Ann Thorac Surg 2009;88:1504-1505. doi:10.1016/j.athoracsur.2009.07.010
© 2009 The Society of Thoracic Surgeons
Original Articles: Adult Cardiac
Invited Commentary
Jerry Braun, MD
Cardiothoracic Surgery, Leiden University Medical Center, Postbus 9600, Leiden, 2300 RC Netherlands
(Email: j.braun{at}lumc.nl).
The percentage of mitral valves that undergo repair rather than replacement is still increasing. This is explained by the reproducibility of repair techniques and the availability of reliable annular remodeling rings. Durability of these repair techniques is high when considering freedom from reoperation as an end-point; however, as surgeons we are not really aware of the true incidence of recurrent mitral regurgitation exceeding grade 2 that does not lead to reintervention, although this should actually be considered a failure of our repair. As a consequence, we are even less aware of the mechanisms that underlie such recurrence.
The article from the Gorman laboratory group [1] presents results from ongoing experimental research into the highly complex mechanics of the mitral valve apparatus. Previous studies from this group have provided valuable insight into the characteristics of the saddle shape of the mitral annulus, and into the strain reduction that this saddle shape confers to the chordal apparatus and to the anterior leaflet of the mitral valve. In this study, the focus is directed at the P2 segment. In an elegant manner, it is demonstrated that an increased saddle shape of the annulus reduces strain in this segment to a significant extent, both in the radial and in the circumferential direction.
How should we interpret these data and implement them in our clinical practice? Most of us feel confident with the "flat" annular remodeling rings, some of which have been on the market for more than 30 years and have proven their value. However, as previously stated, we should shift our attention to repair failure in terms of recurrent mitral regurgitation, and especially to its underlying mechanisms. It is conceivable that high-systolic strain levels in certain parts of the repaired leaflets and in the chordae in degenerative disease might play an important role in the development of recurrent mitral regurgitation. Reducing these strain levels with a saddle-shaped remodeling ring could help in preventing this possible failure mode.
As always in our profession, more knowledge is needed. What happens to the strain levels in the posterior leaflet after partial resection and reconstruction of this leaflet? What are the effects of a remodeling ring after a reconstruction? How does the use of neochords affect the situation? I am sure that future research from this laboratory will provide further answers to questions that arise in our quest for further improvement of mitral valve repair.
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References
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- Padala M, Hutchison RA, Croft LR, et al. Saddle shape of the mitral annulus reduces systolic strains on the P2 segment of the posterior mitral leaflet Ann Thorac Surg 2009;88:1499-1505.[Abstract/Free Full Text]
Related Article
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Saddle Shape of the Mitral Annulus Reduces Systolic Strains on the P2 Segment of the Posterior Mitral Leaflet
- Muralidhar Padala, Ross A. Hutchison, Laura R. Croft, Jorge H. Jimenez, Robert C. Gorman, Joseph H. Gorman, III, Michael S. Sacks, and Ajit P. Yoganathan
Ann. Thorac. Surg. 2009 88: 1499-1504.
[Abstract]
[Full Text]
[PDF]
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References