A selective, non-ischemic, non-pharmacological left ventricular failure animal model.

Selective left ventricular failure was induced in 13 acute anesthetized, closed chest dogs ranging in weight from 18-26 kg. Failure was induced by passing a single, high intensity pulse of current from a defibrillator connected to a left ventricular catheter electrode and a left chest electrode. The intensity of the myocardial damaging shock was related to the predicted current required for transventricular defibrillation, based on heart weight. Thermodilution cardiac output, left ventricular pressure, impedance stroke volume, the cardiac electrogram, and lead II ECG were recorded, along with the pressure impedance (volume) loop, which is a measure of stroke work. It was found that the cardiac output decreased with increasing current intensity. Immediately following the high current shock, cardiac output, and stroke work decreased. In some animals, with a moderate intensity shock, there was a transient increase in cardiac output, followed by a decrease. In the five animals that were monitored continuously for 4 hours, the average percent reduction in cardiac output at this time was 42.5% for an average current overdose ratio of 5.39. The energy setting on the defibrillator to obtain this range of reduction in cardiac output was 175-350 joules. The method described herein is easily applied to the closed chest animal and will allow evaluation of the pumping capabilities of cardiac augmentation techniques, such as dynamic cardio-myoplasty and the skeletal muscle ventricle.