ventricle (lower chamber) or both.

Long QT Syndrome
An abnormality of the heart's electrical system. The mechanical function of the heart is entirely normal. An electrical defect that leads to a very fast heart rhythm which can result in a sudden loss of consciousness and may cause sudden cardiac death. The syndrome may be inherited or acquired.

Sudden Cardiac Death
The sudden abrupt loss of heart function (IE. cardiac arrest) in a person who may or may not have been diagnosed with heart disease. It occurs instantly or shortly after the onset of symptoms.

Wolf - Parkinson-White Syndrome (WPW)
An abnormal heart rhythm in which electrical impulses are conducted along an extra pathway from the atria (upper chambers) to the ventricles (lower chambers), causing episodes of a rapid heart rate.