Introduction
Cardioplegia is an essential cardioprotective pharmacological therapy for electromechanical cardiac arrest during cardiac surgery(1). This is achieved by altering cellular electrochemical gradients to reduce myocardial metabolic demands by inducing electrical quiescence. In addition, cooling of the myocardium to minimise ischaemia-reperfusion (I-R) injury associated with being on cardiopulmonary bypass, which is a significant cause of mortality and morbidity in cardiac surgery(2). As well as myocardial protection, cardioplegia is also indicated for a bloodless and motionless operating field for prolonged periods of time.
There are many forms of cardioplegia that are currently used in clinical practice; this can be classified based on varying parameters such as temperature (cold, tepid or warm), solution (crystalloid or blood), delivery method (anterograde, retrograde or combined) and substances within the solution (glucose with insulin and potassium, Mg2+, HCO3-, procaine etc.). This suggests that there are probably several methods to arrest the myocardium safely, prior to aortic cross-clamping. Nevertheless, there is still an ongoing debate on the relative effectiveness of these variable forms of cardioplegia.
Literature Search:
A comprehensive literature search was done on PubMed, SCOPUS, Embase, Cochrane database, google scholar and Ovid to identify the articles that discussed the use of myocardial protection methods during open heart surgery. Key words used were ‘Cardioplegia’ ‘blood cardioplegia’ ‘crystalloid cardioplegia’ ‘warm cardioplegia’ ‘cold cardioplegia’ ‘myocardial protection’ ‘cardioplegia solutions’ ‘antegrade’ ‘retrograde’. The search terms were used as key word and in combination as MeSH terms to maximize the output from literature findings. A staged literature search was done, whereby a separate literature search was performed for each section within this article and all the relevant studies were identified and summarized separately. If a paper is reporting on many aspects of the myocardial protection, then the results have been shared between different parts of this review. The relevant articles are cited and referenced within each section separately. No limit placed on publication time or language of the article.