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

OBJECTIVES

Myocardial protection is crucial for recovery after cardiac surgery. Despite older patients with more comorbidities, most surgeons still use potassium-induced depolarized arrest with cardioplegic solutions from more than 50 years ago. However, this can cause calcium overload, mitochondrial injury and energy depletion. We tested a new polarizing cardioplegia (STH-pol) versus traditional depolarized arrest (STH-control) in an ischaemia/reperfusion model of hearts with reduced ejection fraction.

METHODS

Myocardial infarction (MI) was induced by permanent ligation of the left anterior descending artery in male Sprague-Dawley rats. Six weeks post-MI, the hearts were isolated and perfused on an erythrocyte-perfused working heart system. Cold ischaemic arrest (4°C, 60 min) was induced by STH-pol (n = 10) or STH-control (n = 8), followed by reperfusion (37°C, 45 min). Haemodynamic variables were recorded throughout reperfusion, and tissue samples were taken at the end of reperfusion to analyse high-energy phosphates (HEP).

RESULTS

Administration of STH-pol resulted in comparable haemodynamic recovery after 60 min ischaemia as STH-control induced cardioplegic arrest (left ventricular systolic pressure: 109.1 ± 3.4 vs 103.3 ± 3.6). Similarly, HEP levels did not differ between the two groups (ATP: 2.5 ± 0.4 nmol/mg protein and 2.2 ± 0.9 nmol/mg).

CONCLUSIONS

Polarizing cardioplegic arrest did not lead to a statistically significant difference in myocardial protection as compared to a clinically relevant, standard cold blood cardioplegia in rat hearts with chronic MI.