Supraventricular and Junctional Rhythms

Supraventricular rhythms, more precisely referred to as supraventricular tachycardias (SVTs), are a group of arrhythmias that originate from within the atrial tissue, pulmonary veins, and/or accessory pathways. Classically, the SVT family is comprised of atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), and paroxysmal atrial tachycardia (pAT). The electrophysiology for each arrhythmia is unique, although delineating one SVT from another may be challenging on a surface ECG. Additionally, frequently encountered arrhythmias like atrial fibrillation (AF) and atrial flutter (AFL) originate from supraventricular foci. Furthermore, both atrial fibrillation and atrial flutter may induce rapid contraction of the atria, even though the ventricular heart rates may be normal or even bradycardic. As such, AF and AFL are oftentimes treated separately due to their significant difference in clinical management compared to the SVT. Finally, junctional rhythms involve AV junctional ectopic beats and other brady- and tachyarrhythmias originating adjacent to the AV node. This chapter serves the imperative tasks of teaching the reader about complex but interesting (and clinically relevant) arrhythmias.