Hemodynamic Performance of the Biventricular Bypass System Operated in an Independent Variable Rate Mode

The present study was undertaken to determine whether a biventricular bypass system operated in an independent variable rate (VR) mode can maintain the entire circulation. Two pusher-plate pumps which incorporated the Hall effect position sensors were used to bypass the right and left ventricles in 10 sheep under fibrillation. The flow distributions of the pump output to the carotid and renal arteries were investigated every 6 h using ultrasonic blood flow meters for 24 h in 5 animals, and the controllability of the VR mode was evaluated in 5 long-term experiments. The carotid artery flow ratio to the pump output decreased significantly from 4.7 +/- 0.8% before the bypass to 2.7 +/- 0.9% after 24 h. However, the renal artery flow ratio did not change throughout the experiments. In the long-term experiments, the animals were kept alive from 3 to 48 days (mean 15.6 days). The mean pump output had been maintained at more than 90 ml/min/kg for the first 7 days. After the surgery, the pump driving conditions were not readjusted in any experiment. The results indicate that the biventricular bypass system operated in the independent VR mode automatically maintains the entire circulation at a satisfactory level.</p

Leukocyte depletion reduced reperfusion injury in hearts preserved hypothermically for 6 hours

Recent studies suggest that circulating leukocytes trapped in the post ischemic-reperfused organ release active oxygen species and leukotrienes, and cause tissue damage. Canine hearts statically preserved for six hours, were reperfused with whole blood (group Ⅰ, n=7), with leukocyte depleted blood (group Ⅱ, n=14), and with leukocyte and protein depleted blood (group Ⅲ, n=7). After initial perfusion, whole blood prefusion was started at 15 minutes of post reperfusion (group Ⅱa, n=7) and at 30 minutes of post reperfusion (group Ⅱb, n=7; group Ⅲ, n=7). Significant leukocytes sequestration wsa demonstrated only in group Ⅰ and group Ⅱa. Left ventricular function recovery, coronary flow and mitochondrial phospholyration activity were significantly better preserved in the groups reperfused with leukocyte depleted blood, especially gorup Ⅲ. These date suggest that leukocyte depletion amelioraes reperfusion injury of preserved hearts