Impact of Shunt/Pulmonary Artery Ratio on Outcomes in Modified Blalock-Taussig Shunt Patients

Mario Hendri RW ^1*, Arief Rakhman Hakim ¹, Heroe Soebroto ¹, Erdyanto Akbar ¹, Hari Daswin Pagehgiri ¹

This study showed the importance of the S/PA ratio in predicting mortality and recovery outcomes post-modified Blalock-Taussig shunt.

Abstract

Background: The modified Blalock-Taussig shunt (mBTT shunt) is a critical procedure for managing congenital heart defects by improving pulmonary circulation. Traditionally, shunt size is determined based on patient weight and standard guidelines. However, recent evidence indicates that the shunt size relative to the pulmonary artery diameter (S/PA ratio) may be a more accurate predictor of outcomes. This study evaluates the impact of the S/PA ratio on mortality and other clinical outcomes in patients undergoing the mBTT shunt. Methods: This retrospective study analyzed the medical records of 36 patients who underwent mBTT shunt at Soetomo General Academic Hospital between 2021 and 2023. Data on demographics, clinical characteristics, procedural details, and outcomes were collected, focusing on variables such as age, weight, McGoon ratio, pre- and post-operative SpO2 levels, and S/PA ratio. Statistical analyses included Chi-square tests for categorical variables and independent t-tests for continuous variables, with a p-value of <0.05 considered significant. Results: The cohort had a mean age of 54.81 months and a mean weight of 12.18 kg. Preoperative SpO2 averaged 71.44%, improving to 79.26% post-operatively. Patients with an S/PA ratio >1.00 had a significantly higher mortality rate (37.5%) compared to those with an S/PA ratio <1.00 (7.7%) (p = 0.029). These patients also experienced longer ICU stays (4.92 vs. 2.06 days, p = 0.005) and more ventilation days (3.40 vs. 1.68 days, p = 0.047). The hospital stay was also extended in the higher ratio group (8.60 vs. 5.50 days, p = 0.076). No significant differences were observed in pre- and post-operative SpO2 levels or inotropic use. Conclusion: A higher S/PA ratio is associated with increased mortality, longer ICU and hospital stays, and greater ventilation needs following the mBTT shunt. These findings suggest that optimizing shunt size relative to pulmonary artery diameter could lead to better outcomes. Further research is needed to confirm these results and refine surgical strategies for enhanced patient care.

Keywords: mBTT shunt, S/PA ratio, congenital heart defects, pulmonary circulation, surgical outcomes

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