Assessing the Hemodynamic Impact of Anterior Leaflet Laceration in Transcatheter Mitral Valve Replacement: An in silico Study

Figures

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  FIGURE 1. 3D anatomical models created for each subject. The left model represents the actual performed procedure (TMVR with LAMPOON). In this model, the left ventricular anatomy and implanted transcatheter valve geometry were segmented directly from the post-procedure CT dataset. The number and location of transcatheter valve cells exposed by LAMPOON were modeled based on visualization of the anterior leaflet splay in the post-procedure CT dataset. To simulate a “virtual control” procedure in which LAMPOON was not performed (TMVR without LAMPOON), we artificially closed the exposed cells of the transcatheter valve as shown in the right model. Ao, aorta; LV, left ventricle; THV, transcatheter heart valve.

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  FIGURE 2. Effect of LAMPOON on left ventricular flow patterns. Simulated flow patterns for a representative subject (Subject 5) are shown in color maps (red = highest velocity, blue = lowest velocity) with streamlines. The left column shows the flow simulation for the virtual control procedure (TMVR without LAMPOON). For this condition, all flow is directed through the narrowed residual LVOT (neo-LVOT), resulting in a narrowed and high-velocity outflow jet. Additionally, there is a region of reduced flow in the immediate vicinity of the valve (upper left image). The right column shows the flow simulation for the actual performed procedure (TMVR with LAMPOON). For this condition, additional flow occurs through exposed cells of the transcatheter valve due to LAMPOON. Following LAMPOON, the velocity of flow through the neo-LVOT is reduced, and there is improved flow in the immediate vicinity of the valve (upper right image). Ao, aorta; LV, left ventricle; neo-LVOT, neo-left ventricular outflow tract; THV, transcatheter heart valve.

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  FIGURE 3. Effect of LAMPOON on left ventricular pressure fields. Simulated pressure fields for a representative subject (Subject 5) are shown in color maps (red = highest pressure, blue = lowest pressure). The left column shows the simulated pressure drop at the LVOT for the virtual control procedure (TMVR without LAMPOON). The right column shows the simulated pressure drop at the LVOT for the actual performed procedure (TMVR with LAMPOON). The simulated LVOT gradient is substantially reduced following LAMPOON. In this subject, LAMPOON exposed three cells of the transcatheter valve, corresponding to a total increase in flow area of 87 mm2.

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  FIGURE 4. Comparison of simulated hemodynamics following TMVR with and without LAMPOON. Simulated hemodynamics following TMVR with LAMPOON were superior to those following TMVR without LAMPOON for all subjects. Following LAMPOON, the simulated peak outflow gradient (ΔPpeak) and velocity (vpeak) decreased in all subjects (p < 0.05 for both comparisons) (A,B). Additionally, the simulated peak effective orifice area (EOApeak) increased following LAMPOON in all subjects (p < 0.05) (C). LVOT, left ventricular outflow tract.

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  FIGURE 5. Relationship between post-procedure neo-LVOT area and hemodynamic improvement with LAMPOON. Subjects with a smaller post-procedure neo-LVOT area experienced a greater hemodynamic improvement with LAMPOON. The largest improvement in simulated LVOT gradient (32 mmHg reduction in gradient) was observed in the subject with the smallest post-procedure neo-LVOT area (49 mm2). As neo-LVOT area increased beyond 250 mm2, there was a smaller hemodynamic improvement with LAMPOON (<2 mmHg reduction in gradient). Neo-LVOT area = cross-sectional area at the narrowest point of the neo-left ventricular outflow tract. Skirt neo-LVOT area = cross-sectional area of the neo-left ventricular outflow tract measured at the level of the transcatheter valve skirt.

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  FIGURE 6. Flow simulations demonstrating the relationship between neo-LVOT size and LAMPOON efficacy. Two representative subjects are shown, where the subject shown in the top panel (Subject 6) has a larger neo-LVOT area as compared to the subject shown in the bottom panel (Subject 7). 3D models and simulated flow patterns are shown for the conditions of TMVR with and without LAMPOON. As neo-LVOT area decreases, the hemodynamic effect of LAMPOON increases. The total area of the transcatheter valve cells exposed by the splayed anterior leaflet were identical in both subjects (88 mm2). Ao, aorta; LV, left ventricle; neo-LVOT, neo-left ventricular outflow tract; THV, transcatheter heart valve.