Effect of ischemia, hypertrophy, hypoxia, acidosis, and alkalosis on canine defibrillation

Publisher Website
Google Scholar
Abstract
The effect of myocardial ischemia, left ventricular hypertrophy, and systemic hypoxia and acid-base abnormalities on the energy requirements for defibrillation were assessed. The defibrillation threshold (DFT), the minimum energy required to defibrillate was determined. DFT was not significantly elevated after left anterior descending coronary occlusion, nor was there a relationship between the size of the occluded coronary distribution area (coronary risk area) and the change in DFT in individual animals. Renal hypertension and left ventricular hypertrophy were induced by unilateral nephrectomy and contralateral renal artery stenosis. DFT in left ventricular hypertrophy dogs was not significantly higher than in dogs without hypertrophy. Finally, systemic hypoxia and acid-base abnormalities were induced. Neither respiratory nor metabolic acid-base disturbances affected DFT, but during systemic hypoxia (O2 tension 45 .+-. 2) DFT fell from 83 .+-. 49 to 58 .+-. 28 J (P < 0.01). Thus in dogs, myocardial ischemia, left ventricular hypertrophy, and acid-base abnormalities do not elevate defibrillation energy requirements, whereas hypoxia reduces the energy needed to defibrillate.