Objectives: This study aimed to investigate whether selective antegrade cerebral perfusion or retrograde cerebral perfusion is a better technique for brain protection in deep hypothermic circulatory arrest by obtaining metabolic evidence from microdialysis.
Design: Randomized, animal study.
Setting: Assisted circulation laboratory.
Subjects: Eighteen piglets of either sex (9.8 ± 3.1 kg).
Interventions: Animals were randomly assigned to 40 minutes of circulatory arrest at 18°C without cerebral perfusion (deep hypothermic circulatory arrest group, n = 6) or with selective antegrade cerebral perfusion (selective antegrade cerebral perfusion group, n = 6) or retrograde cerebral perfusion (retrograde cerebral perfusion group, n = 6). Reperfusion was continued for 3 hours.
Measurements and Main Results: Microdialysis (glucose, lactate, pyruvate, and glycerol) variables in the cortex dialysate were measured every 30 minutes. Intracerebral pressure and serum S-100 levels were also monitored. After 3 hours of reperfusion, cortical tissue was harvested for terminal deoxynucleotidyl transferase dUTP nick-end labeling staining. After 40 minutes of circulatory arrest, the deep hypothermic circulatory arrest group presented marked elevations of intracerebral pressure, and serum S-100 levels were higher in the deep hypothermic circulatory arrest group than in the other two groups (p < 0.001, respectively). The selective antegrade cerebral perfusion group exhibited higher glucose, lower lactate, and lower glycerol levels and a lower lactate-to-pyruvate ratio in comparison to the deep hypothermic circulatory arrest group (p < 0.05, respectively); the retrograde cerebral perfusion group had lower lactate and glycerol levels and a lower lactate-to-pyruvate ratio (p < 0.05, respectively) but similar glucose levels compared to deep hypothermic circulatory arrest alone. Furthermore, selective antegrade cerebral perfusion provided better preservation of energy and cell integrity than retrograde cerebral perfusion with higher glucose and lower glycerol levels (p < 0.05, respectively). After 3 hours of reperfusion, fewer apoptotic neurons were found in selective antegrade cerebral perfusion animals than in the other two groups (p < 0.05, respectively).
Conclusions: Both selective antegrade cerebral perfusion and retrograde cerebral perfusion were superior to deep hypothermic circulatory arrest alone during circulatory arrest. Retrograde cerebral perfusion was a moderate technique that had similar advantages with regard to less cerebral edema, better clearance of metabolic waste, and lower levels of biomarkers of injury than selective antegrade cerebral perfusion, but its capacity for energy preservation, maintenance of cellular integrity, and protection against apoptosis was lower than that of selective antegrade cerebral perfusion.