Cardiac transplantation: indications, eligibility and current outcomes

Hypoxia inducible factor 2α promotes tolerogenic macrophage development during cardiac transplantation through transcriptional regulation of colony stimulating factor 1 receptor

Solid organ transplantation mobilizes myeloid cells, including monocytes and macrophages, which are central protagonists of allograft rejection. However, myeloid cells can also be functionally reprogrammed by perioperative costimulatory blockade to promote a state of transplantation tolerance. Transplantation tolerance holds promise to reduce complications from chronic immunosuppression and promote long-term survival in transplant recipients. We sought to identify different mediators of transplantation tolerance by performing single-cell RNA sequencing of acute rejecting or tolerized cardiac allografts. This led to the unbiased identification of the transcription factor, hypoxia inducible factor (HIF)-2α, in a subset of tolerogenic monocytes. Using flow cytometric analyses and mice with conditional loss or gain of function, we uncovered that myeloid cell expression of HIF-2α was required for costimulatory blockade-induced transplantation tolerance. While HIF-2α was dispensable for mobilization of tolerogenic monocytes, which were sourced in part from the spleen, it promoted the expression of colony stimulating factor 1 receptor (CSF1R). CSF1R mediates monocyte differentiation into tolerogenic macrophages and was found to be a direct transcriptional target of HIF-2α in splenic monocytes. Administration of the HIF stabilizer, roxadustat, within micelles to target myeloid cells, increased HIF-2α in splenic monocytes, which was associated with increased CSF1R expression and enhanced cardiac allograft survival. These data support further exploration of HIF-2α activation in myeloid cells as a therapeutic strategy for transplantation tolerance.

Understanding Tricuspid Regurgitation Post Cardiac Transplantation; Why "Anatomical" and "Functional" Just Won't Cut It

Tricuspid regurgitation (TR) is common after cardiac transplantation and results in poorer outcomes. Transplant recipients are at high prohibitive risk for redo surgical procedures because of risks associated with a subsequent sternotomy, immunosuppression, and renal failure. Percutaneous therapies have recently become available and may be an option for transplant recipients. However, transplant recipients have complex geometry, and there is a myriad of causes of TR posttransplant. There is a need for careful patient selection for all percutaneous valve interventions, and this is particularly true in transplant recipients who suffer from right ventricular failure and rejection and may undergo repeated endomyocardial biopsies. Cognizant of the rapid developments in this space, this review article focuses on the causes of TR, treatments, and future therapies in heart transplantation recipients to the transplant cardiologist navigate this complex area.

Left ventricular assist device implantation and concomitant mitral valve surgery: A systematic review and meta-analysis

BACKGROUND

The management of concomitant valvular lesions in patients undergoing left ventricular assist device (LVAD) implantation remains a topic of debate. This systematic review and meta-analysis aimed to evaluate the existing evidence on postoperative outcomes following LVAD implantation, with and without concomitant MV surgery.

METHODS

A systematic database search was conducted as per PRISMA guidelines, of original articles comparing LVAD alone to LVAD plus concomitant MV surgery up to February 2023. The primary outcomes assessed were overall mortality and early mortality, while secondary outcomes included stroke, need for right ventricular assist device (RVAD) implantation, postoperative mitral valve regurgitation, major bleeding, and renal dysfunction.

RESULTS

The meta-analysis included 10 studies comprising 32 184 patients. It revealed that concomitant MV surgery during LVAD implantation did not significantly affect overall mortality (OR:0.83; 95% CI: 0.53 to 1.29; p = 0.40), early mortality (OR:1.17; 95% CI: 0.63 to 2.17; p = 0.63), stroke, need for RVAD implantation, postoperative mitral valve regurgitation, major bleeding, or renal dysfunction. These findings suggest that concomitant MV surgery appears not to confer additional benefits in terms of these clinical outcomes.

CONCLUSION

Based on the available evidence, concomitant MV surgery during LVAD implantation does not appear to have a significant impact on postoperative outcomes. However, decision-making regarding MV surgery should be individualized, considering patient-specific factors and characteristics. Further research with prospective studies focusing on specific patient populations and newer LVAD devices is warranted to provide more robust evidence and guide clinical practice in the management of valvular lesions in LVAD recipients.

Digital pathology in cardiac transplant diagnostics: from biopsies to algorithms

In the field of heart transplantation, the ability to accurately and promptly diagnose cardiac allograft rejection is crucial. This comprehensive review explores the transformative role of digital pathology and computational pathology, especially through machine learning, in this critical domain. These methodologies harness large datasets to extract subtle patterns and valuable information that extend beyond human perceptual capabilities, potentially enhancing diagnostic outcomes. Current research indicates that these computer-based systems could offer accuracy and performance matching, or even exceeding, that of expert pathologists, thereby introducing more objectivity and reducing observer variability. Despite promising results, several challenges such as limited sample sizes, diverse data sources, and the absence of standardized protocols pose significant barriers to the widespread adoption of these techniques. The future of digital pathology in heart transplantation diagnostics depends on utilizing larger, more diverse patient cohorts, standardizing data collection, processing, and evaluation protocols, and fostering collaborative research efforts. The integration of various data types, including clinical, demographic, and imaging information, could further refine diagnostic precision. As researchers address these challenges and promote collaborative efforts, digital pathology has the potential to become an integral part of clinical practice, ultimately improving patient care in heart transplantation.

Recent advances in soluble decellularized extracellular matrix for heart tissue engineering and organ modeling

Despite the advent of tissue engineering (TE) for the remodeling, restoring, and replacing damaged cardiovascular tissues, the progress is hindered by the optimal mechanical and chemical properties required to induce cardiac tissue-specific cellular behaviors including migration, adhesion, proliferation, and differentiation. Cardiac extracellular matrix (ECM) consists of numerous structural and functional molecules and tissue-specific cells, therefore it plays an important role in stimulating cell proliferation and differentiation, guiding cell migration, and activating regulatory signaling pathways. With the improvement and modification of cell removal methods, decellularized ECM (dECM) preserves biochemical complexity, and bio-inductive properties of the native matrix and improves the process of generating functional tissue. In this review, we first provide an overview of the latest advancements in the utilization of dECM in in vitro model systems for disease and tissue modeling, as well as drug screening. Then, we explore the role of dECM-based biomaterials in cardiovascular regenerative medicine (RM), including both invasive and non-invasive methods. In the next step, we elucidate the engineering and material considerations in the preparation of dECM-based biomaterials, namely various decellularization techniques, dECM sources, modulation, characterizations, and fabrication approaches. Finally, we discuss the limitations and future directions in fabrication of dECM-based biomaterials for cardiovascular modeling, RM, and clinical translation.

The ABC of Heart Transplantation-Part 1: Indication, Eligibility, Donor Selection, and Surgical Technique

Cardiac transplantation represents the gold standard of treatment for selected patients with advanced heart failure who have poor functional capacity and prognosis despite guideline-directed medical therapy and device-based therapy. Proper patient selection and appropriate referral of patients to centers for the treatment of advanced heart failure are the first but decisive steps for screening patients eligible for cardiac transplantation. The eligibility and the decision to list for cardiac transplantation, even for patients with relative contraindications, are based on a multidisciplinary evaluation of a transplant team. This review will discuss the practical indications, the process of patient eligibility for cardiac transplantation, the principle of donor selection, as well as the surgical technique.

How to Select Patients for Left Ventricular Assist Devices? A Guide for Clinical Practice

In recent years, a significant improvement in left ventricular assist device (LVAD) technology has occurred, and the continuous-flow devices currently used can last more than 10 years in a patient. Current studies report that the 5-year survival rate after LVAD implantation approaches that after a heart transplant. However, the outcome is influenced by the correct selection of the patients, as well as the choice of the optimal time for implantation. This review summarizes the indications, the red flags for prompt initiation of LVAD evaluation, and the principles for appropriate patient screening.

Primary cardiac sarcomas: A clinicopathologic study in a single institution with 25 years of experience with an emphasis on MDM2 expression and adjuvant therapy for prognosis

BACKGROUND

Primary cardiac sarcomas are rare and their clinicopathologic features are heterogeneous. Among them, particularly intimal sarcoma is a diagnostic challenge due to nonspecific histologic features. Recently, MDM2 amplification reported to be a characteristic genetic event in the intimal sarcoma. In this study, we aimed to identify the types and incidence of primary cardiac sarcomas that occurred over 25 years in tertiary medical institutions, and to find clinicopatholgical significance through reclassification of diagnoses using additional immunohistochemistry (IHC).

METHODS

We reviewed the primary cardiac sarcoma cases between January 1993 and June 2018 at Asan Medical Center, South Korea, with their clinicopathologic findings, and reclassified the subtypes, especially using IHC for MDM2 and then, analyzed the significance of prognosis.

RESULTS

Forty-eight (6.8%) cases of a primary cardiac sarcoma were retrieved. The tumors most frequently involved the right atrium (n = 25, 52.1%), and the most frequent tumor subtype was angiosarcoma (n = 23, 47.9%). Seven cases (53.8%) were newly reclassified as an intimal sarcoma by IHC for MDM2. Twenty-nine (60.4%) patients died of disease (mean, 19.8 months). Four patients underwent a heart transplantation and had a median survival of 26.8 months. This transplantation group tended to show good clinical outcomes in the earlier stages, but this was not statistically significant (p = 0.318). MDM2 positive intimal sarcoma showed the better overall survival (p = 0.003) than undifferentiated pleomorphic sarcoma. Adjuvant treatment is beneficial for patient survival (p < 0.001), particularly in angiosarcoma (p < 0.001), but not in intimal sarcoma (p = 0.154).

CONCLUSION

Our study supports the use of adjuvant treatment in primary cardiac sarcoma, as it was associated with a significantly better overall survival rate. Further consideration of tumor histology may be important in determining the optimal use of adjuvant treatment for different types of sarcomas. Therefore, accurate diagnosis by MDM2 test is important condsidering patient's prognosis and treatment.

Endothelial cell direct reprogramming: Past, present, and future

Ischemic cardiovascular disease still remains as a leading cause of morbidity and mortality despite various medical, surgical, and interventional therapy. As such, cell therapy has emerged as an attractive option because it tackles underlying problem of the diseases by inducing neovascularization in ischemic tissue. After overall failure of adult stem or progenitor cells, studies attempted to generate endothelial cells (ECs) from pluripotent stem cells (PSCs). While endothelial cells (ECs) differentiated from PSCs successfully induced vascular regeneration, differentiating volatility and tumorigenic potential is a concern for their clinical applications. Alternatively, direct reprogramming strategies employ lineage-specific factors to change cell fate without achieving pluripotency. ECs have been successfully reprogrammed via ectopic expression of transcription factors (TFs) from endothelial lineage. The reprogrammed ECs induced neovascularization in vitro and in vivo and thus demonstrated their therapeutic value in animal models of vascular insufficiency. Methods of delivering reprogramming factors include lentiviral or retroviral vectors and more clinically relevant, non-integrative adenoviral and episomal vectors. Most studies made use of fibroblast as a source cell for reprogramming, but reprogrammability of other clinically relevant source cell types has to be evaluated. Specific mechanisms and small molecules that are involved in the aforementioned processes tackles challenges associated with direct reprogramming efficiency and maintenance of reprogrammed EC characteristics. After all, this review provides summary of past and contemporary methods of direct endothelial reprogramming and discusses the future direction to overcome these challenges to acquire clinically applicable reprogrammed ECs.

Mildly Elevated Pulmonary Artery Systolic Pressure is Associated with Extracorporeal Membrane Oxygenation Support after Heart Transplantation

Background. Pulmonary hypertension is a well-known risk factor for hemodynamic instability after heart transplantation. However, it remains unclear whether a mild elevation of pulmonary artery systolic pressure (PASP) is associated with higher risks of graft dysfunction and resultant extracorporeal membrane oxygenation (ECMO) support. Methods. From 2016 to 2021, 102 adult recipients undergoing orthotopic heart transplantation at our institution were investigated (mean age, 48.5 ± 13.2 years; 22.5% female). This study cohort was stratified into 3 groups based on the PASP measured by right heart catheterization before surgery: >50 mmHg, 35–50 mmHg, and <35 mmHg. The primary end point was ECMO support after procedure. Results. ECMO was implemented in 24 (23.5%) patients due to difficult weaning from cardiopulmonary bypass or cardiac low output in the intensive care unit, which was likely to be associated with higher mortality ( $P=0.053$ ). Age, gender, comorbidities, preoperative medications, and graft ischemia time were comparable across the 3 groups. The use of ECMO was significantly more common in patients with baseline PASP >50 mmHg (11/36, 30.6%) and 35–50 mmHg (12/38, 31.6%), while only 1 (3.6%) patient with baseline PASP <35 mmHg required ECMO support after transplant ( $P=0.007$ ). Multivariate logistic models demonstrated that PASP (odds ratio = 2.34; $P=0.028$ ) and cardiopulmonary bypass time (odds ratio = 1.01; $P<0.001$ ) were independent risk factors for postoperative ECMO. Conclusions. A mild elevation of pretransplant PASP (e.g., 35–50 mmHg) is related to low cardiac output and subsequent ECMO after heart transplantation, for which prompt administration of vasodilators before transplant may be protective.

The ebb and flow of cardiac lymphatics: a tidal wave of new discoveries

The heart is imbued with a vast lymphatic network that is responsible for fluid homeostasis and immune cell trafficking. Disturbances in the forces that regulate microvascular fluid movement can result in myocardial edema, which has profibrotic and proinflammatory consequences and contributes to cardiovascular dysfunction. This review explores the complex relationship between cardiac lymphatics, myocardial edema, and cardiac disease. It covers the revised paradigm of microvascular forces and fluid movement around the capillary as well as the arsenal of preclinical tools and animal models used to model myocardial edema and cardiac disease. Clinical studies of myocardial edema and their prognostic significance are examined in parallel to the recent elegant animal studies discerning the pathophysiological role and therapeutic potential of cardiac lymphatics in different cardiovascular disease models. This review highlights the outstanding questions of interest to both basic scientists and clinicians regarding the roles of cardiac lymphatics in health and disease.

Emerging technologies and ethics-exogenic chimeric humanized organs

Organ transplantation is limited due to the scarcity of donor organs. In order to expand the supply of organs for transplantation, interspecies chimeras have been examined as a potential future source of humanized organs. Recent studies using gene editing technologies in combination with somatic cell nuclear transfer technology and hiPSCs successfully engineered humanized skeletal muscle in the porcine embryo. As these technologies progress, there are ethical issues that warrant consideration and dialogue.

Generation and Application of Directly Reprogrammed Endothelial Cells

Cell-based therapy has emerged as a promising option for treating advanced ischemic cardiovascular disease by inducing vascular regeneration. However, clinical trials with adult cells turned out disappointing in general. As a newer approach, direct reprogramming has emerged to efficiently generate endothelial cells (ECs), which can promote neovascularization and vascular regeneration. This review provides recent updates on the direct endothelial reprogramming. In general, directly reprogrammed ECs can be generated by two approaches: one by transitioning through a plastic intermediate state and the other in a one-step transition without any intermediate states toward pluripotency. Moreover, the methods to deliver reprogramming factors and chemicals for the fate conversion are highlighted. Next, the therapeutic effects of the directly reprogrammed ECs on animal models are reviewed in detail. Other applications using directly reprogrammed ECs, such as tissue engineering and disease modeling, are also discussed. Lastly, the remaining questions and foremost challenges are addressed.

Kidney Re-Transplantation after Simultaneous Heart and Kidney Transplant: Case Study and Literature Review

The kidney is one of most frequent transplants to be performed in multi-organ transplantation. A simultaneous heart and kidney transplant (SHKT) is the best-known treatment method in patients with severe heart failure and end-stage renal disease (ESRD). Here, the authors describe the case of a kidney re-transplantation after SHKT, which is in accordance with the majority of studies, and proves the safety of simultaneous procedures. The article highlights the complex care required after the transplant, followed by the multi-factor qualification for re-transplantation. In conclusion, the case shows that SHKT provides long-term favorable outcomes and enables a repeated kidney transplantation with satisfactory one-year follow-up results.

Cardiac rehabilitation in a heart failure patient after left ventricular assist device insertion and subsequent heart transplantation: A case report

BACKGROUND

Insertion of a left ventricular assist device (LVAD) and heart transplantation (HT) improve the survival of patients with heart failure. In addition, cardiac rehabilitation (CR) further increases the functional capacity. This case report describes a successful case of CR after LVAD insertion and subsequent HT.

CASE SUMMARY

In the present case, during the LVAD insertion period, peak oxygen consumption (VO₂) increased by 12.16% after CR. HT was performed 7 mo after the LVAD insertion, and the patient participated in phases I and II CR. The peak VO₂ increased from 17.24 to 22.29 mL/kg/min. This improvement was more significant than that reported in previous studies on CR after LVAD insertion or HT. The patient’s quality of life also improved. The total average score of the short form-36 questionnaire increased from 29.5 points at admission to 53.3 points 9 mo after HT.

CONCLUSION

A tailored CR program after LVAD insertion or HT may improve the patients’ quality of life and increase survival.

The prognostic value of neutrophil-to-lymphocyte ratio across all stages of coronary artery disease

The natural history of coronary heart disease (CAD) commonly begins with atherosclerosis, progressing to chronic coronary syndrome (CCS), acute coronary syndrome (ACS), and eventually, heart failure. Despite advancements in preventive and therapeutic strategies, there is room for further cardiovascular risk reduction. Recently, inflammation has emerged as a potential therapeutic target. The neutrophil-to-lymphocyte ratio (NLR) is a novel inflammatory biomarker which predicts poor prognosis in several conditions such as metabolic syndrome, sepsis, malignancy and CAD. In atherosclerosis, a high NLR predicts plaque vulnerability and severe stenosis. This is consistent with observations in CCS, where an elevated NLR predicts long-term major adverse cardiac events (MACEs). In ACS patients, high NLR levels are associated with larger infarct sizes and poor long-term outcomes. Possible reasons for this include failure of fibrinolysis, ischemia-reperfusion injury and in-stent restenosis, all of which are associated with raised NLR levels. Following myocardial infarction, an elevated NLR correlates with pathological cardiac remodeling which propagates chronic heart failure. Finally, in heart failure patients, an elevated NLR predicts long-term MACEs, mortality, and poor left ventricular assist device and transplant outcomes. Further studies must evaluate whether the addition of NLR to current risk-stratification models can better identify high-risk CAD patients.

Combined heart and liver transplantation: an updated systematic review

INTRODUCTION

Combined heart and liver transplantation (CHLT) is one of the most complex procedures of surgery that has been implemented in the last 35 years. The aim of our meta-analysis was to investigate the safety and efficacy of CHLT.

MATERIALS

The meta-analysis was designed according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) and AMSTAR (A MeaSurement Tool to Assess systematic Reviews) recommendations. A literature search was conducted up to April 2020 using the MEDLINE,® SCOPUS,® ClinicalTrials.gov, Embase™, Cochrane Central Register of Controlled Trials and Google Scholar™ databases.

RESULTS

Our meta-analysis included 16 studies with 860 patients. The mortality rate following CHLT was 14.1%. One and five-year survival rates were 85.3% and 71.4% while the heart and liver rejection rates were 6.1% and 9.1% respectively. The hospital stay was 25.8 days and the intensive care unit stay was 9.9 days. Pooled values were also calculated for cardiopulmonary bypass duration, units of transfused red blood cells and fresh frozen plasma, postoperative infection rate, mechanical ventilation rate and follow-up duration.

CONCLUSIONS

Despite its complexity, CHLT is a safe and effective procedure for the management of lethal diseases that lead to progressive heart and/or liver failure. Nevertheless, there must be strict adherence to the indications for surgery, and future studies should compare CHLT with isolated cardiac and hepatic transplantations.

Self-adhesive hydrogels for tissue engineering

Hydrogels consisting of a three-dimensional hydrophilic network of biocompatible polymers have been widely used in tissue engineering. Owing to their tunable mechanical properties, hydrogels have been applied in both hard and soft tissues. However, most hydrogels lack self-adhesive properties that enable integration with surrounding tissues, which may result in suture or low repair efficacy. Self-adhesive hydrogels (SAHs), an emerging class of hydrogels based on a combination of three-dimensional hydrophilic networks and self-adhesive properties, continue to garner increased attention in recent years. SAHs exhibit reliable and suitable adherence to tissues, and easily integrate into tissues to promote repair efficiency. SAHs are designed either by mimicking the adhesion mechanism of natural organisms, such as mussels and sandcastle worms, or by using supramolecular strategies. This review summarizes the design and processing strategies of SAHs, clarifies underlying adhesive mechanisms, and discusses their applications in tissue engineering, as well as future challenges.

Cardiac Rehabilitation in a Patient With Severe Heart Failure and Ventricular Septal Defect Secondary to Acute Myocardial Infarction

The treatment of choice for patients with advanced heart failure (HF) and with limiting symptoms with evidence of a poor prognosis despite optimal conventional treatment is a heart transplant. However, there is little literature dealing with the effects of cardiovascular prehabilitation with an important change in physical capacity, which can influence the admission on the waiting list for a heart transplant. We presented one young male, smoker, with no prior history of cardiovascular disease, severe ventricular dysfunction, interventricular defect, and HF. It was decided to implant a cardioverter-defibrillator as primary prevention of sudden death and start the pre-cardiac transplant evaluation and subsequent inclusion in the waiting list on an elective basis. While waiting for the transplant, cardiopulmonary rehabilitation (CPR) was indicated. After 15 months of CPR, the patient improved his left ventricular ejection fraction (LVEF; 20% to 40%), systolic pulmonary artery pressure (55 to 40 mmHg), and peak oxygen uptake (23.9 to 29.1 ml/kg/min). In this patient, a program of CPR improved cardiac function and physical capacity, allowing him to be removed from the national waiting list for a heart transplant.

Preserved electrical conduction between donor and recipient right atria as the cause of macroreentrant atrial tachycardia after heart transplantation

Atrial arrhythmias after heart transplantation are common and usually originate from reentrant circuits inside the donor and recipient atria. A case is presented of macroreentrant atrial tachycardia with a reentry circuit incorporating preserved electrical conduction from the donor and recipient right atria. An invasive electrophysiological study including high-density electroanatomical mapping with a multipolar catheter was performed during tachycardia. A reentry circuit with an area of slow conduction at the supero-lateral aspect of the surgical anastomosis could be demonstrated. Catheter ablation at the site of slow conduction successfully terminated and permanently suppressed the tachycardia.

Renoprotection by long-term low-dose tolvaptan in patients with heart failure and hyponatremia

AIMS

In previous randomized controlled trials, the use of tolvaptan (TLV) at a fixed dose of 30 mg/day for 1 year did not provide renal benefits in patients with heart failure (HF). This retrospective, cohort study examined the renoprotective effects of long-term, flexible-dose, and lower-dose TLV use.

METHODS AND RESULTS

Tolvaptan users were defined as patients receiving TLV for at least 180 consecutive days or those who continued it until death, any cardiac events, or renal replacement therapy even if it was taken for <180 days. Of a total of 584 HF patients, 78 TLV users were identified. The median age, baseline B-type natriuretic peptide, and estimated glomerular filtration rate (eGFR) were 71 years, 243 pg/mL, and 54 mL/min/1.73 m² , respectively. During follow-up (median, 461 days), TLV use (median average dose, 7.5 mg/day) was associated with frequent dose reductions of loop diuretics (incidence rate ratio [IRR], 1.5; 95% confidence interval [CI], 1.1-2.2), particularly in patients with serum sodium ≤135 mEq/L (IRR, 2.9; 95% CI, 1.5-5.7) (P_interaction  = 0.04). In a mixed effects model, propensity score (PS)-matched TLV users had higher eGFRs over time than PS-matched never-users (P < 0.01). The entire cohort analyses (N = 584) yielded similar results. The renal benefit of TLV in terms of annualized eGFR slope was more pronounced in patients with lower sodium levels (P_interaction  = 0.03). This effect modification was extinguished when patients who underwent a loop diuretic dose reduction during the follow-up period were excluded from the analysis.

CONCLUSIONS

Long-term, flexible-dose, and low-dose TLV use was associated with better renal function, particularly in hyponatremic HF, possibly due to its loop diuretic dose-sparing effect in the long term.

Zebrafish as a New Tool in Heart Preservation Research

Heart transplantation became a reality at the end of the 1960s as a life-saving option for patients with end-stage heart failure. Static cold storage (SCS) at 4-6 °C has remained the standard for heart preservation for decades. However, SCS only allows for short-term storage that precludes optimal matching programs, requires emergency surgeries, and results in the unnecessary discard of organs. Among the alternatives seeking to extend ex vivo lifespan and mitigate the shortage of organs are sub-zero or machine perfusion modalities. Sub-zero approaches aim to prolong cold ischemia tolerance by deepening metabolic stasis, while machine perfusion aims to support metabolism through the continuous delivery of oxygen and nutrients. Each of these approaches hold promise; however, complex barriers must be overcome before their potential can be fully realized. We suggest that one barrier facing all experimental efforts to extend ex vivo lifespan are limited research tools. Mammalian models are usually the first choice due to translational aspects, yet experimentation can be restricted by expertise, time, and resources. Instead, there are instances when smaller vertebrate models, like the zebrafish, could fill critical experimental gaps in the field. Taken together, this review provides a summary of the current gold standard for heart preservation as well as new technologies in ex vivo lifespan extension. Furthermore, we describe how existing tools in zebrafish research, including isolated organ, cell specific and functional assays, as well as molecular tools, could complement and elevate heart preservation research.

Decreased Nutritional Risk Index is associated with mortality after heart transplantation

INTRODUCTION

Validated scoring tools, such as the Nutritional Risk Index (NRI), can aid clinicians in quantifying the degree of malnourishment in patients prior to an operation. We evaluated the association between NRI and outcomes after heart transplantation.

METHODS

The United Network for Organ Sharing (UNOS) database was used to identify adult patients (age > 18) undergoing heart transplantation between 1987 and 2016. NRI was calculated and categorized into previously established groupings representing severity of malnutrition. Multivariate Cox proportional hazards modeling were used to assess the primary outcome of all-cause mortality.

RESULTS

A total of 25,236 patients were included in the analysis. Most patients (75.4%) were male. Malnourishment was absent (NRI ≥ 100) in 11,022 (44%) patients, while 2,898 (12%) were mildly malnourished (97.5 ≤ NRI < 100), 8,685 (34%) were moderately malnourished (83.5 ≤ NRI < 97.5), and 2,631 (10%) were severely malnourished (NRI < 83.5). Moderate-to-severe malnutrition was associated with increased mortality (HR = 1.18, p < .001, 95%CI: 1.13-1.24), and post-transplant renal failure requiring dialysis (OR: 1.13, p < .001, 95%CI: 1.03-1.23).

CONCLUSION

Malnourishment determined by NRI is independently associated with mortality and post-transplant dialysis after heart transplant. This is the largest study of NRI in heart transplant recipients.

Artemisinin Attenuates Transplant Rejection by Inhibiting Multiple Lymphocytes and Prolongs Cardiac Allograft Survival

Immunological rejection is an important factor resulting in allograft dysfunction, and more valid therapeutic methods need to be explored to improve allograft outcomes. Many researches have indicated that artemisinin and its derivative exhibits immunosuppressive functions, apart from serving as a traditional anti-malarial drug. In this assay, we further explored the therapeutic effects of artemisinin for transplant rejection in a rat cardiac transplantation model. We found that it markedly attenuated allograft rejection and histological injury and significantly prolonged the survival of allograft. Upon further exploring the mechanism, we demonstrated that artemisinin not only attenuated T cell-mediated rejection (TCMR) by reducing effector T cell infiltration and inflammatory cytokine secretion and increasing regulatory T cell infiltration and immunoregulatory cytokine levels, but also attenuated antibody-mediated rejection (ABMR) through inhibition of B cells activation and antibody production. Furthermore, artemisinin also reduced macrophage infiltration in allografts, which was determined to be important for TCMR and ABMR. Moreover, we demonstrated that artemisinin significantly inhibited the function of pure T cells, B cells, and macrophages in vitro. All in all, this study provide evidence that artemisinin significantly attenuates TCMR and ABMR by targeting multiple effectors. Therefore, this agent might have potential for use in clinical settings to protect against transplant rejection.

Contemporary review of exercise in heart transplant recipients

Heart transplantation (HTx) is a therapeutic option for a selected group of patients with end-stage heart failure. Although secondary prevention including exercise therapy is recommended in the management of patients following HTx, little information is available on their metabolic and physiological consequences in HTx. Therefore, we aimed to conduct a contemporary review the effectiveness of exercise therapy on functional capacity, cardiovascular health and health-related quality of life for adult HTx patients. We searched the database MEDLINE for articles published between January 2015 and October 2020 and were able to include 6 studies involving 202 patients. Larger improvements in exercise capacity were seen after high-intensity interval training and in patients with evidence of cardiac reinnervation. Clinically relevant reductions were observed for daytime and 24 h ambulatory blood pressure after exercise training and following a single bout of aerobic exercise. Finally, limited data suggest that quality of life is higher in HTx patients following high-intensity training. In summary, the available evidence shows the potential for exercise as a vital treatment in patients following HTx. Yet, the scant data calls for more well-designed and adequately powered studies to support its effectiveness and to unravel optimal exercise characteristics, which would allow for more effective and person-tailored exercise prescription.

Dose- and Time-Dependent Effects of Human Mesenchymal Stromal Cell Infusion on Cardiac Allograft Rejection in Mice

Heart transplantation is the final life-saving therapeutic strategy for many end-stage heart diseases. Long-term immunosuppressive regimens are needed to prevent allograft rejection. Mesenchymal stromal cells (MSCs) have been shown as immunomodulatory therapy for organ transplantation. However, the effect of dose and timing of MSC treatment on heart transplantation has not yet been examined. In this study, we infused three doses (1 × 106, 2 × 106, or 5 × 106 cells) of human MSCs (hMSCs) to the recipient BALB/c mice before (7 days or 24 h) or after (24 h) receiving C57BL/6 cardiac transplants. We found that infusion of high dose hMSCs (5 × 106) at 24 h post-transplantation significantly prolonged the survival time of cardiac grafts. To delineate the underlying mechanism, grafts, spleens, and draining lymph nodes were harvested for analysis. Dose-dependent effect of hMSC treatment was shown in: (1) alleviation of International Society of Heart and Lung Transplantation (ISHLT) score in grafts; (2) reduction of the population of CD4+ and CD8+ T cells; (3) increase of regulatory T (Treg) cells; (4) and decrease of serum levels of inflammatory cytokines and donor-specific antibodies. Taken together, we showed timing critical and dose-dependent immunomodulatory effects of hMSC treatment against acute allograft rejection in a mouse model of heart transplantation.

Implications for body weight extremes in solid organ transplantation

The pharmacokinetic profiles of medications are altered in overweight and underweight patients, but few studies have described these differences in patients with body mass index extremes. As solid organ transplant programs expand their candidate selection criteria to accommodate a growing population of patients with weight extremes, it has become imperative to understand and evaluate the impact weight extremes have on the pharmacokinetics of life-sustaining immunosuppression in this population. This review will describe pharmacokinetic and dosing considerations for weight extremes in solid organ transplant recipients, including changes following bariatric surgeries, non-pharmacologic and pharmacologic management strategies for weight loss and gain, and potential drug-drug interactions with popular weight management products.

Donor-recipient Matching in Heart Transplantation

Heart transplantation remains the treatment of choice for end-stage Heart Failure (HF). Due to the shortage of organs for transplantation and the occurrence of perioperative complications, a key problem is donor matching, which should result in increased survival and improved quality of life for patients. The success of this procedure depends on various parameters such as gender, weight, ABO blood group and Human Leukocyte Antigen (HLA) system of both the recipient and the donor. Furthermore, non-HLA antigens may also be valuable in donor-recipient matching. The aim of this article is to summarize the recent knowledge on the impact of various factors on accurate donor-recipient matching to heart transplantation.

Cytomegalovirus chemokine receptor M33 knockout reduces chronic allograft rejection in a murine aortic transplant model

BACKGROUND

Numerous studies suggest that cytomegalovirus (CMV) infection may act as isolated risk factor in the development of cardiac allograft vasculopathy (CAV). Viral G protein-coupled receptors (GPCRs) are thought to contribute to the pathogenic changes associated with CMV infection. The aim of this study was to investigate the role of murine cytomegalovirus GPCR M33 in the development of CAV in a murine aortic allograft model.

METHODS

MHC I-mismatched aortas of C.B10 (H2^b) mice were transplanted into BALB/c (H2^d) recipients, which were either mock-infected, infected with wild type (WT) MCMV or MCMV with a deleted M33-receptor gene (delM33). Persistence of cytomegalovirus infection was confirmed by qPCR and by luciferase assay to ensure active viral replication. Grafts were harvested on days 21 and 37 for intragraft mRNA expression and histological analysis.

RESULTS

Active viral replication was demonstrated and MCMV presence was confirmed by PCR within spleen, liver, salivary glands, lung and the aortic transplant. Infection with delM33 resulted in significantly less intimal proliferation compared to WT-MCMV but more pronounced proliferation than in mock-infected allografts (32.19% [delM33] vs. 41.71% [WT-MCMV] vs. 24.33% [MCMV-]). Intragraft expression of most analyzed genes was significantly increased in infected mice. VCAM-1, ICAM-1, PDGFβ, CXCR3 and Granzyme B were distinctly less expressed in grafts of delM33 infected compared to WT infected mice. Cellular infiltration revealed reduced dendritic cells and T cells in grafts infected with delM33 compared to WT MCMV.

CONCLUSIONS

These data suggest that the MCMV encoded receptor M33 plays an important role as a viral effector mechanism contributing to the development of CAV in a murine aortic transplant model.

Developing a Heart Transplantation Self-Management Support Mobile Health App in Taiwan: Qualitative Study

BACKGROUND

Heart transplantation (HTx) is the most effective treatment for end-stage heart failure patients. After transplantation, patients face physiological, psychological, social, and other health care problems. Mobile health (mHealth) apps can change the delivery of conventional health care to ubiquitous care and improve health care quality. However, a dearth of mHealth apps exists for patients with HTx worldwide, including in Taiwan.

OBJECTIVE

The aim of this study was to investigate the information needed and to develop a preliminary framework for an mHealth app for post-HTx patients.

METHODS

A qualitative approach with individual in-depth interviews was conducted at a heart center in the regional hospital of northern Taiwan from June to November 2017. Patients that had undergone HTx and their health professionals were recruited for purposeful sampling. A semistructured interview guideline was used for individual interviews and transcribed. Thematic analysis was used for data analysis.

RESULTS

A total of 21 subjects, including 17 patients and 4 health professionals, were recruited for the study. The following five major themes were identified: reminding, querying, experience sharing, diet, and expert consulting. Minor themes included a desire to use the app with artificial intelligence and integration with professional management.

CONCLUSIONS

An intelligent mHealth app that addresses the five main themes and integrates the processes of using a mobile app could facilitate HTx self-management for Taiwanese patients.

Management of nonischemic-dilated cardiomyopathies in clinical practice: a position paper of the working group on myocardial and pericardial diseases of Italian Society of Cardiology

: Nonischemic-dilated cardiomyopathy (NIDCM) is an entity that gathers extremely heterogeneous diseases. This awareness, although leading to continuous improvement in survival, has increased the complexity of NIDCM patients' management. Even though the endorsed 'red-flags' approach helps clinicians in pursuing an accurate etiological definition in clinical practice, it is not clear when and how peripheral centers should interact with referral centers with specific expertise in challenging scenarios (e.g. postmyocarditis and genetically determined dilated cardiomyopathy) and with easier access to second-line diagnostic tools and therapies. This position paper will summarize each step in NIDCM management, highlighting the multiple interactions between peripheral and referral centers, from first-line diagnostic workup and therapy to advanced heart failure management and long-term follow-up.

A review of the management of patients with advanced heart failure in the intensive care unit

Despite progress in the medical and device therapy for heart failure (HF), the prognosis for those with advanced HF remains poor. Acute heart failure (AcHF) is the rapid development of, or worsening of symptoms and signs of HF typically leading to hospitalization. Whilst many HF decompensations are managed at a ward-based level, a proportion of patients require higher acuity care in the intensive care unit (ICU). Admission to ICU is associated with a higher risk of in-hospital mortality, and in those who fail to respond to standard supportive and medical therapy, a proportion maybe suitable for mechanical circulatory support (MCS). The optimal pre-operative management of advanced HF patients awaiting durable MCS or cardiac transplantation (CTx) is vital in improving both short and longer-term outcomes. This review will summarize the clinical assessment, hemodynamic profiling and management of the patient with AcHF in the ICU. The general principles of pre-surgical optimization encompassing individual systems (the kidneys, the liver, blood and glycemic control) will be discussed. Other factors impacting upon post-operative outcomes including nutrition and sarcopenia and pre-surgical skin decolonization have been included. Issues specific to durable MCS including the assessment of the right ventricle and strategies for optimization will also be discussed.

Health-Related Quality of Life of Heart Transplant Recipients Living in a Developing Country

BACKGROUND

Heart transplantation (HT) is the treatment for patients with end-stage heart failure (HF). It is hoped that the procedure increases both survival rates and the level of health-related quality of life (HRQoL), which may, however, be compromised by post-transplant complications. The objective of this study was to analyze the level of HRQoL in HT recipients and considered the influence of variables from social and clinical contexts.

MATERIALS AND METHODS

This is a cross-sectional study of HT recipients. The level of HRQoL was assessed by the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire during outpatient consultation.

RESULTS

This study analyzed 186 HT recipients from a total of 192 eligible patients. The median level of HRQoL was ≥67.8 points in all domains of the WHOQOL-BREF questionnaire (physical, psychological, social relationships, and environment) and general score of perception of the level of quality of life (QoL) and health. Variables such as age, ethnicity, per capita income, time from last hospitalization, number of current medications, and number of hospitalizations after HT were significantly related to at least 1 domain of the WHOQOL-BREF.

CONCLUSION

In this study, HRQoL of HT recipients living in a developing country can be considered satisfactory given the high score obtained in all domains of WHOQOL-BREF and in the perception of the level of QoL and health.

Impact of Preoperative Pulmonary Hypertension on Survival in Patients Undergoing Elective Heart Transplant

BACKGROUND

Pulmonary arterial hypertension (PAH) represents a marker of bad prognosis in left heart disease. Nonetheless, the effect on survival after heart transplant remains controversial. The objective was to study the impact of preoperative PAH on survival in patients undergoing elective heart transplant.

METHODS

A retrospective study of 173 transplant recipients was conducted at a single hospital from January 2009 to December 2018. Congenital etiology and emergent heart transplant were exclusion criteria as well as those patients without enough data in the hemodynamic study. Two groups were considered: A (without PAH) and B (with HTP). PAH was classified as mild (mean pulmonary arterial pressure [mPAP] 25-34 mm Hg, pulmonary vascular resistance [PVR] 2.5-3.4 Wood units and/or transpulmonary gradient [TPG] 13-16 mm Hg), moderate (mPAP 35-44 mm Hg, PVR 3.5-4.9 Wood units and/or TPG 17-19 mm Hg), and severe (mPAP > 44 mm Hg, PVR > 4.9 Wood units and/or TPG > 19 mm Hg).

RESULTS

A total of 102 patients were enrolled; 71.6% were male and average age was 52.3 (SD, 10.02) years. The main etiology was ischemic cardiomyopathy; 13.7% underwent previous heart operations. A total of 61 patients (59.8%) had PAH prior to heart transplant: 25 mild, 34 moderate, and 2 severe. Mean overall survival after transplant was 79.9 (SD, 5.68) months, without differences between the 2 groups (P = .82). One-month survival was 89% (the main cause of mortality was primary graft dysfunction), and 1-year survival was 78%. Four patients required mechanical circulatory support during early post-transplant period.

CONCLUSIONS

Preoperative PAH does not have a significant impact on survival in elective heart transplant.

Kidney transplantation and cardiomyopathy: Concepts and controversies in clinical decision-making

Increasing comorbidities and an aging population have led to a tremendous increase in the burden of both kidney and cardiac dysfunction. Concomitant cardiomyopathy exposes the patients with kidney disease to further physiological, hemodynamic, and pathologic alterations. Kidney transplantation imposes lesser anesthetic and surgical complexities compared to another solid organ transplant. The surgical decision-making remains an unsettled issue in these conditions. The surgical choices, techniques, and sequences in kidney transplant and cardiac surgery depend on the pathophysiological perturbations and perioperative outcomes. The absence of randomized controlled trials eludes us from suggesting definite management protocol in patients with end-stage kidney disease with cardiomyopathy. Nevertheless, in this review, we extracted data from published literature to understand the pathophysiologic interactions between end-stage renal diseases with cardiomyopathy and also proposed the management algorithm in this challenging scenario. The proposed management algorithm would ensure consensus across all stakeholders involved in decision-making. Our simplistic evidence-based approach would augur future randomized trials and would further ensure refinement in our management approach after the emergence of more definitive evidence.