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September 20, 1976

Ventricular Tachycardia

Author Affiliations

Columbia-Presbyterian Medical Center New York

JAMA. 1976;236(12):1354. doi:10.1001/jama.1976.03270130018013

To the Editor.—  In his article entitled "Pacemaker-Induced Ventricular Tachycardia: Reversion to Normal Sinus Rhythm by Carotid Sinus Massage" (235:282-283, 1976), Donald Lorentzen, MD, suggested (1) that the tracings shown had to represent ventricular tachycardia, (2) that the tachycardia terminated in 2:1 block, and (3) that "it seems certain that the mechanism of the ventricular tachycardia is repetitive spontaneous depolarization of an ectopic focus in the right ventricle" because reentry should not have terminated in 2:1 block.I would contend that closer evaluation will reveal another more possible explanation for the rhythm strips presented. (1) The tachycardia in both instances probably terminates not in 2:1 block but is terminated by a QRS complex narrower than that of the tachycardia after a pause that is greater than twice the cycle length of the tachycardia. This suggests that the tachycardia may have stopped at the onset of the pause and that the