Doming Volume in Mitral Valve Prolapse: Pathophysiology, Imaging Implications and Clinical Relevance

Figures

• 

  Figure 1. Conceptual representation of doming volume. Left panel: Systolic configuration in normal mitral valve with proper leaflet coaptation at the level of the mitral annular plane and absence of doming volume. Middle panel: Systole in mitral valve prolapse, showing displacement of the mitral leaflets into the left atrium and formation of the doming volume (green arrows, green area). Right panel: During diastole, in addition to the physiological transmitral inflow from the left atrium (blue arrows), the doming volume re-enters the left ventricle (green arrows, green area). Beyond this schematic representation, DV represents a three-dimensional blood compartment formed during systole, whose size and geometry depend on mitral valve morphology, and the severity and extent of leaflet prolapse.

• 

  Figure 2. Determinants of doming volume magnitude. Left panels: Myxomatous (Barlow-type) mitral valve prolapse shown in the four-chamber (a) and three-chamber (b) views, characterized by thickened, redundant leaflets, bileaflet involvement, and annular dilatation, compared with fibroelastic deficiency in the four-chamber (c) and three-chamber (d) views, typically showing thin leaflets, localized prolapse, and relatively limited annular enlargement. Right panels: Main anatomical determinants of doming volume magnitude, including leaflet thickness > 5 mm (e), leaflet redundancy (f), and mitral annular diameter > 35 mm (g). Doming volume is highlighted in green.

• 

  Figure 3. Apical four-chamber and two-chamber views used for biplane volumetric assessment of left ventricular volumes and ejection fraction according to the modified Simpson’s rule. Four-chamber view at end-diastole (a) and at end-systole (b), two-chamber view at end-diastole (c), and at end-systole (d). Endocardial contours are traced excluding the region located above the mitral annular plane. In the presence of mitral valve prolapse, the blood compartment interposed between the mitral annular plane and the ventricular surface of the prolapsing leaflets (doming volume; highlighted in green) is generally excluded from end-systolic contouring, which may lead to underestimation of LV end-systolic volume and consequent overestimation of ejection fraction.

• 

  Figure 4. Cardiac magnetic resonance assessment of left ventricular volumes and ejection fraction with inclusion of doming volume. Representative cardiac magnetic resonance images illustrating left ventricular volumetric assessment. Basal short-axis view at end-diastole with left ventricular endocardial contouring (a) and corresponding long-axis reference view indicating the position of the basal slice (yellow line) (b). Basal short-axis view at end-systole (c) with corresponding long-axis reference view at end-systole (yellow line) (d). Side-by-side comparison with long-axis views enables accurate identification of the true ventricular extent and inclusion of the blood compartment located between the mitral annular plane and the ventricular surface of prolapsing leaflets into left ventricular volumetric analysis.

• 

  Figure 5. Cardiovascular magnetic resonance-based quantification of doming volume in mitral valve prolapse. Doming volume quantification using standard long-axis cine cardiovascular magnetic resonance images acquired at end-systole. Prolapse area is delineated in the four-chamber, two-chamber, and three-chamber views as the region bounded by the mitral annular plane and the ventricular surface of the prolapsing leaflets (green areas). The mitral annular plane is defined by a reference line connecting the medial and lateral annular hinge points. For each view, prolapse height is calculated as the ratio between prolapse area and annular diameter. Mean prolapse height is obtained by averaging measurements from the four-, three-, and two-chamber views. Mitral annular area is estimated assuming an elliptical geometry, using the three-chamber annular diameter as the minor axis and the larger of the four- or two-chamber diameters as the major axis. Doming volume is calculated as the product of mean prolapse height and annular area. The total volume load is defined as the sum of the doming volume and the mitral regurgitant volume.