LEFT-VENTRICULAR UNLOADING BY TRANSVALVULAR AXIAL-FLOW PUMPING IN EXPERIMENTAL CARDIOGENIC-SHOCK AND DURING REGIONAL MYOCARDIAL-ISCHEMIA

The efficacy of the transfemoral left-ventricular assist device Hemopu mp(TM) (HP; 21 Fr outer diameter) was examined in experiments with adu lt sheep in two different models of cardiogenic shock (tachycardia sho ck; ischemia shock), and during ventricular fibrillation. During tachy cardia (high frequency pacing-induced; n = 14), HP assist led to a sig nificant increase in cardiac output (from 2.2 to 2.8 liters/min), mean aortic pressure (from 47.6 to 65.6 mm Hg), and myocardial perfusion p ressure (from 25.5 to 59.0 mm Hg). Simultaneously, a normalization of body oxygen-uptake (from 1.4 to 2.5 ml/min.kg), a decrease in myocardi al oxygen consumption (from 6.1 to 4.8 ml/min.100 g), and a normalizat ion of myocardial lactate metabolism were ovserved during HP assist. D uring regional myocardial ischemia (PTCA balloon occlusion of the prox imal LAD (3.5 min; n = 12), HP assist led to significant decrease in L V enddiastolic pressure (from 2 1.1 to 12.1 mm Hg), and increase in di astolic aortic pressure (from 58 to 67 mm Hg) resulting in significant increase in coronary perfusion pressure. In the early reperfusion per iod, myocardial release of both lactate and potassium was significantl y lowered with HP assist. During ventricular fibrillation (induced by electrical stimulation; n = 9), HP flow rates decreased from 2.5 (afte r 10 min) to 2.1 liters/min (after 30 min). Mean aortic pressures simu ltaneously decreased from 64.0 to 54.6 mm Hg. Perfusion conditions wer e sufficient for maintenance of aerobic myocardial metabolism, but wer e borderline for peripheral circulation. Our hemodynamic and metabolic data demonstrate beneficial effects of cardiac assist with the Hemopu mp 21 Fr in both tachycardia-induced severe cardiogenic shock and duri ng acute regional myocardial ischemia. During ventricular fibrillation , flow conditions were sufficient to maintain aerobic myocardial metab olism, but circulatory supply to the total organism was borderline.