Ann Thorac Surg 2008;85:1536. doi:10.1016/j.athoracsur.2008.02.044
© 2008 The Society of Thoracic Surgeons
Original Articles: Adult Cardiac
Invited Commentary
Robert A.E. Dion, MD, PhD
Department of Cardiac Surgery, Ziekenhuis Oost-Limburg – Campus St. Jan, Schiepse Bos 6, Genk 3600, Belgium
(Email: robert.dion{at}zol.be).
The authors [1] conclude that intrinsic mitral valve (MV) pathology is frequently observed in hypertrophic cardiomyopathy (HCM) and that durable repair is feasible in only approximately half of the patients. I would add that this is only done by experienced surgeons, indeed, as a prosthetic valve has no systolic anterior motion (SAM) of the mitral coaptation line, and the authors have not been able to demonstrate a difference in survival between repair and replacement.
Their analysis identified 6 nonmutually exclusive groups, but why is a "long-leaflets group" different from the degenerative and myxomatous ones? Also, I hardly distinguished between group D and group E as restricted chordae imply restricted leaflets and the only difference lies in the structure of the leaflets. In addition, in group D, it would seem logical to perform chordal replacement rather than chordal elongation, as advocated by the authors.
There is one configuration I have encountered five times in the last 3 years in a center performing approximately 200 mitral valve repairs per year: it associates a short anterior leaflet (AL) (with or without abnormal anchoring to the septum) with an extra long posterior leaflet (PL), and with a sharp mitro-aortic angle resulting in an impressive septal "shoulder" and a SAM. Approaching the MV through the atrium, the base of the AL was detached from commissure to commissure; it was then easy to perform an extensive septal myectomy and to resect any abnormal chord. The operation was completed by a large augmentation of AL (pericardial patch), a stringent decrease of the height of PL, leading to a posterior displacement of the leaflets coaptation away from the septum, and the placement of an annuloplasty ring, which was oversized according to the new length of the AL. This has consistently given a nice echocardiographic result.
One of the reviewers argued that MV surgery was only rarely necessary and suspected the authors of "overtreatment." Dr Smedira went through all the data again and found that "25% of the patients underwent some form of MV intervention without the presence of classic valve pathology," considering the possibility of overtreatment or "overclassification." On the other hand, the authors are right to underline that we should "begin to examine the complex and little understood relationship of the septum and morphogenesis of mitral valve leaflets and subvalvular apparatus." To my suggestion then of approaching the lesions through the atrium, Smedira answered that he could more easily assess and repair more subvalvular abnormalities through the aortic approach. But maybe, only for the sake of a thorough valve analysis, and to avoid overtreatment or overclassification, is it still preferable to choose a concomitant atrial approach in complex cases.
Classifying complex anomalies of the mitral valve in HCM is a thankless task, particularly if the authors are determined to achieve complete and durable relief of this difficult pathology without sacrificing the valve. The size of the patient cohort, the merits of the scrupulous classification, and the talent of the surgeons make this work a hallmark in the field.
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References
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- Kaple RK, Murphy RT, DiPaola LM, et al. Mitral valve abnormalities in hypertrophic cardiomyopathy: echocardiographic features and surgical outcomes Ann Thorac Surg 2008;851527–36.e1–2.
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