paroxysmal supraventricular tachycardia, an ectopic heart rhythm with a rate of 170 to 250 beats/min. It begins abruptly with a premature atrial or ventricular beat and is supported by an atrioventricular (AV) nodal reentry mechanism or by an AV reentry mechanism involving an accessory pathway. Formerly called paroxysmal atrial tachycardia, paroxysmal junctional tachycardia.
