Intravenous calcium chloride in the conversion of paroxysmal supraventricular tachycardia to normal sinus rhythm

This brief report describes several cases of paroxysmal supraventricular tachycardia that converted promptly to normal sinus rhythm within 1 to 2 minutes of receiving intravenous calcium salts as pretreatment in anticipation of verapamil therapy. A review of calciumʹs hemodynamic and dromotropic effects suggests that this probably was due to electrophysiological effects rather than mere coincidence. Calcium raises blood pressure, which may reflexively increase cardiac parasympathetic tone, and also has a direct slowing effect on atrioventricular conduction. Adenosine remains the drug of choice in the treatment of paroxysmal supraventricular tachycardia. However, in addition to preventing hypotension when used as pretreatment to overapamil, intravenous calcium itself may terminate supraventricular tachycardia.