CARD16: Prolonged Normothermic Ex Vivo Heart Perfusion with Hemofiltration in Resting and Intermittent Working-heart Models

Abstract

Introduction: Cold static storage (5C) or normothermic (37C) ex vivo heart perfusion (NEVHP) in the beating but resting mode (Langendorff) successfully preserves hearts for transplantation for up to 6 hours. Previous attempts to prolong the preservation period increases morbidity and mortality following transplantation. In addition, the 6-hour limit imposes geographic restrictions for recipients, prevents optimal organ assessment, and reduces the number of hearts available for transplantation. We have successfully maintained 10 consecutive pediatric hearts (60±8.8 g) for 24 hours using NEVHP with hemofiltration in the beating, resting-heart mode. Although this prolonged NEVHP model was successful, cardiac function could not be comprehensively assessed in the beating, resting-heart mode. We sought to expand our prolonged NEVHP model to include intermittent left atrial (LA) perfusion that would allow cardiac assessment in the working-heart mode. Methods: We performed 24-hour NEVHP on 5 consecutive hearts (276 ±22.6 g). Following anesthetic induction, sternotomy, cardioplegia administration, explantation, and back-table instrumentation, NEVHP was initiated in beating, resting mode. After 1 hour the circuit was transitioned to LA perfusion working-heart mode for 30 minutes, baseline working-heart parameters were documented (Figure 1) and perfusion was returned to beating, resting-heart mode. Intermittent LA perfusion with working-heart assessment was performed every 4-6 hours. Final working-heart measurements were obtained at 24 hours. Results: All hearts survived 24 hours and all maintained working-heart parameters statistically identical to baseline. Mean LA pressure was 8.2±7.5 mmHg, peak left ventricle (LV) pressure was 33.9±8.7 mmHg, mean LV pressure was 12.0±13.7 mmHg, peak aortic pressure was 35.6±7.8 mmHg, mean aortic pressure was 22.8±7.7 mmHg, coronary resistance 0.15±0.05 mmHg/L/min, and lactate levels were 2.7±0.6 mmol/L. Conclusions: We have successfully developed and validated a porcine NEVHP model for assessment of cardiac function in the working-heart mode using intermittent LA perfusion. While intermittent LA perfusion is an important step toward comprehensive ex vivo assessment of donor heart function, proof of cardiac preservation following prolonged NEVHP still requires successful transplantation and complete assessment in the recipient. We plan to perform this as our next step toward prolonged ex vivo heart preservation. Techniques and cannula for intermittent LA perfusion in the pediatric model will also be developed.