Evaluation of myocardial ischemia during beating-heart aortic arch repair in a piglet model

Objectives: Aortic arch repair on the beating heart is well established in the clinical routine of congenital cardiac surgery. However, the method lacks validation in an animal model proving its superiority compared to the standard cardioplegia technique.

Methods: Twenty piglets (mean weight 11.1 ± 1.2 kg) were operated with antegrade cerebral perfusion and randomized to either beating-heart with selective myocardial perfusion (group-BH) or crystalloid cardioplegia (group-CC) for 60 minutes aortic cross-clamp time. Blood levels of myoglobin (MYO), creatin-kinase-MB-isoenzym (CKMB), and Troponin-I (TNI) were evaluated during aortic cross-clamp at 20 (T3) and 40 minutes (T4), reperfusion (T5), off bypass (T6), and after 2 hours (T8).

Results: MYO-levels at T3 and T4, and TNI-levels at T5 were significantly higher in group-BH (MYO: 358 ± 131 µg/l vs. 215 ± 110 µg/l, and 479 ± 283 µg/l vs. 229 ± 119 µg/l, TNI: 5.7 ± 1.5 ng/l vs. 2.5 ± 1.4 ng/l; p = 0.016, 0.026, < 0.01, respectively). At T6 and T8 absolute levels of cardiac ischemia parameters were not significantly different between groups. However, reperfusion related increase of MYO, CKMB, and TNI was significantly higher in group-CC at T6 (MYO: 76 ± 26% vs. 145 ± 71%, CKMB: 98 ± 15% vs. 151 ± 63%, and TNI: 136 ± 84% vs. 232 ± 107%, p = 0.012, 0.024, and 0.041, respectively) and of TNI at T8 (TNI: 53 ± 9% vs. 282 ± 122%; p < 0.01).

Conclusions: Compared to cardioplegia, aortic arch repair on the beating-heart induces higher blood levels of cardiac ischemia during aortic cross-clamping. However, after reperfusion ischemic parameters with cardioplegia ultimately increase to not significantly different levels due to secondary wash-out phenomena. Thus, outcome of cardiac ischemia was independent from the chosen surgical technique in our model.