Impact of surgical ventricular restoration on ventricular shape, wall stress, and function in heart failure patients

Abstract

Surgical ventricular restoration (SVR) was designed to treat patients with aneurysms or large akinetic walls and dilated ventricles. Yet, crucial aspects essential to the efficacy of this procedure like optimal shape and size of the left ventricle (LV) are still debatable. The objective of this study is to quantify the efficacy of SVR based on LV regional shape in terms of curvedness, wall stress, and ventricular systolic function. A total of 40 patients underwent magnetic resonance imaging (MRI) before and after SVR. Both short-axis and long-axis MRI were used to reconstruct end-diastolic and end-systolic three-dimensional LV geometry. The regional shape in terms of surface curvedness, wall thickness, and wall stress indexes were determined for the entire LV. The infarct, border, and remote zones were defined in terms of end-diastolic wall thickness. The LV global systolic function in terms of global ejection fraction, the ratio between stroke work (SW) and end-diastolic volume (SW/EDV), the maximal rate of change of pressure-normalized stress (dσ*/dt(max)), and the regional function in terms of surface area change were examined. The LV end-diastolic and end-systolic volumes were significantly reduced, and global systolic function was improved in ejection fraction, SW/EDV, and dσ*/dt(max). In addition, the end-diastolic and end-systolic stresses in all zones were reduced. Although there was a slight increase in regional curvedness and surface area change in each zone, the change was not significant. Also, while SVR reduced LV wall stress with increased global LV systolic function, regional LV shape and function did not significantly improve.

Fig. 1.

Magnetic resonance image showing a short-axis slice (top) at the level of the equator and long-axis slice (middle) at end diastole and end systole, with the left ventricular endocardial and epicardial surfaces denoted by yellow lines. Its corresponding three-dimensional (3-D) reconstructed left ventricular shape (bottom) at end diastole and end systole are shown before (A) and after (B) surgical ventricular restoration (SVR).

Fig. 2.

3-D geometry of the left ventricle before and after SVR. Surface was classified into 3 regions: remote zone (RZ), border zone (BZ), and infarcted zone (IZ).

Fig. 3.

Left ventricular regional curvedness at end diastole (C_ED) and end systole (C_ES) in RZ, BZ, and IZ before and after SVR. There is no significantly change in curvedness in each zone. *P < 0.05, pre- vs. post-SVR. NS, not significant.

Fig. 4.

Left ventricular regional wall stress indexes at end diastole (σ/P_ED) and end systole (σ/P_ES) and end-systolic wall stress (σ_ES) in RZ, BZ, and IZ before and after SVR. End-diastolic wall stress index decreased significantly in each zone.