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This study used computational fluid dynamics to analyze blood flow in modified Blalock-Taussig-Thomas shunts (mBTTS) from 10 infants, finding that the angle at which the shunt connects to the subclavian artery and the shunt diameter are key geometric factors influencing thrombosis risk. Shunts with insertion angles deviating more from perpendicular and smaller diameters showed higher wall shear rates and elongational strain rates at the junction point, corresponding with increased thrombosis occurrence. These hemodynamic abnormalities consistently localized to the shunt-subclavian junction in 8 of 10 patients, including all 4 cases that developed clots.
Why it matters
The findings suggest surgeons could reduce the 8-12% shunt thrombosis rate in infants with congenital heart disease by optimizing insertion angle and diameter during surgery, offering a patient-specific approach beyond systemic anticoagulation which has limited efficacy. This could improve outcomes for a vulnerable patient population where shunt failure carries substantial mortality.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
ABSTRACT Background: The modified Blalock-Taussig-Thomas shunt (mBTTS) sustains pulmonary blood flow in infants with cyanotic or single-ventricle heart disease, but shunt thrombosis occurs in 8-12% of cases and carries substantial mortality. Systemic anticoagulation has limited efficacy. Objectives: This study tested whether surgically modifiable shunt geometry might form a second, patient-specific approach to maintaining shunt patency, via management of thrombogenic hemodynamics. Methods: Three-dimensional mBTTS anatomies were reconstructed from computed tomography in 10 infants (4 thrombosed, 6 patent). Pulsatile inlet waveforms derived from Doppler ultrasound were coupled with three-element Windkessel outlet models individually calibrated to catheter-derived pressures. Transient computational fluid dynamics simulations predicted wall shear rate (WSR) and elongational strain rate (ESR). Associations between surgically relevant geometric parameters and hemodynamic metrics were evaluated. Results: Simulated pressures closely matched clinical measurements at all four outlets in all 10 models. Despite substantial anatomic variability, peak WSR and ESR consistently localized to the shunt-subclavian junction in 8 of 10 patients, including all 4 thrombosed shunts. Greater deviation of shunt insertion angle from perpendicular was associated with higher systolic and cycle-averaged normalized WSR ({rho} = 0.94, p < 0.001; {rho} = 0.88, p = 0.002) and ESR ({rho} = 0.82, p = 0.007; {rho} = 0.70, p = 0.03). Larger shunt diameter was associated with lower WSR and ESR. Thrombosed shunts demonstrated higher shear-related metrics than patent shunts, particularly during systole. Conclusions: In patient-specific mBTTS anatomies, insertion angle and shunt diameter are determinants of local abnormal flow, concentrated at the shunt-subclavian junction. Patient-specific hemodynamic assessment may inform shunt construction and interstage risk stratification.