Servocontrolled cardiac assistance: Effects of left ventricular to aortic and left atrial to aortic assistance on infarct size

Devices for cardiac assistance are effective in supporting the falling circulation. In this study the effect of left ventricular to aortic assistance in salvaging ischemic myocardlum was evaluated in dogs and compared with the effect of left atrlal to aortic assistance. In a control group, there was good correlation between measurements of infarct size obtained with S-T segment mapping at 20 minutes, trlphenyl tetrazollum chloride staining at 5 hours and determination of the distribution of radioactive mlcrospheres ( P < 0.01). A Servocontrolled roller pump used to control pump speed according to left atrlal pressure allowed reduction of left ventricular pressure to 38 percent of systemic levels and provided stable bypass for prolonged periods. The pressure-time index was reduced to 37 percent of baseline levels ( P < 0.005). A reduced infarct size, as measured with S-T segment mapping and triphenyl tetrazollum chloride staining, was observed in Group II, dogs given left ventricular to aortic assistance before occlusion of the left anterior descending coronary artery ( P < 0.05), and in Group III, dogs given assistance 20 minutes after occlusion ( P < 0.05). Left atrlal to aortic assistance did not reduce infarct size in this model. Electron microscopic studies confirmed the infarct distribution. Blood flow distribution measured with use of radioactive mlcrospheres showed that in the ischemic area endocardial/eplcardial ratio increased with left ventricular assistance; in the control group and with left atrlal assistance the ratio decreased with the second occlusion ( P < 0.05). Left ventricular to aortic assistance is thus superior to left atrial to aortic assistance in ability to salvage ischemlc myocardlum. The Servocontrolled roller pump offers an effective, simple method of postoperative cardiac assistance.