24 - Paroxysmal supraventricular tachycardias

Abstract

A “supraventricular” origin of a tachycardia implies the obligatory involvement of one or more cardiac structures above the bifurcation of the His bundle (HB), including atrial myocardium, atrioventricular node (AVN), proximal HB, coronary sinus, pulmonary veins, venae cavae, or abnormal atrioventricular (AV) connections other than the HB (i.e., bypass tracts). Narrow complex supraventricular tachycardias (SVTs) include sinus tachycardia, inappropriate sinus tachycardia, sinoatrial nodal reentrant tachycardia, focal atrial tachycardia (AT), multifocal AT, atrial fibrillation (AF), atrial flutter (AFL), junctional tachycardia, AVN reentrant tachycardia (AVNRT), and AV reentrant tachycardia (AVRT). Paroxysmal SVT is the term generally applied to intermittent SVT other than AF, AFL, and multifocal AT, and describes a clinical syndrome characterized by the presence of a regular and rapid tachycardia of abrupt onset and termination. The major causes are AVNRT (approximately 50% to 60% of cases), AVRT (approximately 30% of cases), and focal AT (approximately 10% of cases). Most paroxysmal SVTs are generally benign and do not influence survival; therefore, the primary indication for treatment is to alleviate symptoms and improve quality of life. The threshold for initiation of therapy and the decision to treat SVT with oral pharmacological therapy or catheter ablation depends on the frequency and duration of the arrhythmia, severity of symptoms, presence of concomitant structural heart disease, and patient preference. Given the high success rates and the low complication rate, catheter ablation is the treatment of choice in patients who desire to avoid or are unresponsive or intolerant to drug therapy.