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J Thorac Cardiovasc Surg 1994;107:943-945
© 1994 Mosby, Inc.

LETTERS TO THE EDITOR

Atrioventricular septal defect with native subaortic stenosis: Correction by extended valvular detachment

Department of Cardiovascular and Pediatric Cardiac Surgery
Marie Lannelongue Hospital and Paris-Sud University
133, avenue de la Résistance
92350 Le Plessis Robinson, France

To the Editor:

When associated with atrioventricular septal defect (AVSD), treatment of native subaortic stenosis remains a surgical challenge. Four different techniques ¹ can be used for surgical correction: (1) fibromuscular resection; (2) modified Konno procedure; (3) apico-aortic conduit interposition; and (4) valvular detachment. Whereas this last option seems logical from an anatomic point of view and is recognized as a preventive procedure, ² lack of data exists about its application for the correction of a native subaortic stenosis. ¹

A 12-year-old girl was referred for evaluation of a subaortic stenosis. Color-coded echocardiographic study disclosed a partial AVSD associated with a native subaortic stenosis and a left ventricle–ascending aorta gradient of 115 mm Hg. At operation, intracardiac assessment revealed an associated minimal fibrous shelf under the aortic valve. The subaortic stenosis was, in fact, mainly related to the convex protrusion of the superior leaflet of the left atrioventricular (AV)valve into the left ventricular outflow tract (LVOT). The first operative step was to divide the insertions of the superior component of the left AV valve from the septal crest (Fig. 1, blank arrow). It achieved the enlargement of the right boundary of the LVOT without complete correction of the anterior protrusion of the superior leaflet and allowed resection of the minimal fibrous shelf. A second operative step was performed by extending the detachment of the superior leaflet into the aorta–left superior leaflet continuity (Fig. 1, shaded arrow). The created defect and the gap in the aorta–left superior leaflet continuity was patched with a single oval polytetrafluoroethylene patch to inverse the convexity of the superior leaflet (Fig. 2). The modification of the shape of the left AV valve did not result in any incompetence, but the cleft had to be closed. Finally, the ostium primum was closed in the usual manner.

View larger version (25K): [in this window] [in a new window]   Fig. 1. Left AV valve detachment (as seen by the surgeon) along the septal crest (blank arrow) and along the aorta-left superior leaflet continuity (shaded arrow). a, Right boundary;b, posterior boundary.

View larger version (27K): [in this window] [in a new window]   Fig. 2. Final appearance after patch enlargement.

Whereas echographically subaortic stenosis is generally categorized as discrete or tunnel outflow tract obstruction, ³ anatomic studies underline malattachment of the left superior leaflet as in itself a third cause. ² Moreover, in case of partial AVSD, asubaortic stenosis is more likely to occur because the left superior leaflet is tightly connected to the septal crest, implying a convex insertion toward the ventricles. To place this in perspective, the LVOT, as described by Ebels and coworkers, ⁴ comprises three boundaries: (1) anterior (i.e.,left ventricular free wall); (2) right (i.e., conus septum and septal insertion of the valvular leaflets); and (3) posterior (i.e., aorta–left AV valve continuity and superior leaflet of the left AV valve).The upper part of the posterior boundary is an area of fibrous continuity between the aortic valve and the left superior leaflet. The lower part of the posterior boundary is the superior leaflet of the left AV valve. The hinge of the superior leaflet is not near the level of the aortic valve but rather between the upper and lower parts of the LVOT and hangs under the aortic valve underlining the particular importance of this anatomic level. ⁴

If the subaortic stenosis is related to a discrete subvalvular aortic stenosis or a septal hypertrophy, the surgical option is to perform a fibromuscular resection. In the presence of a true tunnel outflow tract, the modified Konno procedure is mandatory.

When subaortic stenosis is related to malattachement of the left AV valve, valvular procedures are anatomically a reasonable choice. The proposed modified Manouguian procedure, involving only the posterior boundary at its upper and lower parts, has not been clinically reported as yet. ⁴ The procedure described by Chang and Becker ² consists of the detachment of the superior leaflet from the septal crest, therefore involving the right boundary (Fig. 1, blank arrow). The aim of this valvular detachment is the prevention of a postoperative subaortic stenosis when the left superior leaflet is tightly connected to the septal crest. The efficacy of this procedure is threefold: (1) It allows the correct repositioning of the malattached left AV valve; (2) the defect, which is created, can be closed with a large patch giving an extra width at the basal level of the right boundary, becoming more pronounced if the patch is inserted along the right aspect of the septal crest; (3) it allows an improved exposure of the LVOT. To our knowledge, only one such procedure has been reported in the literature in front of a native obstruction, leading to a secondary mitral insufficiency resulting from endocarditis. The subaortic stenosis was effectively relieved despite the insertion of a "mitral" prosthesis. ¹

According to the anatomic features, we modified this procedure, to perform a larger anteroposterior widening, by extending the right boundary valvular detachment into the posterior boundary of the LVOT at its upper part (Fig. 1, shaded arrow). The risk of left AV valve dysfunction was forestalled, because the subvalvular apparatus was left intact. Moreover, a similar patch insertion, for left AV valve replacement in AVSD, avoids a postoperative subaortic stenosis. ⁵ However, long-term evaluation is needed because the small residual gradient that was left in our patient could present a risk of recurrence. Thereby, the technique could be directed toward the correction of the pathoanatomic features of the disease, providing that the sole cause of the subaortic stenosis is a malattachment of the left superior leaflet.

References

1. Deleon SY, Ilbawi MN, Wilson WR, et al. Surgical options in subaortic stenosis associated with endocardial cushion defects. Ann Thorac Surg 1991;52:1076-83.[Abstract]
   
2. Chang CI, Becker AE. Surgical anatomy of left ventricular outflow tract obstruction in completec atrioventricular septal defect: a concept for operative repair. J THORAC CARDIOVASC SURG 1987;94:897-903.[Abstract]
   
3. Reeder GS, Danielson GK, Seward JB, Driscoll DJ, Tajik AJ. Fixed subaortic stenosis in atrioventricular canal defects: a Doppler echocardiographic study. J Am Coll Cardiol 1992;20:386-94.[Abstract]
   
4. Ebels T, Ho SY, Anderson RH, Meijboom EJ, Eijgelaar A. The surgical anatomy of the left ventricular outflow tract in atrioventricular septal defect. Ann Thorac Surg 1986;41:483-8.[Abstract]
   
5. McGrath LB, Kirklin JW, Soto B, Bargeron LM Jr. Secondary left atrioventricular valve replacement in atrioventricular septal (AV canal) defect: a method to avoid left ventricular outflow tract obstruction. J THORAC CARDIOVASC SURG 1985;89:632-5.[Abstract]
   

This article has been cited by other articles:

				L. Mace, P. Dervanian, T. Folliguet, J.-F. Verrier, J. Losay, and J.-Y. Neveux Atrioventricular septal defect with subaortic stenosis: Extended valvular detachment and leaflet augmentation J. Thorac. Cardiovasc. Surg., March 1, 1997; 113(3): 615 - 616. [Full Text]

This Article Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Loíc Macé Thierry Folliguet Jean Michel Grinda Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Macé, L. Articles by Neveux, J. Y. Search for Related Content PubMed PubMed Citation Articles by Macé, L. Articles by Neveux, J. Y.