Abstract
Dilated cardiomyopathy (DCM) is the most common myocardial disease. It not only leads to systolic dysfunction but also diastolic deficiency. We sought to investigate the effect of idiopathic and ischemic DCM on the intraventricular fluid dynamics and myocardial wall mechanics using a 2D axisymmetrical fluid structure interaction model. In addition, we also studied the individual effect of parameters related to DCM, i.e. peak E-wave velocity, end systolic volume, wall compliance and sphericity index on several important fluid dynamics and myocardial wall mechanics variables during ventricular filling. Intraventricular fluid dynamics and myocardial wall deformation are significantly impaired under DCM conditions, being demonstrated by low vortex intensity, low flow propagation velocity, low intraventricular pressure difference (IVPD) and strain rates, and high-end diastolic pressure and wall stress. Our sensitivity analysis results showed that flow propagation velocity substantially decreases with an increase in wall stiffness, and is relatively independent of preload at low-peak E-wave velocity. Early IVPD is mainly affected by the rate of change of the early filling velocity and end systolic volume which changes the ventriculo:annular ratio. Regional strain rate, on the other hand, is significantly correlated with regional stiffness, and therefore forms a useful indicator for myocardial regional ischemia. The sensitivity analysis results enhance our understanding of the mechanisms leading to clinically observable changes in patients with DCM.
Highlights
Dilated cardiomyopathy (DCM) is associated with complex remodeling of one or both ventricles, resulting in a change of the ventricle shape and the architecture of the myocardium fibers
The aim of the present study is twofold: (i) to investigate the effect of idiopathic and ischemic DCM on intraventricular fluid dynamics and myocardial wall mechanics using a 2D axisymmetrical fluid structure interaction (FSI) model; and (ii) to investigate the individual effect of parameters related to DCM, i.e. peak E-wave velocity, end systolic volume (ESV), wall stiffness and sphericity index (SI) on intraventricular fluid dynamics and myocardial wall mechanics during left ventricle (LV) filling
The mitral valve is modeled as a circular inlet with a fixed ventriculo:annular ratio while the aortic valve is closed throughout the filling phase
Summary
DCM is associated with complex remodeling of one or both ventricles, resulting in a change of the ventricle shape and the architecture of the myocardium fibers. The ventricular shape changes from an elliptical to a more spherical form [1,2]. Patients with DCM may have a stiffer myocardial wall, caused by increased myocardial mass and alteration in the extracellular collagen network [3]. DCM secondary to ischemic heart disease, may have different areas of viable myocardium and non-viable myocardium. The viable myocardium would be contracting normally while the non-viable myocardium contracts weakly. Parodi et al [4] observed a more heterogeneous transmural blood flow distribution in patients with ischemic DCM and a higher percentage of fibrosis in these patients in their clinical studies despite having a similar mechanical compensation and global hemodynamics,
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