Assessment of deformation of the mitral valve complex during off-pump coronary artery bypass surgery using three-dimensional echocardiography in a porcine model.

BACKGROUND: This study aimed to assess the deformation of the mitral valve complex during the displacement of the beating heart by using three-dimensional echocardiography in a porcine off-pump coronary artery bypass grafting (OPCAB) model.

METHODS: In nine healthy swine, we positioned the beating heart as an OPCAB model, i.e. control, left anterior descending artery (LAD), right coronary artery (RCA), and left circumflex artery (LCX) positions. In each position, three-dimensional echocardiography was performed to assess the mitral valve complex with hemodynamic parameters. We analyzed the deformation of the mitral valve and the three-dimensional coordinates of the papillary muscles.

RESULTS: There was a significant increase in maximum tenting length and tenting volume (control 0.70±0.30, LAD 0.65±0.27, RCA 0.79±0.23, LCX 0.95±0.34cm3 , p<0.05) in the LCX position compared with the other positions. The posterior papillary muscle (PPM) angle had a significant relationship with the tenting volume (r=-0.643, p<0.001). The PPM was displaced to the medial side in the LAD and LCX positions (p<0.01).

CONCLUSIONS: The prime cause of the deformation of the mitral leaflets is suggested to be the displacement of the PPM associated with the change in geometry of the left ventricle in a porcine model.