Supraventricular tachycardia Health Dictionary

An abnormally fast but regular heart-rate that occurs in episodes lasting for several hours or days. Supraventricular tachycardia occurs when abnormal electrical impulses that arise in the atria of the heart take control of the heartbeat from the sinoatrial node. Symptoms include palpitations, breathlessness, chest pain, or fainting (see Stokes–Adams syndrome).

Diagnosis is by an ECG.

An attack can sometimes be terminated by Valsalva’s manoeuvre or by drinking cold water.

Recurrent attacks are treated with antiarrhythmic drugs.

Rarely, the condition may require application of an electric shock to the heart (see defibrillation).

An unusually fast but regular beating of the HEART occurring for periods that may last several hours or days. In most people with this abnormality the heart rate is between 140 and 180 beats a minute; rarely, the rate may rise as high as 250–300 beats. The condition occurs when abnormal electrical impulses that arise in the upper chambers (atria) of the heart override the normal control centre – the sinoatrial node – for the heartbeat. Symptoms usually include breathlessness, palpitations, pain in the chest and fainting. An ELECTROCARDIOGRAM (ECG) is taken to help make the diagnosis. An acute episode can sometimes be stopped by VALSAVA’S MANOEUVRE or by drinking cold water. Anti-arrhythmic drugs (see ARRHYTHMIA) such as adenosine and digoxin are used to treat recurrent attacks. Occasionally, a severe attack may need to be treated with an electric shock to the heart: this is known as DEFIBRILLATION.

(SVT) a rapid regular heartbeat that is usually due to a re-entry circuit between the atria and ventricles (see re-entry tachycardia). It is less commonly due to an ectopic focus in an atrium that is spontaneously discharging at a fast rate (atrial tachycardia).