Examination Of The Positional Relationships Between Mitral Annulus And Coronary Artery Using The Computed Tomography
Noriaki Kishimoto, Yosuke Takahashi, Hiromichi Fujii, Akimasa Morisaki, Yoshito Sakon, Kokoro Yamane, Takumi Kawase, Yosuke Sumii, Toshihiko Shibata.
Osaka city university hospital, Osaka, Japan.
Background Coronary artery injury during the mitral valve surgery is rarely but fatal complications. We try to evaluate the risk of coronary injury before mitral valve surgery by using cardiac computed tomography (CT). Methods Sixty-one patients were examined in our study. Of these, three patients who had coronary injury were included. All patients were performed cardiac CT preoperatively. We divided all cases into three groups depending on the coronary dominance. Group A is a balanced type of coronary system (48 cases), group B is a right dominant type (9 cases) and group C is a left dominant type (4 cases). We constructed three-dimensional figures of both coronary artery and mitral annulus by using cardiac CT data. We evaluated the closest distance between left circumflex artery and mitral annulus (CAD) and named this point on mitral annuls as “X point”. Posterior mitral annular length (PAL) and the length from X point to the left fibrous trigon (LXL) were also measured. We compared three groups and evaluated the risk factors for coronary injury by analysis of variance using the data of left atrial volume index (LAVI), left ventricular diastolic diameter, PAL and LXL. Results Left dominant type has short CAD than that of other groups (p = 0.0262) (The CAD of group A, B and C were 5.94 ± 0.31 mm, 4.83 ± 0.69mm, and group C 3.22 ± 1.03 mm, respectively). Balanced type has longer CAD, whereas LXL is shorter (P = 0.0014). (The LXL of group A, B and C were17.24 ± 2.41mm, 39.9 ± 5.38mm, and 22.9 ± 8.07mm, respectively). All patients who complicated with coronary injury were group B and X point was located near the left fibrous trigon. The risk factor of coronary injury using receiver operating characteristic curve revealed that the cut-off value of CAD is 4mm, and LAVI is 35 ml/m2. Conclusions We need to pay much attention to make a stich at the mitral annulus in patients with left dominant type, X points existed near the left fibrous trigon, LAVI less than 35 ml/m2, and/or CAD less than 4 mm. 
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