Mitral valve replacement and trans-mitral myectomy for a child with Noonan syndrome accompanied by hypertrophic obstructive cardiomyopathy

A 4-year-old boy with Noonan syndromeaccompanied by hypertrophic obstructive cardiomyopathypresented with refractory heart failure owing to severe left ventricular outflow obstruction and mitral regurgitation. He underwent mitral valve replacementand trans-mitral myectomy. The pathology of the resected myocardium was consistent with hypertrophic cardiomyopathy, and the mitral valveleaflets were severely degenerated. Compared with a control patient who is a non-syndromic 4-year-old boy with hypertrophic obstructive cardiomyopathy, mitral pathology was much more severe in Noonan syndrome. Regarding trans-mitral myectomy, residual pressure gradient at the mid-ventricular level made us think about more aggressive muscle resection with various approaches.