Hypothermic oxygenated perfusion (HOPE) safely and effectively extends acceptable donor heart preservation times: Results of the Australian and New Zealand trial

Expanding the Donor Pool

Given the aging population and despite advances in heart failure therapies, the number of patients with advanced heart failure in need of heart transplantation continues to increase, and the longstanding mismatch between organ demand and organ supply persists. In an effort to address this mismatch and expand the donor pool, a number of strategies are being pursued. This article reviews several of those strategies, including transplantation from hepatitis C virus-infected donors, transplantation from donors after circulatory death, the role of organ preservation technologies in facilitating transplantation of hearts that might otherwise be discarded, and the impact of public education and national donation policies.

Effects of ex vivo machine perfusion on preservation time and donor age in donation after brain death heart transplantation

With encouraging early experience, ex vivo machine perfusion (MP) systems are increasingly employed in heart transplantation. In this study, utilizing a national registry database, 2 separate analyses were performed to evaluate the effects of MP on graft preservation time (total n = 22,794; n = 308 with MP) and donor age (total n = 22,581; n = 95 with MP) in donation after brain death (DBD) heart transplantation. The cohort was stratified based on total preservation time (<4 and ≥4 hours) and donor age (<45 and ≥45 years). During the study period, the use of MP in isolated DBD heart transplantation significantly increased. Utilization of MP was associated with improved 90-day post-transplant survival among the recipients with preservation times ≥4 hours or donor age ≥45 years, compared to cases where MP was not utilized. These findings positively highlight the potential utility of ex vivo MP in DBD heart transplantation involving longer graft preservation times and in older donors.

Direct Procurement and Perfusion Using Hypothermic Oxygenated Perfusion for DCD Cardiac Allografts in North America

BACKGROUND

Donation after circulatory death (DCD) is a viable avenue for recovery of cardiac allografts for transplantation. Previous methods have utilized direct procurement and perfusion (DPP) using commercially available normothermic perfusion systems or in situ normothermic regional perfusion. A novel portable hypothermic oxygenated perfusion device (HOPE) (XVIVO Perfusion) has been developed and is in clinical trials for preservation of cardiac allografts. Here, we report the first North American experience using a HOPE preservation device for DPP recovery of DCD cardiac allografts and detail our experience and early patient outcomes.

METHODS

DCD cardiac allografts were procured and preserved using the HOPE platform and transported to our medical center for transplantation into awaiting recipients. Patient clinical course and outcomes are reported. Permission for this report was granted by the study sponsor and by our institutional review board.

RESULTS

Five end-stage heart failure patients underwent orthotopic heart transplantation at our institution using DCD allografts preserved with the HOPE platform. Average preservation time was 298 min with no observed cases of severe primary graft dysfunction. One patient died because of multiple extracardiac complications, but with preserved allograft function, and 1 patient required mechanical circulatory support for secondary graft dysfunction. All patients surviving to discharge were alive at last follow-up.

CONCLUSIONS

This early, limited, single-institution experience of DPP preservation of DCD cardiac allografts using a HOPE platform demonstrates early success in transplanting adequately functioning allografts with acceptable patient outcomes. Further study and experience with HOPE for DCD allografts is needed.

Innovative approaches to organ preservation in heart transplantation: A comprehensive review by the French Society of Thoracic and Cardiovascular Surgery

Improved approaches for organ preservation have been recently applied in heart transplantation to prevent the risk of primary graft dysfunction. To review heart-graft preservation systems and to identify criteria for using innovative devices in each specific situation. A working group of the French Society of Thoracic and Cardiovascular Surgery performed a literature review focusing on organ preservation and post-transplant outcomes. Static cold storage is the most widely used method but involves cold ischaemia and is therefore limited for prolonged preservation. Optimizing this method by ensuring uniform and stable cooling (SherpaPak™) seems to be associated with favourable results, even with expanded-criteria grafts. Continuous normothermic organ perfusion (Organ Care System) shortens the cold ischaemia time, thus maintaining heart-graft viability despite long transportation times or long waits to achieve complex recipient-heart explantation. Moreover, this method can rehabilitate Maastricht III heart grafts. Continuous hypothermic oxygenated perfusion (XVivo™, not yet approved by regulatory authorities) has recently been associated with favourable outcomes, even in case of extended out-of-body preservation>8hours. The new devices for heart preservation can be expected to allow successful transplantation despite long transport times, lengthy explantation procedures and the use of grafts from expanded-criteria donors, including donors after controlled circulatory arrest. Further studies are needed to assess patient and graft outcomes, determine the optimal device for each situation and evaluate the cost-benefit ratio.

Current approaches to optimize the donor heart for transplantation

Heart transplantation remains a critical therapy for patients with end-stage heart failure, offering incremental survival and improved quality of life. One of the key components behind the success of heart transplantation is the condition and preservation of the donor's heart. In this review, we provide a comprehensive overview of ischemic reperfusion injury, risk factors associated with primary graft dysfunction, current use of various preservation solutions for organ procurement, and recent advancements in donor heart procurement technologies. This state-of-the-art review will explore factors associated with bringing the "ideal" donor heart to the operating room in the contemporary era.

Cardiac preservation using ex vivo organ perfusion: new therapies for the treatment of heart failure by harnessing the power of growth factors using BMP mimetics like THR-184

As heart transplantation continues to be the gold standard therapy for end-stage heart failure, the imbalance between the supply of hearts, and the demand for them, continues to get worse. In the US alone, with less than 4,000 hearts suitable for transplant and over 100,000 potential recipients, this therapy is only available to a very few. The use of hearts Donated after Circulatory Death (DCD) and Donation after Brain Death (DBD) using ex vivo machine perfusion (EVMP) is a promising approach that has already increased the availability of suitable organs for heart transplantation. EVMP offers the promise of enabling the expansion of the overall number of heart transplants and lower rates of early graft dysfunction. These are realized through (1) safe extension of the time between procurement and transplantation and (2) ex vivo assessment of preserved hearts. Notably, ex vivo perfusion has facilitated the donation of DCD hearts and improved the success of transplantation. Nevertheless, DCD hearts suffer from serious preharvest ischemia/reperfusion injury (IRI). Despite these developments, only 40% of hearts offered for transplantation can be utilized. These devices do offer an opportunity to evaluate donor hearts for transplantation, resuscitate organs previously deemed unsuitable for transplantation, and provide a platform for the development of novel therapeutics to limit cardiac injury. Bone Morphogenetic Protein (BMP) signaling is a new target which holds the potential for ameliorating myocardial IRI. Recent studies have demonstrated that BMP signaling has a significant role in blocking the deleterious effects of injury to the heart. We have designed novel small peptide BMP mimetics that act via activin receptor-like kinase (ALK3), a type I BMP receptor. They are capable of (1) inhibiting inflammation and apoptosis, (2) blocking/reversing the epithelial-mesenchymal transition (EMT) and fibrosis, and (3) promoting tissue regeneration. In this review, we explore the promise that novel therapeutics, including these BMP mimetics, offer for the protection of hearts against myocardial injury during ex vivo transportation for cardiac transplantation. This protection represents a significant advance and a promising ex vivo therapeutic approach to expanding the donor pool by increasing the number of transplantable hearts.

Heart Transplantation Utilizing Brain-Dead Donors Procured From Extended Distances Under the 2018 New Allocation Policy

PURPOSE

There are limited data regarding outcomes of a new heart allocation policy on recovering brain-death donors (DBD) from extended distances.

METHODS

From May 6, 2014, to March 31, 2023, the United Network for Organ Sharing database was queried where 1885 cases (8.3%) out of 22 806 isolated heart transplants received donor hearts from extended distances (ED) greater than 500 miles. Patients were divided into groups based on the transplanted date before or after the policy change (October 18, 2018): old (N = 443) versus new (N = 1383). A total of 439 pairs were matched utilizing propensity score matching.

RESULTS

The utilization of hearts from ED in the new system increased 2.7 times. Before matching, characteristics that differed included new group recipients with higher usage of temporary mechanical circulatory support devices and donors with more anoxia as the cause of death (new, 47% vs. old, 37%; p < 0.001). In the matched cohort, the incidences of dialysis (14% vs. 11%, p = 0.18), stroke (3.9% vs. 2.7%, p = 0.44), or pacemaker implantation (3.0% vs. 2.5%, p = 0.83) were similar. Both groups showed similar 1-year recipient survival (90.9% vs. 90.4%, p = 0.79) and graft survival (90.7% vs. 90.2%, p = 0.8).

CONCLUSION

In the new allocation policy, the utilization of hearts from ED has increased approximately three-fold compared to the period before the policy change without affecting transplant outcomes.

Machine Perfusion for Recovery of Brain Death Donor Hearts From Extended Distances

The emerging ex vivo machine perfusion (MP) enables the extension of ex situ intervals, potentially expanding the heart transplant (OHT) donor pool. From October 18, 2018, to June 30, 2023, isolated OHT using donation after brain death (DBD) from extended distances (>500 miles) were identified in the United Network for Organ Sharing database, and categorized into cold storage (non-MP, N = 1,212) and MP group (N = 152). The MP utilization rate for DBD hearts from extended distances surged from 0% in 2018 to 27.7% in 2023. Recipient characteristics including listing status were similar except for history of cardiac surgery (non-MP, 32% vs. MP, 41%, p = 0.019). The travel distance was longer in MP group (696 vs. 894 miles, p < 0.001), as was donor organ preservation time (4.42 vs. 6.27 hours, p < 0.001). One-year survival was similar between groups (non-MP, 93.0 ± 0.8% vs. MP, 90.5 ± 2.9%, p = 0.23). In multivariable Cox hazards models, MP was not associated with mortality (hazard ratio, 1.19; p = 0.60). Among MP cohort, survival was comparable between hearts transported between 500-999 miles (N = 112) and those over 1,000 miles (N = 40). The utilization of MP for DBD heart recovery allows for safe DBD recovery from extended distance with comparable survival to cold storage.

Heart Transplantation and Donation After Circulatory Death in Children. A Review of the Technological, Logistical and Ethical Framework

Heart transplant for adults following Donation after Circulatory Death (DCD) is well established in many parts of the world, including the United Kingdom (UK). Small child DCD hearts have now been recovered in the UK and internationally utilising novel technologies. Despite these recent advances, extension of this practice to pediatric cardiac transplantation has been slow and difficult despite the severe shortage of donors for children leading to a high number of deaths annually of children waiting for heart transplant. This is in direct contrast with the thriving UK programme of adult DCD heart transplant and pediatric DCD donation for non-cardiac organs. There has been insufficient action in addressing this inequality thus far. Barriers to development of a pediatric cardiac DCD programme are multifaceted: ethical concerns, technological paucity, financial and logistical hurdles. We describe the background, live issues, current developments and how we are driving resources toward a sustainable DCD programme for small children in the UK to provide valuable insights to other countries of the elements and principles at play. This is a call to responsible bodies to take urgent and achievable actions to establish an equitable paediatric DCD cardiac programme for donors, recipients and their families.

Clinical Outcomes of Machine Perfusion and Temperature Control Systems in Heart Transplantation: Where We Stand

Heart transplantation remains the preferred treatment for carefully selected patients with end-stage heart failure refractory to medical therapy. Advances in donor management, organ preservation, donor and recipient selection, immunosuppressive strategies, and mechanical circulatory support have significantly improved the safety and efficacy of heart transplantation. However, the persistent shortage of donor hearts and their limited preservation period continues to restrict access to this lifesaving procedure. The advent of innovative machine perfusion and temperature control systems for heart allograft preservation offers a promising avenue to address these challenges. These technologies aim to extend preservation times and enable the use of extended-criteria donors, thereby expanding the donor pool. In this review, we examine the outcomes from clinical trials, registry data, and single-center studies, utilizing the TransMedics Organ Care System Heart, Paragonix SherpaPak Cardiac Transport System, and XVIVO Heart Preservation System. As the field of heart transplantation evolves to accommodate longer ischemia times, expand organ sharing, and utilize donors previously considered marginal, the integration of these advanced technologies will be essential for optimizing post-transplant outcomes.

The state of combined thoracoabdominal triple-organ transplantation in the United States

Background

As triple-organ transplantation (TOT) has become more common, we evaluate patient characteristics, risk factors, and clinical outcomes of patients undergoing thoracoabdominal TOT.

Methods

This retrospective study utilized data from heart-lung-liver (HLL), heart-lung-kidney (HLK), heart-kidney-liver (HKL), and heart-kidney-pancreas (HKP) recipients from the United Network for Organ Sharing registry between 1989 and 2023. Recipient and donor characteristics and risk factors for mortality were analyzed using Cox regression hazard models. Recipient survival up to 10 years was analyzed using the Kaplan-Meier method.

Results

During the study period, 81 TOTs were performed (13 HLLs, 13 HLKs, 46 HKLs, and 9 HKPs). There were no statistically significant differences in long-term survival between TOTs (p = 0.13). However, HLL and HLK recipients had significantly worse (p < 0.0001) and improved (p < 0.0001) survival, respectively, when compared to heart-lung, isolated heart, and lung transplant recipients. HLK was associated with improved survival (hazard ratios [HR]: 0.22, p = 0.033). We found no differences in survival among HKL (p = 0.24) and HKP (p = 0.19) recipients compared to their dual- and single-organ counterparts. TOTs after 2007 (HR: 0.29, p = 0.003) were associated with improved survival, whereas increased recipient age (HR: 1.06, p = 0.037), estimated glomerular filtration rate (HR: 1.02, p = 0.005), and donor age (HR:1.05, p = 0.031) were associated with higher mortality.

Conclusions

The prevalence of TOTs has dramatically increased over the past decade. While overall survival between TOTs appears similar, adding a liver to a heart-lung transplant may be associated with a poorer prognosis compared to adding a kidney. A careful, multidisciplinary approach to patient selection and management remains paramount in optimizing outcomes for high-risk patients undergoing TOTs.

A perspective on the added value of red blood cells during cardiac hypothermic oxygenated perfusion

Hypothermic oxygenated perfusion (HOPE) is an emerging technique for donor heart preservation that is currently being studied in multiple clinical trials with promising results. When compared to HOPE for other organs, cardiac protocols involve red blood cell (RBC) supplementation, despite absence of comparative evidence for its benefits. In this perspective paper, we discuss the pros and cons of the addition of RBCs during cardiac HOPE. Although the current clinical results with RBC supplementation during HOPE seem promising, potential downsides of RBC supplementation cannot be ruled out. The impact of supplemented RBCs during cardiac HOPE requires further investigation to improve HOPE protocols, to optimize heart preservation using this promising technology.

Limitations of the inotrope score use as a measure of primary graft dysfunction

Allograft dysfunction is the major cause of early morbidity and mortality following cardiac transplantation. Poor graft function can be secondary to transplant complications or, when no identifiable cause is present, primary graft dysfunction (PGD). To standardize the definition of PGD, a consensus conference was convened which produced a document that defines severity categories and criteria for assessing left and right ventricular dysfunction. A critical sub-criterion in the consensus definition of PGD is a score intended to reflect the need for inotropic support after transplant. However, during the Australian and New Zealand trial of Hypothermic Oxygenated Perfusion preservation of donor hearts, we realized that the consensus inotrope score was inflated by the disproportionate impact of norepinephrine (NE), upcoding PGD grades from mild to moderate. A review of 50 heart transplant patients at The Alfred Hospital showed that in 38% of the instances when the inotropic score exceeded the consensus cutoff value due to NE, there was no identifiable PGD or vasoplegia and in 16% of instances, the cutoff was exceeded due to vasoplegia without PGD. Given the importance of accurate PGD classification in an era when static cold storage preservation is being replaced by machine perfusion and temperature controlled static storage, we contend that NE should be removed from the inotrope score equation to prevent up coding of mild to moderate PGD. Furthermore, we think that PGD classification should incorporate sensitive load- independent cardiac performance measures in the context of given levels of pharmacological and mechanical cardiac support.

Ten hour donor heart ischemic time with 10ºC static storage

Utilization of 10ºC static storage safely extended both ischemic time and travel radius in heart transplantation. A 57-year-old man with ischemic cardiomyopathy, a left ventricular assist device (LVAD), and end-stage renal disease was listed for combined heart-kidney transplant. The donor hospital in Anchorage, AK, was located approximately 2,700 nautical miles and 8 hours from the recipient center. The organ was transported in 10ºC static storage with over 10 hours of ischemic time and had superb early allograft function. Excellent outcomes with extended ischemic times can be achieved without machine perfusion, provided good recovery, storage, and implant techniques are followed.

Severe primary graft failure: Are there lasting impacts? Analysis from the PHTS Database

Background

Primary graft failure (PGF) is a leading cause of early morbidity and mortality after heart transplantation (HTx). PGF is secondary to graft ischemia and ischemia-reperfusion injuries to the cardiomyocytes and vasculature of the donor heart after transplantation. Longer-term outcomes after PGF are not well studied.

Methods

Patients with an HTx (January 1, 2010 to June 30, 2022) were identified using the Pediatric Heart Transplant Society registry. PGF was defined as death, retransplantation, or need for mechanical circulatory support within 72 hours of HTx. Kaplan-Meier analysis and Cox proportional hazard modeling were utilized.

Results

Of the 4,982 patients with a primary HTx, 5.4% (n = 269) met criteria for PGF. Patients with PGF were younger, with higher proportion of congenital heart disease, longer cardiopulmonary bypass and ischemic times (IT), and more likely to be on extracorporeal membrane oxygenation or ventilator at HTx (all p < 0.0001, IT p = 0.0006). PGF resulted in lower overall survival (1 year: 54% vs 94%, p < 0.001). This remained true when conditional survival was examined at 30 and 90 days but not at 1 year (p = 0.1143). Freedom from rejection did not differ between the groups at overall or conditional on 30 days but was slightly higher for those with PGF at 90 and 365 days. There was no difference in freedom from coronary allograft vasculopathy (CAV). PGF was an independent predictor of overall graft loss (hazard ratios [HR] 4.7, p < 0.0001) and conditional survival to 30 days (HR 2.47, p < 0.0001) and 90 days (HR 1.6, p = 0.012) but not beyond 1 year.

Conclusions

Severe PGF is an independent predictor of early mortality post-HTx but subsequently does not further impact long-term survival, overall risk of rejection, or CAV. Understanding the impact of milder forms of PGF on survival and long-term outcomes is still needed. Methods to decrease the risk of PGF, such as alternative preservation and storage techniques, may impact early mortality post-HTx.

Effects of Nighttime Procurement and Transplantation on Outcomes Following Heart Transplantation

BACKGROUND

This study evaluates the effects of nighttime procurement and transplantation on outcomes following heart transplantation.

METHODS

The UNOS registry was queried to analyze adult recipients who underwent isolated orthotopic heart transplantation between January 1, 2010, and September 30, 2022. The cohort was stratified into daytime (4 am-8 pm) and nighttime (8 pm-4 am) transplant groups. The primary outcome was 1-year survival. Propensity score-matching was performed. Risk adjustment was performed using multivariable Cox regression. Restricted cubic spline was used to model the association between the time of transplantation and the likelihood of 1-year mortality. Sub-analysis was performed to evaluate the impact of nighttime procurement.

RESULTS

Altogether 30 426 recipients were analyzed, where 10 807 recipients (35.5%) underwent nighttime transplantation. The nighttime recipients had reduced 1-year post-transplant survival compared to the daytime recipients (90.6% vs. 91.5%, p = 0.019), and this lower survival persisted in the propensity score-matched comparison. After adjusting for established predictors for post-transplant mortality, nighttime transplantation continued to have a significantly increased risk of 1-year mortality (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.03-1.21, p = 0.005). The spline model demonstrated increased odds of 1-year mortality between 5 pm and 4 am, with the highest odds at 11 pm (odds ratio [OR] 1.25, 95% CI 1.07-1.47), compared to the reference transplantation time of 7 am. When assessing the impact of procurement timing, nighttime procurement negatively impacted 1-year post-transplant survival among the daytime recipients.

CONCLUSION

This study demonstrates the adverse impact of nighttime heart procurement and transplantation on early post-transplant survival. With emerging organ perfusion and thermal protection systems, additional studies are warranted to assess the safety of extending the heart preservation period to optimize the timing of transplantation.

Primary Graft Dysfunction after Heart Transplantation: Current Evidence and Implications for Clinical Practice

PURPOSE OF REVIEW

This review summarizes the current literature on primary graft dysfunction highlighting the current definition, reviewing epidemiology, and describing donor, recipient, and perioperative risk factors in the contemporary era.

RECENT FINDINGS

PGD, in its most severe form, complicates 8% of heart transplants and portends a 1-year mortality of close to 40%. PGD is multifactorial and heterogeneous with contributions from donor and recipient risk as well as organ recovery and preservation modalities. Biomarkers may enhance risk stratification and lend insight into the underlying mechanism of PGD. Temperature-controlled storage and hypothermic oxygenation perfusion systems, in particular, may have significant potential to mitigate PGD risk. PGD is a devastating early complication of heart transplantation that is both complex and multifactorial. Despite its incidence and impact the underlying biology of PGD remains poorly understood. Future studies mechanistic studies are needed to address the underlying pathophysiology of PGD to develop targeted prophylactic and/or therapeutic interventions.

Beyond the icebox: modern strategies in organ preservation for transplantation

Organ transplantation, a critical treatment for end-stage organ failure, has witnessed significant advancements due to the integration of improved surgical techniques, immunosuppressive therapies, and donor-recipient matching. This review explores the progress of organ preservation, focusing on the shift from static cold storage (SCS) to advanced machine perfusion techniques such as hypothermic (HMP) and normothermic machine perfusion (NMP). Although SCS has been the standard approach, its limitations in preserving marginal organs and preventing ischemia-reperfusion injury (IRI) have led to the adoption of HMP and NMP. HMP, which is now the gold standard for high-risk donor kidneys, reduces metabolic activity and improves posttransplant outcomes. NMP allows real-time organ viability assessment and reconditioning, especially for liver transplants. Controlled oxygenated rewarming further minimizes IRI by addressing mitochondrial dysfunction. The review also highlights the potential of cryopreservation for long-term organ storage, despite challenges with ice formation. These advances are crucial for expanding the donor pool, improving transplant success rates, and addressing organ shortages. Continued innovation is necessary to meet the growing demands of transplantation and save more lives.

The Rapidly Evolving Landscape of DCD Heart Transplantation

PURPOSE OF REVIEW

To summarise current international clinical outcomes from donation after circulatory death heart transplantation (DCD-HT); discuss procurement strategies, their impact on outcomes and overall organ procurement; and identify novel approaches and future areas for research in DCD-HT.

RECENT FINDINGS

Globally, DCD-HT survival outcomes (regardless of procurement strategy) are comparable to heart transplantation from brain dead donors (BDD). Experience with normothermic machine perfusion sees improvement in rates of primary graft dysfunction. Techniques have evolved to reduce cold ischaemic exposure to directly procured DCD hearts, though controlled periods of cold ischaemia can likely be tolerated. There is interest in hypothermic machine perfusion (HMP) for directly procured DCD hearts, with promising early results. Survival outcomes are firmly established to be equivalent between BDD and DCD-HT. Procurement strategy (direct procurement vs. regional perfusion) remains a source of debate. Methods to improve allograft warm ischaemic tolerance are of interest and will be key to the uptake of HMP for directly procured DCD hearts.

Ex vivo evaluation of the whole heart function allowing selective investigation of the right and left heart

Objectives. The aim was to demonstrate a reliable ex vivo method to test the function of the whole heart. Design. Pigs of varying sizes (44-80 kg) were exposed to dose response of adrenaline. Blood pressures and cardiac output were measured. The explanted hearts were tested in a novel ex vivo system to see if we could replicate the in vivo values at maximal adrenaline stimulation. The perfusion solution was STEEN Solution™ with erythrocytes and continuous infusion of essential drugs. In contrast to normal body circulation which is sequential, the heart evaluation system is divided into left and right heart circuits which are operating in parallel, making it possible to test the right and left heart individually or as a whole. The system provides coronary flow measurements. The nonlinear dynamic resistances are constructed to stabilize systolic and diastolic pressures in a broad range and independently from cardiac output. It is important for the functional evaluation to avoid pumping help for the heart; therefore, atrial vortexes are constructed to minimize pump flow directionality and energy from entering atria. Results. Ex vivo evaluation was able to match the maximal in vivo effect of adrenaline on cardiac output and blood pressures. After 2 h of evaluation, the blood gases and lactate were normal and free haemoglobin was zero. Autopsy of the hearts showed no macroscopic pathology. Conclusions. The system is able to give a reliable functional evaluation of the heart ex vivo.

Open-lung ventilation versus no ventilation during cardiopulmonary bypass in an innovative animal model of heart transplantation

Open-lung ventilation during cardiopulmonary bypass (CPB) in patients undergoing heart transplantation (HTx) is a potential strategy to mitigate postoperative acute respiratory distress syndrome (ARDS). We utilized an ovine HTx model to investigate whether open-lung ventilation during CPB reduces postoperative lung damage and complications. Eighteen sheep from an ovine HTx model were included, with ventilatory interventions randomly assigned during CPB: the OPENVENT group received low tidal volume (VT) of 3 mL/kg and positive end-expiratory pressure (PEEP) of 8 cm H20, while no ventilation was provided in the NOVENT group as per standard of care. The recipient sheep were monitored for 6 h post-surgery. The primary outcome was histological lung damage, scored at the end of the study. Secondary outcomes included pulmonary shunt, driving pressure, hemodynamics and inflammatory lung infiltration. All animals completed the study. The OPENVENT group showed significantly lower histological lung damage versus the NOVENT group (0.22 vs 0.27, p = 0.042) and lower pulmonary shunt (19.2 vs 32.1%, p = 0.001). In addition, the OPENVENT group exhibited a reduced driving pressure (9.6 cm H2O vs. 12.8 cm H2O, p = 0.039), lower neutrophil (5.25% vs 7.97%, p ≤ 0.001) and macrophage infiltrations (11.1% vs 19.6%, p < 0.001). No significant differences were observed in hemodynamic parameters. In an ovine model of HTx, open-lung ventilation during CPB significantly reduced lung histological injury and inflammatory infiltration. This highlights the value of an open-lung approach during CPB and emphasizes the need for further clinical evidence to decrease risks of lung injury in HTx patients.

European Society of Organ Transplantation (ESOT) Consensus Statement on Machine Perfusion in Cardiothoracic Transplant

The machine perfusion (MP) of transplantable grafts has emerged as an upcoming field in Cardiothoracic (CT) transplantation during the last decade. This technology carries the potential to assess, preserve, and even recondition thoracic grafts before transplantation, so it is a possible game-changer in the field. This technology field has reached a critical turning point, with a growing number of publications coming predominantly from a few leading institutions, but still need solid scientific evidence. Due to the increasing need to expand the donor pool, especially in Europe, where the donor age is steeply increased, a consensus has been established to address the growing need and knowledge of machine perfusion in cardiothoracic transplantation, targeting the unmet scientific need in this growing field but also, priorities for development, and regional differences in utilization rates and organizational issues. To address MP in CT, the European Society of Organ Transplantation (ESOT) convened a dedicated Working group comprised of experts in CT to review literature about MP to develop guidelines that were subsequently discussed and voted on during the Consensus Conference that took place in person in Prague during the TLJ 3.0 in November 2022. The findings and recommendations of the Cardiothoracic Working Group on MP are presented in this article.

Differences in outcomes of combined heart-liver transplantation by primary cardiac diagnosis

Background

Combined heart-liver transplantation (CHLT) is a complex procedure with rising demand and is subject to ongoing assessment. Here, we provide an update on indications, patient outcomes, and risk factors.

Methods

This retrospective study utilized CHLT data from the United Network for Organ Sharing registry between 1990 and 2023. Recipient and donor characteristics, and risk factors for mortality were analyzed using Cox regression hazard models. Recipient and graft survival at 30 days, 1 year, and 5 years were analyzed using the Kaplan-Meier method.

Results

This cohort included 532 patients with median survival of 16.9 years (SD: 1.09). The most common indications for CHLT were congenital heart disease (36%) and dilated cardiomyopathy (31%). Patient survival at 30 days, 1 year, and 5 years were 94%, 85%, and 77%, respectively. Combined heart-liver graft survival was 93%, 85%, and 77%, respectively. Diabetes (hazard ratio [HR]: 1.74; p = 0.04) was associated with multigraft failure and mortality in multivariate analysis. Compared to congenital heart disease, dilated (HR: 0.55; p = 0.03) and restrictive myopathies (HR: 0.5; p = 0.03) were associated with improved graft and overall survival. Higher donor left ventricular ejection fraction (EF) was also associated with improved graft and overall survival (HR: 0.96; p = 0.008).

Conclusions

CHLTs are being performed at increasingly higher rates with comparable survival to single-organ transplants. Diabetes was associated with increased mortality. Recipient dilated or restrictive myopathies and higher donor EF were correlated with improved survival compared to congenital heart disease. Further studies are needed to better understand these observations.

Innovations in transplant techniques for complex anomalies

PURPOSE OF REVIEW

With advances in the field of congenital cardiac surgery and in the management of congenital heart defects in early life, the population of adult congenital heart disease (ACHD) patients is increasing. End-stage heart failure is currently the main cause of cardiovascular mortality and is expected to increase in the coming years. This review summarizes recent innovations in transplant techniques, with special attention to what is known in the population of ACHD recipients.

RECENT FINDINGS

The use of machine perfusion for heart preservation enables longer preservation times. Normothermic (organ care system - OCS) and hypothermic (hypothermic oxygenated perfusion - HOPE) machine perfusion will alleviate the time pressure associated with heart transplantation in the ACHD population, may allow for expansion of the geographical range in which donors can be matched and may improve graft quality. Donation after circulatory death (DCD) heart transplantation, either through direct procurement-machine perfusion (DP-MP) or thoraco-abdominal normothermic regional perfusion (TA-NRP) is a viable strategy to further expand the donor pool.

SUMMARY

The use of machine perfusion and DCD donors in ACHD is feasible and shows promise. Time pressure and shortage of donors is even more critical in ACHD than in other patient populations, making these innovations particularly relevant. Further clinical experience and research is needed to elucidate their impact.

Machine Perfusion and Bioengineering Strategies in Transplantation-Beyond the Emerging Concepts

Solid organ transplantation has progressed rapidly over the decades from the first experimental procedures to its role in the modern era as an established treatment for end-stage organ disease. Solid organ transplantation including liver, kidney, pancreas, heart, and lung transplantation, is the definitive option for many patients, but despite the advances that have been made, there are still significant challenges in meeting the demand for viable donor grafts. Furthermore, post-operatively, the recipient faces several hurdles, including poor early outcomes like primary graft dysfunction and acute and chronic forms of graft rejection. In an effort to address these issues, innovations in organ engineering and treatment have been developed. This review covers efforts made to expand the donor pool including bioengineering techniques and the use of ex vivo graft perfusion. It also covers modifications and treatments that have been trialed, in addition to research efforts in both abdominal organs and thoracic organs. Overall, this article discusses recent innovations in machine perfusion and organ bioengineering with the aim of improving and increasing the quality of donor organs.

Hypothermic oxygenated perfusion of the donor heart in heart transplantation: the short-term outcome from a randomised, controlled, open-label, multicentre clinical trial

BACKGROUND

Static cold storage (SCS) remains the gold standard for preserving donor hearts before transplantation but is associated with ischaemia, anaerobic metabolism, and organ injuries, leading to patient morbidity and mortality. We aimed to evaluate whether continuous, hypothermic oxygenated machine perfusion (HOPE) of the donor heart is safe and superior compared with SCS.

METHODS

We performed a multinational, multicentre, randomised, controlled, open-label clinical trial with a superiority design at 15 transplant centres across eight European countries. Adult candidates for heart transplantation were eligible and randomly assigned in a 1:1 ratio. Donor inclusion criteria were age 18-70 years with no previous sternotomy and donation after brain death. In the treatment group, the preservation protocol involved the use of a portable machine perfusion system ensuring HOPE of the resting donor heart. The donor hearts in the control group underwent ischaemic SCS according to standard practices. The primary outcome was time to first event of a composite of either cardiac-related death, moderate or severe primary graft dysfunction (PGD) of the left ventricle, PGD of the right ventricle, acute cellular rejection at least grade 2R, or graft failure (with use of mechanical circulatory support or re-transplantation) within 30 days after transplantation. We included all patients who were randomly assigned, fulfilled inclusion and exclusion criteria, and received a transplant in the primary analysis and all patients who were randomly assigned and received a transplant in the safety analyses. This trial was registered with ClicalTrials.gov (NCT03991923) and is ongoing.

FINDINGS

A total of 229 patients were enrolled between Nov 25, 2020, and May 19, 2023. The primary analysis population included 204 patients who received a transplant. There were no patients who received a transplant lost to follow-up. All 100 donor hearts preserved with HOPE were transplantable after perfusion. The primary endpoint was registered in 19 (19%) of 101 patients in the HOPE group and 31 (30%) of 103 patients in the SCS group, corresponding to a risk reduction of 44% (hazard ratio 0·56; 95% CI 0·32-0·99; log-rank test p=0·059). PGD was the primary outcome event in 11 (11%) patients in the HOPE group and 29 (28%) in the SCS group (risk ratio 0·39; 95% CI 0·20-0·73). In the HOPE group, 63 (65%) patients had a reported serious adverse event (158 events) versus 87 (70%; 222 events) in the SCS group. Major adverse cardiac transplant events were reported in 18 (18%) and 33 (32%) patients in the HOPE and SCS group (risk ratio 0·56; 95% CI 0·34-0·92).

INTERPRETATION

Although there was not a significant difference in the primary endpoint, the 44% risk reduction associated with HOPE was suggested to be a clinically meaningful benefit. Post-transplant complications, measured as major adverse cardiac transplant events, were reduced. Analysis of secondary outcomes suggested that HOPE was beneficial in reducing primary graft dysfunction. HOPE in donor heart preservation addresses the existing challenges associated with graft preservation and the increasing complexity of donors and heart transplantation recipients. Future investigation will help to further elucidate the benefit of HOPE.

FUNDING

XVIVO Perfusion.

Combined Organ Transplantation in Patients with Advanced Liver Disease

Transplantation of the liver in combination with other organs is an increasingly performed procedure. Over the years, continuous improvement in survival could be realized through careful patient selection and refined organ preservation techniques, in spite of the challenges posed by aging recipients and donors, as well as the increased use of steatotic liver grafts. Herein, we revisit the epidemiology, allocation policies in different transplant zones, indications, and outcomes with regard to simultaneous organ transplants involving the liver, that is combined heart-liver, liver-lung, liver-kidney, and multivisceral transplantation. We address challenges surrounding combined organ transplantation such as equity, utility, and logistics of dual organ implantation, but also advantages that come along with combined transplantation, thereby focusing on molecular mechanisms underlying immunoprotection provided by the liver to the other allografts. In addition, the current standing and knowledge of machine perfusion in combined organ transplantation, mostly based on center experience, will be reviewed. Notwithstanding all the technical advances, shortage of organs, and the lack of universal eligibility criteria for certain multi-organ combinations are hurdles that need to be tackled in the future.

Effect of sodium glucose cotransporter 2 inhibition immediately prior to heart transplantation

Sodium glucose cotransporter 2 inhibitors (SGLT2i) are an established treatment for heart failure and type 2 diabetes. Guidelines suggest withholding SGLT2i preoperatively due to the risk of ketoacidosis. Orthotopic heart transplantation (OHT) occurs without sufficient notice to cease SGLT2i treatment before surgery. In a retrospective analysis of 163 OHT recipients (40 exposed to SGLT2i, 123 not exposed), we show no increase in rates of mild, moderate, or severe acidosis postoperatively. No cases of ketoacidosis occurred, likely due to the fact that 97% of patients received insulin infusions postoperatively for transient postoperative hyperglycemia. Patients exposed to SGLT2i had shorter length of stay in the intensive care unit and improved adjusted survival overall. These findings support the safety of SGLT2i use up to the time of OHT with routine use of a postoperative insulin infusion.

Revolutionizing Donor Heart Procurement: Innovations and Future Directions for Enhanced Transplantation Outcomes

Heart failure persists as a critical public health challenge, with heart transplantation esteemed as the optimal treatment for patients with end-stage heart failure. However, the limited availability of donor hearts presents a major obstacle to meeting patient needs. In recent years, the most groundbreaking progress in heart transplantation has been in donor heart procurement, significantly expanding the donor pool and enhancing clinical outcomes. This review comprehensively examines these advancements, including the resurgence of heart donation after circulatory death and innovative recovery and evaluation technologies such as normothermic machine perfusion and thoraco-abdominal normothermic regional perfusion. Additionally, novel preservation methods, including controlled hypothermic preservation and hypothermic oxygenated perfusion, are evaluated. The review also explores the use of extended-criteria donors, post-cardiopulmonary resuscitation donors, and high-risk donors, all contributing to increased donor availability without compromising outcomes. Future directions, such as xenotransplantation, biomarkers, and artificial intelligence in donor heart evaluation and procurement, are discussed. These innovations promise to address current limitations and optimize donor heart utilization, ultimately enhancing transplantation success. By identifying recent advancements and proposing future research directions, this review aims to provide insights into advancing heart transplantation and improving patient outcomes.

Determinants of survival following heart transplantation in adults with congenital heart disease

BACKGROUND

Adult patients surviving with congenital heart disease (ACHD) is growing. We examine the factors associated with heart transplant outcomes in this challenging population with complex anatomy requiring redo-surgeries.

METHODS

We reviewed the United Network for Organ Sharing-Standard Transplant Analysis and Research database and analyzed 35,952 heart transplants from January 1st, 2000, to September 30th, 2018. We compared transplant characteristics for ischemic cardiomyopathy (ICM) (n = 14,236), nonischemic cardiomyopathy (NICM) (n = 20,676), and ACHD (n = 1040). Mean follow-up was 6.20 ± 4.84 years. Kaplan-Meier survival curves and Cox-proportional hazards analysis were used to analyze survival data.

RESULTS

Multivariable analysis confirmed that ACHD was associated greater in-hospital death compared to ICM (HR = 0.54, P < 0.001) and NICM (HR = 0.46, P < 0.001). Notable factors associated with increased mortality were history of cerebrovascular disease (HR = 1.11, P = 0.026), prior history of malignancy (HR = 1.12, P = 0.006), pre-transplant biventricular support (HR = 1.12, P = 0.069), postoperative stroke (HR = 1.47, P < 0.001) and postoperative dialysis (HR = 1.71, P < 0.001). ACHD transplants had a longer donor heart ischemic time (P < 0.001) and trend towards more deaths from primary graft dysfunction (P = 0.07). In-hospital deaths were more likely with ACHD and use of mechanical support such as use of right ventricular assist device (HR = 2.20, P = 0.049), biventricular support (HR = 1.62, P < 0.001) and extracorporeal membrane oxygenation (HR = 2.36, P < 0.001). Conditional survival after censoring hospital deaths was significantly higher in ACHD (P < 0.001).

CONCLUSION

Heart transplant in ACHD is associated with a higher post-operative mortality given anatomical complexity but a better long-term conditional survival. Normothermic donor heart perfusion may improve outcomes in the ACHD population by reducing the impact of longer ischemic times.

The Advent of Semi-Elective Lung Transplantation-Prolonged Static Cold Storage at 10°C

Since the early days of clinical lung transplantation the preservation of donor organs has become a fairly standardized procedure and most centers do follow similar processes. This includes the use of low-potassium high dextran flush solutions and static cold storage (SCS) in a cooler filled with ice. Depending on the length of SCS, organs usually arrive at the recipient hospital at a temperature of 0°C-4°C. The question of the optimal storage temperature for donor lung preservation has been revisited as data from large animal experiments demonstrated that organs stored at 10°C experience less mitochondrial damage. Thus, prolonged cold ischemic times can be better tolerated at 10°C-even in pre-damaged organs. The clinical applicability of these findings was demonstrated in an international multi-center observational study including three high-volume lung transplant centers. Total clinical preservation times of up to 24 hrs have been successfully achieved in organs stored at 10°C without hampering primary organ function and short-term outcomes. Currently, a randomized-controlled trial (RCT) is recruiting patients with the aim to compare standard SCS on ice with prolonged SCS protocol at 10°C. If, as anticipated, this RCT confirms data from previous studies, lung transplantation could indeed become a semi-elective procedure.