Prevention of Systolic Anterior Motion after Mitral Valve Repair

The article by doctors Sternik and Zehr¹ in an earlier issue of the THI Journal introduces a new technique to prevent systolic anterior motion of the mitral valve (SAM) after repair. The authors envisaged the possibility of SAM in 6 patients with myxomatous mitral valves. The surgical technique consisted of resection of the P2 scallop of the posterior mitral leaflet (PML) and posterior band annuloplasty, reducing the mitral annulus circumference to 10 cm. Posteriorly directed mid-PML secondary chordae were transferred to the underside of the mid-anterior leaflet with a small piece of valve. The technique was applied in order to prevent SAM, rather than to correct it after the repair. The factors predisposing patients to SAM, as outlined by the authors, are excess leaflet tissue, reduced left ventricular outflow tract (LVOT) diameter, and a left ventricle (LV) that is of near-normal size and hyperdynamic. The following are some points for further discussion.

Excess leaflet tissue can be the result of the disease itself, the result of surgical intervention, or both. Resection of a part of the PML changes the ratio between the circumferential insertion of the anterior mitral leaflet (AML) and the PML, allowing more than the normal one third to the AML. In addition, the angle between the aortic and mitral annular planes is reduced by any intervention that diminishes the annulus, thus bringing the mitral valve closer to the septum.² This is more evident in small left ventricles.

Sternik and Zehr's technique has some important advantages. It is both easy to perform and reproducible. It could also be performed from the LV, as in cases of LV aneurysms and mitral annular dilatation. Compared with the edge-to-edge technique,³ it does not create a double-orifice mitral valve, and it allows normal coaptation of the leaflets (that is, “under” the plane of the annulus), probably with less stress on the leaflets. It bears more resemblance to the septal-lateral cinching technique,⁴ indirectly preventing dilatation of the annulus in a septal-lateral direction (which represents a limit of the flexible bands). The technique of Sternik and Zehr may prevent LV and annular dilatation in patients with ischemic mitral insufficiency and might help maintain the normal ventricular geometry. It would be tempting to evaluate this technique in cases of hypertrophic cardiomyopathy.

Nevertheless, the technique has some limitations. It can be applied in only a few selected patients who have intact chordae tendineae, and therefore would not be as suitable for patients with myxomatous disease or fibroelastic deficiency, who tend to have elongated, thin, and frail chordae. The chordae tendineae and the papillary heads of origin must also have a suitable disposition: the best situation would be with an additional head of the posterior papillary muscle just beneath the P2⁵ (resembling the central papillary muscle in birds). The Teflon pledget affixing the PML isle should theoretically be placed at the level of the rough zone of the AML but “above” the coaptation line in order to avoid contact lesions on the opposing leaflet.

Anticipation of possible SAM would be aided by the measurement of LVOT diameter, LV dimensions, and the aortic–mitral angle. Undoubtedly, larger series and studies over longer periods will better define the indications for this novel method.

The technique presented by the authors offers an important tool to the cardiac surgeon performing mitral valve repair. It adds new and important details and provides a basis for further research. I congratulate the authors for this elegant surgical solution.

Horia Muresian, MD, PhD
Cardiovascular Surgery, San Donato – Milan, Italy