The Management of Systemic-Pulmonary Collateral Blood Flow in Cyanotic Children During Cardiopulmonary Bypass - Pilot Study

A great number of studies have shown that MAPCAs are a real issue for these patients, who require far higher blood flows than previously suggested. However, the optimal method of CPB is still unknown. Recent research by Sakamoto et al., showed that a raised carbon dioxide (pCO2) increased brain blood flow in cyanotic patients, suggesting a noticeable decrease in aorto-pulmonary blood shunting. However, the mechanism of this action is not understood and it is unclear if this observation is an associated or causative one. Whilst the vasoconstrictive (narrowing of vessels) effect of hypoxia has been well documented, with and without high carbon dioxide, there are no reports indicating that pCO2 alone increases the narrowing of blood vessels in the lung. We hypothesize that a rise in pCO2 could cause a shift in blood flow from pulmonary to systemic circulation, either through direct constricting action on MAPCA vessels, or through a vasoconstriction of blood vessels in the lung. Furthermore, we predict the phenomenon could potentially be used to optimize the method of treatment, ensuring that vital organs receive the correct amount of blood flow during the surgical correction of these rare congenital heart diseases.