Myocardial Metabolism is Better Preserved After Blood Cardioplegia in Infants

Myocardial protection in the arterial switch operation: Custodiol versus cold blood cardioplegia

OBJECTIVES

The optimal myocardial protective solution in the neonatal arterial switch operation remains controversial. The aim of this study was to demonstrate that Bretschneider's histidine-tryptophan-ketoglutarate crystalloid solution (Custodiol) offers protection at least similar to that of cold blood cardioplegia.

METHODS

Patients who underwent the neonatal arterial switch operation with Custodiol between January 2016 and December 2018 (n = 23) were compared with an historical cohort from August 2010 to December 2015 in which cold blood cardioplegia was used (n = 41). A linear mixed-effect model for repeated measures was performed to test the recovery of myocardial function based on inotropic and vasoactive inotropic scores, cardiac enzyme release and left ventricular ejection fraction.

RESULTS

Patients in the cold blood cardioplegia group had higher inotropic scores in the first 24 h (0 h, P = 0.001 and 24 h, P = 0.006) and higher vasoactive inotropic scores in the first 72 h (0 h, 24 h and 48 h, P < 0.001; 72 h, P = 0.012). Cardiac troponin-I concentrations were higher in the cold blood cardioplegia group at postoperative hours 1-72 (1 h, 6 h, 12 h and 24 h, P < 0.001; 48 h, P = 0.001 and 72 h, P = 0.003). Creatinine-kinase-MB concentrations were higher in the cold blood cardioplegia group at postoperative hours 1-24 (1 h, 6 h and 12 h, P < 0.001; 24 h, P = 0.042). The left ventricular ejection fraction was higher in the Custodiol group just after the operation (P = 0.005), at 24 h (P = 0.001) and on the first day without inotropic support (P = 0.011).

CONCLUSIONS

Neonatal myocardium protected with Custodiol during the arterial switch operation presented optimal ventricular function recovery with less inotropic support and less myocardial damage compared with cold blood cardioplegia.

Blood Versus Crystalloid Cardioplegia in Pediatric Cardiac Surgery: A Systematic Review and Meta-analysis

The benefit of blood cardioplegia (BCP) compared to crystalloid cardioplegia (CCP) is still debatable. Our aim was to systematically review and synthesize all available evidence on the use of BCP and CCP to assess if any modality provides superior outcomes in pediatric cardiac surgery. A systematic literature search of the PubMed and Cochrane databases was performed with respect to the PRISMA statement (end-of-search date: January 30th, 2017). We extracted data on study design, demographics, cardioplegia regimens, and perioperative outcomes as well as relevant biochemical markers, namely cardiac troponin I (cTnI), lactate, and ATP levels at baseline, after reperfusion and postoperatively at 1, 4, 12, and 24 h as applicable. Data were appropriately pooled using random and mixed effects models. Our systematic review includes 56 studies reporting on a total of 7711 pediatric patients. A meta-analysis of the 10 eligible studies directly comparing BCP (n = 416) to CCP (n = 281) was also performed. There was no significant difference between the two groups with regard to cTnI and Lac at any measured time point, ATP levels after reperfusion, length of intensive care unit stay (WMD: -0.08, 95% CI -1.52 to 1.36), length of hospital stay (WMD: 0.13, 95% CI -0.85 to 1.12), and 30-day mortality (OR 1.11, 95% CI 0.43-2.88). Only cTnI levels at 4 h postoperatively were significantly lower with BCP (WMD: -1.62, 95% CI -2.07 to -1.18). Based on the available data, neither cardioplegia modality seems to be superior in terms of clinical outcomes, ischemia severity, and overall functional recovery.

Evidence-based medicine and myocardial protection — where is the evidence?

Objective:

Myocardial protection with cardioplegia is an integral component of most cardiac surgical procedures, providing protection of the heart by limiting metabolic activity and increasing the myocardium’s capacity to withstand ischemia for prolonged periods of time. Cardioplegia has greatly affected the landscape of cardiothoracic surgery since its introduction in the 1960s, but, to this day, there continues to be a debate over what the ideal cardioplegic solution should be. The goal of this analysis is to describe current practices in cardioplegia and to point out the lack of quality human research and subsequent publications that prevent best practices from being utilized.

Methods:

This study is a systematic review of journal publications pertaining to the composition of commonly used cardioplegic solutions. Four main types of cardioplegia were assessed to give a narrower field of examination; specifically, microplegia, del Nido, Custodiol HTK, and 4:1 blood cardioplegia. Other combinations of cardioplegia, including St. Thomas’s Solution and the University of Wisconsin (UW) Solution, were considered when applicable according to the context of the publication being reviewed. Factors being assessed consisted of scientific validity, nature of the test subject (isolated organ vs. animal vs. human studies), experimental setup (retrospective trials vs. randomized clinical trials) and patient outcomes.

Results:

There are very few randomized clinical trials with human subjects comparing commonly used cardioplegic solutions. Numerous retrospective studies exist, but often show similar intraoperative and postoperative outcomes between the solutions. Some solutions, del Nido cardioplegia in particular, were found to have few or no significant human trials to back the rigor required in such a highly specialized field as cardiovascular surgery. A wide variation in the types of surgeries and primary outcomes were included in the publications, so it is difficult to perform an accurate systematic review of the topic.

Conclusion:

Uniform variables among different studies would be preferable for analysis of this topic; thus, it is the researchers’ recommendation that the collection of multicenter data be undertaken in order to more fully answer this research question. Comparative effectiveness studies to associate commonly used solutions are needed. Without this research, surgeon preference remains the primary determining factor for deciding which cardioplegic solution to use. Cardioplegia selection should rely more on higher scientific research, using evidenced-based medicine and ranking of clinical studies.

Aspartate and glutamate prevents isoproterenol-induced cardiac toxicity by alleviating oxidative stress in rats

The protective effect of aspartate and glutamate in isoproterenol induced myocardial infarction (MI) was investigated in experimental animals. Male albino wistar rats were pretreated with aspartate [100mg (kg body weight)-1 day-1] or glutamate [100mg (kg body weight)-1 day-1] intraperitoneally for a period of 7 days. Following amino acid treatment, MI was induced in rats by subcutaneous injection of isoproterenol [200mg (kg body weight)-1 day-1] for 2 days. After 24h following the last injection, the animals were sacrificed and the biochemical analysis was carried out. The activities of cardiac marker enzymes (alanine transaminase, aspartate transaminase, lactate dehydrogenase and creatine phosphokinase) were increased significantly (P<0.05) in the serum of MI induced rats as compared to control rats. The levels of glutathione and mitochondrial ATP and the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione transferase and glutathione reductase) were decreased whereas lipid peroxides increased significantly (P<0.05) in the heart of MI induced rats as compared to control rats. However, pretreatment with aspartate or glutamate to MI induced rats significantly (P<0.05) reduced the activities of cardiac marker enzymes and increased the activities of antioxidant enzymes as compared to MI induced rats. Aspartate or glutamate pretreatment also increased the levels of glutathione and mitochondrial ATP while decreased the level of lipid peroxides in the cardiac tissue. The overall effects of aspartate and glutamate in reducing the oxidative stress in MI induced rats are similar. There was no significant difference between the control rats and aspartate or glutamate treated control rats. The present study shows that aspartate and glutamate could reduce oxidative stress in MI induced rats.

Complications relating to perfusion and extracorporeal circulation associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease

The International Consortium for Evidence-Based Perfusion (www.bestpracticeperfusion.org) is a collaborative partnership of societies of perfusionists, professional medical societies, and interested clinicians, whose aim is to promote the continuous improvement of the delivery of care and outcomes for patients undergoing extracorporeal circulation. Despite the many advances made throughout the history of cardiopulmonary bypass, significant variation in practice and potential for complication remains. To help address this issue, the International Consortium for Evidence-Based Perfusion has joined the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease to develop a list of complications in congenital cardiac surgery related to extracorporeal circulation conducted via cardiopulmonary bypass, extracorporeal membrane oxygenation, or mechanical circulatory support devices, which include ventricular assist devices and intra-aortic balloon pumps. Understanding and defining the complications that may occur related to extracorporeal circulation in congenital patients is requisite for assessing and subsequently improving the care provided to the patients we serve. The aim of this manuscript is to identify and define the myriad of complications directly related to the extracorporeal circulation of congenital patients.

Results with all blood retrograde microplegia as a myocardial protection strategy for complex neonatal arch reconstruction

Neonatal arch reconstructions present a challenge for myocardial protection. We report our results for eight patients treated with intermittent cold all blood retrograde cardioplegia during arch reconstruction using continuous selective normothermic cerebral perfusion. Over a 10-month period eight consecutive neonates underwent complex arch reconstruction. Mean age was 8.4 days (range 2-23); weight 3.1 kg (range 2.7-3.8). Diagnosis was hypoplastic left heart syndrome (5), interrupted aortic arch/ventriculoseptal defect (2), and complex AP window (1). Mean cardiopulmonary bypass time was 149 minutes (range 80-201), mean cross-clamp time was 74 (range 51-101). All patients had primary chest closure and none required extra-corporeal membrane oxigenation. One patient (12%) had a period of low cardiac output syndrome, which resolved with high dose inotropes. All patients were discharged alive and well. Intermittent all blood retrograde microplegia is an effective myocardial protection strategy for complex neonatal arch reconstruction. Postoperative myocardial function is very good. This protection approach facilitates continuous selective normothermic cerebral perfusion.

Myocardial substrates in children with congenital heart disease: relationship to substrate supply, age, growth and desaturation

AIM

The myocardial uptake of substrates in children has only been investigated on a small scale. The purpose of this study was to define myocardial substrate uptake in relation to the arterial supply of substrates, age, growth and oxygen saturation.

METHODS

Thirty patients with congenital heart disease, aged 3 months to 16 years, were studied during cardiac catheterization. Arterial and coronary sinus blood was analyzed for the major fuel metabolites and amino acids.

RESULTS

The uptake of all major substrates correlated significantly with the arterial supply: free fatty acids (r = 0.52, p = 0.004), beta-hydroxybutyrate (r = 0.74, p < 0.0001), lactate (r = 0.70, p < 0.0001) and glucose (r = 0.48, p = 0.01). Free fatty acids were the dominant substrate, irrespective of age, growth and saturation. With age, there was an increase in the uptake of lactate (r = 0.61, p = 0.0004) and a decrease in the uptake of beta-hydroxybutyrate (r =-0.41, p = 0.02). In multivariate analyses, these changes were explained by the arterial supply of the substrates, while age per se did not contribute significantly.

CONCLUSION

The uptake of myocardial metabolites correlated with the arterial supply. Free fatty acids were the dominant substrate at all ages. The uptake of lactate and beta-hydroxybutyrate, although varying with age, was also determined by the arterial supply.