Three-dimensional changes in left and right ventricular geometry in chronic mitral regurgitation

Area of Science:

• Cardiovascular Physiology
• Cardiac Mechanics
• Medical Imaging

Background:

• Mitral regurgitation (MR) is a common cardiac condition affecting ventricular function.
• Understanding the three-dimensional (3-D) geometric changes in the ventricles due to MR is crucial for assessing disease progression and guiding treatment.
• Previous studies have focused on overall ventricular volumes, but regional shape alterations remain less understood.

Purpose of the Study:

• To investigate regional 3-D right ventricular (RV) and left ventricular (LV) geometry changes in dogs with chronic mitral regurgitation (MR).
• To quantify ventricular shape alterations using a 3-D finite-element model fitted to cardiac magnetic resonance imaging (CMR) data.
• To elucidate the impact of MR on LV and RV mass and their contributions to stroke volume.

Main Methods:

• Regional 3-D ventricular geometry was assessed in eight dogs before and 5-6 months after MR induction.
• A 3-D finite-element model was fitted to chamber contours derived from CMR images to quantify shape changes.
• Key geometric parameters including end-diastolic volume, stroke volume, and ventricular mass were measured for both RV and LV.

Main Results:

• MR significantly increased LV end-diastolic volume (LVEDV) and LV stroke volume (LVSV).
• A marked rightward shift of the septum was observed, indicating asymmetric LV dilation.
• LV mass increased, while RV end-diastolic volume decreased, though RV stroke volume was maintained, suggesting ventricular interaction.

Conclusions:

• Chronic MR induces asymmetric LV dilation with significant regional variations in geometry.
• The septum plays an increased role in contributing to LVSV, potentially at the expense of RVEDV.
• RV stroke volume maintenance may be attributed to inter-ventricular mechanical coupling.