Panels A (circular orifice) and B (arc-shaped orifice) depict the long axis of flow in the sagittal and coronal view, with vena contracta (VC) short-axis area shown in the transverse view, and three-dimensional (3D) jet in the lower right panels. For each orifice shape used in the in vitro model, the transverse view demonstrates that the shape of the VC area is defined by the shape of orifice.

Step 1: rotation and cropping of the 3D dataset to bisect the long axis of regurgitant flow in 2 orthogonal planes (sagittal and coronal orientation). This important step ensured that the subsequent VC area determination would be a true short-axis measurement. Step 2: identification of the frame with the largest VC zone (defined as the smallest cross-sectional area of the regurgitant jet, distal to the regurgitant orifice). Step 3: the color border of the VC short-axis area was manually traced as depicted in the transverse image. Measured VC area (arrowhead) is shown in relation to expanding 3D regurgitant jet. The Online Video shows rotation of the 3D jet and VC area. Abbreviations as in Figure 1.

Vena contracta (VC) area assessed from an imaging window either parallel (apical equivalent) or perpendicular (parasternal equivalent) to the long axis of flow in the in vitro model. For individual orifice shapes, the VC area measurements were different (p < 0.05) for only the smallest circle orifice. This statistical difference is likely related to the small variance of those small area measurements. Combining all orifice shapes, VC area assessed from the image window perpendicular to flow was more accurate and statistically different (p < 0.05) from the VC area assessed from the parallel imaging window. Orange bar indicates the actual area for each orifice.

Relation between effective regurgitant orifice area (EROA) derived by the volumetric Doppler method and two-dimensional (2D)-VC diameter (left) and 3D-VC area (right). For the comparison of EROA and 2D-VC diameter, the dotted orange line depicts the projected correlation (based on current American Society of Echocardiography guidelines for the quantification of regurgitation severity). Using a nonlinear correlation model, the relation between VC diameter and EROA did not improve (R² = 0.45 linear model vs. R² = 0.46 nonlinear model). In contrast, the stronger relation observed between 3D-VC area and EROA had a linear regression equation close the line of identity (also shown as a dotted orange line). Abbreviations as in Figure 1.

Upper panels depict the relation of VC diameter (A) and VC area (B) to effective regurgitant orifice area (EROA) for patients with a central mitral regurgitation (MR) jet. Lower panels depict the relation of VC diameter (C) and VC area (D) to EROA for patients with an eccentric MR jet. Dotted orange lines as in Figure 4. The relation between EROA and two-dimensional (2D)-VC area was best for central MR (A). In contrast, the relation between EROA and 3D-VC area was best for eccentric MR (D).

Upper panels depict the relation of 2D-VC diameter to EROA (A) and 3D-VC area to EROA (B) for MR severity grades 1 and 2. Lower panels depict the same relation in patients with MR severity grades 3 or 4. Dotted orange lines as in Figure 4. The relation between EROA and 2D-VC area was best for mild and mild-to-moderate MR (A). In contrast, the relation between EROA and 3D-VC area was best for moderate-to-severe and severe MR (D). Abbreviations as in Figures 1 and 5.

MR severity (grades 1 to 4) as defined by a comprehensive evaluation of qualitative and quantitative echocardiographic parameters as recommended by the American Society of Echocardiography. Note the effective differentiation of grades 2, 3, or 4 MR by either Doppler-derived EROA or VC area measurement. Dotted orange lines depict the threshold EROA values recommended by the American Society of Echocardiography to define mild (EROA <0.2 cm²) and severe (EROA 0.4 cm²) MR. Abbreviations as in Figures 1 and 5.

To evaluate the impact of regurgitant orifice shape, a VC sphericity index was derived from a single 3D-VC area measure by dividing the largest VC diameter by the smallest VC diameter. Upper panels depict the relation of 2D-VC diameter to EROA (A) and 3D-VC area to EROA (B) for sphericity index 2 (circular or elliptical VC shape); lower panels depict the same relations for a sphericity index >2 (irregular VC shape). Dotted orange lines as in Figure 4. Abbreviations as in Figures 1 and 5.