Donor Hearts Research Articles

Characterizing Adaptive Changes and Patient Survival After 2018 Donor Allocation Restructuring: A UNOS Database Analysis.

We sought to characterize adaptive changes to the revised United Network for Organ Sharing donor heart allocation policy and estimate long-term survival trends for heart transplant (HTx) recipients. Patients listed for HTx between October 17, 2013 and September 30, 2021 were identified from the United Network for Organ Sharing database, and stratified into pre- and postpolicy revision groups. Subanalyses were performed to examine trends in device utilization for extracorporeal membranous oxygenation (ECMO), durable left ventricular assist device (LVAD), intra-aortic balloon pump (IABP), microaxial support (Impella), and no mechanical circulatory support (non-MCS). Survival data post-HTx were fitted to parametric distributions and extrapolated to 5 years. We identified 27,523 HTx waitlist candidates during the study period, most of whom (n = 16,376) were waitlisted in the prepolicy change period. Overall, 19,554 patients underwent HTx during the study period (pre: 12,037 and post: 7517). Listings increased after the policy change for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients. Listings for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients decreased. HTx increased for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients after the policy change and decreased for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients. Waitlist survival increased for the overall ( P < 0.01), ECMO ( P < 0.01), IABP ( P < 0.01), and non-MCS ( P < 0.01) groups. Waitlist survival did not differ for the LVAD ( P = 0.8) and Impella ( P = 0.1) groups. Post-transplant survival decreased for the overall ( P < 0.01), LVAD ( P < 0.01), and non-MCS ( P < 0.01) populations. Allocation policy revisions have contributed to greater utilization of ECMO, Impella, and IABP, decreased utilization of LVADs and non-MCS, increased waitlist survival, and decreased post-HTx survival.

Exercise capacity and cardiac allograft ischemic time in recent heart transplant recipients

BackgroundProlonged ischemic times (IT) for transplant hearts transported under cold storage conditions are associated with an increased risk of mortality, however the impact of IT on functional outcomes, such as exercise capacity, is not fully understood. This prospective, observational cohort study aimed to determine the association between exercise capacity, a strong predictor for post-transplant survival, and relatively longer IT. MethodsThirty heart transplant recipients were grouped dichotomously according to relatively longer (>180 min) or shorter (≤180 min) IT. A cardiopulmonary exercise test (CPET) was performed post-transplant upon entry into cardiac rehabilitation, during which peak VO2 was measured using a metabolic cart. CPET variables, including exercise capacity and test duration, were compared between groups. ResultsThis cohort was predominantly male (n=22, 73%) with a median age of 57.5 years [Q1-Q3: 54.0 - 65.0]). Baseline demographics and characteristics were similar between groups aside from UNOS listing status, in which patients listed as Status 1 or 2 were more likely to have long IT. Twelve (40%) participants received a donor heart with long IT. Surprisingly, higher peak VO2 was observed in those with long (15.0±2.8) than short (13.1±3.7) IT (p=0.009). However, CPET duration was significantly shorter in recipients with a long IT (6.3 vs. 7.7 minutes, p=0.048) despite similar time since transplant, rate of perceived exertion, protocol performed, and exercise capacity. ConclusionsIn this modest-sized cohort, exercise capacity was higher in heart transplant recipients with donor IT >180 minutes compared to those with IT ≤180 minutes. However, exercise duration was significantly shorter in those with relatively longer IT.

Single-nucleus multi-omic profiling of polyploid heart nuclei identifies fusion-derived cardiomyocytes in the human heart.

Understanding the mechanisms of polyploidization in cardiomyocytes is crucial for advancing strategies to stimulate myocardial regeneration. Although endoreplication has long been considered the primary source of polyploid human cardiomyocytes, recent animal work suggests the potential for cardiomyocyte fusion. Moreover, the effects of polyploidization on the genomic-transcriptomic repertoire of human cardiomyocytes have not been studied previously. We applied single-nuclei whole genome sequencing, single nuclei RNA sequencing, and multiome ATAC + gene expression (from the same nuclei) techniques to nuclei isolated from 11 healthy hearts. Utilizing post-zygotic non-inherited somatic mutations occurring during development as "endogenous barcodes," to reconstruct lineage relationships of polyploid cardiomyocytes. Of 482 cardiomyocytes from multiple healthy donor hearts 75.7% can be sorted into several developmental clades marked by one or more somatic single-nucleotide variants (SNVs). At least ~10% of tetraploid cardiomyocytes contain cells from distinct clades, indicating fusion of lineally distinct cells, whereas 60% of higher-ploidy cardiomyocytes contain fused cells from distinct clades. Combined snRNA-seq and snATAC-seq revealed transcriptome and chromatin landscapes of polyploid cardiomyocytes distinct from diploid cardiomyocytes, and show some higher-ploidy cardiomyocytes with transcriptional signatures suggesting fusion between cardiomyocytes and endothelial and fibroblast cells. These observations provide the first evidence for cell and nuclear fusion of human cardiomyocytes, raising the possibility that cell fusion may contribute to developing or maintaining polyploid cardiomyocytes in the human heart.

Cryopreservation of human adult ventricular tissue for the preparation of viable myocardial slices

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): REGeRNA Myocardial slices are ultra-thin slices of living adult myocardium which can be cultured. As a multicellular 3-D culture model, myocardial slices offer a novel opportunity to investigate how adult cardiomyocytes (CMs) interact with other cardiac cell types and the extracellular matrix, while providing long-term preservation of CMs cytoarchitecture and electrical phenotype. Additionally, myocardial slices are a new tool in drug discovery by allowing to test chronic treatments, as opposed to isolated CMs which are limited to acute timepoints. Despite their benefits over other cardiac preparations, myocardial slices also have several limitations, of which one is the quality of the slices. The main determinant of myocardial slice quality is the procedure by which the cardiac tissue block is handled. Current methods depend on the preparation of slices directly after tissue excision, therefore limiting the moment when the experiment is performed. We developed a protocol for the cryopreservation of human adult ventricular tissue allowing preparation of viable myocardial slices afterwards. Fresh and cryopreserved cardiac tissue from donor hearts was processed and evaluated for viability, tissue integrity, and inflammatory markers using molecular biology and histological assays. The tissue samples retained viability, biomass, and tissue and vascular integrity following cryopreservation compared to fresh tissue. Additionally, we compared myocardial slices obtained from fresh or cryopreserved tissue and cultured for 24 hours. Histologically, normal cytomorphological features and gap junctions between CMs were preserved in all slices. Comparable retention of tissue viability and structural integrity post cryopreservation (4-6 weeks) and culture (up to 7 days) was observed in cardiac samples from 3 additional donors. In summary, cold storage extends the time-interval between sample collection and slice preparation, allowing for more long-term, complex endpoints. Moreover, efficient banking of cryopreserved cardiac samples from various donors and disease states is critical for regular use of myocardial tissue slices in drug discovery and development. Additional research on the effects of cryopreservation on different cardiac cell types will allow to improve donor organ management to extend the donor pool and increase utilization rate.

The smooth-walled human RVOT contains trabeculations that cause conduction delay

Abstract Funding Acknowledgements None. Background The right ventricular outflow tract (RVOT) is the outlet from the right ventricle and is the initiating substrate of life-threatening arrhythmias. While the luminal wall of the RVOT is often assumed to be without the complex trabecular meshwork that characterizes the right ventricular free wall, the anatomy of the RVOT is an understudied subject. Aim to investigate whether trabeculations occur in the RVOT and to assess whether this impacts electrical propagation. Methods Human hearts were investigated using high-resolution MRI, histology, RNA-sequencing, and optical and electrical mapping. Results We used high-resolution MRI and serial sectioning to reconstruct the macroscopic details of the human RVOT and identified cases exhibiting much trabeculation. The smooth lumen of the RVOT varied between 9% and 23% of the total RV anterior surface (N=11). Histological analysis on additional six hearts indicated that the RVOT compact layer is thinner when trabeculations are present. RNA sequencing of four human donor hearts revealed enrichment in the subendocardial region of 88 genes associated with cardiac conduction and trabeculations (P adjusted&amp;lt;0.05). Finally, we selected two human donor hearts showing trabeculations in the RVOT from which we generated wedge preparation and performed optical and electrical mapping. The trabecular regions demonstrated high degree of fractionation when compared to non-trabeculated regions, which coincided with delayed activation. Conclusion Trabeculations are found in the RVOT, and their extent varies among individuals. This impacts on the thickness of the compact wall in the RVOT, restricting the depth of tissue at which clinical interventions can be performed, as well as influencing electrical propagation and possible arrhythmogenicity.

Organ Donation by the Imminently Dead: Addressing the Organ Shortage and the Dead Donor Rule.

The dead donor rule (DDR) has facilitated the saving of hundreds of thousands of lives. Recent advances in heart donation, however, have exposed how DDR has limited donation of all organs. We propose advancing the moment in the dying process at which death can be determined to increase substantially the supply of organs for transplantation. We justify this approach by identifying certain flaws in the Uniform Determination of Death Act and proposing a modification of that law that permits earlier procurement of healthier organs in greater numbers.

Introduction of ex vivo perfusion of extended-criteria donor hearts in a single center in Asia.

The shortage of organs for heart transplantation has created a need to explore the use of extended-criteria organs. We report the preliminary use of normothermic TransMedics Organ Care System-an ex vivo approach to preserve extended-criteria brain-dead donor hearts. This System maintains a normal temperature, provides continuous perfusion and oxygenation, reduces ischemic time, and enables additional viability assessment options. In a retrospective single-centre study conducted from April 2020 to March 2023, four extended criteria brain-dead donor hearts were perfused and monitored using the Organ Care System. Suitability for transplantation was assessed based on stable or decreasing lactate levels, along with appropriate perfusion parameters. The Organ Care for use of the Organ Care System were coronary artery disease, left ventricular hypertrophy, high-dose inotrope use in the donor, a downtime exceeding 20min, and a left ventricular ejection fraction of 40-50%. Three out of the four donor hearts were transplanted, while one was discarded due to rising lactate concentration. The three recipients had a higher surgical risk profile for heart transplant. All showed normal cardiac function and no primary graft dysfunction postoperatively. At 2-3years post-transplant, all recipients have a ventricular function of > 60%, with only one showing evidence of mild rejection. The Organ Care System enables the successful transplantation of marginal donor organs in high-risk recipients, showcasing the feasibility of recruiting donors with extended criteria. This technique is safe and promising, expanding the donor pool and addressing the organ shortage in heart transplantation in Hong Kong.

The role of ventricular assist device in the management of advanced heart failure: a literature review

The ventricular assist device has become a reliable and enduring therapy for patients with end-stage heart failure, with over 22,000 implantations to date. Initially designed as a bridge-to-transplant option but now it has become permanent cure for patients with acute heart failure. VAD has significant advancements in medical management and technology, particularly with the introduction of newer-generation devices, have greatly enhanced patient outcomes. This progress has led to an increasing use of ventricular assist devices as a destination therapy. Nonetheless, the substantial burden of adverse events remains a critical challenge in the current state of ventricular assist device therapy, despite this, its viable alternative of heart transplantation as it has solved the complications of donor heart and proved significant success among patient with acute heart failure.

The Potential for Heart Donation After Death Determination by Circulatory Criteria in the Province of Québec

BackgroundHeart donation (HD) by those with death determination by circulatory criteria (DDCC) has been proposed as a method to increase the heart donor pool in response to the growing need for heart transplantation (HT). However, the potential level of HD after DDCC in the province of Québec has not yet been reported. This study aims to assess the suitability for HD among donors with DDCC, and to estimate its impact on HT activity. MethodsDonation records by those with DDCC in the province of Québec, from January 2016 to December 2020, were retrospectively reviewed for donor and predonation characteristics. Predetermined exclusion criteria were used to evaluate eligibility for HD. ResultsOf the 122 patients with DDCC who were included, 42 (34%) were identified as potentially-eligible heart donors. The median age of potentially-eligible donors was 52 years; 60% were female; and the most prevalent causes leading to organ donation in this group were medical aid in dying (26%), traumatic brain injury (26%), and anoxia (24%). A 19% increase (42 of 225) in potential HT activity was estimated using strict criteria. In only one case did functional warm ischemia time exceed the 30-minute limit. ConclusionsUsing those with DDCC as a new source of heart donors can significantly increase the volume of heart donation in the province of Québec. Implementing an HD program for those with DDCC in Québec may reduce waiting time and increase the number of heart recipients.

In vivo mitral valve repair for the transplanted donor heart in orthotopic heart transplantation

A 53-year-old woman with the dilated phase of hypertrophic cardiomyopathy underwent orthotopic heart transplantation. The donor heart was evaluated as normal preoperatively without mitral regurgitation or the left atrium dilation, transplanted using the modified bicaval technique. Although the heart beat satisfactorily after aortic declamping, massive mitral regurgitation was observed without any prolapse or annular dilation. Because of the difficulty in weaning from cardiopulmonary bypass, a second aortic cross-clamp was applied, and we detached the inferior vena cava and the right side of the left atrial anastomosis to approach the mitral valve, obtaining a satisfactory exposure. No abnormalities were observed in the mitral valve leaflets, annulus or subvalvular apparatus. Subsequent in vivo mitral annuloplasty using prosthetic full ring successfully controlled the regurgitation, and the patient was easily weaned from cardiopulmonary bypass. She discharged to home with good mitral valve and cardiac functions. And the patient has been doing well without any recurrence of MR or heart failure for over a year after surgery.

Progresses and perspectives on natural polysaccharide based hydrogels for repair of infarcted myocardium

Myocardial infarction (MI) is serious health threat and impairs the quality of life. It is a major causative factor of morbidity and mortality. MI leads to the necrosis of cardio-myocytes, cardiac remodelling and dysfunction, eventually leading to heart failure. The limitations of conventional therapeutic and surgical interventions and lack of heart donors have necessitated the evolution of alternate treatment approaches for MI. Polysaccharide hydrogel based repair of infarcted myocardium have surfaced as viable option for MI treatment. Polysaccharide hydrogels may be injectable hydrogels or cardiac patches. Injectable hydrogels can in situ deliver cells and bio-actives, facilitating in situ cardiac regeneration and repair. Polysaccharide hydrogel cardiac patches reduce cardiac wall stress, and inhibit ventricular expansion and promote angiogenesis. Herein, we discuss about MI pathophysiology and myocardial microenvironment and how polysaccharide hydrogels are designed to mimic and support the microenvironment for cardiac repair. We also put forward the versatility of the different polysaccharide hydrogels in mimicking diverse cardiac properties, and acting as a medium for delivery of cells, and therapeutics for promoting angiogenesis and cardiac repair. The objectives of this review is to summarize the factors leading to MI and to put forward how polysaccharide based hydrogels promote cardiac repair. This review is written to enable researchers understand the factors promoting MI so that they can undertake and design novel hydrogels for cardiac regeneration.

Bioprinting in cardiovascular medicine: Possibilities, challenges, and future perspectives for low and middle-income countries.

Cardiovascular diseases (CVD) stemming from various factors significantly impact the quality of life (QoL) and are prevalent with high mortality rates in both developed and developing countries. In cases where pharmacotherapy proves insufficient and end-stage disease ensues, a heart transplant/surgical repair becomes the only feasible treatment option. However, challenges such as a limited supply of heart donors, complications associated with rejection, and issues related to medication compliance introduce an additional burden to healthcare services and adversely affect patient outcomes. The emergence of bioprinting has facilitated advancements in creating structures, including ventricles, valves, and blood vessels. Notably, the development of myocardial/cardiac patches through bioprinting has offered a promising avenue for revascularizing, strengthening, and regenerating ventricles. Employment loss in developing countries as a circumstance of disability or death can severely impact a family's well-being and means for sustainable living. Innovations by means of life sustaining treatment options can provide hope for the impoverished and help reduce disability burden on the economy of low- to middle-income countries (LMICs). Such developments can have a significant impact that can last for generations, especially in developing countries. In this review, the authors delve into various types of bioprinting techniques, exploring their possibilities, challenges, and potential future applications in treating various end-stage cardiovascular conditions in LMICs.

Gene Expression and Ultrastructural Evidence for Metabolic Derangement in the Primary Mitral Regurgitation Heart

Abstract Aims Chronic neurohormonal activation and hemodynamic load cause derangement in myocardial substrate utilization. We test the hypothesis that the primary mitral regurgitation heart (PMR) heart shows altered metabolic gene profile and cardiac ultrastructure consistent with decreased fatty acid and glucose metabolism despite LVEF &amp;gt; 60%. Methods and Results Metabolic gene expression in right atrial (RA), left atrial (LA), and left ventricular (LV) biopsies from donor hearts (n = 10) and from patients with moderate to severe PMR (n = 11) at surgery showed decreased mRNA glucose transporter type 4 (GLUT-4), GLUT-1 and insulin receptor substrate 2 and increased mRNA hexokinase 2, O-linked N-acetylglucosamine transferase and O-GlcNAcase, rate-limiting steps in the hexosamine biosynthetic pathway. Pericardial fluid levels of Neuropeptide Y were 4-fold higher than simultaneous plasma indicative of increased sympathetic drive. Quantitative TEM shows glycogen accumulation, glycophagy, increased lipid droplets, and mitochondrial cristae lysis. These findings are associated with increased mRNA for glycogen synthase kinase 3β, decreased carnitine palmitoyl transferase 2, and fatty acid synthase in PMR vs. normals. Cardiac magnetic resonance/positron emission tomography for 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) uptake showed decreased LV [18F]FDG uptake and increased plasma HbA1c, free fatty acids, mtDAMPs in a separate cohort of stable moderate PMR patients with LVEF &amp;gt; 60% (n = 8) vs. normal controls (n = 8). Conclusions The PMR heart has a global ultrastructural and metabolic gene expression pattern of decreased glucose uptake along with increased glycogen and lipid droplets. Further studies must determine whether this presentation is an adaptation or maladaptation in the PMR heart in the clinical evaluation of PMR.

Exploring Endocrine Signaling between Adipose Tissues and the Heart using Transfer Learning and Induced Pluripotent Stem Cell Models

Background: Because of the amount of evidence pointed toward obesity as a co-morbidity of heart disease, our goal in this study is to use a data-driven method to discover potential cross talk signals between adipose and cardiac tissues, which may reveal a physiological reason for this association. For this study, we hypothesized that adipose-cardiac crosstalk signaling can be found by unexpected co-expression between adipose tissue genes encoding secreted proteins and cardiac tissue genes and vice versa. By discovering new crosstalk signals between these two tissues, we can find new associations between heart disease and obesity. Methods: Cross-tissue correlations of gene expression have been used to identify candidate endocrine signals that mediate tissue crosstalk, which are otherwise diffcult to detect in circulation. However, the identification of significant cross-tissue gene co-expression is hindered by immense multiple-testing burden. Our goal here is to abstract gene expression patterns of tissues into eigengenes and then test their correlation with secreted protein coding genes across tissues in a pairwise fashion. We first used the NIH Common Fund Genotype-Tissue Expression data set (GTEx v8) which contains RNA seq gene expression data from matched tissues of over 17,000 transcriptomes, to learn the latent structure of gene expression across tissues. To do so, we used PLIER (pathway level information extractor), a matrix factorization algorithm to extract the latent targets as eigengenes that map to specific biological pathways in the target tissue (e.g., pathways in the heart in the case of adipose to heart crosstalk). The learned gene expression structure is then transferred to a smaller data set with matching donor adipose and heart transcript expression data, from which a correlation matrix is constructed to find significant relationships between source tissue crosstalk signals and target tissue eigengenes and nominate novel crosstalk signals. Results: Adipose to heart tissue cross talk correlations using PLIER derived latent eigengene targets revealed many adipokines that had strong correlations with pathways found in the heart tissue through similar gene expression. Among these strong correlations were eigengene targets that were wrapped in metabolism pathways particularly those of fatty acid, phospholipid, and protein metabolism. Adipokines that showed high significant and positive correlation with cardiac latent variable expression included Adiponectin (R = 0.32, p = 4.7e−13), Glutathione Peroxidase 3 (R = 0.34, p = 5e−15) and Galectin 9 (R = 0.37, p &lt; 2.2e−16) among others. Based on these results, we nominated new potential relationships between adipose and cardiac tissue. Work is currently under way to validate these candidate crosstalk signals using human induced pluripotent stem cell (iPSC)-derived cardiomyocytes. Future Directions In conclusion, we have found strong evidence in silico to suggest a relationship between known secreted proteins from adipose tissue (adipokine) and the expression of important pathways (such as fatty acid and protein metabolism) in the heart. Based on the findings of these correlations between adipokines and latent eigengene pathways within the heart, our future directions will involved the understanding of potential downstream functional consequences mediated by the adipose secreted proteins in iPSC derived models. This project was supported in part by NIH award R03-OD032666 and the University of Colorado Translational Research Scholar Program to E.L. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Donor heart dysfunction and graft survival in liver and kidney transplants-A register-based study from Sweden.

Stress cardiomyopathy in donors can potentially affect graft function and longevity. This study aims to investigate the association between echocardiographic left ventricular ejection fraction (LVEF)<50%, and/or the presence of left ventricular regional wall motion abnormalities (RWMA) in organ donors, and short- and long-term liver and kidney graft survival. Our secondary aim was to link graft survival with donor and recipient characteristics. All donors considered for liver and kidney donation with echocardiographic records at Sahlgrenska University Hospital between 2006 and 2016 were matched with their recipients through the Scandiatransplant register. The studied outcomes were graft survival, re-transplantation, and recipient death. Kaplan-Meier curves were used to plot time to event. Multivariate Cox-regression was used to test independence. There were 370 liver donors and 312 kidney donors (matched with 458 recipients) with echocardiographic records at Sahlgrenska University Hospital between June 2006 and November 2016. Of patients with LV dysfunction by echocardiography, there were 102 liver- and 72 kidney donors. Univariate survival analyses showed no statistical difference in the short- and long-term graft survival from donors with LV dysfunction compared to donors without. Donor age>65 years, recipient re-transplantation and recipient liver tumor were predictors of worse outcome in liver transplants (p<.05). Donor age>65, donor hypertension, recipient re-transplantation, and a recipient diagnosis of diabetes or nephritis/glomerulonephritis had a negative association with graft survival in kidney transplants (p<.05). We found no significant association between donor LV dysfunction and short- and long-term graft survival in liver and kidney transplants, suggesting that livers and kidneys from such donors can be safely transplanted.

Assessment of Selected Parameters of Heart Donors and Recipients and Their Impact on the Transplantation Result

ObjectiveTo evaluate the impact of heart donors and recipients parameters on the outcomes after orthotopic heart transplantation (OHT). MethodologyTwo hundred fifteen patients who underwent OHT from 2020 to 2023 were analyzed. ResultsAverage donors age 36.3 (±13.1) years, 74 women (34.42%), BMI 25.3 (±4.99), Na+ concentration 153.7 (±11.8) mmol/L. Mean intraventricular septum thickness 10.0 (±2.2) mm, left ventricular end-diastolic diameter 44.3 (±6) mm, ejection fraction 60.3 (±7.92) %. Median procalcitonin was 0.6 ng/mL. Levonor was used in 75.8%, Empressin in 4.2%, Dopamine in 5.1%, Dobutamine in 3.7%, and Adrenaline in 3.7% of donors. The most common cause of death: intracranial injury (34.42%). Cardiopulmonary resuscitation occurred in 34%, alcoholism in 20.9%, nicotinism in 16.3%, and drug addiction in 7.4% of donors. Mean aortic cross-clamping time was 200.3 (±48.8) minutes. Intra-aortic balloon pump (IABP) after OHT required 6.1%, extra corporeal membrane oxygenation (ECMO) 6.1%, and renal dialysis 36% of recipients. The 1-year mortality rate was 19.1%. Death after OHT correlated with: longer aortic cross-clamping time (207.6 vs 198.59 minutes, P = .292), longer extracorporeal circulation time (196.3 vs 186.47 minutes, P = .335), lower Empressin dose (median 0.01 vs 0.02 j.m/min, P = .03) in donors, longer postoperative mechanical ventilation (mean 101.46 vs 23.09 hours, P = .001), more frequent dialysis, IABP or ECMO (P = .001) and older age of the recipient (51.2 vs 44.8 years, P = .014). Previous cardiac surgery or any surgical intervention after transplantation significantly influenced mortality. The remaining donor factors had no impact on the OHT result. ConclusionsIdentification of risk factors in the donor and recipient may improve treatment outcomes after OHT.

Normothermic Ex Vivo Heart Perfusion With Exosomes From Human Umbilical Cord Mesenchymal Stem Cells Improves Graft Function in Donation After Circulatory Death Hearts.

This study aimed to investigate the cardioprotective effect of exosomes derived from human umbilical cord mesenchymal stem cells on donation after circulatory death (DCD) hearts preserved with normothermic ex vivo heart perfusion (EVHP) in a rat heart transplantation model. Thirty-two male Lewis rats were divided into 2 groups: the control group and the exosome group. The donor-heart rats were subjected to the DCD procedure by suffering a 15-min warm ischemia injury, subsequently preserved with EVHP for 90 min, and then transplanted into recipients via abdominal heterotopic heart transplantation. Vehicle or exosome was added into the perfusate of normothermic EVHP in the control or exosome group. We evaluated left ventricular graft function, myocardial inflammation, and myocardial apoptosis of the donor heart 1.5 h after heart transplantation. Furthermore, we investigate the alternation of myocardial gene expression in the donor hearts between both groups by transcriptome sequencing. The treatment with exosome significantly enhanced cardiac function through increasing left ventricular developed pressure, dp/dtmax, and dp/dtmin of DCD hearts at 90 min after heart transplantation compared with the control group. The myocardial cells in the exosome group exhibited an orderly arrangement without obvious edema. Furthermore, exosome added into perfusate in the exosome group significantly attenuated the level of inflammatory response and apoptosis. Transcriptome sequencing and RT-qPCR showed the phosphoinositide 3-kinase/protein kinase B pathway was activated after exosome treatment. Normothermic EVHP combined with exosome can be a promising and novel DCD heart preservation strategy, alleviating myocardial ischemia-reperfusion injury in the DCD heart.

"Take it or leave it": Analysis of pediatric heart offers for transplantation in Switzerland.

There is a shortage of donor hearts in Switzerland, especially for pediatric recipients. However, the rate and reason for refusals of pediatric donor hearts offered in Switzerland has not been systematically analyzed. The national transplant database, Swiss Organ Allocation System, was searched for all hearts from Swiss and foreign donors younger than 16 years from 2015 to 2020. The numbers of accepted and refused hearts and early outcome were assessed, and the reasons for refusal were retrospectively analyzed. A total of 136 organs were offered to the three Swiss pediatric heart centers and foreign donor procurement organizations. Of these, 26/136 (19%) organs were accepted and transplanted: 18 hearts were transplanted in Switzerland, and 13 of these were foreign. Reasons for refusal were (1) no compatible recipient due to blood group or weight mismatch, 89.4%; (2) medical, meaning organ too marginal for transplantation, 7.4%; (3) logistic, 1.4%; and (4) other, 1.8%. Five organs were refused in Switzerland by one center but later accepted and successfully transplanted by another center. Hearts from outside Switzerland were transplanted significantly less than Swiss hearts (n = 16/120 vs. 10/16, p < .001). The most common reason for refusing a pediatric donor heart is lack of compatibility with the recipient. Few hearts are refused for medical reasons. A more generous acceptance seems to be justified in selected patients. Switzerland receives a high number of foreign offers, but their rate of acceptance is lower than that of Swiss donations.

Metabolomic insights in advanced cardiomyopathy of chronic chagasic and idiopathic patients that underwent heart transplant

Heart failure (HF) studies typically focus on ischemic and idiopathic heart diseases. Chronic chagasic cardiomyopathy (CCC) is a progressive degenerative inflammatory condition highly prevalent in Latin America that leads to a disturbance of cardiac conduction system. Despite its clinical and epidemiological importance, CCC molecular pathogenesis is poorly understood. Here we characterize and discriminate the plasma metabolomic profile of 15 patients with advanced HF referred for heart transplantation – 8 patients with CCC and 7 with idiopathic dilated cardiomyopathy (IDC) – using gas chromatography/quadrupole time-of-flight mass spectrometry. Compared to the 12 heart donor individuals, also included to represent the control (CTRL) scenario, patients with advanced HF exhibited a metabolic imbalance with 21 discriminating metabolites, mostly indicative of accumulation of fatty acids, amino acids and important components of the tricarboxylic acid (TCA) cycle. CCC vs. IDC analyses revealed a metabolic disparity between conditions, with 12 CCC distinctive metabolites vs. 11 IDC representative metabolites. Disturbances were mainly related to amino acid metabolism profile. Although mitochondrial dysfunction and loss of metabolic flexibility may be a central mechanistic event in advanced HF, metabolic imbalance differs between CCC and IDC populations, possibly explaining the dissimilar clinical course of Chagas’ patients.

Pediatric donor heart utilization variability among organ procurement organizations.

Organ procurement organizations (OPOs) are responsible for the medical management of organ donors. Given the variability in pediatric donor heart utilization among OPOs, we examined factors that may explain this variability, including differences in donor medical management, organ quality, and candidate factors. The Organ Procurement and Transplant Network database was queried for pediatric (<18 years) heart donors and candidates receiving pediatric donor heart offers from 2010 to 2019. OPOs were stratified by pediatric donor heart utilization rate, and the top and bottom quintiles were compared based on donor management strategies and outcomes. A machine learning algorithm, combining 11 OPO, donor, candidate, and offer variables, was used to determine factors most predictive of whether a heart offer is accepted. There was no clinically significant difference between the top and bottom quintile OPOs in baseline donor characteristics, distance between donor and listing center, management strategies, or organ quality. Machine learning modeling suggested neither OPO donor management nor cardiac function is the primary driver of whether an organ is accepted. Instead, number of prior donor offer refusals and individual listing center receiving the offer were two of the most predictive variables of organ acceptance. OPO clinical practice variation does not seem to account for the discrepancy in pediatric donor heart utilization rates among OPOs. Listing center acceptance practice and prior number of donor refusals seem to be the important drivers of heart utilization and may at least partially account for the variation in OPO heart utilization rates given the regional association between OPOs and listing centers.