The Interval between Brain Stem Death and Cardiac Assessment Influences the Retrieval of Hearts for Transplantation

Heart Transplantation From Brain Dead Donors: A Systematic Review of Animal Models

Despite advances in mechanical circulatory devices and pharmacologic therapies, heart transplantation (HTx) is the definitive and most effective therapy for an important proportion of qualifying patients with end-stage heart failure. However, the demand for donor hearts significantly outweighs the supply. Hearts are sourced from donors following brain death, which exposes donor hearts to substantial pathophysiological perturbations that can influence heart transplant success and recipient survival. Although significant advances in recipient selection, donor and HTx recipient management, immunosuppression, and pretransplant mechanical circulatory support have been achieved, primary graft dysfunction after cardiac transplantation continues to be an important cause of morbidity and mortality. Animal models, when appropriate, can guide/inform medical practice, and fill gaps in knowledge that are unattainable in clinical settings. Consequently, we performed a systematic review of existing animal models that incorporate donor brain death and subsequent HTx and assessed studies for scientific rigor and clinical relevance. Following literature screening via the U.S National Library of Medicine bibliographic database (MEDLINE) and Embase, 29 studies were assessed. Analysis of included studies identified marked heterogeneity in animal models of donor brain death coupled to HTx, with few research groups worldwide identified as utilizing these models. General reporting of important determinants of heart transplant success was mixed, and assessment of posttransplant cardiac function was limited to an invasive technique (pressure-volume analysis), which is limitedly applied in clinical settings. This review highlights translational challenges between available animal models and clinical heart transplant settings that are potentially hindering advancement of this field of investigation.

Does duration of donor brain injury impact heart transplantation outcomes?

AIM

We aimed to study the implications of pre-transplantation time intervals on HT outcomes.

METHODS

Brain injury time (BIT) was defined as the period from the donor brain injury to brain death declaration. Brain death interval (BDI) was defined as the period from brain death to application of an aortic cross-clamp during donor heart procurement. Allograft ischemia was defined as the time from donor aortic cross-clamp to aortic unclamping. End points included mortality and rejections.

RESULTS

Between 1997 and 2017, we assessed 173 patients. Kaplan-Meier analyses showed that prolonged donor BIT, BDI, allograft ischemia, and total injury time had no significant effect on mortality and rejections. Patients were subdivided into short BIT (<97 hours, n = 87) and long BIT (≥97 hours, n = 86) groups. No differences in rejection scores nor in time to first rejection were noted. Kaplan-Meier analysis showed a similar long-term survival in the two groups. Sub-analysis of both groups according to their median BDI (12 hours) revealed no differences in mortality or time to rejection.

CONCLUSIONS

Pre-transplantation time intervals do not affect mortality or rejection. Our findings have important clinical implications regarding HT allocation and organ availability.