Effects of an abdominal left ventricular assist device on myocardial oxygen supply/demand ratios in normally perfused and ischemic bovine myocardium.

The effects of an abdominal left ventricular assist device (ALVAD) on subendocardial oxygen supply/demand ratios as reflected by diastolic pressure-time index/tension-time index (DPTI/TTI) were investigated in calves. Control DPTI/TTI ratios were 1.09 plus or minus 0.12 (mean plus or minus SD). With ALVAD actuation the ratios increased to 5.73 plus or minus 3.2. Following circumflex coronary artery occlusion, control ratios decreased to 0.04 plus or minus 0.05 in the ischemic area and 0.97 plus or minus 0.20 in the nonischemic areas. With ALVAD actuation in the presence of circumflex occlusion, the depressed ratios were increased to 1.37 plus or minus 0.39 in the ischemic zone and 9.71 plus or minus 2.5 in the nonoccluded segments. Subendocardial oxygen supply/demand ratios were significantly improved by ALVAD assistance following induced subendocardial ischemia.