A histopathological comparison of del Nido and blood cardioplegia in a rat model of global myocardial ischemia

Effective myocardial protection during cardiac surgery is essential to minimize ischemic injury. Del Nido (DN) cardioplegia has been increasingly used as an alternative to multidose blood cardioplegia consisting of autologous blood supplemented with potassium chloride, magnesium sulfate and sodium bicarbonate (BC); however, experimental data comparing their myocardial effects at the tissue level remain limited. Sixteen Wistar albino rats were randomized to receive either a single 4-mL dose of del Nido (DN) cardioplegia or conventional blood cardioplegia (BC) administered as a 2-mL induction dose followed by two 1-mL maintenance doses at 20 and 40 min (total volume 4 mL in both groups) during a standardized 60-minute period of global myocardial ischemia. Hearts were harvested immediately after completion of the 60-minute ischemic period. Left ventricular tissue samples were evaluated histopathologically for vacuolization, inflammation, edema, and glycogen content. Immunohistochemical expression of Caspase-3 and inducible nitric oxide synthase (iNOS) was quantified using ImageJ-based analysis. Between-group comparisons were performed using non-parametric tests, and within-group associations were explored using Spearman correlation. No statistically significant differences were observed between the DN and BC groups in histopathological injury scores, including vacuolization ( p = 0.561), inflammation ( p = 0.349), and edema ( p = 0.529). Glycogen preservation scores were numerically higher in the DN group (median 3 [IQR 2–3] vs. 2 [IQR 1–3]), although this difference did not reach statistical significance ( p = 0.164). Quantitative immunohistochemical analysis demonstrated no significant between-group differences in Caspase-3 ( p = 0.233) or iNOS expression ( p = 0.218). Within-group exploratory analysis revealed a positive correlation between iNOS and Caspase-3 expression in the DN group (ρ = 0.744, p = 0.034), whereas this association was weaker and non-significant in the BC group (ρ = 0.243, p = 0.562). In this experimental rat model of global myocardial ischemia, del Nido cardioplegia provided myocardial preservation comparable to blood cardioplegia. These findings suggest that DN represents a feasible alternative myocardial protection strategy; however, larger studies incorporating reperfusion, functional assessment, and adequate statistical power are required before definitive conclusions can be drawn.