Hearts from DCD donors display acceptable biventricular function after heart transplantation in pigs

Outcomes of Heart Transplantation From Donation After Circulatory Death: An Up-to-date Systematic Meta-analysis

BACKGROUND

Donation after circulatory death (DCD) heart transplantation (HTx) significantly expands the donor pool and reduces waitlist mortality. However, high-level evidence-based data on its safety and effectiveness are lacking. This meta-analysis aimed to compare the outcomes between DCD and donation after brain death (DBD) HTxs.

METHODS

Databases, including MEDLINE, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials, were systematically searched for randomized controlled trials and observational studies reporting the outcomes of DCD and DBD HTxs published from 2014 onward. The data were pooled using random-effects models. Risk ratios (RRs) with 95% confidence intervals (CIs) were used as the summary measures for categorical outcomes and mean differences were used for continuous outcomes.

RESULTS

Twelve eligible studies were included in the meta-analysis. DCD HTx was associated with lower 1-y mortality rate (DCD 8.13% versus DBD 10.24%; RR = 0.75; 95% CI, 0.59-0.96; P  = 0.02) and 5-y mortality rate (DCD 14.61% versus DBD 20.57%; RR = 0.72; 95% CI, 0.54-0.97; P  = 0.03) compared with DBD HTx.

CONCLUSIONS

Using the current DCD criteria, HTx emerges as a promising alternative to DBD transplantation. The safety and feasibility of DCD hearts deserve further exploration and investigation.

Considerations for the use of porcine organ donation models in preclinical organ donor intervention research

Use of animal models in preclinical transplant research is essential to the optimization of human allografts for clinical transplantation. Animal models of organ donation and preservation help to advance and improve technical elements of solid organ recovery and facilitate research of ischemia-reperfusion injury, organ preservation strategies, and future donor-based interventions. Important considerations include cost, public opinion regarding the conduct of animal research, translational value, and relevance of the animal model for clinical practice. We present an overview of two porcine models of organ donation: donation following brain death (DBD) and donation following circulatory death (DCD). The cardiovascular anatomy and physiology of pigs closely resembles those of humans, making this species the most appropriate for pre-clinical research. Pigs are also considered a potential source of organs for human heart and kidney xenotransplantation. It is imperative to minimize animal loss during procedures that are surgically complex. We present our experience with these models and describe in detail the use cases, procedural approach, challenges, alternatives, and limitations of each model.

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.

Metabolomic profiling of cardiac allografts after controlled circulatory death

BACKGROUND

Assessment of myocardial viability during ex situ heart perfusion (ESHP) is based on the measurement of lactate concentrations. As this provides with limited information, we sought to investigate the metabolic signature associated with donation after circulatory death (DCD) and the impact of ESHP on the myocardial metabolome.

METHODS

Porcine hearts were retrieved either after warm ischemia (DCD group, N = 6); after brain-stem death (BSD group, N = 6); or without DCD nor BSD (Control group, N = 6). Hearts were perfused using normothermic oxygenated blood for 240 minutes. Plasma and myocardial samples were collected respectively every 30 and 60 minutes, and analyzed by an untargeted metabolomic approach using liquid chromatography coupled to high-resolution mass spectrometry.

RESULTS

Median duration of warm ischemia was 23 minutes [19-29] in DCD animals. Lactate level within myocardial biopsies was not significantly different between groups at T0 (p = 0.281), and remained stable over the 4-hour period of ESHP. More than 300 metabolites were detected in plasma and heart biopsy samples. Compared to BSD animals, metabolomics changes involving energy and nucleotide metabolisms were observed in plasma samples of DCD animals before initiation of ESHP, whereas 2 metabolites (inosine monophosphate and methylbutyrate) exhibited concentration changes in biopsy samples. Normalization of DCD metabolic profile was remarkable after 4 hours of ESHP.

CONCLUSION

A specific metabolic profile was observed in DCD hearts, mainly characterized by an increased nucleotide catabolism. DCD and BSD metabolomes proved normalized during ESHP. Complementary investigations are needed to correlate these findings to cardiac performances.

The international experience of in-situ recovery of the DCD heart: a multicentre retrospective observational study

BACKGROUND

Heart transplantation is an effective treatment offering the best recovery in both quality and quantity of life in those affected by refractory, severe heart failure. However, transplantation is limited by donor organ availability. The reintroduction of heart donation after the circulatory determination of death (DCD) in 2014 offered an uplift in transplant activity by 30%. Thoraco-abdominal normothermic regional perfusion (taNRP) enables in-situ reperfusion of the DCD heart. The objective of this paper is to assess the clinical outcomes of DCD donor hearts recovered and transplanted from donors undergoing taNRP.

METHOD

This was a multicentre retrospective observational study. Outcomes included functional warm ischaemic time, use of mechanical support immediately following transplantation, perioperative and long-term actuarial survival and incidence of acute rejection requiring treatment. 157 taNRP DCD heart transplants, performed between February 2, 2015, and July 29, 2022, have been included from 15 major transplant centres worldwide including the UK, Spain, the USA and Belgium. 673 donations after the neurological determination of death (DBD) heart transplantations from the same centres were used as a comparison group for survival.

FINDINGS

taNRP resulted in a 23% increase in heart transplantation activity. Survival was similar in the taNRP group when compared to DBD. 30-day survival was 96.8% ([92.5%-98.6%] 95% CI, n = 156), 1-year survival was 93.2% ([87.7%-96.3%] 95% CI, n = 72) and 5-year survival was 84.3% ([69.6%-92.2%] 95% CI, n = 13).

INTERPRETATION

Our study suggests that taNRP provides a significant boost to heart transplantation activity. The survival rates of taNRP are comparable to those obtained for DBD transplantation in this study. The similar survival may in part be related to a short warm ischaemic time or through a possible selection bias of younger donors, this being an uncontrolled observational study. Therefore, our study suggests that taNRP offers an effective method of organ preservation and procurement. This early success of the technique warrants further investigation and use.

FUNDING

None of the authors have a financial relationship with a commercial entity that has an interest in the subject.

Ex-situ oxygenated hypothermic machine perfusion in donation after circulatory death heart transplantation following either direct procurement or in-situ normothermic regional perfusion

BACKGROUND

Heart transplantation in donation after circulatory death (DCD) relies on warm perfusion using either in situ normothermic regional perfusion (NRP) or ex situ normothermic machine perfusion. In this study, we explore an alternative: oxygenated hypothermic machine perfusion (HMP) using a novel clinically applicable perfusion system, which is compared to NRP with static cold storage (SCS).

METHODS

In a porcine model, a DCD setting was simulated, followed by either (1) NRP and SCS (2) NRP and HMP with the XVIVO Heart preservation system or (3) direct procurement (DPP) and HMP. After preservation, heart transplantation (HTX) was performed. After weaning from cardiopulmonary bypass (CPB), biventricular function was assessed by admittance and Swan-Ganz catheters.

RESULTS

Only transplanted hearts in the HMP groups showed significantly increased biventricular contractility (end-systole elastance) 2 hour post-CPB (left ventricle absolute change: NRP HMP: +1.8 ± 0.56, p = 0.047, DPP HMP: +1.5 ± 0.43, p = 0.045 and NRP SCS: +0.97 ± 0.47 mmHg/ml, p = 0.21; right ventricle absolute change: NRP HMP: +0.50 ± 0.12, p = 0.025, DPP HMP: +0.82 ± 0.23, p = 0.039 and NRP SCS: +0.28 ± 0.26, p = 0.52) while receiving significantly less dobutamine to maintain a cardiac output >4l/min compared to SCS. Diastolic function was preserved in all groups. Post-HTX, both HMP groups showed significantly less increments in plasma troponin T compared to SCS.

CONCLUSION

In DCD HTX, increased biventricular contractility post-HTX was only observed in hearts preserved with HMP. In addition, the need for inotropic support and signs of myocardial damage were lower in the HMP groups. DCD HTX can be successfully performed using DPP followed by preservation with HMP in a preclinical setting.

Clamping of the Aortic Arch Vessels During Normothermic Regional Perfusion Does Not Negatively Affect Donor Cardiac Function in Donation After Circulatory Death

BACKGROUND

The hemodynamic effects of aortic arch vessel (AAV) clamping during normothermic regional perfusion (NRP) in donation after circulatory death is unknown. We investigated effects of AAV clamping during NRP compared with no clamping in a porcine model.

METHODS

In 16 pigs, hemodynamic parameters were recorded including biventricular pressure-volume measurements and invasive blood pressure. Additionally, blood gas parameters and inflammatory cytokines were used to assess the effect of AAV clamping. The animals were centrally cannulated for NRP, and baseline measurements were obtained before hypoxic circulatory arrest was induced by halting mechanical ventilation. During an 8-min asystole period, the animals were randomized to clamp (n = 8) or no-clamp (n = 8) of the AAV before commencement of NRP. During NRP, circulation was supported with norepinephrine (NE) and dobutamine. After 30 min of NRP, animals were weaned and observed for 180 min post-NRP.

RESULTS

All hearts were successfully reanimated and weaned from NRP. The nonclamp groups received significantly more NE to maintain a mean arterial pressure >60 mm Hg during and after NRP compared with the clamp group. There were no between group differences in blood pressure or cardiac output. Pressure-volume measurements demonstrated preserved cardiac function' including ejection fraction and diastolic and systolic function. No between group differences in inflammatory markers were observed.

CONCLUSIONS

AAV clamping did not negatively affect donor cardiac function or inflammation after circulatory death and NRP. Significantly less NE was used to support in the clamp group than in the nonclamp group.

Early Outcomes of Heart Transplantation Using Donation After Circulatory Death Donors in the United States

BACKGROUND

Limited donor availability and evolution in procurement techniques have renewed interest in heart transplantation (HT) with donation after circulatory death (DCD). The aim of this study is to evaluate outcomes of HT using DCD in the United States.

METHODS

The United Network for Organ Sharing registry was used to identify adult HT recipients from 2019 to 2021. Recipients were stratified between DCD and donation after brain death. Propensity-score matching was performed. Cox proportional hazards was used to identify independent predictors of 1-year mortality. Kaplan-Meier analysis was used to estimate 1-year survival.

RESULTS

Of 7496 HTs, 229 DCD and 7267 donation after brain death recipients were analyzed. The frequency of DCD HT increased from 0.2% of all HT in 2019 to 6.4% in 2021 (P<0.001), and the number of centers performing DCD HT increased from 3 of 120 centers to 20 of 121 centers (P<0.001). DCD donors were more likely to be younger, male, and White. After propensity matching, 1-year survival was 92.5% for DCD versus 90.3% for donation after brain death (hazard ratio, 0.80 [95% CI, 0.44-1.43]; P=0.44). Among DCD HTs, increasing recipient age and waitlist time predicted 1-year mortality on univariable analysis.

CONCLUSIONS

Rates of DCD HT in the United States are increasing. This practice appears safe and feasible as mortality outcomes are comparable to donation after brain death. Although this study represents early adopting centers, outcomes of the experience for DCD HT in the United States is consistent with existing international data and encourages broader utilization of this practice.

High Oxygenation During Normothermic Regional Perfusion After Circulatory Death Is Beneficial on Donor Cardiac Function in a Porcine Model

BACKGROUND

Thoracoabdominal normothermic regional perfusion (NRP) is a new method for in situ reperfusion and reanimation of potential donor organs in donation after circulatory death by reperfusion of the thoracic and abdominal organs with oxygenated blood. We investigated effects of high oxygenation (HOX) versus low oxygenation (LOX) during NRP on donor heart function in a porcine model.

METHODS

Pigs (80 kg) underwent a 15-min anoxic cardiac arrest followed by cardiac reanimation on NRP using a heart-lung bypass machine with subsequent assessment 180 minutes post-NRP. The animals were randomized to HOX (FiO2 1.0) or LOX (FiO2 0.21 increased to 0.40 during NRP). Hemodynamic data were obtained by invasive blood pressure and biventricular pressure-volume measurements. Blood gases, biomarkers of inflammation, and oxidative stress were measured.

RESULTS

Eight of 9 animals in the HOX group and 7 of 10 in the LOX group were successfully weaned from NRP. Right ventricular end-systole elastance was significantly improved in the HOX group compared with the LOX group, whereas left ventricular end-systole elastance was preserved at baseline levels. Post-NRP cardiac output, mean arterial, central venous, and pulmonary capillary wedge pressure were all comparable to baseline. Creatinine kinase-MB increased more in the LOX group than the HOX group, whereas proinflammatory cytokines increased more in the HOX group than the LOX group. No difference was found in oxidative stress between groups.

CONCLUSIONS

All hearts weaned from NRP showed acceptable hemodynamic function for transplantation. Hearts exposed to LOX showed more myocardial damage and showed poorer contractile performance than hearts reperfused with high oxygen.

Treatment of Advanced Heart Failure-Focus on Transplantation and Durable Mechanical Circulatory Support: What Does the Future Hold?

Heart transplantation (HTx) is the treatment of choice in patients with late-stage advanced heart failure (Advanced HF). Survival rates 1, 5, and 10 years after transplantation are 87%, 77%, and 57%, respectively, and the average life expectancy is 9.16 years. However, because of the donor organ shortage, waiting times often exceed life expectancy, resulting in a waiting list mortality of around 20%. This review aims to provide an overview of current standard, recent advances, and future developments in the treatment of Advanced HF with a focus on long-term mechanical circulatory support and HTx.

Effects of graft preservation conditions on coronary endothelium and cardiac functional recovery in a rat model of donation after circulatory death

BACKGROUND

Use of cardiac grafts obtained with donation after circulatory death (DCD) could significantly improve donor heart availability. As DCD hearts undergo potentially deleterious warm ischemia and reperfusion, clinical protocols require optimization to ensure graft quality. Thus, we investigated effects of alternative preservation conditions on endothelial and/or vascular and contractile function in comparison with the current clinical standard.

METHODS

Using a rat DCD model, we compared currently used graft preservation conditions, St. Thomas n°2 (St. T) at 4°C, with potentially more suitable conditions for DCD hearts, adenosine-lidocaine preservation solution (A-L) at 4°C or 22°C. Following general anesthesia and diaphragm transection, hearts underwent either 0 or 18 min of in-situ warm ischemia, were explanted, flushed and stored for 15 min with either St. T at 4°C or A-L at 4°C or 22°C, and then reperfused under normothermic, aerobic conditions. Endothelial integrity and contractile function were determined.

RESULTS

Compared to 4°C preservation, 22°C A-L significantly increased endothelial nitric oxide synthase (eNOS) dimerization and reduced oxidative tissue damage (p < 0.05 for all). Furthermore, A-L at 22°C better preserved the endothelial glycocalyx and coronary flow compared with St. T, tended to reduce tissue calcium overload, and stimulated pro-survival signaling. No significant differences were observed in cardiac function among ischemic groups.

CONCLUSIONS

Twenty-two-degree Celsius A-L solution better preserves the coronary endothelium compared to 4°C St. T, which likely results from greater eNOS dimerization, reduced oxidative stress, and activation of the reperfusion injury salvage kinase (RISK) pathway. Improving heart preservation conditions immediately following warm ischemia constitutes a promising approach for the optimization of clinical protocols in DCD heart transplantation.

Combined Assessment of Functional and Metabolic Performance of Human Donor Hearts: Possible Application in Donation After Circulatory Death

BACKGROUND

Donation after circulatory death (DCD) represents an increasing source of organs. However, evaluating the suitability of DCD hearts for transplantation represents a challenge. Contractile function is the ultimate determinant of recovery. We developed a novel technique in an ex vivo rig for the measurement of contractility using intraventricular balloons. We compared this technique with the measurement of lactate metabolism, the current gold standard.

METHODS

Human DCD (n = 6) and donation after brain death (n = 6) hearts were preserved by perfusion with a cold oxygenated crystalloid solution for 4 h, transferred to a blood perfusion rig at 37 °C where balloons were inserted into the left (LV) and right (RV) ventricles to measure developed pressure (DP = systolic minus diastolic). Perfusate lactate levels were measured for metabolic assessment. Concordance between LVDP and lactate was assessed during 4 h using cutoffs for LVDP of 70 mm Hg and for lactate of 10 mmol/L.

RESULTS

Measurements of contractile function (LVDP) and metabolism (lactate levels) were deemed concordant in 7 hearts with either a high LVDP (mean 100 mm Hg) with low lactate (mean 6.7 mmol/L)) or a low LVDP (15 mm Hg) with high lactate (mean 17.3 mmol/). In the remaining 5 hearts, measurements were deemed discordant: 4 hearts had high LVDP (mean 124 mm Hg), despite high lactate levels 17.3 mmol/L) and 1 had low LVDP (54 mm Hg) but low lactate (6.9 mmol/L).

CONCLUSIONS

The intraventricular balloon technique provides useful information regarding contractile recovery of donor hearts that if combined with lactate metabolism has potential application for the evaluation of DCD and marginal donation after brain death hearts before transplant.

Heart Donation From Donors After Controlled Circulatory Death

The gold-standard therapy for advanced-stage heart failure is cardiac transplantation. Since the first heart transplant in 1967, the majority of hearts transplanted came from brain death donors. Nevertheless, in recent years, the option of donation after circulatory death (DCD) is gaining importance to increase donor pool. Currently, heart-transplant programs using controlled donation after circulatory death (cDCD) have been implemented in the United Kingdom, Belgium, Australia, United States of America, and, recently, in Spain. In this article, we performed a concise review of the literature in heart cDCD; we summarize the pathophysiology involved in ischemia and reperfusion injury during this process, the different techniques of heart retrieval in cDCD donors, and the strategies that can be used to minimize the damage during retrieval and until transplantation. Heart transplant using DCD hearts is in continuous improvement and must be implemented in experienced cardiac transplant centers.

Ex Situ Perfusion of Hearts Donated After Euthanasia: A Promising Contribution to Heart Transplantation

Organ donation after euthanasia is performed in an increasing number of countries. In this donation after circulatory death procedure, it has not been possible to donate the heart. Recent literature, however, reports positive results of heart donation after circulatory death. Therefore, patients who donate organs following euthanasia might be suitable candidates for heart donation. We want to confirm this assumption by sharing the results of 2 cases of heart donation following euthanasia with ex situ subnormothermic heart preservation. Our aim is to raise awareness of the potential of heart donation following euthanasia for both clinical transplantation and research.

Methods

The data of 2 consecutive heart donations following euthanasia were collected prospectively. Informed consent was obtained from the patients themselves for heart donation for research purposes. An acellular oxygenated subnormothermic machine perfusion strategy was used to preserve both donor hearts. Subsequently, the hearts were evaluated on a normothermic perfusion machine using a balloon in the left ventricle.

Results

Heart donation following euthanasia was feasible without significant changes in existing retrieval protocols. Duration of machine perfusion preservation was 408 and 432 minutes, for heart 1 and 2, respectively. For heart 1, developed pressure (P_dev) was 119 mm Hg, maximal rate of pressure rise (dP/dt_max), and fall (dP/dt_min) were 1524 mm Hg/s and -1057 mm Hg/s, respectively. For heart 2, P_dev was 142 mm Hg, dP/dt_max was 1098 mm Hg/s, and dP/dt_min was -802 mm Hg/s.

Conclusions

Hearts donated following euthanasia are highly valuable for research purposes and can have sufficient quality to be transplanted. With the implementation of ex situ heart perfusion, patients who are to donate their organs following euthanasia should also be able to donate their hearts. The complex combination of euthanasia and heart donation is ethically sound and surgically feasible and can contribute to shortening the heart transplant waiting list.

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

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

Ischemia and reperfusion injury to mitochondria and cardiac function in donation after circulatory death hearts- an experimental study

The ultimate treatment for patients with end-stage heart failure is heart transplantation. The number of donor hearts which are primarily procured from donation after brain death (DBD) donors is limited, but donation after circulatory death (DCD) donor hearts can increase the heart donor pool. However, ischemia and reperfusion injuries associated with the DCD process causes myocardial damage, limiting the use of DCD hearts in transplantation. Addressing this problem is critical in the exploration of DCD hearts as suitable donor hearts for transplantation. In this study, rat hearts were procured following the control beating-heart donor (CBD) or DCD donation process. Changes in mitochondria and cardiac function from DCD hearts subjected to 25 or 35 minutes of ischemia followed by 60 minutes of reperfusion were compared to CBD hearts. Following ischemia, rates of oxidative phosphorylation and calcium retention capacity were progressively impaired in DCD hearts compared to CBD hearts. Reperfusion caused additional mitochondrial dysfunction in DCD hearts. Developed pressure, inotropy and lusitropy, were significantly reduced in DCD hearts compared to CBD hearts. We, therefore, suggest that interventional strategies targeted before the onset of ischemia and at reperfusion could protect mitochondria, thus potentially making DCD hearts suitable for heart transplantation.

Assessment of the right ventricle in donation after circulatory death hearts

In donation after circulatory death heart transplantation, the donor heart is exposed to circulatory load. The right ventricle, due to its structure, has high compliance for volume load but is particularly vulnerable to increased pressure load. This study used a porcine model to conduct a functional assessment of the hemodynamics of the heart, with a focus on the right ventricle. Six pigs weighing 24.6 ± 1.4 kg were used. Circulatory death was induced by asphyxiation after median sternotomy. After 30 minutes in the state of global warm ischemia, the ascending aorta was clamped, followed by a 20-minute reperfusion of the heart with a 20°C blood cardioplegia solution. Systemic circulation was established by cardiopulmonary bypass after aortic cross-clamping. After initial reperfusion, the blood cardioplegia solution was replaced with blood. The blood was then rewarmed while the heart was still in a non-working state. Cardiac function was assessed twice in situ, first by the thermodilution method, and then, by the pressure-volume measurement both at preischemia and at three hours after initiation of reperfusion. The recovery rate of cardiac output was 75%. End-systolic elastance (P = .02) and pulmonary arterial elastance significantly increased (P = .03), but the ratio of arterial elastance to end-systolic elastance was preserved (P = .91) in the right ventricle. Despite a decrease in cardiac output after reperfusion from warm ischemia, the right ventricle had a potential to respond the elevated afterload. It is important that donations after circulatory death heart transplantation should be performed with attention to avoiding right ventricular distension.

A 5-year single-center early experience of heart transplantation from donation after circulatory-determined death donors

BACKGROUND

In an effort to address the increasing demand for heart transplantation within the United Kingdom (UK), we established a clinical program of heart transplantation from donation after circulatory-determined death (DCD) donors in 2015. After 5 years, we report the clinical early outcomes and impact of the program.

METHODS

This is a single-center, retrospective, matched, observational cohort study comparing outcomes of hearts transplanted from DCD donors from March 1, 2015 to February 29, 2020 with those from matched donation after brain death (DBD) donors at Royal Papworth Hospital (RPH) (Cambridge, UK). DCD hearts were either retrieved using thoracoabdominal normothermic regional perfusion or the direct procurement and perfusion technique. All DBD hearts were procured using standard cold static storage. The primary outcomes were recipient 30-day and 1-year survival.

RESULTS

During the 5-year study, DCD heart donation increased overall heart transplant activity by 48% (79 for DCD and 164 for DBD). There was no difference in survival at 30 days (97% for DCD vs 99% for DBD, p = 1.00) or 1 year (91% for DCD vs 89% for DBD, p = 0.72). There was no difference in the length of stay in the intensive care unit (7 for DCD vs 6 for DBD days, p = 0.24) or in the hospital (24 for DCD vs 25 for DBD days, p = 0.84).

CONCLUSIONS

DCD heart donation increased overall heart transplant activity at RPH by 48%, with no difference in 30-day or 1-year survival in comparison with conventional DBD heart transplantations. DCD heart donation is set to make a dramatic difference in the number of patients who can benefit from heart transplantation.

Heart transplantation from donation after circulatory death donors: Present and future

The first successful human heart transplantation was reported on 3 December 1967, by Christiaan Barnard in South Africa. Since then this life-saving procedure has been performed in over 120 000 patients. A limitation to the performance of this procedure is the availability of donor hearts with as many as 20% of patients dying before a donor's heart is available for transplant. Today, hearts for transplantation are procured from individuals experiencing donation after brain death (DBD). Interestingly, this, however, was not always the case as the first heart transplants occurred after circulatory death. Revisiting the availability of hearts for transplant from those experiencing donation after circulatory death (DCD) could further expand the number of hearts suitable for transplantation. There are several considerations pertinent to transplanting hearts from those undergoing circulatory death. In this review, we summarize the main distinctions between DBD and DCD heart donation and discuss the research relevant to increasing the number of hearts available for transplantation by including individual's hearts that experience circulatory death.

Flow-targeted pediatric ex vivo heart perfusion in donation after circulatory death: A porcine model

BACKGROUND

The optimal blood flow and pressure to perfuse pediatric hearts from donation after circulatory death (DCD) on the ex vivo perfusion system has not been elucidated. This study sought to investigate the optimal perfusion strategy for pediatric DCD hearts by using a juvenile porcine model comparing pressure- vs flow-targeted strategy.

METHODS

The hearts of the juvenile DCD pigs were explanted, and the coronary arteries were perfused for 2 hours by the ex vivo heart perfusion system with 2 different perfusion strategies; pressure-targeted perfusion (target coronary perfusion pressure: 40 mm Hg, group A) and flow-targeted perfusion (target coronary perfusion flow: 10 ml/kg/min, group B). The working model heart perfusion was used to assess systolic and diastolic myocardial performance.

RESULTS

The body weight, warm and cold ischemic time, and ex vivo perfusion time were comparable between the groups. In the working model, group B showed significantly preserved cardiac output (A: 70.5 ± 15.3 ml/kg/min vs B: 113.8 ± 15.0 ml/kg/min, p < 0.01), stroke volume (A: 0.4 ± 0.1 ml/kg vs B: 0.7 ± 0.1 ml/kg, p < 0.01), and ejection fraction (A: 18.8% ± 5.9% vs B: 35.0% ± 10.6%, p < 0.01). E/e' and Tei index were also significantly preserved in group B. The percentage gain of heart weight after ex vivo (net increase of the heart weight divided by heart weight at baseline) was significantly smaller in group B (A: 20.0% ± 5.3% vs B: 11.6% ± 5.0%, p < 0.05). Troponin-I, myocardial hemorrhage, oxidative stress markers; myeloperoxidase and 8-hydroxy-2'-deoxyguanosine were also significantly lower after ex vivo perfusion in group B (p < 0.05).

CONCLUSIONS

The tightly controlled flow-targeted myocardial perfusion strategy for DCD donor hearts achieved better myocardial performance by causing less myocardial edema and limiting myocardial reperfusion injury.

Organ preservation: from the past to the future

Organ transplantation is the most effective therapy for patients with end-stage disease. Preservation solutions and techniques are crucial for donor organ quality, which is directly related to morbidity and survival after transplantation. Currently, static cold storage (SCS) is the standard method for organ preservation. However, preservation time with SCS is limited as prolonged cold storage increases the risk of early graft dysfunction that contributes to chronic complications. Furthermore, the growing demand for the use of marginal donor organs requires methods for organ assessment and repair. Machine perfusion has resurfaced and dominates current research on organ preservation. It is credited to its dynamic nature and physiological-like environment. The development of more sophisticated machine perfusion techniques and better perfusates may lead to organ repair/reconditioning. This review describes the history of organ preservation, summarizes the progresses that has been made to date, and discusses future directions for organ preservation.

Machine perfusion of thoracic organs

This article summarizes recent knowledge and clinical advances in machine perfusion (MP) of thoracic organs. MP of thoracic organs has gained much attention during the last decade. Clinical studies are investigating the role of MP to preserve, resuscitate, and assess heart and lungs prior to transplantation. Currently, MP of the cardiac allograft is essential in all type DCD heart transplantation while MP of the pulmonary allograft is mandatory in uncontrolled DCD lung transplantation. MP of thoracic organs also offers an exciting platform to further investigate downregulation of the innate and adaptive immunity prior to reperfusion of the allograft in recipients. MP provides a promising technology that allows pre-transplant preservation, resuscitation, assessment, repair, and conditioning of cardiac and pulmonary allografts outside the body in a near physiologic state prior to planned transplantation. Results of ongoing clinical trials are awaited to estimate the true clinical value of this new technology in advancing the field of heart and lung transplantation by increasing the total number and the quality of available organs and by further improving recipient early and long-term outcome.

Transplantation of Hearts Donated after Circulatory Death

Cardiac transplantation has become limited by a critical shortage of suitable organs from brain-dead donors. Reports describing the successful clinical transplantation of hearts donated after circulatory death (DCD) have recently emerged. Hearts from DCD donors suffer significant ischemic injury prior to organ procurement; therefore, the traditional approach to the transplantation of hearts from brain-dead donors is not applicable to the DCD context. Advances in our understanding of ischemic post-conditioning have facilitated the development of DCD heart resuscitation strategies that can be used to minimize ischemia-reperfusion injury at the time of organ procurement. The availability of a clinically approved ex situ heart perfusion device now allows DCD heart preservation in a normothermic beating state and minimizes exposure to incremental cold ischemia. This technology also facilitates assessments of organ viability to be undertaken prior to transplantation, thereby minimizing the risk of primary graft dysfunction. The application of a tailored approach to DCD heart transplantation that focuses on organ resuscitation at the time of procurement, ex situ preservation, and pre-transplant assessments of organ viability has facilitated the successful clinical application of DCD heart transplantation. The transplantation of hearts from DCD donors is now a clinical reality. Investigating ways to optimize the resuscitation, preservation, evaluation, and long-term outcomes is vital to ensure a broader application of DCD heart transplantation in the future.

Heart transplantation from donation after circulatory determined death

Fifty years since the first successful human heart transplant from a non-heart beating donor, this concept of heart transplantation from donation after circulatory determined death (DCD) promises to be one of the most exciting developments in heart transplantation. Heart transplantation has established itself as the best therapeutic option for patients with end-stage heart failure, with the opportunity to provide these patients with a near-normal quality of life. However, this treatment is severely limited by the availability of suitable donor hearts. In recent times, heart transplantation has been limited to using donor hearts from donors following brain stem death. The use of donor hearts from DCD had been thought to be associated with high risk and poor outcomes until recent developments in organ perfusion and retrieval techniques have shown that this valuable resource may provide an answer to the global shortage of suitable donor hearts. With established DCD heart transplant programmes reporting encouraging results, this technique has been shown to be comparable to the current gold standard of donation after brain death (DBD) heart transplantation.

Pathophysiological Trends During Withdrawal of Life Support: Implications for Organ Donation After Circulatory Death

BACKGROUND

Donation after circulatory death (DCD) provides an alternative pathway to deceased organ transplantation. Although clinical DCD lung, liver, and kidney transplantation are well established, transplantation of hearts retrieved from DCD donors has reached clinical translation only recently. Progress has been limited by concern regarding the viability of DCD hearts. The aim of this study was to document the pathophysiological changes that occur in the heart and circulation during withdrawal of life (WLS) support.

METHODS

In a porcine asphyxia model, we characterized the hemodynamic, volumetric, metabolic, biochemical, and endocrine changes after WLS for up to 40 minutes. Times to circulatory arrest and electrical asystole were recorded.

RESULTS

After WLS, there was rapid onset of profound hypoxemia resulting in acute pulmonary hypertension and right ventricular distension. Concurrently, progressive systemic hypotension occurred with a fall in left atrial pressure and little change in left ventricular volume. Mean times to circulatory arrest and electrical asystole were 8 ± 1 and 16 ± 2 minutes, respectively. Hemodynamic changes were accompanied by a rapid fall in pH, and rise in blood lactate, troponin-T, and potassium. Plasma noradrenaline and adrenaline levels rose rapidly with dramatic increases in coronary sinus levels indicative of myocardial release.

CONCLUSIONS

These findings provide insight into the nature and tempo of the damaging events that occur in the heart and in particular the right ventricle during WLS, and give an indication of the limited timeframe for the implementation of potential postmortem interventions that could be applied to improve organ viability.

In Vivo Post-Cardiac Arrest Myocardial Dysfunction Is Supported by Ca2+/Calmodulin-Dependent Protein Kinase II-Mediated Calcium Long-Term Potentiation and Mitigated by Alda-1, an Agonist of Aldehyde Dehydrogenase Type 2

BACKGROUND

Survival after sudden cardiac arrest is limited by postarrest myocardial dysfunction, but understanding of this phenomenon is constrained by a lack of data from a physiological model of disease. In this study, we established an in vivo model of cardiac arrest and resuscitation, characterized the biology of the associated myocardial dysfunction, and tested novel therapeutic strategies.

METHODS

We developed rodent models of in vivo postarrest myocardial dysfunction using extracorporeal membrane oxygenation resuscitation followed by invasive hemodynamics measurement. In postarrest isolated cardiomyocytes, we assessed mechanical load and Ca(2) (+)-induced Ca(2+) release (CICR) simultaneously using the microcarbon fiber technique and observed reduced function and myofilament calcium sensitivity. We used a novel fiberoptic catheter imaging system and a genetically encoded calcium sensor, GCaMP6f, to image CICR in vivo.

RESULTS

We found potentiation of CICR in isolated cells from this extracorporeal membrane oxygenation model and in cells isolated from an ischemia/reperfusion Langendorff model perfused with oxygenated blood from an arrested animal but not when reperfused in saline. We established that CICR potentiation begins in vivo. The augmented CICR observed after arrest was mediated by the activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Increased phosphorylation of CaMKII, phospholamban, and ryanodine receptor 2 was detected in the postarrest period. Exogenous adrenergic activation in vivo recapitulated Ca(2+) potentiation but was associated with lesser CaMKII activation. Because oxidative stress and aldehydic adduct formation were high after arrest, we tested a small-molecule activator of aldehyde dehydrogenase type 2, Alda-1, which reduced oxidative stress, restored calcium and CaMKII homeostasis, and improved cardiac function and postarrest outcome in vivo.

CONCLUSIONS

Cardiac arrest and reperfusion lead to CaMKII activation and calcium long-term potentiation, which support cardiomyocyte contractility in the face of impaired postarrest myofilament calcium sensitivity. Alda-1 mitigates these effects, normalizes calcium cycling, and improves outcome.

Functional assessment and transplantation of the donor heart after circulatory death

BACKGROUND

After a severe shortage of brain-dead donors, the demand for heart transplantation has never been greater. In an attempt to increase organ supply, abdominal and lung transplant programs have turned to the donation after circulatory-determined death (DCD) donor. However, because heart function cannot be assessed after circulatory death, DCD heart transplantation was deemed high risk and never adopted routinely. We report a novel method of functional assessment of the DCD heart resulting in a successful clinical program.

METHODS

Normothermic regional perfusion (NRP) was used to restore function to the arrested DCD heart within the donor after exclusion of the cerebral circulation. After weaning from support, DCD hearts underwent functional assessment with cardiac-output studies, echocardiography, and pressure-volume loops. In the feasibility phase, hearts were transported perfused before evaluation of function in modified working mode extracorporeally. After the establishment of a reliable assessment technique, hearts with demonstrable good function were then selected for clinical transplantation.

RESULTS

NRP was instituted in 13 adult DCD donors, median age of 33 years (interquartile range [IQR], 28-38 years), after a median ischemic time from withdrawal to perfusion of 24 minutes (IQR, 21-29; range, 17-146 minutes). Two of 4 hearts in the feasibility phase were unsuitable for transplantation after functional assessment. Nine DCD hearts were transplanted in the clinical phase, with 100% survival. The median intensive care duration was 5 days (IQR, 4-5 days), with 2 patients requiring mechanical support. There were no episodes of rejection (total, 1,436 patient-days; range, 48-297). During the same period, we performed 20 standard heart transplants using brain-dead donors.

CONCLUSIONS

NRP allows rapid reperfusion and functional assessment of the DCD donor heart, ensuring only viable hearts are selected for transplantation. This technique minimizes the risk of primary graft dysfunction and maximizes confidence in DCD heart transplantation, realizing a 45% increase in our heart transplant activity.

Targeting the Innate Immune Response to Improve Cardiac Graft Recovery after Heart Transplantation: Implications for the Donation after Cardiac Death

Heart transplantation (HTx) is the ultimate treatment for end-stage heart failure. The number of patients on waiting lists for heart transplants, however, is much higher than the number of available organs. The shortage of donor hearts is a serious concern since the population affected by heart failure is constantly increasing. Furthermore, the long-term success of HTx poses some challenges despite the improvement in the management of the short-term complications and in the methods to limit graft rejection. Myocardial injury occurs during transplantation. Injury initiated in the donor as result of brain or cardiac death is exacerbated by organ procurement and storage, and is ultimately amplified by reperfusion injury at the time of transplantation. The innate immune system is a mechanism of first-line defense against pathogens and cell injury. Innate immunity is activated during myocardial injury and produces deleterious effects on the heart structure and function. Here, we briefly discuss the role of the innate immunity in the initiation of myocardial injury, with particular focus on the Toll-like receptors and inflammasome, and how to potentially expand the donor population by targeting the innate immune response.

Physiologic Changes in the Heart Following Cessation of Mechanical Ventilation in a Porcine Model of Donation After Circulatory Death: Implications for Cardiac Transplantation

Hearts donated following circulatory death (DCD) may represent an additional source of organs for transplantation; however, the impact of donor extubation on the DCD heart has not been well characterized. We sought to describe the physiologic changes that occur following withdrawal of life-sustaining therapy (WLST) in a porcine model of DCD. Physiologic changes were monitored continuously for 20 min following WLST. Ventricular pressure, volume, and function were recorded using a conductance catheter placed into the right (N = 8) and left (N = 8) ventricles, and using magnetic resonance imaging (MRI, N = 3). Hypoxic pulmonary vasoconstriction occurred following WLST, and was associated with distension of the right ventricle (RV) and reduced cardiac output. A 120-fold increase in epinephrine was subsequently observed that produced a transient hyperdynamic phase; however, progressive RV distension developed during this time. Circulatory arrest occurred 7.6±0.3 min following WLST, at which time MRI demonstrated an 18±7% increase in RV volume and a 12±9% decrease in left ventricular volume compared to baseline. We conclude that hypoxic pulmonary vasoconstriction and a profound catecholamine surge occur following WLST that result in distension of the RV. These changes have important implications on the resuscitation, preservation, and evaluation of DCD hearts prior to transplantation.

Successful ECMO-cardiopulmonary resuscitation with the associated post-arrest cardiac dysfunction as demonstrated by MRI

Background

Veno-arterial extracorporeal membrane oxygenation (ECMO-CPR) is a life-saving rescue for selected patients when standard cardiopulmonary resuscitation fails. The use is increasing although the treatment modality is not fully established. Resuscitated patients typically develop a detrimental early post-arrest cardiac dysfunction that also deserves main emphasis. The present study investigates an ECMO-CPR strategy in pigs and assesses early post-arrest left ventricular function in detail. We hypothesised that a significant dysfunction could be demonstrated with this model using magnetic resonance imaging (MRI), not previously used early post-arrest.

Methods

In eight anaesthetised pigs, a 15-min ventricular fibrillation was resuscitated by an ECMO-CPR strategy of 150-min veno-arterial ECMO aiming at high blood flow rate and pharmacologically sustained aortic blood pressure and pulse pressure of 50 and 15 mmHg, respectively. Pre-arrest cardiac MRI and haemodynamic measurements of left ventricular function were compared to measurements performed 300-min post-arrest.

Results

All animals were successfully resuscitated, weaned from the ECMO circuit, and haemodynamically stabilised post-arrest. Cardiac output was maintained by an increased heart rate post-arrest, but left ventricular ejection fraction and stroke volume were decreased by approximately 50 %. Systolic circumferential strain and mitral annular plane systolic excursion as well as the left ventricular wall thickening were reduced by approximately 50–70 % post-arrest. The diastolic function variables measured were unchanged.

Conclusions

The present animal study demonstrates a successful ECMO-CPR strategy resuscitating long-lasting cardiac arrest with adequate post-arrest haemodynamic stability. The associated severe systolic left ventricular dysfunction could be charted in detail by MRI, a valuable tool for future cardiac outcome assessments in resuscitation research.

Trial registration

Institutional protocol number: FOTS 4611/13.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-015-0061-2) contains supplementary material, which is available to authorized users.

Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death: a case series

BACKGROUND

Orthotopic heart transplantation is the gold-standard long-term treatment for medically refractive end-stage heart failure. However, suitable cardiac donors are scarce. Although donation after circulatory death has been used for kidney, liver, and lung transplantation, it is not used for heart transplantation. We report a case series of heart transplantations from donors after circulatory death.

METHODS

The recipients were patients at St Vincent's Hospital, Sydney, Australia. They received Maastricht category III controlled hearts donated after circulatory death from people younger than 40 years and with a maximum warm ischaemic time of 30 min. We retrieved four hearts through initial myocardial protection with supplemented cardioplegia and transferred to an Organ Care System (Transmedics) for preservation, resuscitation, and transportation to the recipient hospital.

FINDINGS

Three recipients (two men, one woman; mean age 52 years) with low transpulmonary gradients (<8 mm Hg) and without previous cardiac surgery received the transplants. Donor heart warm ischaemic times were 28 min, 25 min, and 22 min, with ex-vivo Organ Care System perfusion times of 257 min, 260 min, and 245 min. Arteriovenous lactate values at the start of perfusion were 8·3-8·1 mmol/L for patient 1, 6·79-6·48 mmol/L for patient 2, and 7·6-7·4 mmol/L for patient 3. End of perfusion lactate values were 3·6-3·6 mmol/L, 2·8-2·3 mmol/L, and 2·69-2·54 mmol/L, respectively, showing favourable lactate uptake. Two patients needed temporary mechanical support. All three recipients had normal cardiac function within a week of transplantation and are making a good recovery at 176, 91, and 77 days after transplantation.

INTERPRETATION

Strict limitations on donor eligibility, optimised myocardial protection, and use of a portable ex-vivo organ perfusion platform can enable successful, distantly procured orthotopic transplantation of hearts donated after circulatory death.

FUNDING

NHMRC, John T Reid Charitable Trust, EVOS Trust Fund, Harry Windsor Trust Fund.

Increasing the tolerance of DCD hearts to warm ischemia by pharmacological postconditioning

Donation after circulatory death (DCD) offers a potential additional source of cardiac allografts. We used a porcine asphyxia model to evaluate viability of DCD hearts subjected to warm ischemic times (WIT) of 20–40 min prior to flushing with Celsior (C) solution. We then assessed potential benefits of supplementing C with erythropoietin, glyceryl trinitrate and zoniporide (Cs), a combination that we have shown previously to activate ischemic postconditioning pathways. Hearts flushed with C/Cs were assessed for functional, biochemical and metabolic recovery on an ex vivo working heart apparatus. Hearts exposed to 20-min WIT showed full recovery of functional and metabolic profiles compared with control hearts (no WIT). Hearts subjected to 30- or 40-min WIT prior to C solution showed partial and no recovery, respectively. Hearts exposed to 30-min WIT and Cs solution displayed complete recovery, while hearts exposed to 40-min WIT and Cs solution demonstrated partial recovery. We conclude that DCD hearts flushed with C solution demonstrate complete recovery up to 20-min WIT after which there is rapid loss of viability. Cs extends the limit of WIT tolerability to 30 min. DCD hearts with ≤30-min WIT may be suitable for transplantation and warrant assessment in a transplant model.

Normothermic donor heart perfusion: current clinical experience and the future

Following the first successful heart transplant in 1967, more than 100,000 heart transplants have been carried out worldwide. These procedures have mostly relied on cold ischaemic preservation of the donor heart because this simple technique is inexpensive and relatively reliable. However, the well-known limitations of cold ischaemic preservation imposes significant logistical challenges to heart transplantation which put a ceiling on the immediate success on this life-saving therapy, and limits the number of donor hearts that can be safely transplanted annually. Although the theoretical advantages of normothermic donor heart perfusion have been recognised for over a century, the technology to transport donor hearts in this state has only been developed within the last decade. The Organ Care System (OCS) which is designed and manufactured by TransMedics Inc. is currently the only commercially available device with this capability. This article reviews the history of normothermic heart perfusion and the clinical experience with the TransMedics OCS to date. We have also attempted to speculate on the future possibilities of this innovative and exciting technology.

Recovery of donor hearts after circulatory death with normothermic extracorporeal machine perfusion

OBJECTIVES

A severe donor organ shortage leads to the death of a substantial number of patients who are listed for transplantation. The use of hearts from donors after circulatory death could significantly expand the donor organ pool, but due to concerns about their viability, these are currently not used for transplantation. We propose short-term ex vivo normothermic machine perfusion (MP) to improve the viability of these ischaemic donor hearts.

METHODS

Hearts from male Lewis rats were subjected to 25 min of global in situ warm ischaemia (WI) (37°C), explanted, reconditioned for 60 min with normothermic (37°C) MP with diluted autologous blood and then stored for 4 h at 0-4°C in Custodiol cold preservation solution. Fresh and ischaemic hearts stored for 4 h in Custodiol were used as controls. Graft function was assessed in a blood-perfused Langendorff circuit.

RESULTS

During reconditioning, both the electrical activity and contractility of the ischaemic hearts recovered rapidly. Throughout the Langendorff reperfusion, the reconditioned ischaemic hearts had a higher average heart rate and better contractility compared with untreated ischaemic controls. Moreover, the reconditioned ischaemic hearts had higher tissue adenosine triphosphate levels and a trend towards improved tissue redox state. Perfusate levels of troponin T, creatine kinase and lactate dehydrogenase were not significantly lower than those of untreated ischaemic controls. The micro- and macroscopic appearance of the reconditioned ischaemic hearts were improved compared with ischaemic controls, but in both groups myocardial damage and oedema were evident.

CONCLUSIONS

Our results indicate that functional recovery from global WI is possible during short-term ex vivo reperfusion, allowing subsequent cold storage without compromising organ viability. We expect that once refined and validated, this approach may enable safe transplantation of hearts obtained from donation after circulatory death.

A cardioprotective preservation strategy employing ex vivo heart perfusion facilitates successful transplant of donor hearts after cardiocirculatory death

BACKGROUND

Ex vivo heart perfusion (EVHP) has been proposed as a means to facilitate the resuscitation of donor hearts after cardiocirculatory death (DCD) and increase the donor pool. However, the current approach to clinical EVHP may exacerbate myocardial injury and impair function after transplant. Therefore, we sought to determine if a cardioprotective EVHP strategy that eliminates myocardial exposure to hypothermic hyperkalemia cardioplegia and minimizes cold ischemia could facilitate successful DCD heart transplantation.

METHODS

Anesthetized pigs sustained a hypoxic cardiac arrest and a 15-minute warm ischemic standoff period. Strategy 1 hearts (S1, n = 9) underwent initial reperfusion with a cold hyperkalemic cardioplegia, normothermic EVHP, and transplantation after a cold hyperkalemic cardioplegic arrest (current EVHP strategy). Strategy 2 hearts (S2, n = 8) underwent initial reperfusion with a tepid adenosine-lidocaine cardioplegia, normothermic EVHP, and transplantation with continuous myocardial perfusion (cardioprotective EVHP strategy).

RESULTS

At completion of EVHP, S2 hearts exhibited less weight gain (9.7 ± 6.7 [S2] vs 21.2 ± 6.7 [S1] g/hour, p = 0.008) and less troponin-I release into the coronary sinus effluent (4.2 ± 1.3 [S2] vs 6.3 ± 1.5 [S1] ng/ml; p = 0.014). Mass spectrometry analysis of oxidized pleural in post-transplant myocardium revealed less oxidative stress in S2 hearts. At 30 minutes after wean from cardiopulmonary bypass, post-transplant systolic (pre-load recruitable stroke work: 33.5 ± 1.3 [S2] vs 19.7 ± 10.9 [S1], p = 0.043) and diastolic (isovolumic relaxation constant: 42.9 ± 6.7 [S2] vs 65.2 ± 21.1 [S1], p = 0.020) function were superior in S2 hearts.

CONCLUSION

In this experimental model of DCD, an EVHP strategy using initial reperfusion with a tepid adenosine-lidocaine cardioplegia and continuous myocardial perfusion minimizes myocardial injury and improves short-term post-transplant function compared with the current EVHP strategy using cold hyperkalemic cardioplegia before organ procurement and transplantation.