Cardioplegia in Open Heart Surgery: Age Matters

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.

Novel Strategies to Improve the Cardioprotective Effects of Cardioplegia

The use of cardioprotective strategies as adjuvants of cardioplegic solutions has become an ideal alternative for the improvement of post-surgery heart recovery. The choice of the optimal cardioplegia, as well as its distribution mechanism, remains controversial in the field of cardiovascular surgery. There is still a need to search for new and better cardioprotective methods during cardioplegic procedures. New techniques for the management of cardiovascular complications during cardioplegia have evolved with new alternatives and additives, and each new strategy provides a tool to neutralize the damage after ischemia/reperfusion events. Researchers and clinicians have committed themselves to studying the effect of new strategies and adjuvant components with the potential to improve the cardioprotective effect of cardioplegic solutions in preventing myocardial ischemia/reperfusion-induced injury during cardiac surgery. The aim of this review is to explore the different types of cardioplegia, their protection mechanisms, and which strategies have been proposed to enhance the function of these solutions in hearts exposed to cardiovascular pathologies that require surgical alternatives for their corrective progression.

Myocardial protection in cardiac surgery-hindsight from the 2020s

Myocardial protection and specifically cardioplegia have been extensively investigated in the beginnings of cardiac surgery. After cardiopulmonary bypass had become routine, more and more cardiac operations were possible, requiring reliable and reproducible protection for times of blood flow interruptions to the most energy-demanding organ of the body. The concepts of hypothermia and cardioplegia evolved as tools to extend cardiac ischaemia tolerance to a degree considered safe for the required operation. A plethora of different solutions and delivery techniques were developed achieving remarkable outcomes with cross-clamp times of up to 120 min and more. With the beginning of the new millennium, interest in myocardial protection research declined and, as a consequence, conventional cardiac surgery is currently performed using myocardial protection strategies that have not changed in decades. However, the context, in which cardiac surgery is currently performed, has changed during this time. Patients are now older and suffer from more comorbidities and, thus, other organs move more and more into the centre of risk assessment. Yet, systemic effects of cardioplegic solutions have never been in the focus of attention. They say hindsight is always 20-20. We therefore review the biochemical principles of ischaemia, reperfusion and cardioplegic extension of ischaemia tolerance and address the concepts of myocardial protection with 'hindsight from the 2020s'. In light of rising patient risk profiles, minimizing surgical trauma and improving perioperative morbidity management becomes key today. For cardioplegia, this means accounting not only for cardiac, but also for systemic effects of cardioplegic solutions.

Alterations to Kidney Physiology during Cardiopulmonary Bypass-A Narrative Review of the Literature and Practical Remarks

INTRODUCTION

According to different authors, cardiac surgery-associated acute kidney injury (CSA-AKI) incidence can be as high as 20-50%. This complication increases postoperative morbidity and mortality and impairs long-term kidney function in some patients. This review aims to summarize current knowledge regarding alterations to renal physiology during cardiopulmonary bypass (CPB) and to discuss possible nephroprotective strategies for cardiac surgeries. Relevant sections: Systemic and renal circulation, Vasoactive drugs, Fluid balance and Osmotic regulation and Inflammatory response.

CONCLUSIONS

Considering the available scientific evidence, it is concluded that adequate kidney perfusion and fluid balance are the most critical factors determining postoperative kidney function. By adequate perfusion, one should understand perfusion with proper oxygen delivery and sufficient perfusion pressure. Maintaining the fluid balance is imperative for a normal kidney filtration process, which is essential for preserving the intra- and postoperative kidney function.

FUTURE DIRECTIONS

The review of the available literature regarding kidney function during cardiac surgery revealed a need for a more holistic approach to this subject.