Geometric description for the anatomy of the mitral valve: A review

Abstract

The mitral valve is a complex anatomical structure whose physiological functioning relies on the biomechanical properties and structural integrity of its components. Their compromise can lead to mitral valve dysfunction, associated with morbidity and mortality. Therefore, a review on the morphometry of the mitral valve is crucial, more specifically on the importance of valve dimensions and shape for its function. This review initially provides a brief background on the anatomy and physiology of the mitral valve, followed by an analysis of the morphological information available. A characterisation of mathematical descriptions of several parts of the valve is performed and the impact of different dimensions and shape changes in disease is then outlined. Finally, a section regarding future directions and recommendations for the use of morphometric information in clinical analysis of the mitral valve is presented.

Keywords: biomechanics; computational anatomy; mitral valve; mitral valve disease; morphology analysis.

FIGURE 1

Porcine mitral valve apparatus: (a) displays the anterior leaflet and chordae tendineae and (b) focuses on the subvalvular apparatus, where chordae arise from both PMs and insert into the rough region of the posterior leaflet

FIGURE 2

Human MV leaflet tissue areas. C, clear zone; R, rough zone; B, basal zone

FIGURE 3

Atrial and lateral views of a mitral valve (MV) schematic model based upon nine landmarks. The annulus, anterior and posterior leaflets and papillary muscle tips can be observed

FIGURE 4

Atrial (a) and lateral (b) views of important mitral annular dimensions. AV, aortic valve; LT, left trigone; RT, right trigone; P1, P2, P3, posterior leaflet scallops; AL–PM diameter, anterolateral‐posteromedial diameter; AP, antero‐posterior distance; CW, commissural width; IT, inter‐trigonal distance

FIGURE 5

Circle representing the annulus, according to Okamoto et al. (2007), with relevant dimensions highlighted. LT, left trigone; RT, right trigone; AL–PM diameter, anterolateral‐posteromedial diameter; CW, commissural width; IT distance, inter‐trigonal distance; θTg, trigonal angle; θCom, commissural angle

FIGURE 6

Hyperboloids representing the mitral valve (MV) saddle shape and defined by Equation 11 (Park et al., 2019) are displayed, created from literature values for CW (33.3 mm), AP diameter (28 mm), AL–PM diameter (31 mm) and AHCWR (0.237). Different commissural heights (b) and posterior annular depth (c) in comparison with a pure hyperboloid (a) can be observed, shown by changes in transformation parameters

FIGURE 7

Coaptation triangle. The tenting height divides the base of the triangle (AP diameter) into two segments—the anterior and the posterior cords. α _A, anterior leaflet angle; α _P, posterior leaflet angle

FIGURE 8

Parameters of human MV leaflet geometry, with an extended (a) and closed (b) leaflet representation. A‐B, anterolateral commissure; B‐C, anterior leaflet; C‐D, posteromedial commissure; D‐A′, posterior leaflet; D‐E, posteromedial commissural scallop (P1); E‐F, middle scallop (P2); F‐A′, anterolateral commissural scallop (P3)

FIGURE 9

Measurements describing PM morphology. ALPM, anterolateral PM; PMPM, posteromedial PM

FIGURE 10

Distances between PM tips and o’clock points of mitral annulus, in axial (left) and isometric (right) views (adapted from Sakai et al., 1999; Yamaura et al., 2008). ALPM, anterolateral PM; PMPM, posteromedial PM; 0 o’clock, midpoint of the anterior annular circumference; 2 o’clock, right trigone; 10 o’clock, left trigone; 4 o’clock, separation of posterior and middle scallops of posterior leaflet; 8 o’clock, separation of anterior and middle scallops of posterior leaflet

FIGURE 11

Axial view of C‐shape representation for the PMs, as present in the literature and suggested by expert surgeons, as well as a simplified depiction of chordae tendineae insertion patterns. Blue, green and orange chordae are those inserting into the anterior leaflet, posterior leaflet and paracommissural zones, respectively

FIGURE 12

Example of Reeb graph employed to characterise chordae tendineae topology in Khalighi et al. (2017), illustrating the connectivity between branches. Green, blue and orange vertices correspond to chordal origin (at the PM level), bifurcation points and insertion points into the leaflets, respectively

FIGURE 13

Hyperboloids representing: (a) a mitral annular normal saddle configuration; (b) a configuration associated with type I dysfunction, defined as in Park et al. (2019). The first configuration was created with the dimensions shown on Figure 6 and the diseased configuration on literature values for CW (42.2 mm), AP diameter (38.8 mm), AL–PM diameter (39 mm) and AHCWR (.132)