Paroxysmal Supraventricular Tachycardia (PSVT)

PSVT stands for paroxysmal supraventricular tachycardia, and refers to sudden heart palpitations. The condition is also known as paroxysmal atrial tachycardia (PAT). Heart palpitations caused by PSVT or its variant, Wolff-Parkinson-White syndrome, do not usually require medical treatment, and are characterized by abrupt onset and termination. The physical effects of PSVT, however, can be upsetting and frightening to the person experiencing the heart palpitations.

PSVT's most obvious symptom is rapid heart palpitations. The pulse rate during a PSVT attack varies from 150 to 200 beats per minute. PSVT or Wolff-Parkinson-White syndrome can last a few seconds to several hours.

In most cases, resting slows heart palpitations and returns the pulse rate to normal. Severe cases of PSVT may require medication to slow heart palpitations. If PSVT does not subside, medical intervention becomes necessary.

Most PSVT cases result from an electrical malfunction in the heart known as re-entry phenomenon. This phenomenon arises due to problems with the heart's conduction pathways causing signals to loop back around instead of flowing in a single direction from the atria towards the ventricles.

Wolff-Parkinson-White syndrome is similar to PSVT in that there is a conduction problem with the heart's electrical activity. While most cases of PSVT can be traced to the atrial chambers, Wolff-Parkinson-White syndrome originates in the atrioventricular (AV) node, a "switching station" that controls electric signals traveling from the heart's atrial chambers to the ventricles.

Wolff-Parkinson-White syndrome can cause other types of tachycardia, including atrial flutter and atrial fibrillation.

PSVT and Wolff-Parkinson-White syndrome do not usually require medication, but treatment may be necessary if heart palpitations persist. Medication such as beta blockers and calcium channel blockers may help return heart rates to normal.

Some patients may be candidates for cardiac ablation therapy. Ablation therapy involves inserting a catheter into a leg artery and threading it all the way to the heart. Once localized in the heart, areas of poor conduction can be destroyed ("ablated") using radio waves or other sources of energy. Successful ablation therapy can end or reduce the number of tachycardia attacks.

Resources

American Heart Association. (updated 2005). Arrhythmias originating in the atria.

American Heart Association. (updated 2005). Wolff-Parkinson-White syndrome.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S. & Longo, D. (ed). Harrison's Principles of Internal Medicine, 14th Edition. McGraw-Hill, New York, 1998.

Ganz, L. (updated 2004). Paroxysmal supraventricular tachycardia.

Herbert, M. (updated 2005). Wolff-Parkinson-White syndrome.