The novel St Thomas' Hospital polarizing blood cardioplegia: results in hearts with reduced ejection fraction

Area of Science:

• Cardiology
• Cardiovascular Surgery
• Ischemia-Reperfusion Injury

Background:

• Traditional depolarized cardioplegia, used for over 50 years, can lead to calcium overload, mitochondrial damage, and energy depletion in cardiac surgery patients.
• Older patients often have comorbidities, increasing the need for improved myocardial protection strategies.

Purpose of the Study:

• To evaluate a novel polarizing cardioplegia (STH-pol) against standard depolarized cardioplegia (STH-control) in an ischemia/reperfusion model.
• To assess the efficacy of STH-pol in protecting the myocardium, particularly in hearts with reduced ejection fraction.

Main Methods:

• Myocardial infarction was induced in male Sprague-Dawley rats via LAD artery ligation.
• Six weeks post-MI, hearts were isolated and subjected to 60 minutes of cold (4°C) ischemic arrest using either STH-pol or STH-control, followed by 45 minutes of reperfusion at 37°C.
• Hemodynamic variables and high-energy phosphate (HEP) levels were analyzed post-reperfusion.

Main Results:

• STH-pol demonstrated comparable hemodynamic recovery to STH-control, with similar left ventricular systolic pressures after ischemia.
• Analysis of high-energy phosphates, including ATP levels, showed no statistically significant difference between the STH-pol and STH-control groups.
• Both methods provided similar levels of myocardial protection in terms of energy metabolism.

Conclusions:

• Polarizing cardioplegic arrest (STH-pol) did not result in a statistically significant difference in myocardial protection compared to standard cold blood cardioplegia (STH-control).
• The findings suggest that STH-pol is a viable alternative to traditional methods in this specific experimental model.
• Further research may explore the long-term effects and clinical applicability of polarizing cardioplegia.