Extended distance cardiac allograft can successfully be utilized without impacting long-term survival

Single-center experience of extended brain-death donor heart preservation with the organ care system

BACKGROUND

The Organ Care System (OCS) (Transmedics, Andover, MA) reduces cold ischemic time of donor hearts by producing a normothermic beating state during ex vivo perfusion, enabling extended ex situ intervals, which potentially increases donor pool. We aimed to compare outcomes in utilization of OCS and conventional cold storage technique.

METHODS

Consecutive heart transplants following brain death at our institution between May 2022 and July 2023 were analyzed. Recipients were divided into those receiving hearts preserved with OCS [N = 15] and those with conventional cold storage (Control, N = 27), with OCS utilization when anticipated ischemic time was more than 4 h. Pre-transplant characteristics and transplant outcomes were compared.

RESULTS

OCS utilization allowed a significant increase in distance traveled for heart retrieval (OCS, 624 ± 269 vs. Control, 153 ± 128 miles, p < 0.001), with longer mean total preservation times (6.2 ± 1.1 vs 2.6 ± 0.6 h, p < 0.001). All but one patient displayed a general decrease or plateau in lactate throughout perfusion time by OCS. Both groups experienced similar rates of severe primary graft dysfunction (OCS, 6.7% [N = 1] vs. Control, 11.1% [N = 3], p = 0.63), with 100% in-hospital survival in the OCS group compared to 96.3% in the Control group (p = 0.34). Kaplan-Meier survival analysis showed that estimated one-year survival were comparable (OCS, 93.3 ± 6.4% vs. Control, 88.9 ± 6.0%, p = 0.61).

CONCLUSION

With a mean preservation time of around 6 h and distance covered of over 600 miles, our results using OCS indicate a potential to safely increase the quantity and viability of accessible organs, thus broadening the donor pool without negatively affecting outcomes.

Transport-Associated Vibrational Stress Triggers Drug-Reversible Apoptosis and Cardiac Allograft Failure in Mice

Increasingly complex and long-range donor organ allocation routes coupled with implementation of unmanned aerial vehicles (UAVs) have prompted investigations of the conditions affecting organs once packaged for shipment. Our group has previously demonstrated that different modes of organ transport exert unique environmental stressors, in particular vibration. Using a mouse heart transplant model, we demonstrated that vibrational forces exert tangible, cellular effects in the form of cardiomyocyte apoptosis and cytoskeletal derangement. Functionally, these changes translated into accelerated allograft loss. Notably, administration of an apoptosis inhibitor, Z-VAD-FMK, helped to ameliorate the detrimental cellular and functional effects of mechanical vibration in a dose-dependent manner. These findings constitute one of the first reports of the negative impact of transit environment on transplant outcomes, a contributing mechanism underpinning this effect, and a potential agent to prophylax against this process. Given current limitations in measuring donor organ transit environments in situ, further study is required to better characterize the impact of transport environment and to potentially improve the care of donor organs during shipment. Clinical and Translational Impact Statement: We show that apoptosis inhibitor, Z-VAD-FMK, ameliorated transport-related vibrational stress in murine heart transplants, which presents a potential therapeutic or preservation solution additive for future use in transporting donor organs.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Recent Changes in Durable Left Ventricular Assist Device Bridging to Heart Transplantation

This study evaluates the impact of the recent United Network for Organ Sharing (UNOS) allocation policy change on outcomes of patients bridged with durable left ventricular assist devices (LVADs) to orthotopic heart transplantation (OHT). Adults bridged to OHT with durable LVADs between 2010 and 2019 were included. Patients were stratified based on the temporal relationship of their OHT to the UNOS policy change on October 18, 2018. The primary outcome was early post-OHT survival. In total, 9,628 OHTs were bridged with durable LVADs, including 701 (7.3%) under the new policy. Of all OHTs performed during the study period, the proportion occurring following durable LVAD bridging decreased from 45% to 34% (p < 0.001). The more recent cohort was higher risk, including more extracorporeal membrane oxygenation bridging (2.6% vs. 0.3%, p < 0.001), more mechanical right ventricular support (9.7% vs. 1.4%, p < 0.001), greater pretransplant ICU admission (22.8% vs. 8.7%, p < 0.001) more need for total functional assistance (62.8% vs. 53.0%, p < 0.001), older donor age (33.3 vs. 31.7 years, p < 0.001), and longer ischemic times (3.38 vs. 3.13 hours, p < 0.001). Despite this, early post-OHT survival was comparable at 30 days (96.1% vs. 96.0%, p = 0.89), 90 days (93.7% vs. 94.0%, p = 0.76), and 6 months (91.0% vs. 93.0%, p = 0.96), findings that persisted after risk-adjustment. In this early analysis, OHT following bridging with durable LVADs is performed less frequently and in higher risk recipients under the new allocation policy. Despite this, short-term posttransplant outcomes appear to be unaffected in this patient cohort in the current era.

Clinical outcome of donor heart with prolonged cold ischemic time: A single-center study

OBJECTIVES

Due to the shortage of donor pool, there has been a need for organs with prolonged cold ischemic time. This study aims to evaluate the short-term results of different cold ischemic times in orthotopic heart transplantation based on a single-center experience in China.

METHODS

We retrospectively analyzed outcomes of the heart transplant patients from 1 January 2015 to 31 December 2017. The recipient population was divided into four groups. Group 1: cold ischemic time greater than 8 hours; group 2: the cold ischemic time between 6 and 8 hours; group 3: the cold ischemic time between 4 and 6 hours; and group 4: cold ischemic time less than 4 hours. Efficacy indicators included after transplant survival, infection rate, rejection rate, and complications.

RESULTS

The four groups have similar donor and recipient baseline characteristics (P > .05). Cold ischemic time greater than 8 hours had more cardiopulmonary bypass (CPB) time (127.62 ± 50.23 minutes; P = .003), CPB-assist time (86.14 ± 36.74 minutes; P = .047), and higher intra-aortic balloon pump (IABP) usage rate postoperatively (47.36%; P = .010). Cold ischemic time greater than 8 hours witnessed a relatively higher mortality rate compared with the other three groups (P = .115, P =  .078, and P =  .114) during the 2-year follow-up. Survival rates of 1 and 2 years for the four groups were 78.95%, 87.13%, 87.32%, and 87.50% and 68.42%, 85.14%, 85.92%, and 83.93%, respectively.

CONCLUSION

Cold ischemic time less than 8 hours can be reasonably applied to expand the heart transplantation donor pool. Cold ischemic time greater than 8 hours might result in longer CPB time, CPB-assist time, and higher IABP usage postoperatively. It might also affect the in-hospital and 2-years survival rate.