Antegrade cerebral perfusion at higher temperatures is more neuroprotective than deep hypothermic circulatory arrest (DHCA) during aortic arch operations in young piglets

Aims: Aortic-arch-operations in pediatric patients using continuous hypothermic low-flow-perfusion-techniques with antegrade cerebral flow have become very popular due to their neuroprotective potential. Modern protocols tend to increase the perfusion-temperature in order to simplify surgery, however a clear hypothermic border and the effectiveness of any subdiaphragmal perfusion via native collaterals are not defined.

Methods: 26 male newborn piglets (10–15kg) underwent aortic-arch-surgery in general anaesthesia using either low-flow-perfusion via the innominate artery (group 1: 30ml/kg/min, 25°C, n=12) or conventional DHCA (group 2: 20°C, n=14). Cortical SSEP, carotid and subdiaphragmal blood flows where measured. Detection of neuron damage consisted of intermittent blood-sampling (NSE and S-100) and histologic examination of 5 different areas at the end of the experiment.

Results: During low-flow-perfusion via the innominate artery only negligible flows of max. 1–3ml/min in the femoral arteries were detected, whereas right-carotid-artery-flow was doubled (group 1). S-100- and NSE-serum-levels did not differ in both groups. Cortical SSEP returned to preoperative values in all but two low-flow-animals. There was no return of SSEP in all piglets operated using DHCA (p<0.01). Surprisingly brain-histologies did not show any significant differences in the investigated areas for both groups.

Conclusion: Low-flow-perfusion via the innominate artery provides superior functional neuroprotection compared to DHCA, despite higher tissue temperature. Quantitative neuron damage seems to be similar in both groups according to histologic examinations and the measurements of S-100 and NSE. Although collateral blood-flow via the subclavian artery and the circulosus willisii have often been suggested only “trickle-flow“ in the inguinal arteries was detectable.