Computational fluid dynamics-based risk stratification of modified Blalock-Taussig-Thomas shunt thrombogenicity

The modified Blalock-Taussig-Thomas shunt (mBTTS) is a critical palliative procedure for infants with single-ventricle physiology, but thrombosis-related occlusion affects 8% to 12% of infants and carries nearly 50% mortality. Meanwhile, existing antithrombotic strategies fail to address the hemodynamic factors driving thrombosis, highlighting the need for a deeper understanding of flow dynamics in shunt failure.

This study aims to identify how mBTTS geometry influences hemodynamics and thrombosis risk, providing quantitative guidance for surgical planning and shunt design optimization.

We used patient-specific imaging data to test 54 idealized mBTTS configurations, systematically varying key geometric factors: pulmonary artery diameter, shunt diameter, and insertion angle. Using computational fluid dynamics, we analyzed how these variables influence wall shear rate, elongation strain rate, and turbulence intensity, as well as hemodynamic parameters known to influence thrombosis risk, to identify patterns linked to thrombosis.

We computationally identified optimal geometric configurations. Peak wall shear rate and elongation strain rate were primarily located at bifurcation points, whereas peak turbulence intensity was concentrated within the shunt channel. Shunt insertion distal to the right carotid artery with a 60° insertion angle and with a 4.0-mm shunt graft demonstrated the most favorable hemodynamic profiles for clot prevention in infants. Statistical analysis confirmed strong correlations between geometric parameters and flow characteristics.

Results provide a framework for optimizing mBTTS design to reduce thrombosis risk based on hemodynamic risk factors, including actionable recommendations for shunt placement and design. These insights provide a foundation for hemodynamically guided surgical interventions with the potential to improve survival rates in this high-risk patient population and for broader applications in cardiovascular surgery.