Surgical treatment of obstructive hypertrophic cardiomyopathy in children with Noonan syndrome

About 80–90% of patients with Noonan syndrome have changes in the cardiovascular system, 30% of which include cardiomyopathy, hypertrophic phenotype in particular. The treatment of cardiomyopathy patients with Noonan syndrome is carried out according to the cli­nical recommendations for the treatment of chronic heart failure (CHF) and cardiomyopathy. Surgical treatment of progressive nature of heart failure with left ventricular outflow tract obstruction and mitral regurgitation can be one of the possible methods. The review presents our experience with septal myectomy (SM) in children suffered from hypertrophic obstructive cardiomyopathy with Noonan syndrome.

Objective. To assess the efficiency of septal myectomy in children suffered from hypertrophic obstructive cardiomyopathy with Noonan syndrome.

Materials and methods. Clinical examination (family history, patient examination), lab tests (NT-proBNP level), echocardiography, electrocardiography, Holter monitoring, Chest X-rays and molecular genetic methods using mass parallel sequencing (NGS) and direct automatic Sanger sequencing. The indications for the SM were determined according to the clinical guidelines for the diagnostic and treatment of hypertrophic cardiomyopathy.

Results. 7 patients out of 48 with Noonan syndrome underwent SM and 1 with Noonan syndrome with multiple lentigo (LEOPARD). Two of them required the removal of obstruction of the outflow tracts of both ventricles, followed by plastic removal of the right ventricle and pulmonary artery valve. Related surgical interventions included aortic (n = 1) and mitral valves (n = 2), permanent pacemaker (n = 1) in the early postoperative period. After a year, all children recorded a decline of NT-proBNP from the average of 16,198 to 3,865 pg/ml, a significant improvement in health, disappearance of shortness of breath, increased physical activity tolerance, improved physical (weight, growth) and speech development. When assessing the dynamics of the Echo parameters 1 year after the SM, normalization of the size of both atria in 4 cases, reduction of severity of isolated dilation of the left atrium in 2 cases was noted. No cases of repeated obstruction have been reported.

Conclusion. Hypertrophic cardiomyopathy (HCM) can be in structure of hereditary syndromes such as Noonan syndrome. Septal myectomy (SM) can now be used in the case of progressive nature of heart failure with left ventricular outflow tract obstruction in children with Noonan syndrome.

Contribution:
Gandaeva L.A., Basargina E.N. — concept and design of the study;
Gandaeva L.A., Basargina E.N., Savostyanov K.V. — collection and processing of material;
Gandaeva L.A. — statistical processing, text writing;
Basargina E.N., Kondakova O.B., Savostyanov K.V. — text editing.
Аll co-authors — аpproval of the final version of the article, responsibility for the integrity of all parts of the article.

Acknowledgement. The study had no financial support.

Conflict of interest. The authors of this article confirmed the lack of financial support and conflict of interest which should be reported.

Received: April 06, 2022
Accepted: April 26, 2022
Published: May 7, 2022

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