Donation After Cardiac Death Heart Transplantation in America Is Clinically Necessary and Ethically Justified

Donation After Circulatory Death Heart Transplant: Current State and Future Directions

Orthotopic heart transplant is the gold standard therapeutic intervention for patients with end-stage heart failure. Conventionally, heart transplant has relied on donation after brain death for organ recovery. Donation after circulatory death (DCD) is the donation of the heart after confirming that circulatory function has irreversibly ceased. DCD-orthotopic heart transplant differs from donation after brain death-orthotopic heart transplant in ways that carry implications for widespread adoption, including differences in organ recovery, storage and ethical considerations surrounding normothermic regional perfusion with DCD. Despite these differences, DCD has shown promising early outcomes, augmenting the donor pool and allowing more individuals to benefit from orthotopic heart transplant. This review aims to present the current state and future trajectory of DCD-heart transplant, examine key differences between DCD and donation after brain death, including clinical experiences and innovations in methodologies, and address the ongoing ethical challenges surrounding the new frontier in heart transplant with DCD donors.

An Ethics Committee's Evaluation of Normothermic Regional Perfusion (NRP) in 2018-Unsatisfactory Answers Then-and Now

An adult university hospital ethics committee evaluated a proposed TA-NRP protocol in the fall of 2018. The protocol raised ethical concerns about violation of the Uniform Determination of Death Act and the prohibition known as the Dead Donor Rule, with potential resultant legal consequences. An additional concern was the potential for increased mistrust by the community of organ donation and transplantation. The ethics committee evaluated the responses to these concerns as unable to surmount the ethical and legal boundaries and the ethics committee declined to endorse the procedure. These concerns endure.

Donation after circulatory death significantly reduces waitlist times while not changing post-heart transplant outcomes: A United Network for Organ Sharing Analysis

BACKGROUND

Recently, several centers in the United States have begun performing donation after circulatory death (DCD) heart transplants (HTs) in adults. We sought to characterize the recent use of DCD HT, waitlist time, and outcomes compared to donation after brain death (DBD).

METHODS

Using the United Network for Organ Sharing database, 10,402 adult (aged >18 years) HT recipients from January 2019 to June 2022 were identified: 425 (4%) were DCD and 9,977 (96%) were DBD recipients. Posttransplant outcomes in matched and unmatched cohorts and waitlist times were compared between groups.

RESULTS

DCD and DBD recipients had similar age (57 years for both, p = 0.791). DCD recipients were more likely White (67% vs 60%, p = 0.002), on left ventricular assist device (LVAD; 40% vs 32%, p < 0.001), and listed as status 4 to 6 (60% vs 24%, p < 0.001); however, less likely to require inotropes (22% vs 40%, p < 0.001) and preoperative extracorporeal membrane oxygenation (0.9% vs 6%, p < 0.001). DCD donors were younger (29 vs 32 years, p < 0.001) and had less renal dysfunction (15% vs 39%, p < 0.001), diabetes (1.9% vs 3.8%, p = 0.050), or hypertension (9.9% vs 16%, p = 0.001). In matched and unmatched cohorts, early survival was similar (p = 0.22). Adjusted waitlist time was shorter in DCD group (21 vs 31 days, p < 0.001) compared to DBD cohort and 5-fold shorter (DCD: 22 days vs DBD: 115 days, p < 0.001) for candidates in status 4 to 6, which was 60% of DCD cohort.

CONCLUSIONS

The community is using DCD mostly for those recipients who are expected to have extended waitlist times (e.g., durable LVADs, status >4). DCD recipients had similar posttransplant early survival and shorter adjusted waitlist time compared to DBD group. Given this early success, efforts should be made to expand the donor pool using DCD, especially for traditionally disadvantaged recipients on the waitlist.

Heart transplantation: advances in expanding the donor pool and xenotransplantation

Approximately 65 million adults globally have heart failure, and the prevalence is expected to increase substantially with ageing populations. Despite advances in pharmacological and device therapy of heart failure, long-term morbidity and mortality remain high. Many patients progress to advanced heart failure and develop persistently severe symptoms. Heart transplantation remains the gold-standard therapy to improve the quality of life, functional status and survival of these patients. However, there is a large imbalance between the supply of organs and the demand for heart transplants. Therefore, expanding the donor pool is essential to reduce mortality while on the waiting list and improve clinical outcomes in this patient population. A shift has occurred to consider the use of organs from donors with hepatitis C virus, HIV or SARS-CoV-2 infection. Other advances in this field have also expanded the donor pool, including opt-out donation policies, organ donation after circulatory death and xenotransplantation. We provide a comprehensive overview of these various novel strategies, provide objective data on their safety and efficacy, and discuss some of the unresolved issues and controversies of each approach.

Mechanical Circulatory Support Therapy in the Cardiac Intensive Care Unit

Mechanical circulatory support (MCS) includes temporary and durable mechanical devices used for two sets of indications: 1. acute heart failure (HF) secondary sepsis, a myocardial infarction, or pulmonary emboli, and 2. for chronic end-stage HF secondary to worsening cardiomyopathy despite guideline driven medical treatment. This article is to aide cardiac intensive care unit (ICU) nurses in understanding the history of MCS therapy, the care of the MCS patient in the cardiac ICU, the critical and collaborative role of transplant teams with MCS therapy, educational needs for a successful discharge, and implications for education and shared decision-making when placing these devices.

Anesthetic Considerations of Organ Procurement After Brain and Cardiac Death: A Narrative Review

Organ donation procedures have become more frequent in the US as the need for transplants is increasing. Defining the anesthesiologist's role in organ donations after brain and cardiac death is important, as is understanding its ethics and practical physiologic and perioperative implications. Despite this, there are few papers specifically addressing the anesthetic management of organ donors. This review summarizes the preoperative, intraoperative, and postmortem considerations for the anesthesiologist involved in organ donation after either brain or cardiac death. A search of the published literature was performed using PubMed, Excerpta Medica dataBASE (EMBASE), and Google Scholar in March of 2022 for articles addressing anesthetic considerations of organ procurement surgeries after brain and cardiac death. This review demonstrates that anesthesiologists play a significant role in the organ procurement process. Their role in the perioperative management of the donor may affect the outcomes of organ transplantation. The gap between the number of organs harvested and the number of patients awaiting organ transplantation remains high despite continued efforts to increase the number of available organs. Perioperative management of organ donors aims at counteracting the associated unique physiologic derangements and targets optimization of oxygenation of the organs intended for procurement. Optimizing care after death can help ensure the viability of organs and the best outcomes for recipients. As organ donation after cardiac death (DCD) becomes more frequent in the US, anesthesiologists should be aware of the DCD classifications of donors and emerging novel perfusion techniques.

The role of ex-situ perfusion for thoracic organs

PURPOSE OF REVIEW

Ex-situ machine perfusion for both heart (HTx) and lung transplantation (LuTx) reduces ischemia-reperfusion injury (IRI), allows for greater flexibility in geographical donor management, continuous monitoring, organ assessment for extended evaluation, and potential reconditioning of marginal organs. In this review, we will delineate the impact of machine perfusion, characterize novel opportunities, and outline potential challenges lying ahead to improve further implementation.

RECENT FINDINGS

Due to the success of several randomized controlled trials (RCT), comparing cold storage to machine perfusion in HTx and LuTx, implementation and innovation continues. Indeed, it represents a promising interface for organ-specific therapies targeting IRI, allo-immune responses, and graft reconditioning. These mostly experimental efforts range from genetic approaches and nanotechnology to cellular therapies, involving mesenchymal stem cell application. Despite tremendous potential, prior to clinical transition, more data is needed.

SUMMARY

Collectively, machine perfusion constitutes the vanguard in thoracic organ transplantation research with extensive potential for expanding the donor pool, enhancing transplant outcomes as well as developing novel therapy approaches.

Does utilization of heart machine perfusion for donation after cardiac death transplantation affect outcomes of other abdominal transplanted organs?

INTRODUCTION

Machine perfusion of heart for donation after circulatory death (DCD) is being increasingly utilized. Current protocols for utilizing heart DCD's machine perfusion might prolong donor warm ischemic time for nonheart organs. The aim of this study was to analyze the effects of utilizing heart machine perfusion on liver and kidney transplants from the same donor.

METHODS

We analyzed data of DCD donors from the United Network for Organ Sharing (UNOS) from January-2020 to September-2021 among two groups: donors with heart machine perfusion (HM) and without heart machine perfusion (NHM). Propensity score (PS) matching was performed to compare the short-term outcomes of liver and kidney transplants between two groups.

RESULTS

Total of 102 liver and 319 kidney transplants were performed using organs from donors with HM. After PS matching, no statistically significant difference was seen in 1-year graft survival (GS) for both liver and kidney transplants between two groups (liver HM 90.6% vs. NHM 90.2%, p = .47; kidney HM 95.2% vs. NHM 92.9%, p = .40). There was no difference in the delayed graft function (DGF) rates in kidney transplantation (KT) (HM 42% vs. NHM 35%, p = .062).

CONCLUSION

Utilization of heart machine perfusion in DCD donors had no significant impact on 1-year outcomes of liver and kidney transplantation.

Feasibility and Potential Impact of Heart Transplantation From Adult Donors After Circulatory Death

BACKGROUND

A shortage of donation after brain death (DBD) donors for heart transplantation (HT) persists. Recent improvements in organ procurement from donation after circulatory death (DCD) donors and promising early results of DCD-HTs from Europe and Australia have renewed interest in DCD-HT.

OBJECTIVES

The current study evaluated donor and recipient characteristics, early outcomes, and potential impact of adult DCD-HT in the United States.

METHODS

The United Network for Organ Sharing registry was used to identify and compare adult DCD donors based on their use for HT between January 2020 and February 2021. Adult DCD-HTs with available post-HT outcomes data were compared with contemporary adult DBD-HTs during study period using Cox-regression analysis and propensity-matching.

RESULTS

Of the 3,611 adult DCD donors referred during the study period, 136 were used for HT. DCD donors used for HT were younger (median age 29 years), and most were male (90%), and blood type O (79%). On comparing DCD-HT (n = 127) and DBD-HT (n = 2,961) meeting study criteria and with available data on post-HT outcomes, there was no significant difference in 30-day or 6-month mortality, primary graft failure up to 30 days, or other outcomes including in-hospital stroke, pacemaker insertion, hemodialysis, and post-HT length of hospital stay. Results were similar in propensity matched DCD-HT and DBD-HT cohorts. The number of potential adult DCD donors referred has increased substantially (n = 871 in 2010 to n = 3,045 in 2020), and the authors estimated that widespread adoption of DCD-HT could lead to approximately 300 additional adult HTs in the United States annually.

CONCLUSIONS

This preliminary analysis of adult DCD-HTs from the United States showed favorable early outcomes and suggested a potential for substantial increase in adult HT volumes with use of DCD donors.

Zebrafish as a New Tool in Heart Preservation Research

Heart transplantation became a reality at the end of the 1960s as a life-saving option for patients with end-stage heart failure. Static cold storage (SCS) at 4-6 °C has remained the standard for heart preservation for decades. However, SCS only allows for short-term storage that precludes optimal matching programs, requires emergency surgeries, and results in the unnecessary discard of organs. Among the alternatives seeking to extend ex vivo lifespan and mitigate the shortage of organs are sub-zero or machine perfusion modalities. Sub-zero approaches aim to prolong cold ischemia tolerance by deepening metabolic stasis, while machine perfusion aims to support metabolism through the continuous delivery of oxygen and nutrients. Each of these approaches hold promise; however, complex barriers must be overcome before their potential can be fully realized. We suggest that one barrier facing all experimental efforts to extend ex vivo lifespan are limited research tools. Mammalian models are usually the first choice due to translational aspects, yet experimentation can be restricted by expertise, time, and resources. Instead, there are instances when smaller vertebrate models, like the zebrafish, could fill critical experimental gaps in the field. Taken together, this review provides a summary of the current gold standard for heart preservation as well as new technologies in ex vivo lifespan extension. Furthermore, we describe how existing tools in zebrafish research, including isolated organ, cell specific and functional assays, as well as molecular tools, could complement and elevate heart preservation research.

Heart transplantation: the Berlin experience and perspectives

In patients with end-stage heart failure, heart transplants are now an ingrained practice, as they provide satisfying long-term results with good predictability and quality of life. The successful outcome has evolved from the development of effective immunosuppression, recognition of allograft rejection through diagnostic modalities and improvement in donor organ perfusion. Unfortunately, transplant availability is constrained by the shortage of donor organs and is therefore considered a casuistic therapy. The outcome is defined by unwanted effects of immunosuppressants, increased tumor occurrence and chronic transplant angiopathies. In the long term, patients fear primarily the occurrence of renal insufficiency and secondly osteoporosis with its skeletal complications and corresponding pain. Nevertheless, the overall quality of life is not very limited; on the contrary, patients demonstrate a surprisingly meaningful lives 10-20 years after the transplant. Their physical presentation is similar to those with varying co-morbidities. Most of the 20-year surviving patients are physically active and happy with their daily lives. Medical ambition has seen heart transplantation become reality and develop into an influential force regarding heart surgery, immunology, pharmacology, organ logistics and medical ethics. Its development has also molded our definitions of death and has driven public and health care approval of medical advances. It has provided a strong solidarity among politicians, sociologists, physicians and citizens. Problems regarding ethics continue to endure, and will forecast heart transplants as a defining, but temporary era in human medicine. The donor organ shortage has stimulated the use of resuscitated donor hearts and encouraged exploration and advancement of mechanical circulatory support systems and xenotransplantation as alternatives in the management of end-stage heart failure.

The Human Explanted Heart Program: A translational bridge for cardiovascular medicine

The progression of cardiovascular research is often impeded by the lack of reliable disease models that fully recapitulate the pathogenesis in humans. These limitations apply to both in vitro models such as cell-based cultures and in vivo animal models which invariably are limited to simulate the complexity of cardiovascular disease in humans. Implementing human heart tissue in cardiovascular research complements our research strategy using preclinical models. We established the Human Explanted Heart Program (HELP) which integrates clinical, tissue and molecular phenotyping thereby providing a comprehensive evaluation into human heart disease. Our collection and storage of biospecimens allow them to retain key pathogenic findings while providing novel insights into human heart failure. The use of human non-failing control explanted hearts provides a valuable comparison group for the diseased explanted hearts. Using HELP we have been able to create a tissue repository which have been used for genetic, molecular, cellular, and histological studies. This review describes the process of collection and use of explanted human heart specimens encompassing a spectrum of pediatric and adult heart diseases, while highlighting the role of these invaluable specimens in translational research. Furthermore, we highlight the efficient procurement and bio-preservation approaches ensuring analytical quality of heart specimens acquired in the context of heart donation and transplantation.

Review: Ischemia Reperfusion Injury-A Translational Perspective in Organ Transplantation

Thanks to the development of new, more potent and selective immunosuppressive drugs together with advances in surgical techniques, organ transplantation has emerged from an experimental surgery over fifty years ago to being the treatment of choice for many end-stage organ diseases, with over 139,000 organ transplants performed worldwide in 2019. Inherent to the transplantation procedure is the fact that the donor organ is subjected to blood flow cessation and ischemia during harvesting, which is followed by preservation and reperfusion of the organ once transplanted into the recipient. Consequently, ischemia/reperfusion induces a significant injury to the graft with activation of the immune response in the recipient and deleterious effect on the graft. The purpose of this review is to discuss and shed new light on the pathways involved in ischemia/reperfusion injury (IRI) that act at different stages during the donation process, surgery, and immediate post-transplant period. Here, we present strategies that combine various treatments targeted at different mechanistic pathways during several time points to prevent graft loss secondary to the inflammation caused by IRI.

Attitudes of healthcare providers towards cardiac donation after circulatory determination of death: a Canadian nation-wide survey

PURPOSE

The number of patients on cardiac transplant waitlists exceeds the number of available donor organs. Cardiac donation is currently limited to those declared dead by neurologic criteria in all but three countries. Cardiac donation after circulatory determination of death (cardiac DCDD) can be conducted using direct procurement and perfusion (DPP) or normothermic regional perfusion (NRP). Implementation of cardiac DCDD in many countries has been slowed by ethical debates within the donation and transplantation community. We conducted a national survey to determine the perceptions of healthcare providers regarding cardiac DCDD.

METHODS

We conducted an electronic survey of 398 healthcare providers who are involved in the management of heart donors and/or heart transplant recipients in Canada (226 nurses, 82 critical care physicians, 31 donation specialists, and 59 transplant specialists). Our primary outcomes were their attitudes towards and concerns regarding cardiac DCDD protocols and their implementation in Canada. We distributed the survey electronically through several Canadian donation and transplantation organizations.

RESULTS

We identified that 361 of 391 respondents (92.3%; 95% confidence interval [CI], 89.6 to 95.1) believed that DPP is acceptable, and 329 of 377 respondents (87.3%; 95% CI, 83.9 to 90.7) supported its implementation in Canada. We found that 301 of 384 respondents (78.4%; 95% CI, 74.2 to 82.6) believed that NRP is acceptable and 266 of 377 respondents (70.6%; 95% CI, 66.0 to 75.2) supported its implementation in Canada.

CONCLUSION

This is the first survey describing the attitudes of healthcare providers towards cardiac DCDD. We identified widespread support for cardiac DCDD and its implementation in Canada among Canadian healthcare providers within the organ donation and transplantation community in Canada.