Abstract 12332: Tethering of Mitral Leaflets Relates to Displacement of Papillary Muscles by Dislocation of Heart During Off-Pump Coronary Artery Bypass Surgery: Assessment of Mitral Valve Complex by Three-Dimensional Echocardiography in Porcine Model
Introduction: It is considered that morphological changes of mitral valve complex and worsening of mitral regurgitation (MR) cause the hemodynamic deterioration during off-pump coronary artery bypass grafting (OPCAB) in ischemic heart disease.
Hypothesis: Mitral valve tethering is caused by dislocation of papillary muscle and leads to exacerbation of ischemic MR and hemodynamics.
Methods: In 9 healthy swine with median sternotomy, we positioned the beating heart using Starfish heart positioner® and Octopus 2® (Medtronic) as OPCAB model. In 4 positions for CABG, i.e., control, LAD-, RCA-, and LCX- positions, three-dimensional (3D) full volume images by echocardiography were acquired (iE33® and X5-1®, Phillips Healthcare) to assess mitral valve complex with hemodynamic parameters. We assessed the morphological changes of the mitral valve complex in 4 positions using by Real-view® (YD Co.) and Cardio-view® (TomTec).
Results: Systolic arterial pressure was significantly lower in LCX position than in control position (LCX 48.9±2.5 vs control 69.8±2.7 mmHg, P<0.001). There were no significant differences in the mitral annular diameters in each position. On the other hand, there were significantly increased in the maximum tenting height (control 2.9±0.5, LAD 2.7± 0.3, RCA 3.7± 0.3, LCX 4.1± 0.3 mm, P<0.01) and the tenting volume (control 0.7±0.1, LAD 0.6±0.1, RCA 0.8±0.1, LCX 1.0±0.1 cm3, P<0.05) in LCX position compered to other positions. The angle α, i. e., the angle between the posterior papillary muscle-to-annulus line and the least-squares annular plane, were tended to decrease in LCX position, and there was a significantly relationship between the tenting volume and the angle α (r= -0.643, P<0.001). By the assessment of 3D-coordinates of the papillary muscles, posterior papillary muscle was displaced to medial site in LCX position compered to other positions (P<0.001).
Conclusions: In the dislocated and rotated position of the heart, especially in LCX position, the tethering of the mitral valve leaflets was increased, and related to the displacement of posterior papillary muscle. This suggests that mitral valve tethering is caused by dislocation of papillary muscle and leads to exacerbation of ischemic MR and hemodynamics during OPCAB.
Author Disclosures: T. Igarashi: None. M. Iwai-Takano: None. S. Takase: None. H. Yokoyama: None.
- © 2014 by American Heart Association, Inc.