The Effect of Cardiac Preservation Solutions on Heart Transplant Survival

Comparison of HTK-Custodiol and St-Thomas solution as cardiac preservation solutions on early and midterm outcomes following heart transplantation

OBJECTIVES

The choice of the cardiac preservation solution for myocardial protection at time of heart procurement remains controversial and uncertainties persist regarding its effect on the early and midterm heart transplantation (HTx) outcomes. We retrospectively compared our adult HTx performed with 2 different solutions, in terms of hospital mortality, mid-term survival, inotropic score, primary graft dysfunction and rejection score.

METHODS

From January 2009 to December 2020, 154 consecutive HTx of adult patients, followed up in pre- and post-transplantation by 2 different tertiary centres, were performed at the University Hospital of Lausanne, Switzerland. From 2009 to 2015, the cardiac preservation solution used was exclusively St-Thomas, whereafter an institutional decision was made to use HTK-Custodiol only. Patients were classified in 2 groups accordingly.

RESULTS

There were 75 patients in the St-Thomas group and 79 patients in the HTK-Custodiol group. The 2 groups were comparable in terms of preoperative and intraoperative characteristics. Postoperatively, compared to the St-Thomas group, the Custodiol group patients showed significantly lower inotropic scores [median (interquartile range): 35.7 (17.5-60.2) vs 71.8 (31.8-127), P < 0.001], rejection scores [0.08 (0.0-0.25) vs 0.14 (0.05-0.5), P = 0.036] and 30-day mortality rate (2.5% vs 14.7%, P = 0.007) even after adjusting for potential confounders. Microscopic analysis of the endomyocardial biopsies also showed less specific histological features of subendothelial ischaemia (3.8% vs 17.3%, P = 0.006). There was no difference in primary graft dysfunction requiring postoperative extracorporeal membrane oxygenation. The use of HTK-Custodiol solution significantly improved midterm survival (Custodiol versus St-Thomas: hazard ratio = 0.20, 95% confidence interval: 0.069-0.60, P = 0.004).

CONCLUSIONS

This retrospective study comparing St-Thomas solution and HTK-Custodiol as myocardial protection during heart procurement showed that Custodiol improves outcomes after HTx, including postoperative inotropic score, rejection score, 30-day mortality and midterm survival.

Association of cardiac preservation solution with short-term outcomes after heart transplantation

AIMS

There is wide variability in the practice of cardiac preservation for heart transplantation. Prior reports suggest that the type of solution may be linked with a reduced incidence of posttransplantation complications.

METHODS

Adult (≥18 years old) heart recipients who underwent transplantation between 2015 and 2021 in the United States were examined. Recipients were stratified by solution utilized for their grafts at the time of recovery: University of Wisconsin, histidine-tryptophan-ketoglutarate (HTK), or Celsior solution. The primary endpoint was a composite of 30-day mortality, primary graft dysfunction, or re-transplantation. Risk adjustment was performed for the recipient, donor, and procedural characteristics using regression modeling.

RESULTS

Among 16 884 recipients, the group distribution was University of Wisconsin solution 53%, HTK 22%, Celsior solution 15%, and other 10%. The observed incidence of the composite endpoint (University of Wisconsin solution = 3.6%, HTK = 4.0%, Celsior solution = 3.7%, P = 0.301) and 1-year survival (University of Wisconsin solution = 91.7%, HTK = 91.3%, Celsior solution = 91.7%, log-rank P = 0.777) were similar between groups. After adjustment, HTK was associated with a higher risk of the composite endpoint [odds ratio (OR) 1.249, 95% confidence interval (CI) 1.019-1.525, P = 0.030] in reference to University of Wisconsin solution. This association was substantially increased among recipients with ischemic periods of greater than 4 h (OR 1.817, 95% CI 1.188-2.730, P = 0.005). The risks were similar between University of Wisconsin solution and Celsior solution (P = 0.454).

CONCLUSION

The use of the histidine-tryptophan-ketoglutarate solution during cold static storage for cardiac preservation is associated with increased rates of early mortality or primary graft dysfunction. Clinician discretion should guide its use, especially when prolonged ischemic times (>4 h) are anticipated.

Nucleotide metabolism during experimental preservation for transplantation with Transmedium Transplant Fluid (TTF) in comparison to Histidine-Tryptophan-Ketoglutarate (HTK)

Organ preservation solutions are essential to diminish ischemic/hypoxic injury during cold storage and to improve graft survival. In our experiments, we investigated novel solutions that target such mechanisms as Transmedium Transplant Fluid (TTF) in comparison to PlegiStore solution (HTK). Rat hearts were infused with TTF or HTK and then subjected to 4 hours of 4 °C preservation followed by 25 minutes of reperfusion in the Langendorff system. Assessment of purine release from the heart, mechanical function, and cardiac nucleotide content in the heart homogenates was done. A significant increase in the uric acid, hypoxanthine, inosine, and total purine metabolite concentrations were observed in the HTK hearts when compared to TTF. The TTF group had lower left ventricular systolic pressure and left ventricular end-diastolic pressure when compared to the HTK. Left ventricular diastolic pressure, minimal dp/dt, and maximal dp/dt in both groups were similar. The concentration of ADP in the heart homogenates of the HTK group was increased when compared to the TTF group. ATP and GTP concentration showed a tendency to increase in the homogenates of TTF hearts when NAD, AMP, GDP, GMP, and ADPR were similar in both groups of rats. TTF provided enhanced cardioprotection as evidenced by inhibiting the purine nucleotide metabolites released from the rat hearts during reperfusion and enhanced systolic and diastolic mechanical function recovery. In particular, better preservation of GTP and ATP concentrations may translate into enhanced protection of endothelium and the cytoskeleton, which are not adequately protected with current preservation techniques.

Improvement of Left Ventricular Graft Function Using an Iron-Chelator-Supplemented Bretschneider Solution in a Canine Model of Orthotopic Heart Transplantation

Demand for organs is increasing while the number of donors remains constant. Nevertheless, not all organs are utilized due to the limited time window for heart transplantation (HTX). Therefore, we aimed to evaluate whether an iron-chelator-supplemented Bretschneider solution could protect the graft in a clinically relevant canine model of HTX with prolonged ischemic storage. HTX was performed in foxhounds. The ischemic time was standardized to 4 h, 8 h, 12 h or 16 h, depending on the experimental group. Left ventricular (LV) and vascular function were measured. Additionally, the myocardial high energy phosphate and iron content and the in-vitro myocyte force were evaluated. Iron chelator supplementation proved superior at a routine preservation time of 4 h, as well as for prolonged times of 8 h and longer. The supplementation groups recovered quickly compared to their controls. The LV function was preserved and coronary blood flow increased. This was also confirmed by in vitro myocyte force and vasorelaxation experiments. Additionally, the biochemical results showed significantly higher adenosine triphosphate content in the supplementation groups. The iron chelator LK614 played an important role in this mechanism by reducing the chelatable iron content. This study shows that an iron-chelator-supplemented Bretschneider solution effectively prevents myocardial/endothelial damage during short- as well as long-term conservation.

Long-term effects of primary graft dysfunction after heart transplantation

BACKGROUND

We studied the incidence of primary graft dysfunction (PGD), its impact on in-hospital and follow-up outcomes and searched for independent risk factors.

METHODS

During an 18-year period, 508 individuals underwent heart transplantation at our institution. Patients were diagnosed with none, mild, moderate or severe PGD according to ISHLT criteria.

RESULTS

Thirty-eight patients (7.5%) met the ISHLT criteria for mild PGD, 92 (18.1%) for moderate PGD and 23 (4.5%) for severe PGD. Patients were classified into none/mild PGD (77.4%) and moderate/severe PGD (22.6%) groups. In-hospital mortality was 12.4% (7.8% for none/mild PGD and 28.7% for moderate/severe PGD; p < .001). Survival at 1, 5, and 15 years was 85.5 ± 1.9% versus 67.2 ± 4.5%, 80 ± 2.2% versus 63.5 ± 4.7%, and 60.4 ± 3.6% versus 45.9 ± 8.4%, respectively (p < .001). Excluding the events occurring during the first month of follow-up, survival was comparable between the two groups (93.1 ± 1.4% vs. 94.7 ± 2.6 at 1 year and 65.6 ± 3.8% vs. 70.4 ± 10.4% at 15 years, respectively; p = .88). Upon multivariate logistic regression analysis preoperative mechanical circulatory support (odds ratio [OR] = 5.86) and preoperative intra-aortic balloon pump (IABP) (OR = 9.58) were independently associated with moderate/severe PGD.

CONCLUSIONS

Our results confirm that PGD is associated with poor in-hospital outcome. The poor outcome does not extend beyond the first month of follow-up, with comparable survival between patients with none/mild PGD and moderate/severe PGD in the short and long-term. Mechanical circulatory support and preoperative IABP were found to be independent risk factors for moderate/severe PGD.

A Roadmap to Cardiac Tissue-Engineered Construct Preservation: Insights from Cells, Tissues, and Organs

Worldwide, over 26 million patients suffer from heart failure (HF). One strategy aspiring to prevent or even to reverse HF is based on the transplantation of cardiac tissue-engineered (cTE) constructs. These patient-specific constructs aim to closely resemble the native myocardium and, upon implantation on the diseased tissue, support and restore cardiac function, thereby preventing the development of HF. However, cTE constructs off-the-shelf availability in the clinical arena critically depends on the development of efficient preservation methodologies. Short- and long-term preservation of cTE constructs would enable transportation and direct availability. Herein, currently available methods, from normothermic- to hypothermic- to cryopreservation, for the preservation of cardiomyocytes, whole-heart, and regenerative materials are reviewed. A theoretical foundation and recommendations for future research on developing cTE construct specific preservation methods are provided. Current research suggests that vitrification can be a promising procedure to ensure long-term cryopreservation of cTE constructs, despite the need of high doses of cytotoxic cryoprotective agents. Instead, short-term cTE construct preservation can be achieved at normothermic or hypothermic temperatures by administration of protective additives. With further tuning of these promising methods, it is anticipated that cTE construct therapy can be brought one step closer to the patient.

Does the solution used for cold static storage of hearts impact on heart transplant survival?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'For the [cold static storage of donor hearts] does the [cardiac preservation solution] impact on [heart transplant survival]?'. Altogether 182 papers were found using the reported search, of which 9 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. A wide variety of both custom and standardized cardiac preservation solutions are used for the procurement and cold static storage of donor hearts. In heart transplants with shorter cold ischaemic times, survival outcomes appear similar across many of the common cardiac preservation solutions in the long term. However, unspecified cardioplegia (with supraphysiological potassium concentration) is not supported as the final storage solution as it was associated with worse outcomes overall. In the short term, intracellular solutions (<70 mEq/l sodium; including University of Wisconsin solution) may also have better survival outcomes than extracellular solutions. Where extended ischaemic times (>4 h) are necessary or high-risk grafts obtained, the evidence supports University of Wisconsin as the preferred solution. We concluded that choice of cardiac preservation solution could impact both survival and secondary outcomes.

A state-of-the-art review of the current role of cardioprotective techniques in cardiac transplantation

OBJECTIVES

The use of 'extended criteria' donor hearts and reconditioned hearts from donation after circulatory death has corresponded with an increase in primary graft dysfunction, with ischaemia-reperfusion injury being a major contributing factor in its pathogenesis. Limiting ischaemia-reperfusion injury through optimising donor heart preservation may significantly improve outcomes. We sought to review the literature to evaluate the evidence for this.

METHODS

A review of the published literature was performed to assess the potential impact of organ preservation optimisation on cardiac transplantation outcomes.

RESULTS

Ischaemia-reperfusion injury is a major factor in myocardial injury during transplantation with multiple potential therapeutic targets. Innate survival pathways have been identified, which can be mimicked with pharmacological conditioning. Although incompletely understood, discoveries in this domain have yielded extremely encouraging results with one of the most exciting prospects being the synergistic effect of selected agents. Ex situ heart perfusion is an additional promising adjunct.

CONCLUSIONS

Cardiac transplantation presents a unique opportunity to perfuse the whole heart before, or immediately after, the onset of ischaemia, thus maximising the potential for global cardioprotection while limiting possible systemic side effects. While clinical translation in the setting of myocardial infarction has often been disappointing, cardiac transplantation may afford the opportunity for cardioprotection to finally deliver on its preclinical promise.

Primary Graft Dysfunction After Isolated Heart Transplantation - Incidence, Risk Factors, and Clinical Implications Based on a Single-Center Experience

BACKGROUND

Since the international consensus on primary graft dysfunction (PGD) following heart transplantation (HT) was reported in 2014, few clinical studies have been reported. We aimed to analyze the incidence, predictive factors, and clinical implications of PGD following the International Society of Heart and Lung Transplant criteria in a single center.Methods and Results:This study enrolled 570 consecutive adult patients undergoing isolated HT between November 1992 and December 2017. Under a new set of criteria, PGD-left ventricle (PGD-LV) occurred in 35 patients (6.1%; mild, n=1 [0.2%]; moderate, n=14 [2.5%]; severe, n=20 [3.5%]), whereas PGD-right ventricle (PGD-RV) occurred in 3 (0.5%). Multivariable analysis demonstrated that preoperative admission (odds ratio [OR] 4.20; 95% confidence interval [CI] 1.24-14.26; P=0.021), preoperative extracorporeal membrane oxygenation (OR 4.03; 95% CI 1.75-9.26; P=0.001), and prolonged total ischemic time (OR 1.09; 95% CI 1.02-1.15; P=0.006) were significant predictors of moderate to severe PGD-LV. Moderate to severe PGD-LV was an independent and significant risk factor for early death (OR 55.64; 95% CI 11.65-265.73; P<0.001), with its effects extending up to 3 months after HT.

CONCLUSIONS

Moderate to severe PGD-LV, as defined by the new guidelines, is an important predictor of early mortality, with effects extending up to 3 months after HT. Efforts to reduce the occurrence of moderate to severe PGD-LV may lead to better outcomes.

Peritransplant Cardiometabolic and Mitochondrial Function: The Missing Piece in Donor Heart Dysfunction and Graft Failure

Primary graft dysfunction is an important cause of morbidity and mortality after cardiac transplantation. Donor brain stem death (BSD) is a significant contributor to donor heart dysfunction and primary graft dysfunction. There remain substantial gaps in the mechanistic understanding of peritransplant cardiac dysfunction. One of these gaps is cardiac metabolism and metabolic function. The healthy heart is an "omnivore," capable of utilizing multiple sources of nutrients to fuel its enormous energetic demand. When this fails, metabolic inflexibility leads to myocardial dysfunction. Data have hinted at metabolic disturbance in the BSD donor and subsequent heart transplantation; however, there is limited evidence demonstrating specific metabolic or mitochondrial dysfunction. This review will examine the literature surrounding cardiometabolic and mitochondrial function in the BSD donor, organ preservation, and subsequent cardiac transplantation. A more comprehensive understanding of this subject may then help to identify important cardioprotective strategies to improve the number and quality of donor hearts.

Celsior® crystalloid cardioplegia versus standard hyperkalemic normothermic blood cardioplegia: Analysis of myocardial protection in elective mitral valve repair

INTRODUCTION

With the increase and refinement of video assisted mitral valve surgery, cristalloïd cardioplegia started regaining popularity. The aim of our study was to evaluate the effectiveness of Celsior^®, a crystalloid cardioplegic solution, on myocardial protection in elective surgical mitral valve repair in comparison to blood based hyperkalemic cardioplegia.

METHODS

In this observational retrospective study, all consecutive elective isolated surgical mitral valve repair where Celsior^® or normothermic hyperkalemic blood cardioplegia were used were included. Primary endpoint was any sign of myocardial protection failure (troponin levels, need for inotropic or mechanical support, rhythm disturbances, mortality). Secondary endpoint was Celsior^® safety (allergic reactions, bleeding, organ toxicities).

RESULTS

From January 2009 to August 2016, 382 patients underwent elective isolated mitral valve repair in whom normothermic hyperkalemic blood cardioplegia (n = 181) or Celsior^® (n = 201) were used. There were no statistically significant differences in baseline characteristics including Euroscore 2. Peak troponin (pg/ml) release and 30-days mortality were not statistically different. Need for cardioversion was significantly more frequent in the Celsior^® group (47% vs 13%, p < 0.001). There was no statistical difference in post-operative atrial fibrillation, permanent pacemaker implantation, reoperation for bleeding, transfusion, acute kidney injury, haemoglobin at discharge or length of stay. No allergic reaction to Celsior^® occurred.

CONCLUSION

Effective myocardial protection was achieved with the Celsior^® cardioplegic solution with no unexpected toxicity. Celsior^® may be an efficacious and safe cardioprotective strategy in mitral valve repair.

Does pediatric heart transplant survival differ with various cardiac preservation solutions?

BACKGROUND

Few studies directly compare outcomes between the most commonly used preservation solutions in pediatric heart transplantation in a large cohort of recipients. The purpose of this study is to investigate the effect of cardiac preservation solution on survival in pediatric heart transplant recipients.

METHODS

The United Network for Organ Sharing (UNOS) database was retrospectively reviewed from 01/2004-03/2018 for pediatric donor hearts. Saline, University of Wisconsin (UW), "cardioplegia," Celsior, and Custodiol preservation solutions were evaluated. The primary endpoints were recipient survival at 30 days, 1 year, and long term.

RESULTS

After exclusion criteria, 3012 recipients had preservation solution data available. The most common preservation solution used was UW in 1203 patients (40%), followed by Celsior in 542 (18%), cardioplegia in 461 (15%), saline in 408 (14%), and Custodiol in 398 (13%). Survival of recipients whose donor hearts were procured with UW was as follows: 97%-30 day, 92%-1 year; Celsior: 97%-30 day, 92%-1 year; cardioplegia: 97%-30 day, 91%-1 year; saline: 97%-30 day, 91%-1 year; and Custodiol: 96%-30 day and 92%-1 year. Analysis of Cox models for 30-day and long-term survival revealed no statistical differences when comparing UW to Celsior (p = .333), cardioplegia (p = .914), saline (p = .980), or Custodiol (p = .642) in adjusted models.

CONCLUSIONS

There were no significant differences in 30-day or 1-year survival detected between commonly used preservation solutions in the pediatric heart transplant population.