The influence of saddle-shaped annuloplasty on leaflet curvature in patients with ischaemic mitral regurgitation

Abstract

Objectives: Reports indicate that repair procedures for ischaemic mitral regurgitation (IMR) are less durable than previously thought. Repair failure has been shown to be stress related. Leaflet curvature is the major determinant of valve stress. Theoretical and animal experiments have shown that saddle-shaped annuloplasty optimizes leaflet curvature when compared with standard flat ring annuloplasty. Despite this, the influence of the ring shape on leaflet curvature has not been described in patients with IMR. This study uses real-time three-dimensional echocardiography (rt-3DE) to assess the influence of the ring shape on leaflet curvature.

Methods: Rt-3DE was performed in 21 patients with IMR after placement of either a flat (n = 10, CE-Physio, Edwards) or saddle-shaped (n = 11, Profile 3D, Medtronic) annuloplasty ring. A combination of commercially available and customized software was used to measure multiple leaflet curvature parameters across all regions of the mitral valve.

Results: Independently of the shape of the annuloplasty ring, all patients were subject to the same degree of annular undersizing. Patients who received saddle-shaped annuloplasty rings had greater leaflet curvature in all six mitral valve leaflet regions (A1 = 0.36 ± 0.10, A2 = 0.53 ± 0.13, A3 = 0.47 ± 0.13, P1 = 0.35 ± 0.23, P2 = 0.53 ± 0.34, P3 = 0.42 ± 0.20 cm(-2)) compared with patients who received flat annuloplasty rings (A1 = 0.16 ± 0.11, A2 = 0.18 ± 0.09, A3 = 0.16 ± 0.11, P1 = 0.20 ± 0.17, P2 = 0.21 ± 0.11, P3 = 0.18 ± 0.13 cm(-2)). These differences were statistically significant in all regions except the P1 region.

Conclusions: Saddle-shaped annuloplasty rings increase leaflet curvature compared with flat rings in patients with IMR. As a result, saddle-shaped annuloplasty may decrease leaflet stress and potentially increases the durability of the repair in patients with IMR.

Figure 1:

Annular and leaflet modelling. (A) and (B) demonstrate a lateral and oblique view of a data point cloud in a patient with ischaemic mitral regurgitation. The annulus appears flattened and dilated prior to repair. (C) and (D) depict a lateral and oblique view of the same patient after repair with a saddle-shaped annuloplasty ring. The three-dimensional ring (marked by yellow points) helps to restore non-planarity of the annulus and reduce the annular area. (E) and (F) show a second patient after repair with a flat annuloplasty ring (marked by yellow points) for comparison. Although the undersized ring reduces the annular area, the flat ring fails to restore annular non-planarity.

Figure 2:

Comparison of annular height. Average annular height (thick lines) with standard error of the mean (dotted lines) is plotted along the entire circumference of the annulus after repair with a flat or saddle-shaped annuloplasty ring. Patients repaired with saddle-shaped rings demonstrate greater annular height at the mid-anterior annulus (Mid-AA) and the mid-posterior annulus (Mid-PA) compared with patients repaired with flat rings. PC: posterior commissure; AC: anterior commissure.

Figure 3:

Leaflet Gaussian curvatures after mitral valve repair. Average Gaussian curvature with standard error are presented for each leaflet region (A1-P3) for patients repaired with flat or saddle-shaped annuloplasty rings. Patients repaired with saddle-shaped rings show increases in the Gaussian curvature compared with patients repaired with flat rings. These differences are significant in all regions except the P1 region.

Figure 4:

Three-dimensional renderings of the leaflet Gaussian curvature. (A) (flat ring). (B) (saddle-shaped ring). Colour contouring represents leaflet Gaussian curvature. The patient repaired with the saddle-shaped ring (B) demonstrates increased Gaussian curvature compared with the patient repaired with the flat ring (A).

Figure 5:

Intercommissural and septolateral curvature after mitral valve repair. (A) Average intercommissural curvature with standard error for each leaflet region. (B) Average septolateral curvature with standard error for each leaflet region. Significant increases in the intercommissural and septolateral curvature are noted in the saddle group for multiple leaflet zones.

Figure 6:

Three-dimensional contour maps of septolateral and intercommissural curvature. (A) (flat ring) and (B) (saddle ring) represent colour contoured maps for leaflet septolateral curvature. The patient repaired with the saddle ring (B) demonstrates increased septolateral curvature, especially notable in the A2 region, compared with the patient repaired with the flat ring (A). (C, flat) and (D, saddle) represent colour contoured maps for leaflet intercommissural curvature. The patient repaired with the saddle-shaped ring (D) demonstrates increased intercommissural curvature in multiple leaflet zones compared with the patient repaired with the flat ring (C).