Supraventricular Tachycardia

Supraventricular tachycardias are arrhythmias that are usually non-life threatening. The result in a narrow and sometimes wide QRS complex tachycardia on ECG. Supraventricular tachycardia can be due to atrioventricular reentrant tachycardia, atrioventricular nodal reentrant tachycardia, atrial tachycardia, atrial fibrillation, and atrial flutter. This page will study the first three aforementioned tachycardias. Atrial fibrillation and atrial flutter is discussed in other education web pages on this site.

Atrioventricular reentrant tachycardia (AVRT) is due to an accessory pathway which is an abnormal connection between the ventricle and atria. This connection creates the potential for a reentrant arrhythmia, where electrical depolarization can travel down the AV node, to the ventricles, up the accessory pathway, through the atria, and back down the AV node. This creates a narrow complex tachycardia, unless there is a bundle branch block present. The wave of depolarization can travel in the opposite direction (Antegrade activation down the accessory pathway results in abnormal activation of the ventricle and a wide QRS on the ECG. Therapy can be with B-blockers, calcium channel blockers and sometimes antiarrhythmics. Electrophysiology study with mapping and ablation can "cure" 80-98% of these arrhythmias.

Atrioventricular nodal reentrant tachycardia (AVNRT) is due to some extra fibers that enter into the AV node posteriorly called the slow pathway. This slow pathway is in addition to a fast pathway, which can result in a reentrant arrhythmia. Typically the wave of depolarization goes down the slow pathway and back up the fast pathway which results in a narrow complex tachycardia, unless a bundle branch block or an accessory pathway is present. Therapy can be with B-blockers, calcium channel blockers and sometimes antiarrhythmics. Electrophysiology study with mapping and ablation can "cure" 95-98% of these arrhythmias.

Atrial tachycardia is due to some atrial myocytes with "delinquent behavior." These heart cells can be located in the right of left atria, and can sometimes mapped and ablated with an 80-90% chance of success. Therapy can also be with B-blockers, calcium channel blockers and sometimes antiarrhythmics.