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eComment: Discrete subaortic stenosis following repair of atrioventricular septal defects

National Cardiothoracic Centre, Korle Bu Teaching Hospital, PO Box KB 846, Korle Bu, Accra, Ghana

Outcome after reoperation for atrioventricular septal defect repair

We read with interest the report by Birim and colleagues [1]. Their experience highlights the issue of reoperations following the repair of atrioventricular septal defect (AVSD). The important contribution of left ventricular outflow tract obstruction (LVOTO) to reoperations and second reoperations is obvious in their report. However, the authors did not comment on the characteristics of the LVOTO such as the pre- and postoperative gradients and their threshold for intervention. It may be deduced from their operative technique that they were dealing with discrete subaortic stenosis (DSS) as the cause of LVOTO.

DSS is thought to be an acquired lesion secondary to pre-existing anatomic alterations in the left ventricular vestibule [2]. It has been reported after the surgical repair of several congenital heart defects such as coarctation of the aorta and AVSD among others [3]. Morphological substrates that cause turbulence and increased shear stress in the subaortic region are thought to contribute to its development through stimulation of the endothelium. Most patients with significant DSS are asymptomatic, underscoring the importance of regular follow-up.

DSS is a well-defined membranous or fibromembranous ring that partially or completely encircles the subvalvular aortic region. It has the tendency to be progressive with worsening gradients and the appearance or deterioration of aortic incompetence (AI). The necessity for surgical intervention is usually not in doubt. The timing and technique of surgery are, however, without consensus. The indication for surgery has been the relief of LVOTO and the prevention or deterioration of AI. Enucleation with or without septal myectomy provides relief of LVOTO.

Although early surgical intervention relieves the obstruction, recurrence still remains a long-term complication as demonstrated [1]. The time of recurrence appears to be inversely related to the extent of subvalvular resection. For those patients undergoing primary operations for discrete subaortic stenosis, adding a myectomy to enucleation does not guarantee superior results in terms of the relief of LVOTO [4]. However, for patients who have had a previous cardiac operation, concomitant myectomy gives a significantly lower-rate of recurrence of LVOTO (44% for enucleation against 13% for enucleation plus myectomy) [4].

Surgery unfortunately may not have a beneficial impact on AI, both in terms of incidence and severity [5].

	References

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1. Birim O, van Gameren M, de Jong PL, Witsenburg M, van Osch-Gevers L, Bogers AJJC. Outcome after reoperation for atrioventricular septal defect repair. Interact CardioVasc Thorac Surg 2009;9:83–88.[Abstract/Free Full Text]
2. Lampros TD, Cobanoglu A. Discrete subaortic stenosis: an acquired heart disease. Eur J Cardiothorac Surg 1998;14:296–303.[CrossRef][Medline]
3. Kalfa D, Ghez O, Kreitmann B, Metras D. Secondary subaortic stenosis in heart defects without any initial subaortic obstruction: a multifactorial postoperative event. Eur J Cardiothorac Surg 2007;32:582–587.[Abstract/Free Full Text]
4. Hirata Y, Chen JM, Quaegebeur JM, Mosca RS. The role of enucleation with or without septal myectomy for discrete subaortic stenosis. J Thorac Cardiovasc Surg 2009;137:1168–1172.[Abstract/Free Full Text]
5. Gersony WM. Natural history of discrete subvalvar aortic stenosis: management implications. J Am Coll Cardiol 2001;38:843–845.[Free Full Text]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted 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): Frank Edwin Mark M. Tettey Kow Entsua-Mensah Kwabena Frimpong-Boateng Permission Requests Google Scholar Articles by Edwin, F. Articles by Frimpong-Boateng, K. PubMed PubMed Citation Articles by Edwin, F. Articles by Frimpong-Boateng, K. Related Collections Related Article