The Challenge of Improving Donor Heart Preservation

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Overview of the FDA's Circulatory System Devices Panel virtual meeting on the TransMedics Organ Care System (OCS) Heart - portable extracorporeal heart perfusion and monitoring system

There are a limited number of donor hearts available for transplantation every year, and an even lower number of these hearts actually undergo transplantation. One of the barriers to utilizing donor hearts is the inferior outcomes associated with prolonged ischemic times. There have been increasing attempts to develop alternative techniques for prolonged storage to raise the number of heart transplants while maintaining acceptable outcomes. One such new technology utilizes continuous ex vivo perfusion of the donor heart with oxygenated blood and allows for prolonged storage and preservation times. The TransMedics Organ Care System (OCS) Heart (TransMedics; Andover, MA) claims to optimize the condition of the donor organs by preserving them in a warm, functioning environment. On April 6, 2021, the United States Food and Drug Administration convened a virtual meeting of the Circulatory System Devices Panel of the Medical Devices Advisory Committee to provide guidance on the TransMedics OCS Heart System's application for premarket approval. This application was subsequently approved on September 7, 2021. We provide an overview of the meeting, including the results of the clinical trials that were presented.

Depression and Pain in Heart Transplant Recipients

Characterizing how physical and psychological symptoms interact in heart transplant recipients may lead to advances in therapeutic options. This study examined associations between pain and major depression.

Method:

A cross-sectional study was conducted with adult heart transplant recipients. Pain was measured with the bodily pain domain of the Short Form-36 Health Survey and psychological distress with the Kessler Psychological Distress Scale (K-10). The Mini International Neuropsychiatric Interview, version 6.0, was used to identify participants meeting the criteria for major depression. Hierarchical linear regression was used to determine if there was an association between pain and major depression, controlling for pharmacological treatment of depression, severity of psychological distress, and clinical characteristics including immunosuppression medication which may induce pain as a side effect.

Results:

Average pain score of the 48 heart transplant recipients was 43 ( SD ± 10, range 0–100, lower scores indicate worse pain), with moderate pain reported by 39% ( n = 19). Major depression was associated with worse pain ( R2 change = 36%, β = −16, 95% confidence interval [CI] = [−30, −4], p = .012). Pharmacological treatment for depression was associated with better pain scores ( R2 change = 1.5%, β = 13, 95% CI [4, 23], p = .006).

Conclusions:

Heart transplant recipients with major depression had worse pain after controlling for pharmacological treatment of depression, severity of psychological distress, and clinical characteristics. Thus, it is imperative that clinicians devising a treatment regimen for pain in heart transplant recipients take into account co-occurring depression and vice versa.

Marginal donors: can older donor hearts tolerate prolonged cold ischemic storage?

BACKGROUND AND AIMS

Both advanced donor age and prolonged ischemic time are significant risk factors for the 1-year mortality. However, its functional consequences have not been fully evaluated in the early-phase after transplantation; even early graft dysfunction is the main determinant of long-term outcome following transplantation. We evaluated in vivo left-ventricular (LV) cardiac and coronary vascular function of old-donor grafts after short and prolonged cold ischemic times in rats 1 h after heart transplantation.

METHODS

The hearts were excised from young donor (3-month-old) or old donor (18-month-old) rats, stored in cold preservation solution for either 1 or 8 h, and heterotopically transplanted.

RESULTS

After 1 h of ischemic period, in the old-donor group, LV pressure, maximum pressure development (dP/dt max), time constant of LV pressure decay (τ), LV end-diastolic pressure and coronary blood flow did not differ compared with young donors. However, endothelium-dependent vasodilatation to acetylcholine resulted in a significantly lower response of coronary blood flow in the old-donor group (33 ± 4 vs. 51 ± 15 %, p < 0.05). After 8 h preservation, two of the old-donor hearts showed no mechanical activity upon reperfusion. LV pressure (55 ± 6 vs. 72 ± 5 mmHg, p < 0.05), dP/dt max (899 ± 221 vs. 1530 ± 217 mmHg/s, p < 0.05), coronary blood flow and response to acetylcholine were significantly reduced and τ was increased in the old-donor group in comparison to young controls.

CONCLUSIONS

During the early-phase after transplantation, the ischemic tolerance of older-donor hearts is reduced after prolonged preservation time and the endothelium is more vulnerable to ischemia/reperfusion.

The psychological experiences of adult heart transplant recipients: a systematic review and meta-summary of qualitative findings

BACKGROUND

Psychosocial factors and physical health are associated with increased psychological distress post-heart transplant. Integrating findings from qualitative studies could highlight mechanisms for how these factors contribute to psychological well-being, thus aiding the development of interventions.

OBJECTIVE

To integrate qualitative findings regarding adult heart transplant recipients experiences, such as their emotions, perceptions and attitudes.

METHODS

A systematic review and meta-summary were conducted. Data from seven studies were categorized into 16 abstracted findings.

RESULTS

The most prominent finding across the studies related to recipients' perceptions of the importance of social support. Other prominent findings related to factors that promoted psychological well-being, such as faith, optimism and sense of control.

CONCLUSIONS

Psychological well-being may be improved by enhancing perceived control over health and daily life, promoting an optimistic outlook by facilitating access to social support from other heart transplant recipients and ensuring post-transplant recipient-caregiver partnerships adequately support the transition back to independence.

Is there any cardioprotective role of Taurine during cold ischemic period following global myocardial ischemia?

Background

The aim of the present study was to investigate the cardioprotective effect of Taurine on the donor hearts during cold ischemic period.

Methods

32 rats were divided into four groups (sham, taurine, ischemia, treatment group, 8 rats in each). All rats were fed with rat food for three weeks. Taurine and treatment groups were given a 200 mg/kg/day dose of Taurine by oral gavage besides rat feed. Cardiectomy was performed in all rats after three weeks. In ischemia and treatment groups, harvested hearts were kept in 0.9% sodium chloride at +4 degrees C for 5 hours. Tissue samples were taken from left ventricle in all groups. These samples were evaluated by histopathologic and biochemical examination.

Results

In the present study results of the biochemical and histopathological examination reveals the protective effects of Taurine. As a marker of lipid peroxidation, Malondialdehyde (MDA) levels in ischemia group were significantly higher than both Sham and Taurine groups. MDA values were recorded; 3.62 ± 0.197 in the sham group, 2.07 ± 0.751 in the Taurine group, 9.71 ± 1.439 in the ischemia group and 7.68 ± 1.365 in the treatment group. MDA levels decreased in treatment group. (p < 0.05) In accordance with MDA findings, while superoxide dismutase and glutathione peroxidase levels decreased in ischemia group, they increased in treatment group. (p < 0.05) There was no differences in Catalase (CAT) enzyme level between treatment and ischemia group (p = 1.000). CAT level results were recorded; 7.08 ± 0.609 in the sham group, 6.15 ± 0.119 in the Taurine group, 5.02 ± 0.62 in the ischemia group, and 5.36 ± 0.384 in the treatment group. Less intracellular edema and inflammatory cell reaction were observed in histologic examination in favor of treatment group. (p < 0.01)

Conclusion

Taurine decreased myocardial damage during cold ischemic period following global myocardial ischemia.

Fluorimetric characterisation of metabolic activity of ex vivo perfused pig hearts

Autofluorescence of tissues and organs is an indicator of the physiological state of cells. The aim of the study was to investigate whether fluorimetric determination of the redox state of the ex vivo perfused pig heart can provide fast online detection of progressive changes in heart muscle tissue. Measurements on six organs perfused in a four-chamber working heart model were performed using a spectroscopic method exploiting the specific and different fluorescence lifetimes of intrinsic fluorophores such as NADH and flavins and providing a means of internal signal referencing. It was shown that the redox potential of heart muscle tissue can be assessed by fluorescence measurement. In the steady-state phase of the beating heart, spectroscopic measurements revealed a change in redox state from an initial constant level to a continuous decrease, accompanied by a decrease in heart performance and indications of changes in electrolyte equilibrium (K(+) concentration). At the same time, troponin I levels in the perfusate increased. The results indicate that fluorimetric determination of heart muscle metabolic activity yields reliable information about the functional status of the ex vivo heart and may be advantageous for the optimisation of ex vivo organ models.