Can isolated annular dilatation cause significant ischemic mitral regurgitation? Another look at the causative mechanisms.
This study was to investigate the mechanisms of ischemic mitral regurgitation (IMR) by using a finite element (FE) approach. IMR is a common complication of coronary artery disease; and it usually occurs due to myocardial infarction. The pathophysiological mechanisms of IMR have not been fully understood, much debate remains about the exact contribution of each mechanism to IMR. Two patient-specific FE models of normal mitral valves (MV) were reconstructed from multi-slice computed tomography scans. Different grades of IMR during its pathogenesis were created by perturbation of the normal MV geometry. Effects of annular dilatation and papillary muscle (PM) displacement (both isolated and combined) on the severity of IMR were examined. We observed greater increase in IMR (in terms of regurgitant area and coaptation length) in response to isolated annular dilatation than that caused by isolated PM displacement, while a larger PM displacement resulted in higher PM forces. Annular dilation, combined with PM displacement, was able to significantly increase the severity of IMR and PM forces. Our simulations demonstrated that isolated annular dilatation might be a more important determinant of IMR than isolated PM displacement, which could help explain the clinical observation that annular size reduction by restrictive annuloplasty is generally effective in treating IMR.
Tissue Mechanics Laboratory, Biomedical Engineering Department, Georgia Institute of Technology, Atlanta, GA 30313, United States.
Qian
Q
Wang
Cardiology Department, The Hartford Hospital, Hartford, CT 06102, United States.
Charles
C
Primiano
Tissue Mechanics Laboratory, Biomedical Engineering Department, Georgia Institute of Technology, Atlanta, GA 30313, United States. Electronic address: wei.sun@bme.gatech.edu.
Wei
W
Sun
D003198:Computer Simulation; D017023:Coronary Angiography; D004106:Dilatation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000503:physiopathology* / Q000601:surgery; D008944:Mitral Valve Insufficiency / Q000503:physiopathology*; D008955:Models, Cardiovascular; D009203:Myocardial Infarction / Q000503:physiopathology; D010210:Papillary Muscles / Q000503:physiopathology; D013599:Systole
Annuloplasty; Finite element; Ischemic mitral regurgitation; Mitral valve; Patient-specific