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OBJECTIVE: Novel transcatheter mitral repair technologies with annuloplasty may risk unintentional damage to the circumflex artery (CX). This study aims to better characterize the anatomical relationship between the CX and mitral annulus, and to evaluate CX damage following mitral repair.
METHODS: Using cadaveric human hearts (n=27), coronary circulation was dissected and dominance determined. After opening the left atrial wall, the distance between the annulus and the CX was measured at each hour of a visualized clock face using digital calipers (Fig. 1A). Mitral repair with annuloplasty was performed on all hearts, and CX damage was assessed at each hour using a four-point Likert scale (1=no damage, 4=complete occlusion).
RESULTS: The CX was closest on average at the 8:00 position, only 1.91±0.39 mm from the annulus (Fig. 1B). Surprisingly, in left dominant hearts the CX was closest at the 3:00 position, only 1.67±0.60 mm from the annulus, but was also close along the entire annulus from 3:00-8:00. Mitral repairs resulted in damage only between the 7:00-9:00 positions, with the greatest risk of injury at 9:00 (mean Likert value=1.3). There was potential suture injury to the CX occurring 3/27 (11%), 5/27 (19%), and 6/27 (22%) of the time at 7:00, 8:00, and 9:00, respectively. Most injuries were partial thickness suture penetration of the CX (7/81 [9%] sutures from 7:00-9:00). No sutures caused complete CX occlusion.
CONCLUSIONS: The circumflex artery was closest to the mitral annulus at the 7:00-8:00 position, however, it was also closest at the 3:00 position in left dominant hearts, which is previously unrecognized. In a cadaveric model, CX injury most commonly occurred at 9:00 and was mostly partial thickness. When considering novel percutaneous mitral technologies, this anatomical information is of importance for transcatheter device fixation.