Prolonged (≥24 Hours) Normothermic (≥32 °C) Ex Vivo Organ Perfusion: Lessons From the Literature

Abdominal Normothermic Regional Perfusion after Donation after Circulatory Death Improves Pancreatic Islet Isolation Yield

Abdominal Normothermic Regional Perfusion (aNRP) is an in-situ normothermic oxygenated donor perfusion technique before procurement during controlled donation after circulatory death (cDCD) procedures and allows for organ quality evaluation. There are few data on the effect of aNRP on pancreatic islet isolation and subsequent transplantation outcomes. We aim to evaluate the impact of aNRP on cDCD pancreatic islet isolation and transplantation. A retrospective analysis was performed on pancreatic islet isolation outcomes from aNRP, cDCD, and Donation after Brain death (DBD) pancreases. Isolations were compared to previous donor age (60-75) matched isolations. Islet function was asses by a dynamic Glucose Stimulated Insulin Secretion (dGSIS). Donor baseline characteristics did not differ among groups. Isolations from aNRP pancreases (471,739 IEQ [655,435 - 244,851]) yielded more islets compared to cDCD (218,750 IEQ [375,951 - 112,364, p<0.01) and to DBD (206,522 IEQ [385,544 - 142,446, p=0.03) pancreases. dGSIS tests in seven aNRP islet preparations showed a mean stimulation index of 4.91, indicating good functionality. Bilirubin and alanine aminotransferase during aNRP correlated with islet yield (r2=0.685, p=0.002; r2=0.491, p=0.016 respectively). Islet isolation after aNRP in cDCD donors results in a high islet yield with viable functional islets. aNRP could increase the utilization of pancreases for islet transplantation.

Twenty-four-hour Normothermic Ex Vivo Heart Perfusion With Low Flow Functional Assessment in an Adult Porcine Model

BACKGROUND

Cold static storage and normothermic ex vivo heart perfusion are routinely limited to 6 h. This report describes intermittent left atrial (LA) perfusion that allows cardiac functional assessment in a working heart mode.

METHODS

Using our adult porcine model, general anesthesia was induced and a complete cardiectomy was performed following cardioplegic arrest. Back-table instrumentation was completed and normothermic ex vivo heart perfusion (NEHP) was initiated in a nonworking heart mode (Langendorff). After 1 h of resuscitation and recovery, LA perfusion was initiated and the heart was transitioned to a coronary flow-only working heart mode for 30 min. Baseline working heart parameters were documented and the heart was returned to nonworking mode. Working heart assessments were performed for 30 min every 6 h for 24 h.

RESULTS

Twenty-four-hour NEHP on 9 consecutive hearts (280 ± 42.1 g) was successful and no significant differences were found between working heart parameters at baseline and after 24 h of perfusion. There was no difference between initial and final measurements of LA mean pressures (5.0 ± 3.1 versus 9.0 ± 6.5 mm Hg, P  = 0.22), left ventricular systolic pressures (44.3 ± 7.2 versus 39.1 ± 9.0 mm Hg, P  = 0.13), mean aortic pressures (30.9 ± 5.8 versus 28.1 ± 8.1 mm Hg, P  = 0.37), and coronary resistance (0.174 ± 0.046 versus 0.173 ± 0.066 mL/min/g, P  = 0.90). There were also no significant differences between lactate (2.4 ± 0.5 versus 2.6 ± 0.4 mmol/L, P  = 0.17) and glucose (173 ± 75 versus 156 ± 70 mg/dL, P  = 0.37).

CONCLUSIONS

A novel model using intermittent LA perfusion to create a coronary flow-only working heart mode for assessment of ex vivo cardiac function has been successfully developed.

Twenty-Four Hour Normothermic Ex Vivo Heart Perfusion With Hemofiltration In an Adult Porcine Model

BACKGROUND

Historically, cardiac transplantation relied on cold static storage at 5 °C for ex vivo myocardial preservation. Currently, machine perfusion is the standard of care at many transplant centers. These storage methods are limited to 12 hours. We sought to evaluate the efficacy of hemofiltration and filtrate replacement in adult porcine hearts using normothermic heart perfusion (NEVHP) for 24 hours.

METHODS

We performed 24-hour NEVHP on 5 consecutive hearts. After anesthetic induction, sternotomy, cardioplegia administration, explantation, and back-table instrumentation, NEVHP was initiated in beating, unloaded mode. After 1 hour, plasma exchange was performed, and hemofiltration was initiated. Heart function parameters and arterial blood gasses were obtained hourly.

RESULTS

All hearts (n = 5) were viable at the 24-hour mark. The average left ventricular systolic pressure at the beginning of the prep was 36.6 ± 7.9 mm Hg compared with 27 ± 5.5 mm Hg at the end. Coronary resistance at the beginning of prep was 0.79 ± 0.10 mm Hg/L/min and 0.93 ± 0.28 mm Hg/L/min at the end. 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 step in our research is NEVHP evaluation in a working mode using left atrial perfusion.