Comparison by Computerized Numeric Modeling of Energy Losses in Different Fontan Connections

Abstract

The atriopulmonary connection produces higher energy losses than the cavopulmonary connection (+/- 1 mm Hg at rest). The cavopulmonary connection is more efficient when the connection of the caval veins to the pulmonary artery is asymmetrical.

In vivo flow dynamics of the total cavopulmonary connection from three-dimensional multislice magnetic resonance imaging

“…With comparative analysis of these methods, and keeping in mind anatomic space constraints, some cautious clinical implications can be made. First, our and other studies [13] have shown the advan tages of caval offsetting and, we believe, that within any given anatomic space constraints, offsetting should be incorporated as the first step in all TCPC designs. Whether the SVC should be offset more toward the left PA as in the extracardiac TCPC group or toward the right PA as in our intraatrial TCPC group, has not been determined by this study.…”

“…Subsequently, an in vivo magnetic resonance imaging study has also demon strated improved flow dynamics in the TCPC over the atriopulmonary connection [9]. In a recent study, compu tational modeling of different types of TCPC demon strated that offsetting of the caval connection was efficient [13]. Paralleling the in vitro studies and learning from the insights therein, many institutions have continued to modify the TCPC design.…”

In Vivo Evaluation of Fontan Pathway Flow Dynamics by Multidimensional Phase-Velocity Magnetic Resonance Imaging

“…On the basis of the results of those experiments, they advocated the use of TCPC that was designed to produce a more streamlined flow pattern that should lead to less energy loss. Subsequent in vitro 7,[17][18][19][20][21] and computational 8,18,19 studies confirmed those observations. The effect of progressive right atrial dilatation on energy loss and resistance to flow was recently studied by Lardo and associates 20 in an in vitro flow model of explanted sheep hearts with APA-type Fontan pathways.…”

“…Other investigators studied various geometries of TCPC, attempting to find the most efficient connection. 7,8,18,19,21,22 Although these in vitro and computational experiments provided important information regarding isolated aspects of the Fontan circulation, they have not been validated in vivo.…”

“…In an attempt to confirm the hemodynamic advantage of TCPC over APA, several researchers studied the magnitude of energy loss in simulated APA and TCPC circuits. 8,17 Their results, however, predict that the losses of pressure energy due to increased friction would be of very small absolute magnitude (Ͻ1 mm Hg for an APA pathway). 8 Our experience, too, has been that in the absence of a significant anatomical stenosis even markedly dilated Fontan pathways do not exhibit clinically measurable pressure gradients across the right atrial chamber and APA at cardiac catheterization.…”