Changes in mitral valve annular geometry after repair: saddle-shaped versus flat annuloplasty rings

Saddle-shaped annuloplasty rings are being increasingly used during mitral valve (MV) repair to conform the mitral annulus to a more nonplanar shape and possibly reduce leaflet stress. In this study utilizing three-dimensional transesophageal echocardiography we compared the effects of rigid flat rings with those of the saddle rings on the mitral annular geometry. Specifically we measured the changes in nonplanarity angle (NPA) before and after MV repair.

Geometric analysis on 38 patients undergoing MV repair for myxomatous and ischemic mitral regurgitation with full flat rings (n = 18) and saddle rings (n = 18) were performed. The acquired three-dimensional volumetric data were analyzed utilizing the "Image Arena" software (TomTec GmBH, Munich, Germany). Specifically, the degree of change in the NPA was calculated and compared before and after repair for both types of rings.

Both types of annuloplasty rings resulted in significant changes in the geometric structure of the MV after repair. However, saddle rings lead to a decrease in the NPA (7% for ischemic and 8% for myxomatous MV repairs) (ie, made the annulus more nonplanar), whereas flat rings increased the NPA (7.9% for ischemic and 11.8% for myxomatous MV repairs) (ie, made the annulus less nonplanar); p value 0.001 or less.

Implantation of saddle-shaped rings during MV repair surgery is associated with augmentation of the nonplanar shape of the mitral annulus (ie, decreases NPA). This favorable change in the mitral annular geometry could possibly confer a structural advantage to MV repairs with the saddle rings.