Transesophageal Cardioversion and Defibrillation

Transesophageal low-energy cardioversion in an animal model of life-threatening tachyarrhythmias.

Yunchang C, Shoulian F, Duanxing G, Shixiang G, Jifent F, Zhushen K, Zhougfan L. Guizhou Provincial Cardiovascular Institute, Republic of China. Circulation 1989 Nov;80(5):1354-9. The purpose of this study was to determine the feasibility and efficacy of terminating life-threatening ventricular tachyarrhythmia by low-energy synchronous or asynchronous shocks delivered through a transesophageal catheter that had both an anode and a cathode. Forty-three episodes of ventricular fibrillation or flutter (Vf or VF) were provoked by transesophageal asynchronous random shocks occurring during the vulnerable period of the ventricular cycle in seven dogs and seven pigs that were healthy adults. The 43 episodes of Vf or VF were terminated by the transesophageal technique. The defibrillation energy thresholds were 23.11 +/- 6.28 Joules (range, 5-30 J). Seven episodes of ventricular tachycardia (VT) with a cycle length of 360 msec or less (330 +/- 27 msec) were provoked by ventricular pacing stimuli during acute myocardial ischemia resulting from delayed resuscitation in two dogs and three pigs. Five of the seven VTs had a duration of 31 seconds or more, and they were all terminated by transesophageal synchronous shocks, the cardioversion thresholds being 1.71 +/- 2.25 J (range, 0.25-5 J). Fourteen episodes of idioventricular tachycardia (IVT) with a cycle length of 400 msec or more (445 +/- 33.5 msec) spontaneously occurred after the use of adrenaline and after defibrillation in four dogs and five pigs. We also succeeded in terminating seven episodes of IVT with a duration of 34 seconds or more by the same means of treating VT, although IVT is not an indication for cardioversion in the clinical setting. The cardioversion thresholds were 1.45 J (range, 0.25-5 J). The difference between the mean energy levels required for cardioversion of VT and IVT were not significant (t=0.2, p >.05). The remaining 2 VTs and IVTs had a duration 12.5 kg and < 12.5 kg. There were no apparent functional or histologic ill effects in the esophagi that received cumulative shocks of 100 to 378 Joules. In 246 synchronous or asynchronous shocks (including subthreshold shocks) for cardioversion, acceleration of VT or IVT or degeneration to Vf or VF never occurred. We conclude that this new procedure is a safe and effective method for treating life-threatening ventricular tachyarrhythmias.

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