Mathematical Analysis and Physical Profile of Blalock-Taussig Shunt and Sano Modification Procedure in Hypoplastic Left Heart Syndrome: Review of the Literature and Implications for the Anesthesiologist

Abstract

The first stage of surgical treatment for hypoplastic left heart syndrome (HLHS) includes the creation of artificial systemic-to-pulmonary connections to provide pulmonary blood flow. The modified Blalock-Taussig (mBT) shunt has been the technique of choice for this procedure; however, a right ventricle-pulmonary artery (RV-PA) shunt has been introduced into clinical practice with encouraging but still conflicting outcomes when compared with the mBT shunt. The aim of this study is to explore mathematical modeling as a tool for describing physical profiles that could assist the surgical team in predicting complications related to stenosis and malfunction of grafts in an attempt to find correlations with clinical outcomes from clinical studies that compared both surgical techniques and to assist the anesthesiologist in making decisions to manage patients with this complex cardiac anatomy. Mathematical modeling to display the physical characteristics of the chosen surgical shunt is a valuable tool to predict flow patterns, shear stress, and rate distribution as well as energetic performance at the graft level and relative to ventricular efficiency. Such predictions will enable the surgical team to refine the technique so that hemodynamic complications be anticipated and prevented, and are also important for perioperative management by the anesthesia team.

Impact of Left Ventricular Morphology on Adverse Outcomes Following Stage 1 Palliation for Hypoplastic Left Heart Syndrome: 20 Years of National Data From Sweden

“…This could lead to later occurrence of RV dysfunction, ventricular aneurysms, and arrhythmias. 18 , 33 , 34 , 35 In our study, S1P with a Sano shunt had better early and overall outcome than those palliated with a BTs, with less pronounced mortality during the first year of life. Given the low number of individuals who died late after total cavopulmonary connection, a trustworthy interpretation of these data is not possible.…”

“… 18 , 19 , 31 , 32 More stable coronary perfusion because of absent diastolic runoff, which is typically encountered after BTs palliation, have been speculated to account for reduced complications early after S1P. 33 However, there are several drawbacks in palliation with Sano shunts including increased need of shunt reinterventions, focal scarring caused by RV ventriculotomy, and shunt regurgitation caused by the valveless conduit. This could lead to later occurrence of RV dysfunction, ventricular aneurysms, and arrhythmias.…”

Sir William Harvey, Congenital Heart Disease and Anesthesia

“…In their article, Efrain Riveros Perez and Ricardo Riveros explore mathematical models of fluid dynamics through these shunts and explain how such analysis could be a valuable tool to predict flow patterns and help the cardiac team predict and prevent hemodynamic complications. 5…”