Background and aim Neonates with left ventricular outflow tract obstruction (LVOTO) are at risk of developing brain damage, due to either ischemia or hypoxemia. Our aim was to explore the differences in cerebral and renal tissue oxygen saturation (rSO₂) and extraction (FTOE) between neonates with LVOTO with or without compromised antegrade ascending aortic flow.

Methods We included fourteen neonates with LVOTO and categorised them into neonates with compromised antegrade ascending aortic flow (hypoplastic left heart syndrome (n = 6)) and neonates without compromised antegrade ascending aortic flow (coarctatio aortae (n = 7)/non-critical aortic valve stenosis (n = 1)). We measured cerebral and renal rSO₂ using near-infrared spectroscopy during 72 h. Simultaneously, we measured preductal arterial oxygen saturation (SpO₂) and calculated FTOE.

Results On day 1, neonates with compromised antegrade ascending aortic flow had lower cerebral rSO₂ than neonates without compromised antegrade ascending aortic flow (median rSO₂ 68.5% vs. 79.4%, p-value = 0.032). Furthermore, cerebral FTOE tended to be higher in neonates with compromised antegrade ascending aortic flow on day 1 (median FTOE 0.30 vs. 0.14, p-value = 0.086). Significant differences in cerebral rSO₂ and FTOE disappeared the following days. There were no differences in SpO₂, renal rSO₂ and FTOE between both groups.

Conclusions Because there were no differences in SpO₂ between both groups, and cerebral FTOE tended to be higher in neonates with compromised antegrade ascending aortic flow, the lower cerebral oxygen saturation might be due to ischemia rather than hypoxemia. Furthermore, in neonates with antegrade ascending aortic flow, cerebral oxygenation might be spared.