Histidine-tryptophan-ketoglutarate solution versus multidose cardioplegia for myocardial protection in cardiac surgeries: a systematic review and meta-analysis

Comparison Between Histidine-Tryptophan-Ketoglutarate Cardioplegia and Cold Blood Cardioplegia for Myocardial Protection in Tetralogy of Fallot Patients Undergoing Surgical Repair: A Randomized Clinical Trial

OBJECTIVES

This study was conducted to compare the efficacy of histidine-tryptophan-ketoglutarate (HTK) cardioplegia and cold blood cardioplegia (CBC), especially for postoperative right ventricular (RV) function after tetralogy of Fallot repair.

DESIGN

Randomized, double-blinded, parallel-group, controlled clinical trial.

SETTING

Ain Shams University Hospitals.

PARTICIPANTS

A total of 100 children (1 to 5 years old) scheduled for tetralogy of Fallot repair.

INTERVENTIONS

Patients were allocated (double-blinded 1:1 allocation ratio) to either the HTK group that received HTK cardioplegia (30 mL/kg via antegrade route) or the CBC group that received cold blood cardioplegia with blood-to-Ringer solution (4:1) in a volume of 20 mL/kg.

MEASUREMENTS AND MAIN RESULTS

The HTK group showed a statistically significant reduction of the vasoactive inotropic score on admission to the pediatric intensive care unit (13.0 ± 4.1) in comparison to the CBC group (15.5 ± 5.4), with a p value of 0.011. However, after 24 hours, the vasoactive-inotropic score was comparable. Lactate level during the first 24 hours was 6.2 ± 0.7 mmol/L in the HTK group and 6.9 ± 0.4 mmol/L in the CBC group (p < 0.0001). Serial troponin measurements were lower in the HTK group (1.49 ± 0.45) compared to the CBC group (1.69 ± 0.18) at the first 72 hours postoperatively (p = 0.005). Postoperative echocardiographic assessment of RV function by means of tricuspid annular plane systolic excursion and myocardial performance index were better in the HTK group than in the CBC grpup (p < 0.05).

CONCLUSIONS

HTK cardioplegia may offer better cardiac protection to pediatric patients undergoing tetralogy of Fallot repair than our institutional standard CBC with better recovery for the hypertrophic RV.

Comparison of "Huaxi-1" or "histidine-tryptophan-ketoglutarate" cardioplegia in an animal model

Background

Using a pig model of cardiopulmonary bypass, we compared outcomes after cardioplegia either with our in-house "Huaxi-1" solution containing natural blood and crystalloid or with the entirely crystalloid, commercially available "histidine-tryptophan-ketoglutarate" solution.

Methods

Cardiopulmonary bypass was established in 12 healthy male pigs, who were randomized to receive a single dose of either Huaxi-1 or entirely crystalloid. All animals were then subjected to whole-heart ischemia for 90 min, followed by 2 h of reperfusion, after which myocardial injury was assessed in terms of cardiac function, myocardial pathology and levels of biomarkers in plasma, while levels of high-energy phosphate in myocardium were assayed using liquid chromatography.

Results

Animals given Huaxi-1 cardioplegia required significantly less time to be weaned off bypass, they received significantly lower doses of norepinephrine, and they showed significantly higher levels (mean ± SD) of adenosine triphosphate (14 ± 4 vs. 8 ± 2 µg/mg, P = 0.005), adenosine diphosphate (16 ± 2 vs. 13 ± 2 µg/mg, P = 0.046), and total adenine nucleotide (37 ± 4 vs. 30 ± 3 µg/mg, P = 0.006) in myocardium after 2 h of reperfusion. They also showed less severe bleeding, edema and injury to mitochondria and myofibers in myocardium. The two groups did not differ significantly in doses of inotropic drugs received, cardiac output or levels of biomarkers in plasma.

Conclusions

In this animal model of healthy hearts subjected to 90 min of ischemia, Huaxi-1 cardioplegia may be superior to entirely crystalloid cardioplegia for promoting energy generation and attenuating ischemia/reperfusion injury in myocardium.

Myocardial protection: comparing histological effects of single-dose cardioplegic solutions-study protocol for a secondary analysis of the CARDIOPLEGIA trial

Background

Myocardial protection is crucial for successful cardiac surgery, as it prevents heart muscle damage that can occur during the procedure. Prolonged hypoxia without proper protection can lead to adenosine triphosphate consumption, microvilli loss, blister formation, and edema. Custodiol, del Nido, and modified del Nido are single-dose cardioplegic solutions with proven safety and significance in modern surgery. While each has been independently assessed for patient outcomes, limited research directly compares them. This study aims to compare their myocardial protection using histological analysis.

Methods

In a double-blind clinical trial, at least 90 patients will be randomly assigned to receive one of the three cardioplegic solutions. Myocardial biopsies will be collected before cardiopulmonary bypass and 15 minutes after reperfusion. The surgical, anesthetic and perfusion techniques will be the same for all patients, following the Institution's standard protocols.

Discussion

The ideal cardioplegic solution does not exist, and its selection remains challenging for surgeons. In modern surgical practice, understanding the behavior of these solutions and the ischemic tissue damage caused during induced cardiac arrest allows for safer surgical procedures. The results of this clinical trial can help in understanding the behavior of cardioplegic solutions and their tissue effects. Thus, by selecting the best cardioplegic solution, ischemic damage can be minimized, enhancing the effectiveness of this essential technique in cardiac procedures. The study may aid in implementing clinical protocols in several institutions, aiming to choose the solution with a superior myocardial protection profile, increasing safety, and reducing expenses.

Trial Registration

Brazilian Clinical Trials Registry (ReBEC, http://ensaiosclinicos.gov.br/): RBR-997tqhh. Registered: January 26th, 2022.

Melatonin enhanced the cardioprotective effects of HTK solution on Langendorff-perfused mouse hearts subjected to ischemia/reperfusion

Objectives

Cardiac arrest is a crucial procedure in various cardiac surgeries, during which the heart is subjected to an ischemic state. The occurrence of ischemia/reperfusion (I/R) injury is inevitable due to aortic blockage and opening. The Histidine-tryptophan-ketoglutarate (HTK) solution is commonly used as an organ protection liquid to mitigate cardiac injury during cardiac surgery. Despite its widespread use, there is significant potential for improving its protective efficacy.

Materials and Methods

The cardioprotective effect of HTK solution with and without melatonin was evaluated using the isolated Langendorff-perfused mouse heart model. The isolated C57bL/6 mouse hearts were randomly divided into four groups: control, I/R, HTK solution treatment before reperfusion (HTK+I/R), and HTK solution combined with melatonin before reperfusion (HTK+M+I/R). Cardiac function and myocardial injury markers were then measured. AMP-activated protein kinase α2 (AMPKα2) KO mice were used to investigate the underlying mechanism.

Results

In our study, we found that melatonin significantly improved the protective effects of HTK solution in an isolated Langendorff-perfused mouse model, mechanistically by reducing mitochondrial damage, improving energy metabolism, inhibiting cardiomyocyte apoptosis, and reducing myocardial infarction size. We also observed that the HTK solution alone was ineffective in inhibiting ER stress, but when melatonin was added, there was a significant reduction in ER stress. Furthermore, melatonin was found to alleviate carbonyl stress during cardiac I/R. Interestingly, our results showed that the cardioprotective properties of melatonin were dependent on AMPKα2.

Conclusion

The findings presented in this study offer a valuable empirical foundation for the development of perioperative cardioprotective strategies.