Abstract 14615: Relationships Between Inertial Force, Wave Intensity, and Ventricular Function in Patients With Fontan Circulation
Background: The blood flow momentum from the ventricle toward the aorta, quantified as inertial force (IF), is vital for preserving systemic perfusion during diastole. Expansion wave intensity (WI) of the ascending aorta including the effects of IF and ventricular relaxation, represents energy for diastolic systemic output. We hypothesized that decreased expansion WI due to decreased IF characterizes Fontan circulation.
Methods: In 22 Fontan (6.3 ± 3.4 years) and 16 control patients (small septal defects/ductus arteriosus, 5.3 ± 3.5 years) who underwent cardiac catheterization, IF was calculated by phase-loop analysis of ventricular dP/dt-pressure relationship, and WI was computed using time derivatives of pressure and flow waveform in the ascending aorta. Ventricular contractility, diastolic function (Tau, stiffness), preload (end-diastolic volume), and afterload were assessed by invasive pressure-area relationship during caval occlusion; their relationships with IF and WI were examined.
Results: IF was significantly decreased, and Tau was significantly prolonged in the Fontan than in the control group (0.52 ± 1.0 vs. 1.2 ± 1.1 mmHg, IF; 19.7 ± 4.0 vs. 16.7 ± 2.3 ms, Tau; both p<0.005). Expansion WI was also significantly lower in the Fontan than in the control group (1121 ± 423 vs. 1796 ± 764 mmHg.m 1.s-3, p<0.001). Relaxation and IF were significant independent determinants of expansion WI in the control group, and IF was a major determinant of WI in the Fontan group. Multivariate analysis showed end-diastolic volume to be an independent determinant of IF in Fontan circulation (p=0.001). Expansion WI and IF significantly reduced with decreased cardiac output during temporary fenestration occlusion in Fontan patients.
Conclusions: These data imply abnormal quality (IF and WI) as well as quantity (cardiac output) of blood flow in Fontan circulation. As IF and IF-affected WI are representatives of energy that facilitates aortic blood flow, modulation of IF could be useful in improving Fontan hemodynamics, which should be performed via a fenestrated Fontan procedure.
- Fontan physiology
- Ventricular function
- Diastolic function
- Pressure – volume relation
- Congenital heart disease
- © 2013 by American Heart Association, Inc.