Undersized Mitral Annuloplasty Increases Strain in the Proximal Lateral Left Ventricular Wall

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Cardiac Mechanics

Background:

• Recurrence of mitral regurgitation (MR) after mitral annuloplasty (MA) for ischemic MR is common (up to 60%).
• Continued left ventricular (LV) dilation is a suspected cause of MR recurrence after MA.
• This study investigates the impact of undersized MA on LV wall strain.

Purpose of the Study:

• To determine the effect of undersized MA on LV wall strain.
• To understand the mechanisms behind recurrent MR after MA.
• To test the hypothesis that MA-induced shape changes increase strain near the mitral valve.

Main Methods:

• Utilized finite element models based on cardiac MRI from sheep with ischemic MR.
• Simulated a 24-mm undersized MA using a rigid annuloplasty ring.
• Calculated longitudinal and myofiber strains at end-diastole and end-systole.

Main Results:

• Undersized MA significantly increased end-diastolic longitudinal strain in the lateral LV wall.
• Strain increased approximately threefold on the proximal-lateral endocardial surface.
• Postoperative end-diastolic fiber strain decreased in the same region; no significant end-systolic changes were observed.

Conclusions:

• Undersized MA acutely increases end-diastolic longitudinal strain in the proximal lateral LV wall.
• This procedure-induced strain may contribute to LV enlargement and subsequent MR recurrence.
• Findings highlight a potential mechanism for MR recurrence after MA.