Mitral leaflet geometry perturbations with papillary muscle displacement and annular dilatation: an in-vitro study of ischemic mitral regurgitation.
OBJECTIVE
Perturbations of leaflet geometry are the final end point through which left ventricular (LV) ischemia causes incomplete mitral leaflet closure and resultant mitral regurgitation (MR). Geometric inconsistencies observed with valvular or subvalvular structural alterations raise several questions.


METHODS
A new in-vitro LV flexible bag model was developed in order to visualize and analyze leaflet geometric changes under simulated pathological ischemic MR conditions.


RESULTS
Papillary muscle (PM) displacement and annular dilatation decreased leaflet coaptation length, leading to significant MR. Symmetrical PM displacement shifted the coaptation line towards the leaflet edges and created central gaps along this line. Asymmetric PM displacement generated diametrically uneven coaptation with a tent-shaped leaflet at the tethered PM side, while the leaflet bulged at the opposite side towards the left atrium.


CONCLUSIONS
Leaflet geometry during systole is affected by subvalvular structures. Asymmetric PM displacement, which may occur in regional or acute myocardial infarction, induces irregular deformation of the leaflet's coaptation line and, as a result, MR at the tethered side. Direct visualization of leaflet perturbation under these simulated pathological conditions may promote understanding of mechanisms present in ischemic MR.
He
Shengqiu
S
Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech, Atlanta, GA, USA.
Jimenez
Jorge
J
He
Zhaoming
Z
Yoganathan
Ajit P
AP
D000222:Adaptation, Physiological; D000818:Animals; D004108:Dilatation, Pathologic; D018618:Echocardiography, Doppler, Color; D006439:Hemodynamics; D066298:In Vitro Techniques; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008955:Models, Cardiovascular; D017202:Myocardial Ischemia / Q000503:physiopathology*; D010210:Papillary Muscles / Q000473:pathology; D012680:Sensitivity and Specificity; D013552:Swine; D016277:Ventricular Function, Left