Effects of graft preservation conditions on coronary endothelium and cardiac functional recovery in a rat model of donation after circulatory death

Impact of Hemoglobin Level in Ex Vivo Heart Perfusion on Donation After Circulatory Death Hearts: A Juvenile Porcine Experimental Model

BACKGROUND

Ex vivo heart perfusion (EVHP) of donation after circulatory death (DCD) hearts has become an effective strategy in adults; however, the small circulating volume in pediatrics poses the challenge of a low-hemoglobin (Hb) perfusate. We aimed to determine the impact of perfusate Hb levels during EVHP on DCD hearts using a juvenile porcine model.

METHODS

Sixteen DCD piglet hearts (11-14 kg) were reperfused for 4 h in unloaded mode followed by working mode. Metabolism, cardiac function, and cell damage were compared between the low-Hb (Hb, 5.0-5.9 g/dL; n = 8) and control (Hb, 7.5-8.4 g/dL; n = 8) groups. Between-group differences were evaluated using 2-sample t-tests or Fisher's Exact tests.

RESULTS

During unloaded mode, the low-Hb group showed lower myocardial oxygen consumption (P < 0.001), a higher arterial lactate level (P = 0.001), and worse systolic ventricular function (P < 0.001). During working mode, the low-Hb group had a lower cardiac output (mean, 71% versus 106% of normal cardiac output, P = 0.010) and a higher arterial lactate level (P = 0.031). Adjusted cardiac troponin-I (P = 0.112) did not differ between the groups. Morphological myocyte injury in the left ventricle was more severe in the low-Hb group (P = 0.028).

CONCLUSIONS

Low-Hb perfusate with inadequate oxygen delivery induced anaerobic metabolism, resulting in suboptimal DCD heart recovery and declined cardiac function. Arranging an optimal perfusate is crucial to organ protection, and further endeavors to refine the priming volume of EVHP or the transfusion strategy are required.

Heart Transplant and Donors After Circulatory Death: A Clinical-Preclinical Systematic Review

INTRODUCTION

Heart transplantation is the treatment of choice for end-stage heart failure. There is a mismatch between the number of donor hearts available and the number of patients awaiting transplantation. Expanding the donor pool is critically important. The use of hearts donated following circulatory death is one approach to increasing the number of available donor hearts.

MATERIALS AND METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines utilizing Pubmed/MEDLINE and Embase. Articles including adult human studies and preclinical animal studies of heart transplantation following donation after circulatory death were included. Studies of pediatric populations or including organs other than heart were excluded.

RESULTS

Clinical experience and preclinical studies are reviewed. Clinical experience with direct procurement, normothermic regional perfusion, and machine perfusion are included. Preclinical studies addressing organ function assessment and enhancement of performance of marginal organs through preischemic, procurement, preservation, and reperfusion maneuvers are included. Articles addressing the ethical considerations of thoracic transplantation following circulatory death are also reviewed.

CONCLUSIONS

Heart transplantation utilizing organs procured following circulatory death is a promising method to increase the donor pool and offer life-saving transplantation to patients on the waitlist living with end-stage heart failure. There is robust ongoing preclinical and clinical research to optimize this technique and improve organ yield. There are also ongoing ethical considerations that must be addressed by consensus before wide adoption of this approach.

Utilization of Paragonix Sherpapak Cardiac Transport System for the Preservation of Donor Hearts After Circulatory Death

BACKGROUND

Donation after circulatory death (DCD) heart transplantation is being increasingly adopted by transplant centers. The optimal method of DCD heart preservation during transport after in situ thoracoabdominal normothermic regional perfusion (TA-NRP) is not known.

METHODS

We evaluated our experience with the Paragonix SherpaPak Cardiac Transport System (SCTS) for the transport of DCD cardiac allografts after TA-NRP recovery between January 2021 and December 2022. We collected and evaluated donor characteristics, allograft ischemic intervals, and recipient baseline demographic and clinical variables, and short-term outcomes.

RESULTS

Twelve recipients received DCD grafts recovered with TA-NRP and transported in SCTS during the study period. The median age of 10 male and 2 female donors was 32 years (min 15, max 38). The median duration of functional warm ischemia was 12 minutes (min 8, max 22). Hearts were preserved in SCTS for a median of 158 minutes (min 37, max 224). Median recipient age was 61 years (min 28, max 70). Ten recipients (83%) survived to hospital discharge, with one death attributable to graft dysfunction (8%). The median vasoactive-inotropic (VIS) score at 72 hours post-transplantation of the entire cohort was 6 (min 0, max 15). The median length of intensive care unit stay in hospital survivors was 5 days (min 3, max 17) days and hospital stay 17 days (min 9, max 37).

CONCLUSIONS

The Paragonix SCTS provides efficacious preservation of DCD grafts for ≥3.5 hours. Organs transported with this device showed satisfactory post-transplantation function.

Comparison of Different Ex-Vivo Preservation Strategies on Cardiac Metabolism in an Animal Model of Donation after Circulatory Death

Transplantation of heart following donation after circulatory death (DCD) was recently introduced into clinical practice. Ex vivo reperfusion following DCD and retrieval is deemed necessary in order to evaluate the recovery of cardiac viability after the period of warm ischemia. We tested the effect of four different temperatures (4 °C-18 °C-25 °C-35 °C) on cardiac metabolism during 3-h ex vivo reperfusion in a porcine model of DCD heart. We observed a steep fall in high-energy phosphate (ATP) concentrations in the myocardial tissue at the end of the warm ischemic time and only limited regeneration during reperfusion. Lactate concentration in the perfusate increased rapidly during the first hour of reperfusion and slowly decreased afterward. However, the temperature of the solution does not seem to have an effect on either ATP or lactate concentration. Furthermore, all cardiac allografts showed a significant weight increase due to cardiac edema, regardless of the temperature.

Breaking barriers in cardiac donation after circulatory death

BACKGROUND

Heart transplant (HT) from controlled donation after circulatory death (cDCD) is an emerging strategy that is rapidly expanding and may help increase the heart donor pool.

MATERIALS AND METHODS

The use of thoracoabdominal normothermic regional perfusion with extracorporeal membrane oxygenation device has allowed to perform HT after cDCD in our country. We present a successful case of heart transplantation using a graft from cDCD with 201 min cold ischemia time.

DISCUSSION AND CONCLUSION

HT from cDCD could be a good alternative to brain dead donation. This experience suggests than nonlocal cardiac from cDCD could tolerate long periods of cold ischemia time and break the main barriers with this technique.

The Role of Purinergic Signaling in Heart Transplantation

Heart transplantation remains the optimal treatment option for patients with end-stage heart disease. Growing evidence demonstrates that purinergic signals mediated by purine nucleotides and nucleosides play vital roles in heart transplantation, especially in the era of ischemia-reperfusion injury (IRI) and allograft rejection. Purinergic signaling consists of extracellular nucleotides and nucleosides, ecto-enzymes, and cell surface receptors; it participates in the regulation of many physiological and pathological processes. During transplantation, excess adenosine triphosphate (ATP) levels are released from damaged cells, and driver detrimental inflammatory responses largely via purinergic P2 receptors. Ecto-nucleosidases sequentially dephosphorylate extracellular ATP to ADP, AMP, and finally adenosine. Adenosine exerts a cardioprotective effect by its anti-inflammatory, antiplatelet, and vasodilation properties. This review focused on the role of purinergic signaling in IRI and rejection after heart transplantation, as well as the clinical applications and prospects of purinergic signaling.