Demonstration of the mechanism of transient entrainment and interruption of ventricular tachycardia with rapid atrial pacing

• Published in: Journal of the American College of Cardiology Vol. 3; no. 2; pp. 422 - 430
• Main Authors: Waldo, Albert L., Henthorn, Richard W., Plumb, Vance J., MacLean, William A.H.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-02-1984; Elsevier Science
• Subjects: Adult; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Bundle-Branch Block - physiopathology; Cardiac Pacing, Artificial; Electrocardiography; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Heart Atria; Heart Conduction System - physiopathology; Heart Rate; Humans; Intensive care medicine; Male; Medical sciences; Tachycardia - physiopathology; Tachycardia - prevention & control; Atrium; Instrumental stimulation; Paroxysmal ventricular tachycardia; Instrumental treatment; Resuscitation
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/S0735-1097(84)80030-3

An unusual case is presented in which ventricular tachycardia at a rate of 141 beats/min was transiently entrained by rapid atrial pacing at rates of 150, 155 and 160 beats/min, and was interrupted by rapid atrial pacing at a rate of 165 beats/min. During each period of transient entrainment, constant ventricular fusion beats were present except for the last entrained beat, and progressive ventricular fusion (different fusion QRS complexes) was demonstrated when comparing QRS complex configurations during transient entrainment at each pacing rate. Interruption of the ventricular tachycardia was associated with localized conduction block to the right ventricular recording site, followed by activation of that site from a different direction and with a shorter conduction time by the subsequent pacing impulse.
These data clearly distinguish transient entrainment of a tachycardia from overdrive suppression of a tachycardia, and strongly suggest that reentry was the underlying mechanism of the ventricular tachycardia.