PULMONARY MICROCIRCULATION DURING PULSATILE AND NON PULSATILE PERFUSION

During development of a rotary blood pump as an assist device, the eff icacy of non pulsatile perfusion to the end organ has to be verified. However, there are few evaluations of two different perfusion mechanis ms through the tissue microcirculation. In this study, the pulmonary m icrocirculation was analyzed by vital microscopic observation. Wistar rats weighing 400-500 g were anesthetized and ventilated by a respirat or. After establishing right heart bypass from the right atrium to the pulmonary artery using a roller pump, the pulmonary microcirculation was observed during intravenous infusion of bovine albumin tagged with fluorescein isothiocyanate. The images were recorded on a videotape t hrough an ultra-sensitive SIT TV camera. Initially, the pulmonary circ ulation was pulsatile, produced by the native heart, and the pulmonary capillary network was evenly perfused by the blood. After starting th e pump, the flow became non pulsatile and the distribution of capillar y perfusion was displaced to the short circuit connecting the pulmonar y arterioles and venules. Flow distribution during non pulsatile perfu sion was heterogeneous compared with pulsatile perfusion. This result suggests that non pulsatile now may lead to the deterioration of funct ion. Further investigation is necessary to evaluate the relationship b etween the microcirculation and organ function.