Types of supraventricular tachycardia
In addition to atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT), there are several types of supraventricular tachycardia (SVT).
Atrial fibrillation or flutter
Atrial fibrillation is the most common type of SVT.
Sinus tachycardia is present when a person's heart rate is over 100 beats per minute and there is a clear reason for the fast heart rate, such as exercise, pain, or fever. A fast heart rate is normal under these circumstances. With sinus tachycardia, the electrical system of the heart is working normally.
This type of fast heart rate seldom requires treatment other than correcting the underlying health condition that may be causing the fast heart rate.
Sinus node reentrant tachycardia
Sinus node reentrant tachycardia is a rare type of fast heart rate. This type is caused by abnormal conduction of electrical impulses within the sinus node.
Sinus node reentrant tachycardia begins and ends very suddenly. Diagnosis is frequently made during an electrophysiology (EP) study. Treatment may include long-term medicines (such as beta-blockers or calcium channel blockers) or catheter ablation.
Atrial tachycardia is a type of fast heart rate caused by rapid electrical signals that begin in the upper chambers of the heart. As a result, the heart can sometimes beat very rapidly.
Treatment of this type of rhythm depends on the cause of the fast heart rate and often involves taking medicines (such as digoxin, beta-blockers, or calcium channel blockers). Many atrial tachycardias can also be successfully cured using ablation. The site or sites in the atria responsible for the rapid heart rate can be located and destroyed. Only rarely is ablation of the atrioventricular (AV) node and placement of a permanent pacemaker needed.
AV node ablation involves using heat or freezing cold to destroy the AV node. The AV node passes impulses to the lower heart chambers (ventricles). Destroying the AV node prevents fast, erratic pulses from the upper chambers from reaching the lower heart chambers. This can prevent episodes of rapid heart rate. It is most often used in people with difficult-to-control atrial fibrillation and severe symptoms.
After AV node ablation, a pacemaker is needed to send regular impulses to the lower heart chambers (ventricles).
Multifocal atrial tachycardia
Multifocal atrial tachycardia (MAT) is an abnormal, rapid rhythm that occurs most commonly in individuals with severe lung disease. It can also occur after a heart attack, in someone with low blood levels of magnesium or potassium, and as a side effect of certain medicines such as aminophylline.
During this rhythm, three or more different areas of the atrium initiate extra heartbeats. It is somewhat similar to having several different kinds of premature atrial contractions (PACs) occurring in the same person. These different areas of electrical activity can be seen on an electrocardiogram (EKG, ECG) and are used as the criteria for diagnosing this arrhythmia. People with this arrhythmia frequently complain of palpitations.
On EKG, multifocal atrial tachycardia may appear similar to atrial fibrillation, but it is a distinct condition. The problem with this rhythm is that it causes a persistently fast heart rate that may be difficult to control. Calcium channel blockers such as verapamil are occasionally effective. But the most effective way to control this rhythm is by treating the disease causing the arrhythmia, and this is usually lung disease.
Junctional tachycardia is a rare fast heart rate that starts in the area between the upper and lower chambers of the heart. This rhythm frequently affects adults who have heart disease and children who have had heart surgery.
Some people may require catheter ablation. Children may be treated with long-term medicines if the fast heart rate continues.
Inappropriate sinus tachycardia
Inappropriate sinus tachycardia is present when a person's heart rate is over 100 beats per minute with no apparent cause. In this rare condition, the electrical system of the heart is working normally. There are no outside factors present to explain why the heart is beating so fast.
People with inappropriate sinus tachycardia do not generally have any heart disease. Inappropriate sinus tachycardia with no heart disease may mean your autonomic nervous system is not working right.
Treatment of this type of rhythm depends on the cause of the fast heart rate. Treatment often involves taking medicines such as digoxin, beta-blockers, or calcium channel blockers. If the problem continues in spite of these treatments and is causing symptoms, ablation of the atrioventricular (AV) node or sinus node and placement of a permanent pacemaker sometimes may be needed.
Last Updated: September 17, 2008
Author: Robin Parks, MS