The Impact of Whole Blood versus Dilute Whole Blood on Coronary Vascular Tone during Ex Situ Heart Perfusion

Abstract

Ex situ heart perfusion (ESHP) allows continuous functional and metabolic assessment of donor hearts before transplantation. Evidence indicates that circulating chemical mediators in whole blood are involved in the regulation of oxygen delivery. We aim to evaluate the impact of whole blood versus dilute whole blood in the regulation of coronary vascular tone during ESHP. Normal porcine hearts were perfused in working mode for 6 hours either by whole blood (n=5) or whole blood with Krebs-Henseleit solution (1:1) containing 8% albumin (n=5). Cardiac functional parameters, coronary artery flow and metabolism were monitored continuously. Coronary vascular resistance (CVR) was calculated to evaluate coronary artery function. These parameters were compared between groups at different time. The whole blood group had significantly higher hemoglobin concentration than blood+buffer group (p<0.01, Fig. A). Oxygen delivery was significant higher in whole blood group than blood+buffer group at all time points (p<0.01, Fig. B). Coronary flow increased overtime in blood+buffer group (p<0.01), and was significantly higher than whole blood group at each time point (p<0.01, Fig. C). Similarly, CVR decreased significantly in blood+buffer group, and was lower than whole blood group at T1 and T5 (p<0.01, Fig. D). Cardiac function declined, with 80% of baseline function in both groups; however, there was no significant difference between groups (Fig. E). Myocardial oxygen consumption declined in blood+buffer group (p<0.01, Fig. F); however, there was not significantly change in whole blood group. Whole blood appears to play a role in regulating coronary vascular tone, as indicated by relative higher vascular resistance and better oxygen delivery in whole blood perfusion after 6 hours. The relative contribution of hemoglobin content versus plasma protein content is not clear. Whether this translates into improved post-transplant function remains to be determined.