A SELECTIVE, NONISCHEMIC, NONPHARMACOLOGICAL LEFT-VENTRICULAR FAILUREANIMAL-MODEL

Selective left ventricular failure was induced in 13 acute anesthetize d, closed chest dogs ranging in weight from 18-26 kg. Failure was indu ced by passing a single, high intensity pulse of current from a defibr illator connected to a left ventricular catheter electrode and a left chest electrode. The intensity of the myocardial damaging shock was re lated to the predicted current required for transventricular defibrill ation, based on heart weight. Thermodilution cardiac output, left vent ricular pressure, impedance stroke volume, the cardiac electrogram, an d lead II ECG were recorded, along with the pressure impedance (volume ) loop, which is a measure of stroke work. It was found that the cardi ac output decreased with increasing current intensity. Immediately fol lowing the high current shock, cardiac output, and stroke work decreas ed. In some animals, with a moderate intensity shock, there was a tran sient increase in cardiac output, followed by a decrease. In the five animals that were monitored continuously for 4 hours, the average perc ent reduction in cardiac output at this time was 42.5% for an average current overdose ratio of 5.39. The energy setting on the defibrillato r to obtain this range of reduction in cardiac output was 175-350 joul es. The method described herein is easily applied to the closed chest animal and will allow evaluation of the pumping capabilities of cardia c augmentation techniques, such as dynamic cardiomyoplasty and the ske letal muscle ventricle.