Warm Blood Cardioplegia for Myocardial Protection: Concepts and Controversies

Do we correctly calculate doses of cardioplegia during aortic valve replacement procedures? A preliminary report

Introduction

Intraoperative myocardial protection during aortic valve replacement (AVR) for aortic stenosis (AS) is of paramount importance for outcomes. The dose of cardioplegia is usually calculated with reference to body mass.

Aim

To assess whether such a strategy should be applied to all AS patients undergoing AVR.

Material and methods

The study included 94 patients who underwent elective isolated AVR in cardiopulmonary bypass with cold cardioplegic arrest, with a mean age of 65.4 ±7.8 years. They were divided into two subgroup: A with an infusion of high (above median) and subgroup B with a low (below median) volume of cardioplegia indexed for left ventricular mass (LVM). Their doses were referred to the maximal postoperative release of cardiac troponin I (cTnI max). Eventually, it was examined whether the extent of intraoperative myocardial injury translated into long-term survival stratified according to the Kaplan-Meier method.

Results

The mean volume of cardioplegia was 1381 ±279 ml (4.9 ±1.6 ml/g of LV myocardium). cTnI max was much higher in group A than in group B (medians: 14.918 vs. 9.876 μg/l; p = 0.005). Moreover, a negative correlation between the index cardioplegia volume and cTnI max (r = 0.345) was noted. The five-year probability of survival in subgroup A (95.7%) was significantly better than that in subgroup B individuals (82.6%, p = 0.044).

Conclusions

Calculating cardioplegic doses during AVR solely based on body mass may be suboptimal and have a significant impact on postoperative outcomes.

Theoretical and Practical Aspects in the Use of Bretschneider Cardioplegia

The race for an ideal cardioplegic solution has remained enthusiastic since the beginning of the modern cardiac surgery era. The Bretschneider solution, belonging to the “intracellular cardioplegic” group, is safe and practical in myocardial protection during ischemic time. Over time, some particular concerns have arisen regarding the effects on cardiac metabolism and postoperative myocardial functioning. This paper reviews the most important standpoints in terms of theoretical and practical analyses.