Commissural repositioning in bicuspid aortic valve repair: an in vitro acute model to explore and explain different results.

OBJECTIVES: Commissural orientation <160° is a recognized risk factor for bicuspid aortic valve repair failure. Based on this observation, repairing this subtype of aortic valve by reorienting the 2 commissures at 180° has recently been proposed. METHODS: Nine porcine hearts with aortic annulus diameters of 25 mm were selected. A pathological model of a Sievers 1 bicuspid aortic valve was obtained by suturing the coaptation line between the left and right leaflets. Each heart underwent reimplantation procedures both in the native (120°) and the reoriented (180°) configuration. After the operation, each sample was tested on a pulse duplicator at rest (heart rate 60 beats per min) and with mild exercise (heart rate 90 beats per min) conditions. RESULTS: No statistically significant difference was noted in mean and peak transvalvular aortic gradients between the 2 configurations at rest (18.6 ± 5 vs 17.5 ± 4 for the mean aortic gradient; 42.8 ± 12.7 vs 36.3 ± 5.8 for the peak aortic gradient) but the group with the 120°-oriented commissures had significantly higher mean transaortic gradients compared to the group with the 180°-oriented commissures at initial exercise stress conditions (30.1 ± 9.1 vs 24.9 ± 3.8; p value 0.002). CONCLUSIONS: The 180° commissural reorientation of the asymmetrical bicuspid aortic valve does not improve the transvalvular aortic gradient in an acute model at rest conditions, but it could do so under stress situations. Even if it is surgically more complex and time-consuming, this approach could be a good strategy to improve long-term results, particularly in young patients.

Ex Vivo Model of Functional Mitral Regurgitation Using Deer Hearts.

Transcatheter therapies are emerging for functional mitral regurgitation (FMR) treatment, however there is lack of pathological models for their preclinical assessment. We investigated the applicability of deer hearts for this purpose.8 whole deer hearts were housed in a pulsatile flow bench. At baseline, all mitral valves featured normal coaptation. The pathological state was induced by 60-minutes intraventricular constant pressurization. It caused mitral annulus dilation (antero-posterior diameter increase from 31.8 ± 5.6 mm to 39.5 ± 4.9 mm, p = 0.001), leaflets tethering (maximal tenting height increase from 7.3 ± 2.5 mm to 12.7 ± 3.4 mm, p < 0.001) and left ventricular diameter increase (from 67.8 ± 7.5 mm to 79.4 ± 6.5 mm, p = 0.004). These geometrical reconfigurations led to restricted mitral valve leaflets motion and leaflet coaptation loss. Preliminary feasibility assessment of two FMR treatments was performed in the developed model.Deer hearts showed ability to dilate under constant pressurization and have potential to be used for realistic preclinical research of novel FMR therapies. Graphical abstract figure legend: Deer heart mitral valve fiberscopic and echocardiographic images in peak systole at baseline and after inducing the pathological conditions representing functional mitral regurgitation. In the pathological conditions lack of coaptation between the leaflets, enlargement of the antero-posterior distance (red dashed line) and the left ventricular diameter (orange dashed line) were observed.

Preoperative Computed Tomography Scan Analysis of Interleaflets Triangles to Guide Aortic Root Repair Procedures.

BACKGROUND: Stabilization of the ventriculo-aortic junction (VAJ) is gaining increasing interest in the context of aortic valve repair, since its dilation is a well-recognized risk factor for long-term repair failure. Interleaflets triangles are key elements of the VAJ, but cannot be completely visualized using echocardiography. A three-dimensional (3D) reconstruction of electrocardiogram-triggered computed tomography (CT) scan images allows an analysis of the real dimensions and anatomic characteristics of the subcommissural triangles. METHODS: A method was developed to visualize the interleaflets triangle at the CT-scan based on multiplanar post-processing reconstructions. Attention was focused on the triangles' apical angle evaluation. The data obtained with CT-scan reconstructions were compared with those collected in a previous post-mortem study to validate this measurement method. RESULTS: In the CT-scan group the angles between the left and right coronary sinuses, and the right non-coronary and left non-coronary sinuses were 46.23 ± 7.79°, 47.38 ± 6.97°, 45° [range: 42.75- 50.75°], respectively, and in the post-mortem group were 45.44 ± 12.39°, 48.31 ± 1218°, 50.25 ± 7.29°. No statistically significant differences between the two groups were identified (p = 0.84, 0.81, and 0.23). CONCLUSIONS: Based on experience acquired in the operating room, the acute-angle subcommissural triangles were considered normal, the equilateral triangles mildly dilated, and the obtuse triangles severely dilated. According to this classification, different reparative approaches were selected. A CTscan 3D reconstruction method, as validated by the present data, allows a preoperative evaluation of the triangles and VAJ in order to best plan a surgical reparative approach tailored to a single patient.