Emergency Medical Minute

Contributor: Taylor Lynch MD Supraventricular tachycardias (SVTs) arise above the bundle of His The term SVT includes AV nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), atrial tachycardia, atrial fibrillation, atrial flutter, and multifocal atrial tachycardia  AVNRT is the most common form of SVT Paroxysmal Spontaneous or provoked by exertion, coffee, alcohol, or thyroid disease More common in women (3:1 women:men ratio) HR 160-240 Narrow complex with a normal QRS Unstable patients receive synchronized cardioversion at 0.5-1 J/kg Valsalva maneuver is attempted before pharmaceutical interventions Increases vagal tone at the AV node to slow conduction and prolongs its refractory period to normalize the conduction Traditionally, patients are asked to bear down, but this only works in 17% of patients REVERT trial assessed a modified valsalva that worked in 43% of patients Adenosine Slows conduction at the AV node by activating potassium chan