Morphologic Evaluation of the Mitral Annulus During Displacement of the Heart in Off-Pump Coronary Artery Bypass Surgery

Objective To evaluate the morphologic changes of the mitral annulus using 3-dimensional transesophageal echocardiography during heart displacement to expose the anastomosis site in off-pump coronary artery bypass surgery (OPCAB). Design Prospective case series. Setting Single center, university hospital. Participants The study comprised 34 consecutive patients who underwent OPCAB of the left circumflex artery (LCX) and the right coronary artery (RCA). Interventions None. Measurements and Main Results Mitral annulus parameters were measured using the Mitral Valve Quantification program after sternotomy (physiologic position) and during displacement of the heart to expose the LCX (LCX position) and the RCA (RCA position). The height of the mitral annulus was significantly lower in the LCX (5.76 ± 0.90 mm) and RCA (5.92 ± 0.97 mm) positions than in the physiologic position (6.96 ± 0.99 mm; both p v –11.9% ± 3.3%, p = 0.0203) and RCA (–16.9% ± 6.3% v –12.1% ± 3.8%, p = 0.0207) positions. The anteroposterior and intercommissural diameters, annulus perimeter, and surface area of the mitral annulus did not differ significantly among all heart positions. Conclusions The mitral annulus flattened and lost its saddle shape without expanding while in the LCX and RCA positions. The greater percent change in the height of the mitral annulus may aggravate mitral regurgitation.