Mitral valve ring in normal vs dilated left ventricle. Cross-sectional echocardiographic study

Area of Science:

• Cardiology
• Echocardiography
• Cardiac Mechanics

Background:

• Dilated cardiomyopathy (DCM) often presents with left ventricular (LV) dilatation.
• Mitral regurgitation (MR) is a common complication in DCM patients.
• The precise mechanisms underlying MR in DCM remain incompletely understood.

Purpose of the Study:

• To investigate the relationship between mitral valve ring (MVR) dilatation and the development of MR in patients with dilated left ventricles.
• To determine if MVR dilatation is proportional to LV dilatation in DCM.
• To explore alternative mechanisms for MR in DCM.

Main Methods:

• Cross-sectional echocardiography (CE) was performed on 23 normal subjects, 11 DCM patients with MR (Group 2), and 11 DCM patients without MR (Group 3).
• Measurements included MVR diastolic diameter (Dd), systolic diameter (Ds), and LV end-diastolic dimension (LVED).
• Calculated parameters included MVR systolic shortening percentage (delta D%) and the Dd/LVED ratio.

Main Results:

• Patients in Groups 2 and 3 exhibited significantly higher LVED, Dd, and Ds compared to normal subjects.
• The delta D% and Dd/LVED ratio were significantly lower in DCM patients.
• In eight DCM patients (Groups 2 and 3), MVR diameter was within normal limits, with four of these experiencing MR.

Conclusions:

• Mitral annulus dilatation occurs in only a subset of DCM patients and is not consistently proportional to LV dilatation.
• Mitral regurgitation in DCM may arise from mechanisms independent of mitral annulus dilatation.
• Potential alternative mechanisms include loss of annular sphincteric function or papillary muscle malalignment.