Abstract 1745: Mitral Leaflet Adaptation to Ventricular Remodeling: Occurrence and Adequacy in 80 Patients With Functional Mitral Regurgitation

Abstract

Functional mitral regurgitation (FMR) is caused by systolic traction on the mitral leaflets related to ventricular distortion. Little is known about how chronic tethering affects leaflet area, in part because of inability to reconstruct leaflet area in situ. Our aim was to do so in order to explore whether adaptive increases occur that meet the needs of tethered geometry in FMR, and to test the hypothesis that leaflet area influences MR. Methods and Results. A new method for 3D echo measurement of mitral leaflet area was developed and validated in vivo against sheep valves, later excised. This method was used to study 80 consecutive patients in 3 groups: patients with normal hearts (n=20); with FMR (n=29) from inferior wall motion abnormality (IWMA) or dilated cardiomyopathy (DCM); and with IWMA or DCM but no MR (n=31). Patients with FMR had 23±5% increased leaflet area compared with normal subjects. The ratio of leaflet to annular area was 1.95±0.40, not different among groups (figure ), indicating a surplus leaflet area that adapts to left heart changes. In contrast, the ratio of total leaflet area to that required to close the orifice in mid-systole was decreased in patients with FMR versus normal (1.29±0.15 vs 1.78±0.39, p=0.001) and versus patients with IWMA or DCM but no MR (1.81±0.38, p=0.001). After adjusting for measures of LV remodeling and tethering, a leaflet-to-closure area ratio <1.7 was associated with significant MR (OR=23.2, p=0.02). Conclusion. Mitral leaflet area increases in response to chronic tethering in patients with IWMA and DCM. However, the adequacy of leaflet adaptation to tethering geometry varies, and may partly explain the heterogeneity of FMR among patients.

Quantitative Analysis of Mitral Annular Geometry and Function in Healthy Volunteers Using Transthoracic Three-Dimensional Echocardiography

“…In diastole, when the leaflets are wide open, they can be tracked through their entire length. This might explain why our anterior and posterior leaflets' lengths and areas were relatively smaller than those reported by Chaput et al, 36 who measured the same parameters in diastole.…”

Wnt Site Signaling Inhibitor Secreted Frizzled‐Related Protein 3 Protects Mitral Valve Endothelium From Myocardial Infarction–Induced Endothelial‐to‐Mesenchymal Transition

“…Two‐dimensional data were analyzed with Syngo Dynamics (Siemens, Erlangen, Germany), and 3‐dimensional data were analyzed with 4‐dimensional LV analysis version 3.1.2 (TomTec, Unterschlessheim, Germany) for LV volume. 10 , 31 Left ventricular ejection fraction (LVEF) was calculated as ([end‐diastolic LV volume] – [end‐systolic LV volume])/(end‐diastolic LV volume). MI size was measured using ImageJ version 1.48 (National Institutes of Health, Bethesda, MD) by planimetry of the visually determined MI endocardial surface area of the open harvested heart and its ratio to total LV endocardial surface area.…”

“…Increased MV leaflet thickness, stiffness, and fibrosis further contribute to progressive IMR. 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 Valve tethering and LV volume overload without MI induce adaptive MV growth with associated endothelial‐to‐mesenchymal transition (EndMT). 15 , 16 , 17 , 18 , 19 In contrast, MI induces excessive EndMT with overexpression of transforming growth factor beta (TGFβ) and collagen deposition over 2 to 6 months.…”

Overview of the catheter-based methods for treatment of mitralregurgitation

“…Това отчасти се дължи на адаптивното увеличаване на площта на митралните платна, което се наблюдава при някои пациенти с LV дисфункция. Проучване на Chaput et al [29] показва, че пациентите с исхемична MR имат по-малка площ на платната към зоната на затваряне спрямо тези без MR. Неадекватната експанзия на платната с цел компенсация на дилатацията на LV играе роля в механизма на исхемичната MR [30].…”