Aneurysmal Dilatation of the Aortic Sinuses in Marfan's Syndrome

Aneurysmal dilatation of the aortic sinuses in identical twins, aged 2 years, was disclosed after angiocardiography. Knowledge of the association of aortic sinus aneurysms and Marfan's syndrome led to the discovery of bilateral dislocated lenses; these, plus mildly arched palates, dolichocephaly, and slender fingers established the diagnosis of arachnodactyly. Right heart catheterization proved to be normal. A patent foramen ovale in 1 twin permitted pressure measurements in the left atrium and ventricle. Significant mitral insufficiency and aortic stenosis were excluded by the character of the left atrial and ventricular pressures. Aortic sinus dilatation is due to medial degeneration, a common finding in Marfan's syndrome. Endocardial or subendocardial (myxomatous) involvement of the left ventricle is probably the cause of the left ventricular hypertrophy.