Marfan syndrome is an example of an heritable disorder of connective tissue that may have cardiovascular manifestations. It is an autosomal dominant disease that in many cases appears to be due to a mutation in the gene encoding for fibrillin, a component of the connective tissue microfibril. The characteristic skeletal abnormalities of the classic form of Marfan syndrome include increased limb length, pectus excavatum or carinatum, spinal deformities, and arach-nodactyly. Excessive height is due to long lower extremities; therefore, the ratio of upper segment (top of head to pubis) to lower segment (pubis to heel) is abnormally low. Ocular abnormalities include subluxation of the lens and myopia.
Cardiovascular abnormalities, particularly sequelae of dilatation of the ascending aorta, are responsible for the majority of excessive deaths in Marfan syndrome. Aortic insufficiency results primarily from dilatation of the annulus and the ascending aorta. Compared with the mitral valve, myxomatous degeneration of the aortic valve leaflets probably plays only a minor role. The most feared complication of Marfan syndrome is acute dissection or rupture of the aorta, which often results in the patient’s death. The degree of dilatation of the ascending aorta appears to correlate with the risk of aortic regurgitation, aortic dissection, and aortic rupture. Mitral valve prolapse potentially leading to severe mitral regurgitation is also commonly seen in patients with Marfan syndrome. As opposed to aortic insufficiency, the primary pathologic process occurs within the mitral valve leaflets themselves, termed myxomatous degeneration.
Simple bedside examination, chest radiography, and electrocardiography are insufficiently sensitive to diagnose and assess the degree of aortic dilatation, the best predictor of impending acute aortic dissection or rupture. Therefore, annual echocardiography is recommended in all patients with Marfan syndrome. Once the diameter of the aortic root reaches 45-50 mm, it is reasonable to assess the patient every 3 months; once the diameter reaches 55-60 mm, prophylactic surgery should be considered. Pharmacologic beta-adrenergic antagonism may be beneficial in patients with dilated aortic roots who are not yet candidates for surgery. Isometric exercise should be avoided. In addition to assessment of the aorta and aortic valve, echocardiography also allows evaluation of the mitral valve. Finally, antibiotic prophylaxis for infective endocarditis is necessary in patients with mitral or aortic regurgitation.