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Configurations of the mitral valve during off-pump coronary artery bypass grafting: endoscopic and three-dimensional
Shugo Koga1, Yukio Okazaki, Hiromi Kataoka
1Department of Thoracic and Cardiovascular Surgery, Saga University Hospital, Saga, Japan.
Insights
Off-pump coronary artery bypass grafting (CABG) can cause mitral regurgitation (MR). Occluding the left circumflex artery (LCx) typically causes posteromedial MR due to annular enlargement, unlike left anterior descending artery (LAD) occlusion.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anatomy
- Surgical Innovation
Background:
- Off-pump coronary artery bypass grafting (CABG) is associated with mitral regurgitation (MR).
- Understanding mitral valve annular dynamics during CABG is crucial for preventing MR.
- Cardiac displacement during off-pump procedures may affect mitral valve function.
Purpose of the Study:
- To evaluate mitral valve configuration and annular behavior during off-pump CABG.
- To investigate the impact of coronary artery occlusion on mitral annular dynamics.
- To correlate endoscopic and sonomicrometric findings with mitral regurgitation.
Main Methods:
- Simulated off-pump CABG in seven beagle dogs.
- Utilized digital 3-D ultrasound sonomicrometry to measure mitral annular dimensions.
- Employed cardiac endoscopy to observe mitral valve leaflets and annulus.
- Assessed effects of cardiac displacement, LAD occlusion, and LCx occlusion.
Main Results:
- Cardiac displacement alone did not induce MR when coronary perfusion was maintained.
- Left anterior descending artery (LAD) occlusion rarely caused MR from the anterolateral site.
- Left circumflex artery (LCx) occlusion consistently caused posteromedial MR with significant annular enlargement (p < 0.01).
Conclusions:
- Mitral regurgitation during off-pump CABG is primarily linked to coronary artery occlusion, not cardiac displacement alone.
- Posteromedial annular enlargement during LCx occlusion contributes to MR, even with controlled left ventricular end-diastolic pressure.
- Findings highlight the importance of monitoring mitral annular dynamics during specific coronary artery occlusions in off-pump CABG.
Background And Aim Of The Study:
During off-pump coronary artery bypass grafting (CABG), mitral regurgitation (MR) has been experienced in relation to the procedures. The study aim was to evaluate the mitral valve configuration, with particular focus on annular behavior, during off-pump CABG, using cardiac endoscopy and digital 3-D ultrasound sonomicrometry.
Methods:
Following implantation of six crystals of the digital 3-D ultrasound sonomicrometer around the mitral annulus, and two crystals on the epicardial base of the papillary muscles, off-pump CABG was simulated in seven beagle dogs. The heart was perfused with pellucid Krebs-Henseleit solution in situ, with controlled left ventricular end-diastolic pressure (LVEDP). The behaviors of the mitral annulus and leaflets were then observed endoscopically with only cardiac displacement, 15 min occlusion of the left anterior descending artery (LAD), or 15 min occlusion of the left circumflex artery (LCx) with cardiac displacement. Dimensions between the crystals were also recorded using digital 3-D ultrasound sonomicrometry.
Results:
With only cardiac displacement, no MR was observed endoscopically, and no major changes occurred in annular configuration when coronary perfusion was maintained. In one dog, MR was observed only from the anterolateral site after LAD occlusion. MR from the posteromedial site was observed by occlusion of the LCx in all cases, with significant (p < 0.01) enlargement of the mitral annular dimensions.
Conclusion:
Cardiac displacement alone did not cause MR if coronary perfusion was maintained. Occlusion of the LAD rarely caused MR from the anterolateral site, whereas occlusion of the LCx normally caused MR from the posteromedial site; the posteromedial annulus was enlarged, even when the LVEDP was controlled.
