The role of transaortic extended septal myectomy in children with Noonan syndrome and obstructive hypertrophic cardiomyopathy

• Kozhanov R.S.
• Egunov O.A.
• Naumov S.S.
• Vtorushin S.V.
• Krivoshekov E.V.

Abstract

Background. Approximately 20-30% of patients with Noonan syndrome have asymmetric hypertrophic cardiomyopathy (HCM) with left ventricular outflow tract (LVOT) obstruction and mitral regurgitation. There is relatively little data on the role of transaortic extended septal myectomy in children with this syndrome.

Aim. To evaluate the immediate and mid-term results of transaortic extended septal myectomy in children with obstructive HCM and Noonan syndrome.

Material and methods. A retrospective analysis of patients was carried out after transaortic extended septal myectomy performed in the cardiac surgery department No. 2 of the Research Institute of Cardiology of the Tomsk National Research Medical Center from 2010 to 2023. The patients were divided into two groups. Group I included 14 patients with HCM and Noonan syndrome, group II included 26 non-syndromic patients with HCM.

Results. 40 patients were included in the study. Median age was 5.2 [2.3; 10.5] years and 7.5 [3.4; 13.2] years for groups I and II (p=0.281). At the same time, the age of initial diagnosis in group I was 1 [1; 3] months, and in group II – 12 [6; 51] months (р<0.001). The rate of intraoperative complications for group I was 7.1% (n=1), for group II – 23.1% (n=6). All patients in group I were diagnosed with an anomaly of the subvalvular apparatus of the mitral valve; in 14.3% of cases, its replacement with a mechanical bicuspid prosthesis was required to eliminate the obstruction. There was no mortality in the early and mid-term postoperative follow-up period. The median follow-up time for patients in both groups was 3.0 [2.9; 3.2] years. Significant differences according to mid-term observations in patients of group I, compared with group II, were observed in the residual gradient on the LVOT and the z-index of the posterior wall of the left ventricle (p=0.001; p=0.011).

Conclusion. Transaortic extended septal myectomy can effectively relieve LVOT obstruction in children with Noonan syndrome and concomitant obstructive HCM with satisfactory early and mid-term postoperative results.

Keywords:Noonan syndrome; hypertrophic cardiomyopathy; transaortic extended septal myectomy; left ventricular outflow tract obstruction

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