Ideal site for ventricular anchoring of artificial chordae in mitral regurgitation

Objective: Surgical treatment of mitral leaflet prolapse using artificial neochordae shows excellent outcomes. Upcoming devices attempt the same treatment in a minimally invasive way but target the left ventricular apex as an anchoring point, rather than the tip of the corresponding papillary muscle. In this study, cine cardiac magnetic resonance imaging was used to compare these 2 different anchoring positions and their dynamic relationship with the mitral leaflets. Methods: Eleven healthy volunteers (mean age, 31 years; 6 female; mean ejection fraction, 62%) were examined by cardiac magnetic resonance imaging (3 Tesla, cine steady free precession technique with retrospective gating), whereby dedicated software enabled assessment of the physiologic distances among 3 anchoring sites (anterior papillary muscle, posterior papillary muscle, and apex) and the plane of the mitral annulus at the level of leaflet coaptation. These distances were measured in systole and diastole, and the performance of virtual neochordae was analyzed for the 3 potential anchoring sites. Results: Length difference between systole and diastole for the 3 measured distances were 0.19 +/- 0.11 cm (5.9% +/- 3.4%) for the anterior papillary muscle, 0.19 +/- 0.09 cm (6.7% +/- 3.6%) for the posterior papillary muscle, and 1.52 +/- 0.18 cm (17.8% +/- 2.8%) for the left ventricular apex (P = .001). Virtual neochordae between the leaflet and the left ventricular apex were first adjusted in systole to achieve leaflet coaptation. Leaflet tear in diastole can only be avoided if the width of the attached leaflet is larger than the systole-diastole length difference. On the other hand, if virtual neochordae are adjusted in diastole to avoid leaflet tear, residual leaflet prolapse during systole can result. Because the systole-diastole length difference for papillary muscle anchored chordae is smaller than for apical chordae by a factor 10, there is a strongly reduced risk of prolapse or tearing and the leaflet width is unimportant. Furthermore, if the neochordae attached to the anterior mitral leaflet uses the apex as a distal anchoring site, the angle alpha between the aortic valve plane and this mitral leaflet is significantly reduced in diastole and therefore increases the risk of systolic anterior motion. Conclusions: Anchoring of neochordae at the papillary muscles, thereby mimicking the real anatomy, should be preferred over the left ventricular apex. Further analysis of dilated hearts and papillary muscle displacement is necessary to include the whole spectrum of pathologies. (J Thorac Cardiovasc Surg 2012;143:S78-81)