Mitral Annular Flexibility

Abstract

An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valve repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this geometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight normal subjects. The posterior half of the MVA exhibited translational motion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricular contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterior half exhibited a flexible change in shape during systole, thus maintaining a sufficient left ventricular outflow tract (LVOT). The increase in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 +/- 1.0 mm (mean +/- SD), indicates the annular flexibility. The preservation of annular flexibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presented in this article.

Real‐Time 3‐Dimensional Dynamics of Functional Mitral Regurgitation: A Prospective Quantitative and Mechanistic Study

“…This early–annular antero‐posterior contraction, and saddle‐shape accentuation, has been postulated to be owing to either expansion of the aortic root in systole, thought to bring about folding by displacing the aorto‐mitral curtain posteriorly away from the aorta, 24,27 or tethering of the anterior annulus to the aortic root combined with apical translation of the entire annulus resulting in folding across the intercommissural axis. 28–29 Our analysis shows that this very early–annular folding begins during the iso‐volumic contraction, preceding aortic ejection, thus suggesting a major role for the second mechanism which does not depend on ejection and aortic displacement. Once leaflets are firmly opposed by early–annular folding, late‐systolic changes in annular area have little potential for inducing MR because of the firm apposition of the leaflets by increasing intraventricular pressure.…”

Paneth Suture Annuloplasty Abolishes Acute Ischemic Mitral Regurgitation but Preserves Annular and Leaflet Dynamics

“…6,23 Systolic annular flexion displaces the septal annulus away from the LV outflow tract, assisting ejection. 24 Complete rings may predispose toward LV outflow tract obstruction by flattening the annulus 23 and reducing annular flexion. 25,26 Paneth suture tightening did not reduce annular shortening or flexion compared with the ischemic state, thus preserving the putative advantages of normal annular dynamic motion.…”

Basic Mechanisms of Mitral Regurgitation

“…The average MA area in healthy subjects is ~10 cm 2 [10, 18–21]. The flexible posterior MA allows for systolic apical bending along a commissural axis [17, 22]. This mechanism, in combination with the planar kidney-bean and horizontal saddle-shape configuration allows the MA to sphincter-like shrink in area by ~ 20 – 42% from diastole to systole [19–21, 23, 24], which reduces leaflet tissue stress and is important to maintain coaptation (Figure 2 B, C) [25–30].…”