Author + information
- Received August 5, 1987
- Revision received October 8, 1987
- Accepted October 23, 1987
- Published online March 1, 1988.
- G.Neal Kay, MD∗,
- Andrew E. Epstein, MD and
- Vance J. Plumb, MD, FACC
- ↵∗Address for reprints: G. Neal Kay, MD, Division of Cardiovascular Disease, Department of Medicine, 321 Tinsley Harrision Tower, University of Alabama at Birmingham, Birmingham, Alabama 35294.
The demonstration of transient entrainment has been proposed as evidence of reentry, with an excitable gap as the probable mechanism of tachycardia. A prospective series of 27 consecutive patients with sustained ventricular tachycardia induced by programmed electrical stimulation was studied to determine the frequency with which transient entrainment can be demonstrated and to define the optimal location of pacing and recording electrodes.
In all patients, electrodes for pacing and recording were placed in both the left and right ventricles during electrophysiologic study. Among the 19 patients in whom the response to rapid pacing could be evaluated (25 episodes of ventricular tachycardia), transient entrainment was demonstrated in 79% (76% of episodes). Ten of 12 episodes of ventricular tachycardia with a left bundle branch block QRS configuration in lead V1and 9 of 13 episodes with a right bundle branch block QRS configuration could be transiently entrained (p = NS). Transient entrainment was demonstrated for 8 of 11 episodes of ventricular tachycardia with a left bundle branch block configuration during pacing from the left ventricle, but for only 2 of 10 episodes during pacing from the right ventricular apex (p < 0.05). Conversely, 9 of 13 episodes of ventricular tachycardia with a right bundle branch block configuration were transiently entrained during pacing from the right ventricular apex, but 0 of 10 episodes were transiently entrained by left ventricular pacing (p < 0.05). Pacing from the right ventricular outflow tract allowed demonstration of transient entrainment in four of five episodes of ventricular tachycardia with a left bundle branch block configuration and five of nine episodes with a right bundle branch block configuration (p = NS). The location of recording electrodes was also important for demonstration of the transient entrainment criteria. When the first transient entrainment criterion was demonstrated, the last entrained complex always occurred at the paced cycle length in the electrogram recorded at a site of endocardial activation preceding the onset of the surface QRS complex.
These results provide evidence that sustained ventricular tachycardia induced by programmed electrical stimulation is usually based on reentry incorporating an excitable gap.
- Received August 5, 1987.
- Revision received October 8, 1987.
- Accepted October 23, 1987.