Donor selection in heart transplantation

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.

Donor Heart Preservation: Current Knowledge and the New Era of Machine Perfusion

Heart transplantation remains the conventional treatment in end-stage heart failure, with static cold storage (SCS) being the standard technique used for donor preservation. Nevertheless, prolonged cold ischemic storage is associated with the increased risk of early graft dysfunction attributed to residual ischemia, reperfusion, and rewarming damage. In addition, the demand for the use of marginal grafts requires the development of new methods for organ preservation and repair. In this review, we focus on current knowledge and novel methods of donor preservation in heart transplantation. Hypothermic or normothermic machine perfusion may be a promising novel method of donor preservation based on the administration of cardioprotective agents. Machine perfusion seems to be comparable to cold cardioplegia regarding donor preservation and allows potential repair treatments to be employed and the assessment of graft function before implantation. It is also a promising platform for using marginal organs and increasing donor pool. New pharmacological cardiac repair treatments, as well as cardioprotective interventions have emerged and could allow for the optimization of this modality, making it more practical and cost-effective for the real world of transplantation. Recently, the use of triiodothyronine during normothermic perfusion has shown a favorable profile on cardiac function and microvascular dysfunction, likely by suppressing pro-apoptotic signaling and increasing the expression of cardioprotective molecules.

The 2-year postoperative left heart function in marginal donor heart recipients assessing by speckle tracking echocardiography

This study analyzed the differences and explored the donor/recipient factors between marginal and standard donor heart recipients after heart transplantation (HT) by speckle tracking echocardiography (STE). Seventy-two HT patients were enrolled: 25 standard and 47 marginal donor heart recipients. Thirty HT patients completed 2-year continuous follow-up (1, 6, 12, 24 months). Thirty healthy volunteers were controls. STE was used to track the strain characteristics of the left ventricle and atrium for detecting early changes in marginal donor heart recipients, including left ventricular global longitudinal, circumferential and radial strain (LVGLS, LVGCS, LVGRS) and left atrial strain in systole (LAS-S) and late diastole (LAS-A). The perioperative parameters were similar between the standard and marginal groups. No significant differences were found in left heart size, systolic and diastolic function parameters. Left ventricular systolic strain (LVGLS, LVGCS, LVGRS) and systolic and late diastolic left atrial strain (LAS-S, LAS-A) were lower in the HT recipients than the control group (P < 0.05), but there was no difference between the marginal and standard groups (P > 0.05). LVGLS, LVGCS, and LAS-S were low in the marginal group 1 month after surgery but recovered gradually at 6 months. The patients with donor/recipient body weight ratio < 0.8 group had lower LVGLS and LAS-S. STE showed no significant difference between marginal and standard donor recipients. The LVGLS and LAS-S were lower in those with a smaller donor/recipient body weight ratio. The cardiac function of HT patients was lower in the early postoperative period but gradually recovered over time.

Outcomes of COVID-19-Positive Donor Heart Transplantation in the United States

Background Little is known regarding the impact of donor COVID-19 status on recipient outcomes after heart transplantation. In this study, we characterize outcomes of the first 110 heart transplants from organ donors positive for COVID-19 (COVID-19+) in the United States. Methods and Results Retrospective analysis of the United Network for Organ Sharing database was performed for single-organ adult heart transplants from January 2020 to March 2022. Donor COVID-19+ status was defined as a positive nucleic acid amplification, antigen, or other COVID-19 test within 7 days of transplant. Nearest-neighbor propensity score matching used to adjust for differences between recipients of COVID-19+ and nonpositive donor hearts. Overall, 7251 heart transplants were included in analysis, with 110 using COVID-19+ donor hearts. Recipients of COVID-19+ allografts were younger (54 [interquartile range, 41-61]) versus 57 [46-64] years; P=0.02) but had similar rates of female sex and non-White race compared with those receiving allografts from negative donors. Nearest-neighbor propensity score matching resulted in 100 well-matched pairs of recipients of COVID-19+ versus nonpositive donor organs. The 2 matched groups had similar median lengths of stay (15 [11-23] days versus 15 [13-23] days; P=0.40), rates of graft failure (1% versus 0%; P=0.99), 30-day death (3% versus 3%; P=0.99), and 3-month survival (88% versus 94%; P=0.23) compared with recipients of nonpositive donors. No deaths occurred due to COVID-19 infection among the 8 (7%) total deceased recipients of COVID-19+ allografts to date. Conclusions Short-term outcomes of heart transplant recipients receiving COVID-19+ donor organs are reassuring. However, continued monitoring for long-term survival and potential complications are warranted.

Brugada Sign in a Cardiac Transplant Donor

Brugada syndrome (BrS) is a rare entity represented by the Brugada sign on an electrocardiogram (EKG) and is associated with sudden cardiac death (SCD). There is little data to guide the management of donor Brugada syndrome in the setting of cardiac transplantation.

A 31-year-old male sustained out-of-hospital cardiac arrest secondary to polysubstance use and was found asystole. Bystander cardiopulmonary resuscitation (CPR) with advanced cardiovascular life support (ACLS) protocol was initiated. Return of spontaneous circulation (ROSC) was achieved and the patient was taken to the emergency room (ER) in sinus rhythm with an initial presenting EKG showing the Brugada sign. A toxicological screen for cocaine was positive. The patient was eventually declared brain dead and underwent angiographic and echocardiographic evaluation as a donor heart for cardiac transplantation and was accepted for transplantation.

Cardiac arrest in a young patient with a Brugada sign on EKG is a concern for BrS. Cocaine exerts a sodium channel blockade that can unmask BrS. Genetic testing for sodium voltage-gated channel alpha subunit 5 (​​​​​​SCN5A) gene mutation was negative, however, only 15% to 30% of patients carry the mutation. We proceeded with cardiac transplantation and suggested an implantable cardioverter defibrillator (ICD) for primary prevention in the recipient, should further specialized testing reveal a continued concern for BrS. We suggest the necessity for further data to guide decisions in patients with BrS undergoing cardiac transplantation.

Expanding Selection Criteria to Repairable Diseased Hearts to Meet the Demand of Shortage of Donors in Heart Transplantation

Heart transplant surgery is considered the destination therapy for end-stage heart disease. Unfortunately, many patients in the United States of America who are eligible candidates for transplants cannot undergo surgery due to donor shortage. In addition, some donors' hearts are being labeled as unacceptable for transplant surgery because of the rigorous and restricted rules placed on the approval process of using a donor's heart. Over the last few decades, the rising discrepancy between the scarcity of donor hearts and the demand for such organs has led to the discussion of expanding the donor heart selection criteria. A softer view on using marginal hearts for transplants would help those on the waitlist to receive a heart transplant. Marginal hearts that contain the hepatitis c virus (HCV), COVID-19, older age, or repairable heart defects have become viable options to use for a heart transplant. Also, the prioritization based on the new heart allocation system would help efficiently decide which recipients would be the first to get a donor's heart. Recently there has been a consensus to broaden the eligibility of donor's hearts by accepting valvular abnormalities, coronary artery disease, and congenital abnormalities. This review highlights some of those expansions in selection criteria in particular using repairable hearts, which could be fixed in the operating room on the back table before transplantation.

Is a Bioengineered Heart From Recipient Tissues the Answer to the Shortage of Donors in Heart Transplantation?

With the increase in life expectancy worldwide, end-organ failure is becoming more prevalent. In addition, improving post-transplant outcomes has contributed to soaring demand for organs. Unfortunately, thousands have died waiting on the transplant list due to the critical shortage of organs. The success of bioengineered hearts may eventually lead to the production of limitless organs using the patient’s own cells that can be transplanted into them without the need for immunosuppressive medications. Despite being in its infancy, scientists are making tremendous strides in “growing” an artificial heart in the lab. We discuss these processes involved in bioengineering a human-compatible heart in this review. The components of a functional heart must be replicated in a bioengineered heart to make it viable. This review aims to discuss the advances that have already been made and the future challenges of bioengineering a human heart suitable for transplantation.

The outcomes of marginal donor hearts compared with ideal donors: a single-center experience in Iran

Background

Heart transplantation has been considered the gold-standard treatment for patients with end-stage heart failure. This study assessed the survival outcomes of marginal donor hearts compared with ideal donor hearts in Iran.

Methods

This retrospective study is based on the follow-up data of heart donors and recipients in the Sina Hospital Organ Procurement Unit. Among the 93 participants, 75 were categorized as ideal donors (group A) and 18 as marginal donors (group B). Group C included heart recipients who received a standard organ, and group D included heart recipients who received a marginal one. To analyze differences in patient characteristics among the groups, posttransplant heart survival was assessed in all groups. All data were obtained from the hospital records.

Results

The mean age of the donors was 26.27±11.44 years (median age, 28 years). The marginal age showed a significant association with donor age. The age of recipients had a significant effect on survival days in the ideal group. Most patients survived for at least 1 year, with a median of 645 days in recipients from marginal donors and 689 days in recipients from ideal donors.

Conclusions

Considering the lack of organ availability in Iran, it may be possible to use marginal donors for marginal recipients, therefore reducing the number of people on the waitlist. We also recommend establishing a national marginal donor system specifically for Iranian patients to extend the donor pool.

Phase I investigator-initiated study of the safety of MTC001 in patients with chronic ischemic heart failure

BACKGROUND

: Heart failure (HF) is a global pandemic most commonly caused by coronary artery disease. Despite coronary revascularization, the infarcted myocardium can develop into an irreversible scar toward chronic ischemic HF. This is due to the limited regenerative capacity of the adult human heart. Recently, the vascular cell adhesion molecule 1 positive cardiac fibroblast (VCF) has been shown to directly improve cardiac contractility in addition to promoting myocardial growth in preclinical studies. This clinical trial aims to explore the safety and, in part, the efficacy of autologous VCF therapy for chronic ischemic HF.

METHODS

: This first-in-human trial is an open-label, single-arm, phase 1 study conducted at a single center. This study will include 6 patients with chronic ischemic HF in stage C and NYHA class II or III despite receiving the standard of care, including coronary revascularization. Participants will undergo cardiac biopsy to manufacture autologous VCFs expressing CD90 and CD106. Under electro-anatomical mapping guidance, participants will receive a transendocardial injection of VCF in a modified 3 + 3 design. The first 3 patients will receive a standard dose (2 × 107 cells) of VCF with a 4-week interval for safety assessment before subsequent enrollment. In the absence of safety issues, the final 3 patients will receive the standard dose of VCF without a 4-week interval. In the presence of safety issues, the final 3 patients will receive a reduced dose (1.5 × 107 cells) of VCF with the 4-week interval.

DISCUSSION

This is the first clinical study of cardiac regeneration using VCFs for the treatment of chronic ischemic HF. The study results will contribute to the development of a minimally invasive cell therapy for patients with HF failed by the standard of care.

TRIAL REGISTRATION

This study was registered with the Japan Registry of Clinical Trials (jRCT2033210078).

Long-term heart transplant recipients: heart rate-related effects on augmented transfer function coherence during repeated squat-stand maneuvers in males

Previous research has highlighted that squat-stand maneuvers (SSMs) augment coherence values within the cerebral pressure-flow relationship to ∼0.99. However, it is not fully elucidated if mean arterial pressure (MAP) leads to this physiological entrainment independently, or if heart rate (HR) and/or the partial pressure of carbon dioxide (Pco₂) also have contributing influences. A 2:1 control-to-case model was used in the present investigation [participant number (n) = 40; n = 16 age-matched (AM); n = 16 donor control (DM); n = 8 heart transplant recipients (HTRs)]. The latter group was used to mechanistically isolate the extent to which HR influences the cerebral pressure-flow relationship. Participants completed 5 min of squat-stand maneuvers at 0.05 Hz (10 s) and 0.10 Hz (5 s). Linear transfer function analysis (TFA) examined the relationship between different physiological inputs (i.e., MAP, HR, and Pco₂) and output [cerebral blood velocity (CBV)] during SSM; and cardiac baroreceptor sensitivity (BRS). Compared with DM, cardiac BRS was reduced in AM (P < 0.001), which was further reduced in HTR (P < 0.045). In addition, during the SSM, HR was elevated in HTR compared with both control groups (P < 0.001), but all groups had near-maximal coherence metrics ≥0.98 at 0.05 Hz and ≥0.99 at 0.10 Hz (P ≥ 0.399). In contrast, the mean HR-CBV/Pco₂-CBV relationships ranged from 0.38 (HTR) to 0.81 (DM). Despite near abolishment of BRS and blunted HR following heart transplantation, long-term HTR exhibited near-maximal coherence within the MAP-CBV relationship, comparable with AM and DM. Therefore, these results show that the augmented coherence with SSM is driven by blood pressure, whereas elevations in TFA coherence as a result of HR contribution are likely correlational in nature.

The Effect of Increasing Donor Age on Myocardial Ischemic Tolerance in a Rodent Model of Donation After Circulatory Death

Hearts from older donors or procured via donation after circulatory death (DCD) can alleviate transplant waitlist; however, these hearts are particularly vulnerable to injury caused by warm ischemic times (WITs) inherent to DCD. This study investigates how the combination of increasing donor age and pharmacologic supplementation affects the ischemic tolerance and functional recovery of DCD hearts and how age impacts cardiac mitochondrial respiratory capacity and oxidative phosphorylation.

Coronary angiography utilization in the evaluation of a potential heart donor by age: a narrative review

Heart transplant is the gold standard treatment for patients with heart failure. The limitation to providing heart transplantation to patients suffering from end stage heart disease is the stable organ supply within the United States despite increasing demand. Transplant centers across the United States have begun to expand traditional cardiac donor selection metrics previously utilized. As a result, the use of extended criteria donors, such as older donors, those with longer ischemic times, and donors considered high risk has increased. Current guidelines suggest that coronary angiography be performed when evaluating a donor above the age of 45. Angiographic guidelines for evaluation of the donor heart are based specifically on age, with little evidence based guidance surrounding the use of angiography in a younger donor with comorbidities or increased risk behavior which may lead to premature coronary artery disease. Recently, we have seen an increase in younger heart donors, many of whom have succumbed due to drug overdose with ensuing high risk behaviors. Given the increased risk nature of these donors, consideration of performing coronary angiography is determined by clinical “gestalt” of the transplant center evaluating the heart for use, which may lead to underutilization of donor organs without evidence to support the practice. Here, we review the guidelines, literature, and controversy surrounding the use of coronary angiography in evaluating donor hearts for transplantation.

Transplant Center Variability in Organ Offer Acceptance and Mortality Among US Patients on the Heart Transplant Waitlist

Importance

Under the current Centers for Medicare & Medicaid Services guidelines, there is incentivization to optimize posttransplant outcomes regardless of mortality among patients on the waitlist and transplant rates; few data exist with regard to transplant center acceptance practices and survival to heart transplant.

Objectives

To evaluate the extent of variability in organ acceptance practices in the US and whether this center-level behavior is associated with heart transplant candidate survival.

Design, Setting, and Participants

In this retrospective cohort study, the US National Transplant Registry was queried for all match runs of adult candidates listed for isolated heart transplant between May 1, 2007, and March 31, 2017. Data analysis was conducted from October 30, 2018, to May 1, 2019. The final cohort included 93 transplant centers, 19 703 donors, and 9628 candidates.

Main Outcomes and Measures

Center acceptance rates for heart allografts offered to the highest-priority candidates, association between center acceptance rate and mortality among patients on the waitlist, and posttransplant outcomes between candidates who accepted their first-rank offers vs those who accepted previously declined offers.

Results

Among 19 703 unique organ offers, 6302 hearts (32.0%) were accepted for first-rank candidates. After adjustment for donor, candidate, and geographic covariates, transplant centers varied in acceptance rates (12.3%-61.5%) of offers made to first-rank candidates. Higher acceptance rates were associated with lower cumulative incidence of 1-year mortality among patients on the waitlist. For every 10% increase in adjusted center acceptance rate, the risk of mortality decreased by 27% (subdistribution hazard ratio, 0.73; 95% CI, 0.67-0.80). No statistically significant difference was observed in 5-year adjusted posttransplant patient survival (adjusted hazard ratio, 1.02; 95% CI, 0.94-1.11) and graft failure (subdistribution hazard ratio; 0.95; 95% CI, 0.83-1.09) between hearts accepted at the first-rank compared with lower-rank positions.

Conclusions and Relevance

Variability in heart allograft acceptance rates appears to exist among transplant centers, with candidates listed at lower acceptance rate centers being more likely to experience mortality while on the waitlist. Comparable posttransplant survival suggests that allografts that were declined as a first offer perform as well as those that were accepted at their first offer. These findings suggest that organ acceptance rate or time to transplant from being added to the waitlist may be an additional measure of heart transplant program performance.

DNA methyltransferase inhibitor 5-azacytidine in high dose promotes ultrastructural maturation of cardiomyocyte

Background

The adult human heart muscle cells, cardiomyocytes are not capable of regenerate after injury. Stem cells are a powerful means for future regenerative medicine because of their capacity for self-renewal and multipotency. Several studies have reported the cardiogenic potential in human adipose tissue-derived stem cells (ADSCs) differentiation, but there is still no efficient protocol for the induction of cardiac differentiation by 5-azacytidine (5-Aza). The present study involves characterization and mainly, the ultrastructure of ADSCs derived cardiomyocyte-like cells.

Methods

The cultured ADSCs were treated with 50 µM 5-Aza for 24 hours, followed by a 10-week extension. At different time points, cardiomyocyte-like cells were assessed by qRT-PCR and were evaluated by transmission electron microscopy at 10^th week.

Results

The expression of cardiac-specific markers entailing cardiac troponin I (cTnI), connexin 43, myosin light chain-2v (Mlc-2v), increased over 10 weeks and the highest expression was at 10^th week. The expression of the β-myosin heavy chain (β-MHC) increased significantly over 5 weeks and then decreased. At the ultrastructural level myofibrils, transverse tubules (T-tubules), sarcoplasmic reticular membrane, and intercalated discs were present.

Conclusions

These data suggest that treatment with 5-Aza in high dose could promote differentiation of ADSCs into cardiomyocyte-like cells. These differentiated cells could be used for regeneration of damaged cardiomyocytes with the 3D scaffold for delivery of the cells.

The Human Explanted Heart Program: A translational bridge for cardiovascular medicine

The progression of cardiovascular research is often impeded by the lack of reliable disease models that fully recapitulate the pathogenesis in humans. These limitations apply to both in vitro models such as cell-based cultures and in vivo animal models which invariably are limited to simulate the complexity of cardiovascular disease in humans. Implementing human heart tissue in cardiovascular research complements our research strategy using preclinical models. We established the Human Explanted Heart Program (HELP) which integrates clinical, tissue and molecular phenotyping thereby providing a comprehensive evaluation into human heart disease. Our collection and storage of biospecimens allow them to retain key pathogenic findings while providing novel insights into human heart failure. The use of human non-failing control explanted hearts provides a valuable comparison group for the diseased explanted hearts. Using HELP we have been able to create a tissue repository which have been used for genetic, molecular, cellular, and histological studies. This review describes the process of collection and use of explanted human heart specimens encompassing a spectrum of pediatric and adult heart diseases, while highlighting the role of these invaluable specimens in translational research. Furthermore, we highlight the efficient procurement and bio-preservation approaches ensuring analytical quality of heart specimens acquired in the context of heart donation and transplantation.

Transcatheter Aortic Valve Replacement of a Bicuspid Aortic Valve in a Heart Transplant Recipient

Patients with heart transplants who present with severe aortic stenosis may be deemed high-risk surgical candidates due to immunosuppression and multiple comorbid conditions. Appropriately selected patients may be successfully treated with transcatheter aortic valve replacement. (Level of Difficulty: Advanced.)

Hybrid cardiovascular sourced extracellular matrix scaffolds as possible platforms for vascular tissue engineering

The aim when designing a scaffold is to provide a supportive microenvironment for the native cells, which is generally achieved by structurally and biochemically imitating the native tissue. Decellularized extracellular matrix (ECM) possesses the mechanical and biochemical cues designed to promote native cell survival. However, when decellularized and reprocessed, the ECM loses its cell supporting mechanical integrity and architecture. Herein, we propose dissolving the ECM into a polymer/solvent solution and electrospinning it into a fibrous sheet, thus harnessing the biochemical cues from the ECM and the mechanical integrity of the polymer. Bovine aorta and myocardium were selected as ECM sources. Decellularization was achieved using sodium dodecyl sulfate (SDS), and the ECM was combined with polycaprolactone and hexafluoro-2-propanol for electrospinning. The scaffolds were seeded with human umbilical vein endothelial cells (HUVECs). The study found that the inclusion of aorta ECM increased the scaffold's wettability and subsequently lead to increased HUVEC adherence and proliferation. Interestingly, the inclusion of myocardium ECM had no effect on wettability or cell viability. Furthermore, gene expression and mechanical changes were noted with the addition of ECM. The results from this study show the vast potential of electrospun ECM/polymer bioscaffolds and their use in tissue engineering.

Domino heart transplant following heart-lung transplantation: a systematic review and meta-analysis

Background

The domino-donor operation occurs when a "conditioned" heart from the heart-lung transplant (HLT) recipient is transplanted into a separate heart transplant (HT) recipient. The purpose of this systematic review was to investigate the indications and outcomes associated with the domino procedure.

Methods

An electronic search was performed to identify all prospective and retrospective studies on the domino procedure in the English literature. Eight studies reported 183 HLT recipients and 263 HT recipients who were included in the final analysis.

Results

HLT indications included cystic fibrosis in 58% (95% CI: 27-84%) of recipients, primary pulmonary hypertension (PPH) in 17% (95% CI: 12-24%), bronchiectasis in 5% (95% CI: 3-10%), emphysema in 5% (95% CI: 0-45%), and Eisenmenger's syndrome in 4% (95% CI: 2-8%). HT indications included ischemic heart disease in 40% (95% CI: 33-47%), non-ischemic disease in 39% (95% CI: 25-56%), and re-transplantation in 10% (95% CI: 1-59%). The pooled mean pulmonary vascular resistance (PVR) in HT recipients was 3.05 Woods units (95% CI: 0.14-5.95). The overall mortality in the HLT group was 28% (95% CI: 18-41%) at an average follow-up of 15.68 months (95% CI: 0.82-30.54), and 35% (95% CI: 17-58%) in the HT group at an average follow-up of 37.26 months (95% CI: 6.68-67.84). Freedom from rejection in HT was 94% (95% CI: 75-99%) at 1 month, 77% (95% CI: 30-96%) at 6 months, and 41% (95% CI: 33-50%) at 1 year.

Conclusions

The domino procedure appears to be a viable option in properly selected patients that can be performed safely with acceptable outcomes.

Donor and Recipient Characteristics in Heart Transplantation Are Associated with Altered Myocardial Tissue Structure and Cardiac Function

PURPOSE

To use structure-function cardiac MRI in the evaluation of relationships between donor and heart transplantation (HTx) recipient characteristics and changes in cardiac tissue structure and function. HTx candidates and donor hearts are evaluated for donor-recipient matches to improve survival, but the impact of donor and recipient characteristics on changes in myocardial tissue and function in the transplanted heart is not fully understood.

MATERIALS AND METHODS

Cardiac MRI at 1.5 T was performed from August 2014 to June 2017 in 58 HTx recipients (mean age, 51.1 years ± 12.6 [standard deviation], 26 female patients) and included T2 mapping (to evaluate edematous and/or inflammatory changes), precontrast and postcontrast T1 mapping (allowing the calculation of extracellular volume fraction [ECV] to estimate interstitial expansion), and tissue phase mapping (allowing the calculation of myocardial velocities and twist). Donor and recipient demographics (age, sex, height, weight, and body mass index [BMI]) and comorbidities (hypertension, diabetes, and smoking history) were evaluated for relationships with cardiac MRI measures.

RESULTS

Sex-influenced cardiac MRI measures of myocardial tissue and function are as follows: Female HTx recipients demonstrated increased precontrast T1 (P = .002) and reduced systolic peak long-axis velocities (P = .015). Increased age of the donor heart was associated with elevated T2 (r = 0.32; P < .05) and ECV (r = 0.47; P < .01), indicating increased edema and interstitial expansion, as well as impaired diastolic peak long-axis velocities (r = 0.41; P < .01). Recipient-donor differences in age, weight, and BMI were significantly associated with elevated ECV (r = 0.36-0.48; P < .05). Hypertension in donors resulted in increased ECV (31.0% ± 4.2 vs 26.0% ± 3.3; P = .001).

CONCLUSION

Donor and HTx recipient characteristics were significantly associated with cardiac MRI-derived measures of myocardial tissue structure and function.© RSNA, 2019.

Myocardial bridging in the era of a drug epidemic: a case report addressing the need to revisit donor organ assessment

Background

Myocardial bridging (MB), though typically a benign finding, may occasionally lead to syncope, myocardial infarction, arrhythmia, or sudden death. Surgical denervation of transplanted hearts complicates the management of such incidentally detected post-transplant coronary anomalies due to the lack of classic ischaemic symptoms.

Case summary

A middle-aged female underwent an uncomplicated cardiac transplantation from a healthy male donor in his early 20s who had suffered a cardiac arrest while using cocaine. Given the young donor age, a pre-transplant coronary angiogram (CAG) was deferred. However, 6-week post-transplant, routine CAG, and intravascular ultrasound revealed an extensive MB spanning a significant portion of the left anterior descending coronary artery with substantial myocardium at risk. A stress test with myocardial perfusion imaging performed to evaluate the functional significance of the bridge did not reveal any perfusion abnormalities in the myocardium at risk.

Discussion

In current practice, younger donors often do not undergo pre-transplantation CAG routinely performed in older donors given the lower prevalence of significant coronary disease. However, post-operatively this young donor was found to have passed on a potentially life-threatening MB to a denervated recipient, who cannot manifest typical anginal symptoms during ischaemia, thereby challenging providers to choose among strategies of watchful waiting, risk stratification, or pre-emptive intervention. In retrospect, the donor’s mode of death may have signalled an underlying structural abnormality that warranted further pre-transplant characterization. In order to ensure optimal quality of transplanted hearts, young donors may warrant pre-transplant CAG despite their age, particularly those with a history of drug use or suspicious mode of death.

Human Wharton's Jelly-Derived Mesenchymal Stem Cells Minimally Improve the Growth Kinetics and Cardiomyocyte Differentiation of Aged Murine Cardiac c-kit Cells in In Vitro without Rejuvenating Effect

Cardiac c-kit cells show promise in regenerating an injured heart. While heart disease commonly affects elderly patients, it is unclear if autologous cardiac c-kit cells are functionally competent and applicable to these patients. This study characterised cardiac c-kit cells (CCs) from aged mice and studied the effects of human Wharton’s Jelly-derived mesenchymal stem cells (MSCs) on the growth kinetics and cardiac differentiation of aged CCs in vitro. CCs were isolated from 4-week- and 18-month-old C57/BL6N mice and were directly co-cultured with MSCs or separated by transwell insert. Clonogenically expanded aged CCs showed comparable telomere length to young CCs. However, these cells showed lower Gata4, Nkx2.5, and Sox2 gene expressions, with changes of 2.4, 3767.0, and 4.9 folds, respectively. Direct co-culture of both cells increased aged CC migration, which repopulated 54.6 ± 4.4% of the gap area as compared to aged CCs with MSCs in transwell (42.9 ± 2.6%) and CCs without MSCs (44.7 ± 2.5%). Both direct and transwell co-culture improved proliferation in aged CCs by 15.0% and 16.4%, respectively, as traced using carboxyfluorescein succinimidyl ester (CFSE) for three days. These data suggest that MSCs can improve the growth kinetics of aged CCs. CCs retaining intact telomere are present in old hearts and could be obtained based on their self-renewing capability. Although these aged CCs with reduced growth kinetics are improved by MSCs via cell–cell contact, the effect is minimal.

Balancing the risk and rewards of utilizing organs from hepatitis C viremic donors

PURPOSE OF REVIEW

Owing to long waitlist times and high waitlist morbidity and mortality, strategies to increase utilization of hepatitis C viremic-deceased donor organs are under investigation in kidney, liver, heart, and lung transplantation.

RECENT FINDINGS

Direct-acting antiviral medications for hepatitis C virus infection have high cure rates and are well tolerated. Small, single-center trials in kidney and heart transplant recipients have demonstrated that with early posttransplant direct-acting antiviral therapy, 100% of uninfected recipients of hepatitis C viremic organs have been cured of infection after transplantation.

SUMMARY

In this manuscript, we review the risks and rewards of utilizing hepatitis C viremic organs for transplantation.

Complement Therapeutics in the Multi-Organ Donor: Do or Don't?

Over the last decade, striking progress has been made in the field of organ transplantation, such as better surgical expertise and preservation techniques. Therefore, organ transplantation is nowadays considered a successful treatment in end-stage diseases of various organs, e.g. the kidney, liver, intestine, heart, and lungs. However, there are still barriers which prevent a lifelong survival of the donor graft in the recipient. Activation of the immune system is an important limiting factor in the transplantation process. As part of this pro-inflammatory environment, the complement system is triggered. Complement activation plays a key role in the transplantation process, as highlighted by the amount of studies in ischemia-reperfusion injury (IRI) and rejection. However, new insight have shown that complement is not only activated in the later stages of transplantation, but already commences in the donor. In deceased donors, complement activation is associated with deteriorated quality of deceased donor organs. Of importance, since most donor organs are derived from either brain-dead donors or deceased after circulatory death donors. The exact mechanisms and the role of the complement system in the pathophysiology of the deceased donor have been underexposed. This review provides an overview of the current knowledge on complement activation in the (multi-)organ donor. Targeting the complement system might be a promising therapeutic strategy to improve the quality of various donor organs. Therefore, we will discuss the complement therapeutics that already have been tested in the donor. Finally, we question whether complement therapeutics should be translated to the clinics and if all organs share the same potential complement targets, considering the physiological differences of each organ.

Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations

Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.

Myocardial Stunning After Electrocution With Complete Reversibility Within 24 Hours: Role of Repeat Transthoracic Echocardiograms in Potential Cardiac Transplant Donors

Despite the development of ventricular assist devices, cardiac transplantation remains an important procedure for patients with advanced heart failure. The number of transplants done annually has remained stable because of lack of of donors. Left ventricular systolic dysfunction remains one of the most important reasons for seeking a donor heart. Myocardial stunning is an important cause of reversible systolic dysfunction. Electrical injury is a recognized cause of myocardial stunning with variable duration ranging from days to weeks. Repeating the transthoracic echocardiogram to look for reversibility of left ventricular dysfunction can be a cost-effective method to improve the selection of heart donors. This can significantly help to decrease critical organ shortage. We present a case of myocardial stunning after electrocution which was completely reversible within a few hours, thus meeting cardiac transplant donor criteria.

Effects of Older Donor Age and Cold Ischemic Time on Long-Term Outcomes of Heart Transplantation

Using older donor hearts in cardiac transplantation may lead to inferior outcomes: older donors have more comorbidities that reduce graft quality, including coronary artery disease, hypertension, diabetes mellitus, and dyslipidemia. Shorter cold ischemic times might overcome the detrimental effect of older donor age. We examined the relationship between donor allograft age and cold ischemic time on the long-term outcomes of heart transplant recipients. rom 1994 through 2010, surgeons at our hospital performed 745 heart transplantations. We retrospectively classified these cases by donor ages of <50 years (younger) and ≥50 years (older), then by cold ischemic times of <120 min (short), 120 to 240 min (intermediate), and >240 min (long). Endpoints included recipient and graft survival, and freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, and rejection. For intermediate ischemic times, the 5-year recipient survival rate was lower when donors were older (70% vs 82.6%; P=0.02). This was also true for long ischemic times (69.8% vs 87.6%; P=0.09). For short ischemic times, we found no difference in 5-year recipient or graft survival rates (80% older vs 85.6% younger; P=0.79), in freedom from nonfatal major adverse cardiac events (83.3% vs 91.5%; P=0.46), or in freedom from cardiac allograft vasculopathy (50% vs 70.6%; P=0.66). Rejection rates were mostly similar. Long-term graft survival in heart transplantation patients with older donor allografts may improve when cold ischemic times are shorter.

Urinary Proteomics in Predicting Heart Transplantation Outcomes (uPROPHET)-Rationale and database description

OBJECTIVES

Urinary Proteomics in Predicting Heart Transplantation Outcomes (uPROPHET; NCT03152422) aims: (i) to construct new multidimensional urinary proteomic (UP) classifiers that after heart transplantation (HTx) help in detecting graft vasculopathy, monitoring immune system activity and graft performance, and in adjusting immunosuppression; (ii) to sequence UP peptide fragments and to identify key proteins mediating HTx-related complications; (iii) to validate UP classifiers by demonstrating analogy between UP profiles and tissue proteomic signatures (TP) in diseased explanted hearts, to be compared with normal donor hearts; (iv) and to identify new drug targets. This article describes the uPROPHET database construction, follow-up strategies and baseline characteristics of the HTx patients.

METHODS

HTx patients enrolled at the University Hospital Gasthuisberg (Leuven) collected mid-morning urine samples. Cardiac biopsies were obtained at HTx. UP and TP methods and the statistical work flow in pursuit of the research objectives are described in detail in the Data supplement.

RESULTS

Of 352 participants in the UP study (24.4% women), 38.9%, 40.3%, 5.7% and 15.1% had ischemic, dilated, hypertrophic or other cardiomyopathy. The median interval between HTx and first UP assessment (baseline) was 7.8 years. At baseline, mean values were 56.5 years for age, 25.2 kg/m2 for body mass index, 142.3/84.8 mm Hg and 124.2/79.8 mm Hg for office and 24-h ambulatory systolic/diastolic pressure, and 58.6 mL/min/1.73 m2 for the estimated glomerular filtration rate. Of all patients, 37.2% and 6.5% had a history of mild (grade = 1B) or severe (grade ≥ 2) cellular rejection. Anti-body mediated rejection had occurred in 6.2% patients. The number of follow-up urine samples available for future analyses totals over 950. The TP study currently includes biopsies from 7 healthy donors and 15, 14, and 3 patients with ischemic, dilated, and hypertrophic cardiomyopathy.

CONCLUSIONS

uPROPHET constitutes a solid resources for UP and TP research in the field of HTx and has the ambition to lay the foundation for the clinical application of UP in risk stratification in HTx patients.

Guidelines for the assessment and acceptance of potential brain-dead organ donors

Organ transplantation is the only alternative for many patients with terminal diseases. The increasing disproportion between the high demand for organ transplants and the low rate of transplants actually performed is worrisome. Some of the causes of this disproportion are errors in the identification of potential organ donors and in the determination of contraindications by the attending staff. Therefore, the aim of the present document is to provide guidelines for intensive care multi-professional staffs for the recognition, assessment and acceptance of potential organ donors.

Novel 24-h ovine model of brain death to study the profile of the endothelin axis during cardiopulmonary injury

BACKGROUND

Upregulation of the endothelin axis has been observed in pulmonary tissue after brain death, contributing to primary graft dysfunction and ischaemia reperfusion injury. The current study aimed to develop a novel, 24-h, clinically relevant, ovine model of brain death to investigate the profile of the endothelin axis during brain death-associated cardiopulmonary injury. We hypothesised that brain death in sheep would also result in demonstrable injury to other transplantable organs.

METHODS

Twelve merino cross ewes were randomised into two groups. Following induction of general anaesthesia and placement of invasive monitoring, brain death was induced in six animals by inflation of an extradural catheter. All animals were supported in an intensive care unit environment for 24 h. Animal management reflected current human donor management, including administration of vasopressors, inotropes and hormone resuscitation therapy. Activation of the endothelin axis and transplantable organ injury were assessed using ELISA, immunohistochemistry and standard biochemical markers.

RESULTS

All animals were successfully supported for 24 h. ELISA suggested early endothelin-1 and big endothelin-1 release, peaking 1 and 6 h after BD, respectively, but there was no difference at 24 h. Immunohistochemistry confirmed the presence of the endothelin axis in pulmonary tissue. Brain dead animals demonstrated tachycardia and hypertension, followed by haemodynamic collapse, typified by a reduction in systemic vascular resistance to 46 ± 1 % of baseline. Mean pulmonary artery pressure rose to 186 ± 20 % of baseline at induction and remained elevated throughout the protocol, reaching 25 ± 2.2 mmHg at 24 h. Right ventricular stroke work increased 25.9 % above baseline by 24 h. Systemic markers of cardiac and hepatocellular injury were significantly elevated, with no evidence of renal dysfunction.

CONCLUSIONS

This novel, clinically relevant, ovine model of brain death demonstrated that increased pulmonary artery pressures are observed after brain death. This may contribute to right ventricular dysfunction and pulmonary injury. The development of this model will allow for further investigation of therapeutic strategies to minimise the deleterious effects of brain death on potentially transplantable organs.