First clinical experience with the novel cold storage SherpaPak™ system for donor heart transportation

Evaluating Heart Transplant Outcomes Using the SherpaPak Heart Storage System

The SherpaPak Cardiac Transport System (SCTS) is a novel hypothermic organ transport device which maintains an optimal temperature range of 4-8°C during donor heart transport. Its use in many major transplant centers has increased over the last several years. We retrospectively examined 120 heart transplant patients, 60 using SCTS and 60 using traditional cold storage on ice (TCS), at the University of Kansas Medical Center (KUMC) between June 2020 and June 2023. Baseline characteristics were comparable except there were less males in TCS versus SCTS (70% vs. 85%; p = 0.049) and less diabetics (23% vs. 47%; p = 0.07). The TCS group had significantly shorter ischemic times than the SCTS group (177 vs. 204 min; p = 0.008). On analysis, no statistically significant difference was noted in primary graft dysfunction (PGD; 12% vs. 15%; p = 0.59), total length of stay (LOS; 19 vs. 17 days; p = 0.061), 1 year all-cause mortality (12% vs. 8.4%; p = 0.196), and 1 year cardiac allograft vasculopathy (CAV; 58% vs. 63%, p = 0.333] between these two groups. Multivariate analysis also showed no significant difference in PGD and LOS between groups. We conclude that despite having longer ischemic times in the SCTS group, the post-transplant outcomes were comparable to TCS.

Chilling Choices: Heart Transplant Outcomes Using SherpaPak With Long Ischemic Time Versus Traditional Ice Storage With Short Ischemic Time

We performed a retrospective review comparing outcomes between traditional ice storage (ICE) with short ischemic times (<3 hours) to SherpaPak Cardiac Transport System (SCTS) with long ischemic times (>4 hours) using data from the GUARDIAN registry, a retrospective observational trial. To minimize baseline differences, propensity-matched (PSM) cohorts for site and era were performed. SherpaPak Cardiac Transport System travel distance was almost 10-fold greater than ICE (82 miles ICE vs . 765 miles SCTS). There was no significant difference in primary graft dysfunction (PGD) (20.8% vs. 18.2%, p = 0.58), length of stay (LOS) (24.7 vs. 24.8, p = 0.98), posttransplant mechanical circulatory support (MCS) (25.1% vs. 20.3%, p = 0.34), and 30 day survival (100% vs. 98.6%, p = 0.20). SherpaPak Cardiac Transport System showed statistically significant reduction in 24 hour inotrope scores (17.6 vs. 13.6, p = 0.007) and right ventricular (RV) dysfunction (31.1% vs. 15.7%, p = 0.002). Propensity-matched cohorts showed statistically similar rates of MCS utilization and PGD, but SCTS trended toward less RV dysfunction (26.0% vs. 16.2%, p = 0.11) and lower inotrope scores (16.5 vs. 12.9, p = 0.06) despite almost double the ischemic time. In conclusion, donor heart preservation with SCTS continues to be effective in prolonged ischemic times without sacrificing postheart transplantation clinical outcomes. This may aid in expanding donor organ geography.

Investigating Cardiac Temperature During Heart Transplantation Using the Static Cold Storage Paradigm

BACKGROUND

Static cold storage is a mainstay of the heart transplantation (HTx) process. However, the temperature distribution within the organ at each stage of HTx is unknown. In this study, we aimed to quantify how long it took for the heart to warm up and cool down and the nature of temperature distribution with the organ at each stage of HTx.

METHODS

We used high-fidelity computational time-varying biothermal modeling on an anatomical human heart model to model the HTx process in 5 interdependent stages, including cardioplegia, back-table preparation, static cold storage ice box storage and transport, back-table preparation at the recipient institution and warm-up within the recipient body before cross-clamp release.

RESULTS

Results indicate that the heart experiences roller-coaster-like temperature changes in stage, including rapid cool down from body temperature to <10 °C within 15 min in stage 1 with a maximum cooling rate of 5 °C/min. This was followed by cooling and extended duration of temperatures <2 °C in the ice box and rapid warming up to body temperature within 10 min at rates of 2 °C/min and 4 °C/min for the left and right sides, respectively, during implantation. Temperature distribution throughout the heart was heterogeneous, with right-sided temperature change occurring nearly 2× faster than on the left side.

CONCLUSIONS

We present, for the first time, detailed temperature distributions and evolution at each stage of HTx. Quantification of the rapid and heterogeneous temperature changes is crucial to optimize HTx and improve organ viability.

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.

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.

Adult cardiac transplantation utilizing donors after circulatory death

Donation after circulatory death (DCD) presents both opportunities and challenges in the realm of heart transplantation. Its emergence holds promise for narrowing the gap between patients in need of organs and the available donor pool. The rapid emergence of DCD use has allowed heart transplant volume to increase worldwide. Long-term outcomes and best practices remain to be defined and are important considerations in the wider use of these techniques in a broad selection of patients to understand best use and practice moving forward. Expanding DCD donation entails substantial resource allocation, coordination efforts, and training initiatives. Moving forward, standardization is imperative, particularly in aspects such as "stand-off" time, warm ischemic time (WIT), and perfusate composition.

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.

Donation After Circulatory Death Heart Transplantation: A Narrative Review

Heart transplantation is the definitive treatment for refractory, end-stage heart failure. The number of patients awaiting transplantation far exceeds available organs. In an effort to expand the donor pool, donation after circulatory death (DCD) heart transplantation has garnered renewed interest. Unlike donation after brain death, DCD donors do not meet the criteria for brain death and are dependent on life-sustaining therapies. Procurement can include a direct strategy or a normothermic regional perfusion, whereby there is restoration of perfusion to the organ before explantation. There are new developments in cold storage and ex vivo perfusion strategies. Since its inception, there has been a steady improvement in post-transplant outcomes, largely attributed to advancements in operative and procurement strategies. In this narrative review, the authors address the unique considerations of DCD heart transplantation, including withdrawal of care, the logistics of procuring and resuscitating organs, outcomes compared with standard donation after brain death, and ethical considerations.

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.

Long-distance donor heart procurement using an innovative cold static storage system

The global lack of donor shortage poses a major limitation for heart transplantation. New concepts with expanded donor inclusion criteria comprise extended transport distances and prolonged ischemic times with the aim of reaching a larger number of potential donors. Recent developments in cold storage solutions may allow more donor hearts with prolonged ischemic times to be use for transplantation in the future. We present our experience during a long-distance donor heart procurement with the longest reported transport distance and transport time in the current literature. This was made possible through the use of SherpaPak™, an innovative cold storage system which allows for controlled temperatures during transportation.

Impact of controlled hypothermic preservation on outcomes following heart transplantation

BACKGROUND

Severe primary graft dysfunction (PGD) is a major cause of early mortality after heart transplant, but the impact of donor organ preservation conditions on severity of PGD and survival has not been well characterized.

METHODS

Data from US adult heart-transplant recipients in the Global Utilization and Registry Database for Improved Heart Preservation-Heart Registry (NCT04141605) were analyzed to quantify PGD severity, mortality, and associated risk factors. The independent contributions of organ preservation method (traditional ice storage vs controlled hypothermic preservation) and ischemic time were analyzed using propensity matching and logistic regression.

RESULTS

Among 1,061 US adult heart transplants performed between October 2015 and December 2022, controlled hypothermic preservation was associated with a significant reduction in the incidence of severe PGD compared to ice (6.6% [37/559] vs 10.4% [47/452], p = 0.039). Following propensity matching, severe PGD was reduced by 50% (6.0% [17/281] vs 12.1% [34/281], respectively; p = 0.018). The Kaplan-Meier terminal probability of 1-year mortality was 4.2% for recipients without PGD, 7.2% for mild or moderate PGD, and 32.1%, for severe PGD (p < 0.001). The probability of severe PGD increased for both cohorts with longer ischemic time, but donor hearts stored on ice were more likely to develop severe PGD at all ischemic times compared to controlled hypothermic preservation.

CONCLUSIONS

Severe PGD is the deadliest complication of heart transplantation and is associated with a 7.8-fold increase in probability of 1-year mortality. Controlled hypothermic preservation significantly attenuates the risk of severe PGD and is a simple yet highly effective tool for mitigating post-transplant morbidity.

Ex vivo lung perfusion and the Organ Care System: a review

With the increasing prevalence of heart failure and end-stage lung disease, there is a sustained interest in expanding the donor pool to alleviate the thoracic organ shortage crisis. Efforts to extend the standard donor criteria and to include donation after circulatory death have been made to increase the availability of suitable organs. Studies have demonstrated that outcomes with extended-criteria donors are comparable to those with standard-criteria donors. Another promising approach to augment the donor pool is the improvement of organ preservation techniques. Both ex vivo lung perfusion (EVLP) for the lungs and the Organ Care System (OCS, TransMedics) for the heart have shown encouraging results in preserving organs and extending ischemia time through the application of normothermic regional perfusion. EVLP has been effective in improving marginal or borderline lungs by preserving and reconditioning them. The use of OCS is associated with excellent short-term outcomes for cardiac allografts and has improved utilization rates of hearts from extended-criteria donors. While both EVLP and OCS have successfully transitioned from research to clinical practice, the costs associated with commercially available systems and consumables must be considered. The ex vivo perfusion platform, which includes both EVLP and OCS, holds the potential for diverse and innovative therapies, thereby transforming the landscape of thoracic organ transplantation.

Heart graft preservation technics and limits: an update and perspectives

Heart transplantation, the gold standard treatment for end-stage heart failure, is limited by heart graft shortage, justifying expansion of the donor pool. Currently, static cold storage (SCS) of hearts from donations after brainstem death remains the standard practice, but it is usually limited to 240 min. Prolonged cold ischemia and ischemia-reperfusion injury (IRI) have been recognized as major causes of post-transplant graft failure. Continuous ex situ perfusion is a new approach for donor organ management to expand the donor pool and/or increase the utilization rate. Continuous ex situ machine perfusion (MP) can satisfy the metabolic needs of the myocardium, minimizing irreversible ischemic cell damage and cell death. Several hypothermic or normothermic MP methods have been developed and studied, particularly in the preclinical setting, but whether MP is superior to SCS remains controversial. Other approaches seem to be interesting for extending the pool of heart graft donors, such as blocking the paths of apoptosis and necrosis, extracellular vesicle therapy, or donor heart-specific gene therapy. In this systematic review, we summarize the mechanisms involved in IRI during heart transplantation and existing targeting therapies. We also critically evaluate all available data on continuous ex situ perfusion devices for adult donor hearts, highlighting its therapeutic potential and current limitations and shortcomings.

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.

Composition of ex vivo perfusion solutions and kinetics define differential cytokine/chemokine secretion in a porcine cardiac arrest model of lung preservation

Background

Ex vivo lung perfusion (EVLP) uses continuous normothermic perfusion to reduce ischemic damage and to improve post-transplant outcomes, specifically for marginal donor lungs after the donation after circulatory death. Despite major efforts, the optimal perfusion protocol and the composition of the perfusate in clinical lung transplantation have not been identified. Our study aims to compare the concentration levels of cytokine/chemokine in different perfusion solutions during EVLP, after 1 and 9 h of cold static preservation (CSP) in a porcine cardiac arrest model, and to correlate inflammatory parameters to oxygenation capacities.

Methods

Following cardiac arrest, the lungs were harvested and were categorized into two groups: immediate (I-EVLP) and delayed EVLP (D-EVLP), after 1 and 9 h of CSP, respectively. The D-EVLP lungs were perfused with either Steen or modified Custodiol-N solution containing only dextran (CD) or dextran and albumin (CDA). The cytokine/chemokine levels were analyzed at baseline (0 h) and after 1 and 4 h of EVLP using Luminex-based multiplex assays.

Results

Within 4 h of EVLP, the concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-1α, and IL-1β increased significantly (P < 0.05) in all experimental groups. The CD solution contained lower concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-2, IL-12, IL-10, IL-4, IL-1RA, and IL-18 (P < 0.05) compared with those of the Steen solution. The concentration levels of all experimental groups have correlated negatively with the oxygenation capacity values (P < 0.05). Protein concentration levels did not reach statistical significance for I-EVLP vs. D-EVLP and CD vs. CDA solutions.

Conclusion

In a porcine cardiac arrest model, a longer period of CSP prior to EVLP did not result in an enhanced protein secretion into perfusates. The CD solution reduced the cytokine/chemokine secretion most probably by iron chelators and/or by the protecting effects of dextran. Supplementing with albumin did not further reduce the cytokine/chemokine secretion into perfusates. These findings may help in optimizing the preservation procedure of the lungs, thereby increasing the donor pool of organs.

Outcomes of Heart Transplantation Using a Temperature-controlled Hypothermic Storage System

BACKGROUND

The SherpaPak Cardiac Transport System is a novel technology that provides stable, optimal hypothermic control during organ transport. The objectives of this study were to describe our experience using the SherpaPak system and to compare outcomes after heart transplantation after using SherpaPak versus the conventional static cold storage method (non-SherpaPak).

METHODS

From 2018 to June 2021, 62 SherpaPak and 186 non-SherpaPak patients underwent primary heart transplantation at Stanford University with follow-up through May 2022. The primary end point was all-cause mortality, and secondary end points were postoperative complications. Optimal variable ratio matching, cox proportional hazards regression model, and Kaplan-Meier survival analyses were performed.

RESULTS

Before matching, the SherpaPak versus non-SherpaPak patients were older and received organs with significantly longer total allograft ischemic time. After matching, SherpaPak patients required fewer units of blood product for perioperative transfusion compared with non-SherpaPak patients but otherwise had similar postoperative outcomes such as hospital length of stay, primary graft dysfunction, inotrope score, mechanical circulatory support use, cerebral vascular accident, myocardial infarction, respiratory failure, new renal failure requiring dialysis, postoperative bleeding or tamponade requiring reoperation, infection, and survival.

CONCLUSIONS

In conclusion, this is one of the first retrospective comparison studies that evaluated the outcomes of heart transplantation using organs preserved and transported via the SherpaPak system. Given the excellent outcomes, despite prolonged total allograft ischemic time, it may be reasonable to adopt the SherpaPak system to accept organs from a remote location to further expand the donor pool.

Donation after circulatory determination of death in heart transplant: impact on current and future allocation policy

PURPOSE OF REVIEW

Historically, the selection criteria for heart transplant candidates has prioritized posttransplant survival while contemporary allocation policy is focused on improving waitlist survival. Donor scarcity has continued to be the major influence on transplant allocation policy. This review will address the opportunity of donation after circulatory determination of death (DCDD) and potential impact on future policy revisions.

RECENT FINDINGS

In 2018, changes to U.S. heart allocation policy led to several intended and unintended consequences. Beneficial changes include reduced waitlist mortality and broader geographic sharing. Additional impacts include scarcer pathways to transplant for patients with a durable left ventricular assist device, increased reliance on status exceptions, and expanded use of temporary mechanical support. DCDD is anticipated to increase national heart transplant volumes by ∼30% and will impact waitlist management. Centers that offer DCDD procurement will have reduced waitlist times, reduced waitlist mortality, and higher transplant volumes.

SUMMARY

While DCDD will provide more transplant opportunities, donor organ scarcity will persist and influence allocation policies. Differential patient selection, waitlist strategy, and outcome expectations may indicate that allocation is adjusted based on the procurement options at individual centers. Future policy, which will consider posttransplant outcomes, may reflect that different procurement strategies may yield different outcomes.

Normothermic Regional Perfusion is an Emerging Cost-Effective Alternative in Donation After Circulatory Death (DCD) in Heart Transplantation

In donation after circulatory death (DCD) organ transplantation, normothermic regional perfusion (NRP) restores oxygenated blood flow following cardiac arrest and reverses warm ischemia. Recently, NRP has also been used to help recover DCD hearts in addition to the abdominal organs. While DCD donation has increased the number of abdominal organs and lungs pool, it has not been able to increase the number of heart transplants, despite the fact that it has the potential to increase the number of heart transplants by 15-30%. Thoracoabdominal normothermic regional perfusion makes heart transplantation feasible and permits assessing heart function before an organ procurement without affecting the preservation of abdominal organs. NRP can be used in two ways for DCD donor heart transplants: normothermic regional perfusion followed by machine perfusion (NRP-MP) and normothermic regional perfusion followed by static cold storage (NRP-SCS). Normothermic regional perfusion is an emerging technology, a cost-effective alternative in donation after circulatory death (DCD), and will increase the pool of donors in heart transplantation.

Is the Organ Care System (OCS) Still the First Choice With Emerging New Strategies for Donation After Circulatory Death (DCD) in Heart Transplant?

The scarcity of donor hearts continues to be a challenge in transplants for advanced heart failure patients. With an increasing number of patients on the waiting list for a heart transplant, the discrepancy in the number between donors and recipients is gradually increasing and poses a new challenge that plagues the healthcare systems when it comes to the heart. Several technologies have been developed to expand the donor pool in recent years. One such method is the organ care system (OCS). The standard method of organ preservation is the static cold storage (SCS) method which allows up to four hours of safe preservation of the heart. However, beyond four hours of cold ischemia, the incidence of primary graft dysfunction increases significantly. OCS keeps the heart perfused close to the physiological state beyond the four hours with superior results, which allows us to travel further and longer distances, leading to expansion in the donor pool. In this review, we discuss the OCS system, its advantages, and shortcomings.

Packing the donor heart: Is SherpaPak cold preservation technique safer compared to ice cold storage

INTRODUCTION

The present study aimed to compare the clinical outcomes of heart transplant patients whose donor hearts were preserved with the SherpaPak controlled cold organ system versus the conventional ice storage technique.

METHODS

All patients undergoing heart transplantation at our center between January 2019 and April 2021 were divided into two groups according to the technique used during donor heart preservation and transport. The first group consisted of 34 SherpaPak controlled temperature preservation patients, and the second group consisted of 47 patients where the conventional three bags and ice technique was utilized during organ transportation. The two groups were compared based on demographics, operative details, and postoperative outcomes.

RESULTS

There were no significant differences between the groups regarding Vasoactive Inotropic Score (VIS), Primary Graft Dysfunction (PGD), and the need for a transient pacer. However, the VIS, PGD, and pacing trends were lower in the SherpaPak patients even though the total ischemic and cardiopulmonary bypass times were significantly longer. Furthermore, SherpaPak patients exhibited a shorter stay in the ICU with no severe PGD and mortality.

CONCLUSION

The SherpaPak donor heart preservation provides safe outcomes in heart transplant patients. Further research is needed to utilize this method for longer durations of ischemic time and expand travel distances for organ transportation. This article is protected by copyright. All rights reserved.

Heart transplantation: focus on donor recovery strategies, left ventricular assist devices, and novel therapies

Heart transplantation is advocated in selected patients with advanced heart failure in the absence of contraindications. Principal challenges in heart transplantation centre around an insufficient and underutilized donor organ pool, the need to individualize titration of immunosuppressive therapy, and to minimize late complications such as cardiac allograft vasculopathy, malignancy, and renal dysfunction. Advances have served to increase the organ donor pool by advocating the use of donors with underlying hepatitis C virus infection and by expanding the donor source to use hearts donated after circulatory death. New techniques to preserve the donor heart over prolonged ischaemic times, and enabling longer transport times in a safe manner, have been introduced. Mechanical circulatory support as a bridge to transplantation has allowed patients with advanced heart failure to avoid progressive deterioration in hepato-renal function while awaiting an optimal donor organ match. The management of the heart transplantation recipient remains a challenge despite advances in immunosuppression, which provide early gains in rejection avoidance but are associated with infections and late-outcome challenges. In this article, we review contemporary advances and challenges in this field to focus on donor recovery strategies, left ventricular assist devices, and immunosuppressive monitoring therapies with the potential to enhance outcomes. We also describe opportunities for future discovery to include a renewed focus on long-term survival, which continues to be an area that is under-studied and poorly characterized, non-human sources of organs for transplantation including xenotransplantation as well as chimeric transplantation, and technology competitive to human heart transplantation, such as tissue engineering.

Evolving Characteristics of Heart Transplantation Donors and Recipients: JACC Focus Seminar

Although the burden of end-stage heart failure continues to increase, the number of available organs for heart transplantation (HT) remains inadequate. The HT community has been challenged to find ways to expand the number of donor hearts available. Recent advances include use of hearts from donors infected with hepatitis C virus as well as other previously underutilized donors, including those with left ventricular dysfunction, of older age, and with a history of cocaine use. Concurrently, emerging trends in HT surgery include donation after circulatory death, ex vivo normothermic heart perfusion, and controlled hypothermic preservation, which may enable procurement of organs from farther distances and prevent early allograft dysfunction. Contemporary HT recipients have also evolved in light of the 2018 revision to the U.S. heart allocation policy. This focus seminar discusses recent trends in donor and recipient phenotypes and management strategies for successful HT, as well as evolving areas and future directions.

Prolonged Ischemic Times for Heart Transplantation: Impact of the 2018 Allocation Change

BACKGROUND

In 2018, the United Network for Organ Sharing (UNOS) implemented a change in heart allocation policy resulting in increased organ ischemic times in early analyses. This study evaluated the effect of ischemic time on one-year mortality in the context of allocation policy changes implemented in 2006 and 2018.

METHODS

The UNOS registry was utilized to identify adults undergoing heart transplantation from 2000-2020. Patients were stratified by the allocation policy era in which they underwent transplant (2000-June 2006, July 2006-Oct 2018, Oct 2018-2020) and by ischemic time, defined as normal (≤4) and (>6 hours). One-year survival was compared using Kaplan-Meier analysis. Cox regression was used to determine risk-adjusted hazards for ischemic time on one-year mortality.

RESULTS

40,052 patients were included for analysis. Ischemic times were normal in 32,585 (81.36%) and prolonged in 7,467 (18.64%) patients. The proportion of transplantations with prolonged ischemic times increased with each subsequent policy era. After the 2018 policy change, one-year survival was 90.92% with normal ischemic times versus 87.52% with prolonged ischemic times (p<0.001). Ischemic time independently predicted one-year mortality in each era with a hazard ratio of 1.20 per hour (p=0.004) in the current era.

CONCLUSIONS

Prolonged ischemic times occur in a minority of cases but are increasing in frequency. The independent risk of prolonged ischemic time on one-year mortality persists despite advances in storage technology and should remain a consideration in donor-recipient matching.

An innovative cold storage system for donor heart transportation-lessons learned from the first experience in Switzerland

Background

The current standard for donor heart preservation consists of cold organ storage in three sequential plastic bags. This technique can cause freezing injuries of the donor heart as the temperature inside the transport box is not monitored routinely. The SherpaPak™ Cardiac Transport System (CTS) (Paragonix Technologies, Cambridge, MA, USA) aims to resolve this problem by maintaining a controlled preservation temperature between 4 and 8 °C. This study reports the first single-centre experience in Switzerland with this innovative single-use disposable device.

Methods

Between May and December 2020, four heart procurements using SherpaPak™ CTS were performed at our heart centre. Donor heart preservation fluid and ambient temperature were monitored using the InTempConnect^® application (Onset Computer Corporation, Bourne, MA, USA). All patient data were collected retrospectively from the local hospital patient data capture system.

Results

Four recipients of a donor heart preserved with SherpaPak™ CTS were included in this study (3 male, 1 female). Mean transport distance was 86 km (range, 45–276 km). Mean storage time in the cooler was 73.5±19.33 minutes. Mean cold ischemic time was 199.25±11.67 minutes. The device kept the average organ temperature between 5.2 and 8.8 °C and hereby reached the recommended temperature range of 5–10 °C. Modifications of the procurement and storage process provided an optimization of the temperature course in the transportation box. There were no incidents during the transport. Organs transported with this novel storage system showed normal function after transplantation.

Conclusions

The SherpaPak™ CTS provides constant organ temperatures during transportation, prevents freezing injury and ensures mechanical protection of the graft.

Keywords

Heart transplantation; organ procurement; cold storage; hypothermic injury; graft transport