A closed-chest model for the study of electromechanical dissociation of the heart in dogs.
A closed chest model in mechanically ventilated dogs is presented for the study of electromechanical dissociation (EMD) after defibrillation for ventricular fibrillation (VF). In seven dogs VF was induced by internal application of an AC current in the right ventricle. Precordial compression was not performed. When VF was continued for either 30 s or 60 s defibrillation typically resulted in complete restoration of electrical and mechanical cardiac activity. Immediately after defibrillation, the mean arterial blood pressure, pulmonary artery pressure, right ventricular filling pressure and cardiac output were markedly elevated; these elevations were accompanied by a slight increase in lactate and a decline in pH of the arterial blood. When VF was continued for 120 s EMD was observed in each instance after defibrillation in association with a regular rhythm. After 5-20 min, the ventricular fibrillation reappeared. The constancy of EMD in this model provides an experimental basis for study of clinical options, by which EMD may be prevented and/or mechanical competence of the heart may be restored.
D000818:Animals; D004285:Dogs; D004554:Electric Countershock; D005260:Female; D006321:Heart / Q000503:physiopathology; D006327:Heart Block / Q000209:etiology* / Q000503:physiopathology; D006439:Hemodynamics; D008297:Male; D014693:Ventricular Fibrillation / Q000150:complications* / Q000503:physiopathology