Combined St. Thomas and Histidine-Tryptophan-Ketoglutarat Solutions for Myocardial Preservation in Heart Transplantation Patients

Consecutive-Day Ventricular and Atrial Cardiomyocyte Isolations from the Same Heart: Shifting the Cost-Benefit Balance of Cardiac Primary Cell Research

Freshly isolated primary cardiomyocytes (CM) are indispensable for cardiac research. Experimental CM research is generally incompatible with life of the donor animal, while human heart samples are usually small and scarce. CM isolation from animal hearts, traditionally performed by coronary artery perfusion of enzymes, liberates millions of cells from the heart. However, due to progressive cell remodeling following isolation, freshly isolated primary CM need to be used within 4-8 h post-isolation for most functional assays, meaning that the majority of cells is essentially wasted. In addition, coronary perfusion-based isolation cannot easily be applied to human tissue biopsies, and it does not straightforwardly allow for assessment of regional differences in CM function within the same heart. Here, we provide a method of multi-day CM isolation from one animal heart, yielding calcium-tolerant ventricular and atrial CM. This is based on cell isolation from cardiac tissue slices following repeated (usually overnight) storage of the tissue under conditions that prolong CM viability beyond the day of organ excision by two additional days. The maintenance of cells in their near-native microenvironment slows the otherwise rapid structural and functional decline seen in isolated CM during attempts for prolonged storage or culture. Multi-day slice-based CM isolation increases the amount of useful information gained per animal heart, improving reproducibility and reducing the number of experimental animals required in basic cardiac research. It also opens the doors to novel experimental designs, including exploring same-heart regional differences.

The Effect of Supplemental Cardioplegia Infusion before Anastomosis in Patients Undergoing Heart Transplantation with Long Ischemic Times

Background

Prolonged ischemic time is a risk factor for primary graft dysfunction in patients who undergo heart transplantation. We investigated the effect of a supplemental cardioplegia infusion before anastomosis in patients with long ischemic times.

Methods

We identified 236 consecutive patients who underwent orthotopic heart transplantation between February 2010 and December 2014. Among them, the patients with total ischemic times of longer than 3 hours (n=59) were categorized based on whether they were administered a complementary cardioplegia solution (CPS) immediately before implantation (CPS+, n=30; CPS−, n=29).

Results

The mean total ischemic times in the CPS+ and CPS− groups were 238.1±30.1 minutes and 230.1±28.2 minutes, respectively (p=0.3). The incidence of left ventricular primary graft dysfunction (CPS+, n=6 [20.0%]; CPS−, n=5 [17.2%]; p=0.79) was comparable between the groups. In the Kaplan-Meier survival analysis, no significant difference in overall survival at 5 years was observed between the CPS+ and CPS− groups (83.1%±6.9% vs. 89.7%±5.7%, respectively; log-rank p=0.7). No inter-group differences in early mortality (CPS+, n=0; CPS−, n=1 [3.4%]; p=0.98) or complications were observed.

Conclusion

The additional infusion of a cardioplegia solution immediately before implantation in patients with longer ischemic times is a simple, reproducible, and safe procedure. However, we did not observe benefits of this strategy in the present study.

Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review

For patients undergoing cardiopulmonary bypass, myocardial protection is a key for successful recovery and improved outcomes following cardiac surgery that requires cardiac arrest. Different solutions, components and modes of delivery have evolved over the last few decades to optimise myocardial protection. These include cold and warm and blood and crystalloid solution through antegrade, retrograde or combined cardioplegia delivery approach. However, each method has its own advantages and disadvantages, posing a challenge to establish a gold-standard cardioplegic solution with an optimised mode of delivery for enhanced myocardial protection during cardiac surgery. The aim of this review is to provide a brief history of the development of cardioplegia, explain the electrophysiological concepts behind myocardial protection in cardioplegia, analyse the current literature and summarise existing evidence that warrants the use of varying cardioplegic techniques. We provide a comprehensive and comparative overview of the effectiveness of each technique in achieving optimal cardioprotection and propose novel techniques for optimising myocardial protection in the future.

Preservation of the donor heart: from basic science to clinical studies

The methods of donor heart preservation are aimed at minimizing graft dysfunction caused by ischaemia-reperfusion injury (IRI) which inevitably occurs during the ex vivo transport interval. At present, the standard technique of heart preservation is cardiac arrest followed by static cold storage in a crystalloid heart preservation solution (HPS). This technique ensures an acceptable level of heart protection against IRI for <6 h. In clinical trials, comparable levels of myocardial protection against IRI were provided by various HPSs. The growing shortage of donor hearts is one of the major factors stimulating the development of new techniques of heart preservation. Here, we summarize new HPS formulations and provide a focus for optimization of the composition of existing HPSs. Such methods of donor heart preservation as machine perfusion, preservation at sub-zero temperature and oxygen persufflation are also discussed. Furthermore, we review experimental data showing that pre- and post-conditioning of the cardiac graft can improve its function when used in combination with cold storage. The evidence on the feasibility of cardiac donation after circulatory death, as well as the techniques of heart reconditioning after a period of warm ischaemia, is presented. The implementation of new techniques of donor heart preservation may contribute to the use of hearts from extended criteria donors, thereby expanding the total donor pool.

Supplemental Cardioplegia Immediately before Graft Implantation may Improve Early Post-Transplantation Outcome

Background: Preservation of cardiac grafts for transplantation is not standardized and most centers use a single administration of crystalloid solution at the time of harvesting. We investigated possible benefits of an additional dose of cardioplegia dispensed immediately before implantation.

Methods: Consecutive adult cardiac transplantations (2005–2012) were reviewed. Hearts were harvested following a standard protocol (Celsior 2L, 4–8°C). In 2008, 100 ml crystalloid cardioplegic solution was added and administered immediately before implantation. Univariate and logistic regression analyses were used to investigate risk factors for post-operative graft failure and mid-term outcome.

Results: A total of 81 patients, 44 standard (“Cardio⁻”) vs. 37 with additional cardioplegia (“Cardio⁺”) were analyzed. Recipients and donors were comparable in both groups. Cardio⁺ patients demonstrated a reduced need for defibrillation (24 vs. 48%, p = 0.03), post-operative ratio of CK-MB/CK (10.1 ± 3.9 vs. 13.3 ± 4.2%, p = 0.001), intubation time (2.0 ± 1.6 vs. 7.2 ± 11.5 days, p = 0.05), and ICU stay (3.9 ± 2.1 vs. 8.5 ± 7.8 days, p = 0.001). Actuarial survival was reduced when graft ischemic time was >180 min in Cardio⁻ but not in Cardio⁺ patients (p = 0.033). Organ ischemic time >180 min (OR: 5.48, CI: 1.08–27.75), donor female gender (OR: 5.84, CI: 1.13–33.01), and recipient/donor age >60 (OR: 6.33, CI: 0.86–46.75), but not the additional cardioplegia or the observation period appeared independent predictors of post-operative acute graft failure.

Conclusion: An additional dose of cardioplegia administered immediately before implantation may be a simple way to improve early and late outcome of cardiac transplantation, especially in situations of prolonged graft ischemia. A large, ideally multicentric, randomized study is desirable to verify this preliminary observation.