Paroxysmal supraventricular tachycardia

What is Supraventricular tachycardia?

Paroxysmal supraventricular tachycardia is a disturbance of the normal heart rhythm (arrhythmia). Tachycardia is the medical term for a heart rate above 100 beats per minute.

During a normal heartbeat, the cycle starts with an electrical impulse generated in the pacemaker area of the heart called the sinoatrial (SA) node. The SA node lies in the upper left chamber of the heart called the left atrium. The electrical impulse then spreads through the left and right atrium and reaches the atrioventricular (AV) node. Here, the impulse travels down two bundles of nerves (his bundles) and stimulates the ventricles to contract and pump the blood.

Supraventricular tachycardia means that the electrical impulses that stimulate the fast ventricular beat originate outside the ventricles above the his bundles. Paroxysmal refers to the pattern of tachycardia that begins and ends (onset and offset) suddenly and can last from a few seconds to several hours.

The disorder is frequently found in young individuals who have normal hearts. It can also occur in reaction to digitalis or in conjunction with Wolff-Parkinson-White syndrome.

How is it diagnosed?

History: Most individuals are aware of these episodes of rapid heartbeat (palpitations). Other symptoms include anxiety, easy fatigability, shortness of breath (dyspnea), and chest discomfort. The symptoms may be severe if there are underlying heart or lung disorders. Supraventricular tachycardia is suspected in any individual without demonstrable heart disease, or who is under the age of 50 and is experiencing palpitations with sudden onset and offset.

Physical exam during an episode of the arrhythmia will reveal an unusually rapid heartbeat. There are no other specific physical findings unless the tachycardia occurs in the presence of other underlying disorders.

Tests: An EKG will confirm the diagnosis.

How is Supraventricular tachycardia treated?

Most attacks start and stop spontaneously. However, if chest pain is present or if the individual has fainted, the doctor may initiate measures to interrupt tachycardia with carotid massage or drug therapy. The individual also may learn self-help measures such as coughing, holding a breath, or the Vasalva's maneuver (attempting to expel breath while deliberately closing the mouth and nose).

There are several treatment options ranging from no therapy and reassurance, drug treatment (beta-blockers and antiarrhythmic drugs), or radiofrequency catheter ablation (a procedure whereby the site of the reentry pathway is destroyed). Most individuals are advised to avoid nicotine, alcohol, fatigue, and stress, which are known to provoke attacks.

Medications

Tenormin (Atenolol), Cordarone (Amiodarone), Betapace (Sotalol), Cardizem (Diltiazem), Calan (Verapamil), Inderal (Propranolol), Lopressor (Metoprolol)

What might complicate it?

Individuals with underlying pulmonary disease or other heart problems are less able to tolerate the increased stress placed on the cardiovascular system by this disorder. Some individuals experience syncopal attacks with the episodes.

Predicted outcome

There is a wide variation in these cases. Some individuals have infrequent attacks that respond to self-help measures. Others may be able to control the episodes with medication. Some need ablation procedures to control severe, symptomatic attacks.

Alternatives

Ventricular tachycardia, sinus tachycardia, atrial flutter and atrial fibrillation all present with similar symptoms, but the EKG will demonstrate the correct diagnosis.

Appropriate specialists

Cardiologist.

Last updated 10 May 2016