First clinical use of a novel hypothermic storage system for a long-distance donor heart procurement

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.

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.

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.

Cardiac Surgery in Advanced Heart Failure

Mechanical circulatory support and heart transplantation are established surgical options for treatment of advanced heart failure. Since the prevalence of advanced heart failure is progressively increasing, there is a clear need to treat more patients with mechanical circulatory support and to increase the number of heart transplantations. This narrative review summarizes recent progress in surgical treatment options of advanced heart failure and proposes an algorithm for treatment of the advanced heart failure patient at >65 years of age.

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

Innovations in Heart Transplantation: A Review

Advanced heart failure affects tens of thousands of people in the United States alone with high morbidity and mortality. Cardiac transplantation offers the best treatment strategy but has been historically limited by donor availability. Recently, there have been significant advances in organ allocation, donor-recipient matching, organ preservation and expansion of the donor pool. The current heart allocation system prioritizes the sickest patients to minimize waitlist mortality. Advances in donor organ selection including predicted heart mass calculations and more sophisticated antibody detection methods for allosensitized patients offer more effective matching of donors and recipients. Innovations in organ preservation such as with organ preservation systems have geographically widened the donor pool. The use of hepatitis C donors is possible with the advent of effective direct-acting antiviral agents to cure donor-transmitted hepatitis C. Finally, further expansion of the donor pool is occurring with the utilization of higher-risk donors with advanced age, medical comorbidities, and left ventricular dysfunction and advances in donation after circulatory death. This review provides an update on the new technologies and transplantation strategies that serve to widen the donor pool and more effectively match donors and recipients so that heart transplant candidates may derive the best outcomes from heart transplantation.

Extended Static Hypothermic Preservation In Cardiac Transplantation: A Case Report

BACKGROUND

The donor shortage poses a major limitation to use of heart transplantation. Novel strategies such as use of expanded-criteria donors with prolonged ischemia times are being employed to address this need. Recent developments in static hypothermia have allowed for the safe use of cardiac allografts with prolonged ischemic times.

CASE REPORT

We present the case of a 68-year-old woman with valvular cardiomyopathy refractory to medical therapy who underwent orthotopic heart transplantation with a cardiac allograft exposed to elevated ischemic times. This was achieved through use of the federally approved SherpaPak Cardiac Transport System for transportation of the allograft. This method of static hypothermic organ preservation allowed for a 330-minute total ischemic time, including 283 minutes of storage within the preservation system. The patient tolerated the procedure well and was discharged on postoperative day 10, with excellent graft function and no evidence of rejection 3 months postoperatively.

CONCLUSIONS

Though traditionally ischemic times of 240 minutes or less are recommended for cardiac allografts, we demonstrate, to our knowledge, the longest reported ischemic time of 330 minutes via use of a novel method of static hypothermia for organ preservation. The recipient had an excellent outcome postoperatively, demonstrating the potential for this new organ preservation system to expand the donor pool and improve access and use of heart transplantation.

New Approaches to Donor Selection and Preparation in Heart Transplantation

Purpose of review

With increasing survival of patients with stage D heart failure, the demand for heart transplantation has increased. The supply of donor hearts remains relatively limited. Strategies have been investigated and new technologies have been developed to expand the current donor pool. These new approaches will be discussed herein.

Recent findings

Donor hearts are often considered “marginal” due to risk factors such as older age, size mismatch with the intended recipient, prolonged ischemic time, presence of left ventricular hypertrophy, and hepatitis B/C infection. We reviewed recent data regarding the use of donor hearts with these risk factors and suggest ways to safely liberalize current donor heart acceptance criteria. New technologies such as temperature-controlled transport systems and ex vivo cardiac perfusion methods have also demonstrated promising short-term and intermediate outcomes as compared with routine cold storage, by promoting heart preservation and enabling heart procurement from remote sites with shorter cold ischemic time. Recent use of hearts from donation after circulatory death donors has demonstrated comparable outcomes to conventional donation after brain death, which can further expand the current donor pool.

Summary

Careful selection of “marginal” donor hearts, use of ex vivo cardiac perfusion, and acceptance of hearts after circulatory death may expand our current cardiac donor pool with comparable outcomes to conventional donor selection and preparation methods.

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

Background

The current gold standard for donor heart preservation is a three-bag-technique and storage in a cooler filled with slush ice. This technique can cause freezing injury with protein denaturation. We report our early experience with a single-use disposable device (SherpaPak™, Paragonix Technologies, MA, USA) specifically designed for sterile permanent temperature-controlled transportation of donor hearts.

Methods

In this case control study with 2:1 matching we identified 21 patients after heart transplantation depending on type of organ transport (standard three-bag-technique vs. SherpaPak™). The outcome after donor heart storage in the SherpaPak™ was compared with donor heart transportation with the standard technique.

Results

Since July 2018 seven patients (5 males; mean age 50.3±13.2years) underwent heart transplantation with the SherpaPak™ system. Cold ischemic time was longer in the SherpaPak™ group (207.7±23.3 vs. 181.6±21.9, P=0.027). SherpaPak™ kept the organ temperature at 5.1±0.8 °C, with an average outside temperature of 21.4±3.6 °C. Among all 21 transplanted patients four developed fatal early graft failure (28.6% vs. 21.4%, P=0.432). Over the first hours we noticed no difference in hemodynamic parameters, CK-MB levels or vasoactive-inotropic score. During first follow-up we noticed slightly better right heart function in the SherpaPak™ group (TAPSE 17.83±2.71 vs. 14.52±2.61 mm, P=0.020). We identified no positive blood cultures in the SherpaPak™ group within the first 30 days after heart transplantation.

Conclusions

The SherpaPak™ provides a constant temperature during transportation with permanent monitoring, never dropping below 4 °C. Organs transported with this novel device showed a normal perioperative function.