Total Cavopulmonary Connection Flow With Functional Left Pulmonary Artery Stenosis

Abstract

Background-In our multicenter study of the total cavopulmonary connection (TCPC), a cohort of patients with long-segment left pulmonary artery (LPA) stenosis was observed (35%). The clinically recognized detrimental effects of LPA stenosis motivated a computational fluid dynamic simulation study within 3-dimensional patient-specific and idealized TCPC pathways. The goal of this study was to quantify and evaluate the hemodynamic impact of LPA stenosis and to judge interventional strategies aimed at treating it. Methods and Results-Simulations were conducted at equal vascular lung resistance, modeling both discrete stenosis (DS) and diffuse long-segment hypoplasia with varying degrees of obstruction (0% to 80%). Models having fenestrations of 2 to 6 mm and atrium pressures of 4 to 14 mm Hg were explored. A patient-specific, extracardiac TCPC with 85% DS was studied in its original configuration and after virtual surgery that dilated the LPA to 0% stenosis in the computer medium. Performance indices improved exponentially (R 2 Ͼ0.99) with decreasing obstruction. Diffuse long-segment hypoplasia was Ϸ50% more severe with regard to lung perfusion and cardiac energy loss than DS. Virtual angioplasty performed on the 3-dimensional Fontan anatomy exhibiting an 85% DS stenosis produced a 61% increase in left lung perfusion and a 50% decrease in cardiac energy dissipation. After 4-mm fenestration, TCPC baffle pressure dropped by Ϸ10% and left lung perfusion decreased by Ϸ8% compared with the 80% DS case. Conclusions-DS Ͻ60% and diffuse long-segment hypoplasia Ͻ40% could be considered tolerable because both resulted in only a 12% decrease in left lung perfusion. In contrast to angioplasty, a fenestration (right-to-left shunt) reduced TCPC pressure at the cost of decreased left and right lung perfusion. These results suggest that pre-Fontan computational fluid dynamic simulation may be valuable for determining both the hemodynamic significance of LPA stenosis and the potential benefits of intervention. (Circulation. 2005;112:3264-3271.)

Risk Analysis of Unruptured Aneurysms Using Computational Fluid Dynamics Technology: Preliminary Results

“…Recently, EL has been introduced into clinical applications (eg, to estimate the outcomes of artery anastomosis in cardiovascular surgery). 15,19 In this study, we have introduced the EL concept to predict the risk of aneurysmal rupture. The results demonstrated that the EL created when flow passes through the aneurysm was significantly higher in ruptured-IAs than in unruptured-IAs.…”

The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

“…The patientspecific TCPC CFD analysis methodology and in vitro validations of these techniques have been described in previous studies (27,29,42). For each patient geometry, blood flow was modeled at baseline steady-state flow conditions by setting SVC and IVC flows to values derived from PC MRI averaged over the cardiac cycle.…”

Progress in the CFD Modeling of Flow Instabilities in Anatomical Total Cavopulmonary Connections

“…Final mesh numbers and densities utilized for both anatomical models (Table 1) were comparable to the finest mesh sizes that have been used in our previous (steady-state) studies. 22,23,32 The Hex Core meshes were generated in approximately 1 h. This time is similar to that required to generate an unstructured tetrahedral mesh layout, but has the added benefit of containing a core of equally sized hexahedral (brick) elements that covers~80% of the computational domain. Convergence of the Hex Core layout was also considerably faster than that of the tetrahedral mesh layout.…”

“…Advances in fluid flow modeling of complex TCPC anatomies is even more critical as new virtual patient-specific surgical planning tools are introduced 28 and proven to be potentially useful in several clinical cases. 22,32 Accurate modeling of the unsteady flow deserves added emphasis as the right-heart bypass and diaphragm movement introduces significant unsteadiness to the otherwise steady single-ventricle venous flow.…”