CARD23: Comparison of Different Porcine Models Simulating Myocardial Cold Ischemia of the Pediatric Donor Heart

Abstract

Background: Our team previously identified a stem cell-derived cardioprotective additive that can extend myocardial viability during prolonged myocardial cold ischemic time (CIT) in rodent models. The purpose of this study was to utilize a porcine model to compare in-vivo versus ex-vivo simulation of CIT in porcine models in order to determine an optimized method for extension of our studies into larger animals. Methods: Eight 39-55kg Yorkshire X pigs were randomly assigned to either in-vivo or ex-vivo simulation. After administration of general anesthesia and endotracheal intubation, baseline measurement of left ventricular performance was obtained via transesophageal echocardiography (TEE). After midline sternotomy and heparin administration, the aorta was cross-clamped and 2 liters of HTK-Custodiol was introduced via the aortic root. After CIT, measurements of post-ischemic left ventricular performance were obtained. Results are presented as: Mean ± Standard Deviation (Median, Minimum–Maximum). Results: Weight (kilograms) was similar in the in-vivo and ex-vivo group: 44±1.8(44, 42–46) versus 44 ± 5.1(43.5, 39–51), respectively. Cold ischemic time (minutes) was longer in the ex-vivo group: 360±0,(360–360) versus 141±26.7(149, 102–163). Temperature (OCelsius) was colder in the ex-vivo group: 8±0(8, 8–8) versus 16.5±4.2(16, 12–16) In the in-vivo group, baseline ejection fraction and ejection fraction after CIT were: 48.25%±14.95%(48.5%, 33%–63%) and 41.25%±22.32%(41.5%, 20%–62%), respectively. In the ex-vivo group, baseline ejection fraction and ejection fraction after CIT were: 56.4%±5.9%(57%, 50%–67%) and 60.4%±7.7%(61.5%, 51.9%–67%), respectively. Conclusion: The ex-vivo technique is suitable to evaluate cardioplegia additives that may substantially extend myocardial tolerance to cold ischemia.