Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study

Abstract

performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study. Am J Physiol Heart Circ Physiol 307: H1056 -H1072, 2014. First published July 25, 2014 doi:10.1152/ajpheart.00245.2014The physiological limitations of the Fontan circulation have been extensively addressed in the literature. Many studies emphasized the importance of pulmonary vascular resistance in determining cardiac output (CO) but gave little attention to other cardiovascular properties that may play considerable roles as well. The present study was aimed to systemically investigate the effects of various cardiovascular properties on clinically relevant hemodynamic variables (e.g., CO and central venous pressure). To this aim, a computational modeling method was employed. The constructed models provided a useful tool for quantifying the hemodynamic effects of any cardiovascular property of interest by varying the corresponding model parameters in model-based simulations. Herein, the Fontan circulation was studied compared with a normal biventricular circulation so as to highlight the unique characteristics of the Fontan circulation. Based on a series of numerical experiments, it was found that 1) pulmonary vascular resistance, ventricular diastolic function, and systemic vascular compliance play a major role, while heart rate, ventricular contractility, and systemic vascular resistance play a secondary role in the regulation of CO in the Fontan circulation; 2) CO is nonlinearly related to any single cardiovascular property, with their relationship being simultaneously influenced by other cardiovascular properties; and 3) the stability of central venous pressure is significantly reduced in the Fontan circulation. The findings suggest that the hemodynamic performance of the Fontan circulation is codetermined by various cardiovascular properties and hence a full understanding of patientspecific cardiovascular conditions is necessary to optimize the treatment of Fontan patients.

A multi‐scale model of the coronary circulation applied to investigate transmural myocardial flow

“…Finally, venular flows in all myocardial layers were assumed to converge to a venous compartment through which coronary flow is directed to the right atrium. Blood flow through each vascular compartment was governed by the mass and momentum conservation equations as those generally adopted in previous studies . The governing equations of all vascular compartments formed a system of ordinary differential equations.…”

“…P SIP was assumed to be proportional to the effective elastance of cardiac chamber where E is a time‐varying elastance that represents the systolic and diastolic function of a cardiac chamber (for details on the definition of E , please refer to Liang et al). λ was taken to be 7.0 mL so that peak P SIP was approximately 18% of peak P CEP for the left ventricle, which fell in the range (10%‐30%) determined by animal experiments .…”

“…Blood flow through each vascular compartment was governed by the mass and momentum conservation equations as those generally adopted in previous studies. 55,56 The governing equations of all vascular compartments formed a system of ordinary differential equations.…”

“…72,73 These data have been measured in vivo under both normal resting and hyperemic conditions. Calibration of systemic arterial pressures and cardiac output was achieved mainly by tuning the total peripheral vascular resistance and total blood volume following from the methods adopted in Liang et al 56,74 It is noted that the contractility of the left and right ventricles was not determinable based on available clinical data and hence was maintained at its reference state (reported in Liang et al 35 ) for the resting conditions, which was, however, elevated in proportion to heart rate to increase cardiac output under the hyperemic conditions. To calibrate model-predicted flow rates in the LAD, LCx, and RCA to in vivo measurements, the baseline resistances of intramyocardial vessels were tuned via a linear iteration algorithm, in which the relative difference (in percentage) between model-predicted and measured (target) flow rates is set as the objective function of parameter optimization.…”

Mechanical and physiological effect of partial pressure suit: Experiment and numerical study

“…The numerical modeling method is often employed in cardiovascular system studies [15,16]. A whole body mathematical model has been established to interpret the experimentally-derived intracranial pressure-volume relationship [17].…”