EVALUATION OF PULSATILE AND NON-PULSATILE FLOW IN CAPILLARIES OF THE BULBAR CONJUNCTIVA IN THE GOAT IMPLANTED A TOTAL ARTIFICIAL HEART

PURPOSE: To investigate the influence of flow patterns on the microcirculation (MC) in the goat implanted a total artificial heart (TAH). METHODS: The digital high definition microscope was used to observe the MC of the bulbar conjunctiva. An undulation pump total artificial heart (UPTAH) was implanted into the goat, which could produce arbitrary flow patterns. When the whole body condition became stable after the surgery, the flow pattern was changed from pulsatile to non-pulsatile and the change in the MC was observed. RESULTS: When the flow pattern was changed from pulsatile to non-pulsatile, the arteriolae were constricted and the velocity of erythrocytes in the capillaries dropped remarkably (from 526±83 μm/sec to 132±41 μm/sec), and remained low level. And the number of perfused capillaries decreased. After the flow pattern was returned to pulsatile again, the velocity of erythrocytes recovered to the initial level. In many cases, the flow of non-perfused capillaries recovered to the initial level. CONCLUSION: When the flow pattern was changed from pulsatile to non-pulsatile, the decrease in velocity of erythrocytes in the capillaries and the deterioration in capillary density are observed. There is a possibility that non-pulsatile perfusion causes microvascular dysfunction. That could become more severe with prolonged non-pulsatile VAD use or permanent non-pulsatile TAH implantation in the future. This severity needs to be addressed in chronic studies.