Surgical repair of the congenitally malformed mitral valve leaflets in infants and children Eva Maria Delmo Walter Takeshi Komoda Roland Hetzer Deutsches Herzzentrum Berlin Germany
Background and Objective Three cases of severe mitral valve incompetence reported here were unique in terms of the morphology of the entire mitral valve, particularly the leaflets and subvalvular apparatus. We report an excellent surgical repair technique with preservation of the leaflets and its subvalvar apparatus with a highly satisfactory mid-term functional outcome. Patients Three children, aged 4.6 months, 2.4 and 14.5 years, presented with severe mitral incompetence. None of them had a history of rheumatic heart disease, or endocarditis. None had associated congenital diseases. All had left ventricular hypertrophy. Maximal medical therapy offered no improvement of symptoms; hence, surgery was deemed necessary.
Intraoperative findings enormously dilated annulus Both anterior and posterior mitral valve leaflets were mobile but without coaptation points.
Intraoperative findings Both leaflets were prominently and excessively thickened at their free margins, with a smooth outward infolding appearing as ridges. This leaflet free marginal thickening and rolling with fibrosis and retraction formed a clearly demarcated hump from the rest of the smooth and evenly surfaced leaflet body. The anterolateral and posteromedial papillary muscles appeared normal in size and morphology, without any rupture; however, two secondary chordae tendinae of the posteromedial papillary muscles were fused, making them short and positioned higher than the rest of the chordae. This asymmetry of the chordae tendinae, which support the mitral valve rather poorly, in addition to the lack of coaptation surface of the leaflets secondary to the excessive free marginal thickening and outward rolling, made the entire mitral valve incompetent.
Approach to mitral valve repair Approach Exposure of the mitral valve Mitral valve repair is performed through a median sternotomy (optimal if other associated congenital heart lesions are present, especially in infants and children). Aortic and bicaval cannulation. Left atriotomy via a direct incision along the interatrial groove
Exposure of the mitral valve We prefer the left atriotomy approach, extended cephalad beneath the SVC.
Assessment of mitral valve anatomy Particular attention should be given to the leaflet coaptation, the chordae and the position of the papillary muscles Leaflet coaptation is assessed with a forceful injection of saline with a bulb syringe through the valve. This maneuver will demonstrate prolapse of any portion of the valve if present. Using a nerve hook, the posterior leaflet is drawn out near the A-L commissure and the opposing position of the anterior leaflet.there should be a good apposition of the leaflet edges when sufficient coaptation plane exists. Inspection of leaflets, the size of prolapse. and coaptation of the size of the annulus is evaluated.
Measurement of the valve diameter with a Ziemer-Hetzer valve sizer Mitral valve size according to body surface area BSA 0.25 0.30 0.35 0.40 0.45 0.50 Valve size 11.2 12.6 13.6 14.4 15.3 15.8 0.0 16.9 0.70 0.80 0.80 1.00 1.20 1.40 1.60 1.80 2.0 17.9 18.8 19.7 20.2 21.4 22.4 23.1 23.8 24.2 Rowlatt U et al.the quantitative anatomy of the Normal heart. Pediatr clin North Am 1963. 10:499-588
Repaired with modified Paneth-Hetzer technique running suture along the posterior annulus from both trigones to the middle section, tied overa Hegar dilator to prevent narrowing of the valve orifice. Mitral valve repair techniques
Mitral valve repair techniques Continuous suture is anchored to the autologous pericardial pledget and previously- placed trigonal suture, and tied firmly, taking care to avoid further narrowing of the orifice. Shortening the posterior annulus produces wide and even coaptation, in such a way that when the anterior mitral leaflet closess, the border between the smooth and rough surface of the anterior leaflet forms the closure line, without folding. Both sutures are passed onto an untreated autologous pericardial strip attached fromthe midsegment toward the trigones.
Systolic Anterior Motion Systolic anterior motion (SAM) Leaflet coaptation is tested by forceful injection of saline with a bulb syringe through the valve,looking for any residual regurgitation. Precautions must be observed to avoid the SAM phenomenon, seen as folding of the anterior leaflet when the valve is tested with saline instillation into the ventricle. The folding appears when the valve opening is made too narrow by overshortening (overreduction) of the posterior annulus.
Summary and conclusion Mitral valve reconstruction was performed using combined modified Paneth-Hetzer annuloplasty done by shortening the posterior annulus with polypropylene sutures anchored to both trigones with pledgets of untreated autologous pericardium. The valve leaflets and chordae were left untouched. When valve competence was assured, the shortened posterior annulus was stabilized with a strip of untreated autologous pericardial pericardium anchored to both trigones. Intraoperative transesophageal echocardiography showed good coaptation of the leaflets, absence of mitral incompetence and good left ventricular function. The children s postoperative course was unremarkable. Serial echocardiography showed absence of mitral incompetence. Follow-up of each 5 years postoperatively revealed improvement of symptoms and good general condition. Preservation of the congenitally maldeveloped mitral valve leaflet and its subvalvar apparatus in these three cases was made possible by this novel and simple surgical technique with a highly satisfactory mid-term functional outcome.