CARD17: 24 hr Normothermic Ex Vivo Heart Perfusion in Adult Porcine Hearts with Hemofiltration

Abstract

Introduction: Currently, to successfully transplant a heart, cardiac preservation relies on cold static storage at 5C for up to 6 hours. If hearts are stored at this temperature for a longer duration, their function after transplantation is compromised, increasing post-transplant morbidity and mortality. This time restriction negatively impacts the availability of donor hearts and limits distance and transportation options, optimal cross-matching, and organ assessment, all of which facilitate successful transplantation. Previous studies from our group have demonstrated that: 1) Plasma cross circulation at 1 L/hr from a living paracorporeal sheep allowed for safe normothermic ex vivo heart perfusion (NEVHP) for 3 days, 2) NEVHP for 24 hours is feasible with plasma exchange without a paracorporeal animal, 3) 24-hour NEVHP is also feasible with the addition of hemofiltration (22 kDa filter) and filtration replacement. All studies with up to 24hr of NEVHP were performed using piglet hearts (60±8.8 g) The experiments described in this study were designed to evaluate the efficacy of hemofiltration and filtrate replacement in adult porcine hearts. Methods: We performed 24-hour NEVHP on 5 consecutive hearts (mean weight 263±15.5 g). Following anesthetic induction, sternotomy, cardioplegia administration, explantation, and back-table instrumentation, NEVHP was initiated in beating, resting mode. After 1 hour plasma exchange was performed and hemofiltration was initiated. Heart function parameters and arterial blood gasses were obtained hourly and at termination of prep all hearts were removed from circuit and stored in formalin. Results: All hearts (n=5) were viable at the 24-hour mark. Aortic blood flow was adjusted to maintain coronary artery blood flow at 0.7 mL/min/g. Average LV systolic pressure at the beginning of the prep was 36.6±7.9 mmHg compared to 27±5.5 mmHg at the end. Coronary resistance at the beginning of prep was 0.79±0.10 mmHg/L/min and at the end of prep was 0.93±0.28 mmHg/L/min. Glucose levels averaged 223±13.9 mg/dL and the lactate average at the termination of prep was 2.6±0.3 mmol/L. Conclusions: We successfully perfused adult porcine hearts at normothermic temperatures for 24 hours with results comparable to our pediatric porcine heart model. The next steps in our research are NEVHP evaluation in a working mode using left atrial perfusion, extension of NEVHP preservation beyond 24 hours, and verification of functional status of the ex vivo heart by transplantation after 24 hours on our circuit.