Operative procedures and strategy
We previously reported our standard operative procedure and strategy for mitral valve surgery with reduced left ventricular function10. Briefly, the procedures were performed through the median sternotomy approach, and cardiopulmonary bypass was established with ascending aortic and bicaval cannulations. In the re-do cases, cardiopulmonary bypass was established with peripheral cannulations as needed. Concomitant coronary artery bypass grafting was performed in an on-pump beating fashion where possible with the aim of reducing cross-clamp time. Other procedures were performed under cardiac arrest with antegrade, intermittent, cold-blood cardioplegia.
Our strategy for selecting repair or replacement was changed at the beginning of 2014, based on the results of a randomized, controlled study and the good results obtained with chordal-sparing mitral valve replacement.11,12Before 2014, our first choice of mitral procedure was mitral plasty even in cases with reduced cardiac function. Mitral valve replacement was chosen when left ventricular diastolic diameter was >70 mm, in re-do cases or in hemodialysis cases for which reverse remodeling was not expected. Since 2014, we have selected chordal-sparing mitral valve replacement as the first-line procedure in secondary mitral regurgitation with reduced cardiac function. Mitral plasty was performed for younger patients (early 60s or younger), and when left ventricular diastolic diameter was <60 mm.
Apart from this strategy, we have chosen mitral valve replacement for patients for whom a poor prognosis was anticipated, as in patients with advanced age, high frailty, or other critical conditions.
In mitral valve plasty, an undersized annuloplasty ring was used, and whether the mitral sub-valvular apparatus procedure was performed was determined by the surgeon based on the echocardiographic findings, including tethering height >10 mm13 or the location of papillary muscles. Our sub-apparatus procedures consist of papillary muscle re-suspension to the mitral anterior annulus with CV3 or CV4. When papillary muscle heads were separated, the anterior and posterior heads were combined together with the re-suspension stitch, then re-suspended toward the saddle horn, as previously reported.14
In mitral valve replacement, valve leaflets were tucked in the annulus with stitches securing the prosthetic valve, sparing all chordae.
This study was approved (Approval No: NHC2021-0330-11) by the institutional ethics committee on March 30th, 2021, and the need to obtain written consent from patients was waived because of the retrospective study design.