Higher preoperative Qp/Qs ratio is associated with lower preoperative regional cerebral oxygen saturation in children with ventricular septal defect

Purpose: The relationship between regional cerebral oxygen saturation (rSO₂) and the amount of left-to-right shunt in ventricular septal defect (VSD) patients has not yet been investigated. The purpose of this study was to identify the association of preoperative pulmonary to systemic blood flow (Qp/Qs) ratio and preoperative rSO₂ in patients with VSD. Methods: We retrospectively evaluated 49 VSD surgical closure candidates at a single institution. Preoperative Qp/Qs ratio was compared with rSO₂ measurements at the time of VSD closure surgery. Results: Forty-nine were eligible for the final analysis. The median age at surgery was 6 (interquartile range [IQR]: 3, 12) months, and 36.7% were male. Atrial septal defects coexisted in 51.0%. There were no genetic abnormalities except trisomy 21 in 32.6% of the patients. Pulmonary hypertension was found in 42.8%. The median Qp/Qs ratio, calculated based on catheter testing results before the surgery, was 2.7 (IQR: 2.1, 3.7). Postoperative rSO₂ was significantly higher than preoperative values (52.2 ± 12.9, 63.5 ± 13.1%, p < 0.001). There was an inverse relationship of Qp/Qs and preoperative cerebral rSO₂ (r = − 0.11, p = 0.02). Conclusion: A higher Qp/Qs ratio was associated with a lower preoperative cerebral rSO₂ in pediatric patients with VSD.