Rapidly progressive obstructive cardiomyopathy in infants with Noonan's syndrome. Report of two cases.

Abstract

SUMMARYThis 23-month-old white boy was first admitted to Jackson Memorial Hospital, Miami, Florida, at one day of age. He had been the product of a normal pregnancy and delivery, and weighed 3.97 kg at birth. At another hospital he was noted to be cyanotic and heart murmur was heard. A sibling had died of heart failure at two weeks of age. On admission the patient was noted to be cyanotic only when cry- From

Biventricular Hypertrophic Cardiomyopathy With Right Ventricular Outflow Tract Obstruction Associated With Noonan Syndrome in an Adult

“…2,3 HCM is the second most commonly associated cardiac abnormality and tends to affect predominantly the interventricular septum and left ventricle. [4][5][6][7][8][9] In the case presented here, bulging of the hypertrophied septum into the right ventricular outflow tract caused RVOT obstruction, which manifested itself as right-side hypertrophic obstructive cardiomyopathy. 11,12 Because the hypertrophied muscle bundles were positioned infundibulary, this case was thought to be different from double-chambered right ventricle.…”

“…Although several cases of biventricular HCM with right-and/or leftside outflow obstruction have been reported in infants with Noonan syndrome, relatively few cases have been reported in adults. [4][5][6][7] Although no mention was made whether their patients showed the Noonan phenotype, Maron et al reported RVOT obstruction to be relatively common in infants and young children with HCM, but rare in older patients with HCM. 16 This difference between infants and adults can be explained as follows.…”

“…7 Hirsch et al reported fatal outcomes for 2 infants with Noonan syndrome in whom biventricular hypertrophic obstructive cardiomyopathy progressed rapidly. 6 Shimizu et al described a rare case of HCM associated with Noonan syndrome that progressed to dilated cardiomyopathy. 19 The gene for familial Noonan syndrome is located on chromosome 12q, but the gene responsible for cardiac defects accompanying this syndrome has not yet been identified.…”

“…1 The major cardiovascular defects are valvular pulmonary stenosis, commonly due to a dysplastic valve, 2,3 and hypertrophic cardiomyopathy (HCM), which predominantly affects the interventricular septum and left ventricle. [4][5][6][7][8][9] We report an adult case of Noonan syndrome with biventricular HCM accompanied by isolated right ventricular outflow tract (RVOT) obstruction without valvular abnormalities. To the best of our knowledge, these conditions are regarded as rather uncommon manifestations of cardiac defects in adults with Noonan syndrome.…”

Adults with genetic syndromes and cardiovascular abnormalities: clinical history and management

“…The clinical course of hypertrophic cardiomyopathy is variable because it may develop in later childhood and gradually increase in severity, remain stable over many years, or be rapidly progressive in infancy. 203,211 Histopathologic studies demonstrate myocyte fiber disarray resembling nonsyndromic familial hypertrophic cardiomyopathy. Treatment is similar to that in familial hypertrophic cardiomyopathy including the use of beta blockers or surgery to reduce outflow tract obstruction.…”