Aortic 125I-albumin transport in patients with Marfan's syndrome and annuloaortic ectasia.

The morphologic, biochemical, and mechanical abnormalities of connective tissue fibrous proteins in Marfan's syndrome have been well studied, and their role in cardiovascular complications is well accepted. Less is known, however, about the state of the amorphous components of the aortic connective tissue. In the course of a study of transmural transport in blood vessels, we have had the opportunity to study dystrophic aorta from two young men who survived elective surgery; both with aortic insufficiency (AI) histologically compatible with Marfan's syndrome. One had recurrent chronic dissecting aneurysm (RCDA) as well. The aorta of the first (but not the second) was histologically compatible with Marfan's syndrome. Fresh specimens of intact ascending aorta were incubated in Krebs solution, pH 7.4, containing 125I-labelled bovine serum albumin for 2 h at 37 degrees C. The samples were then frozen, and serially sectioned in the plane of the lumenal surface. The radioactivity of the 20-micron thick sections was then determined, and expressed as a tissue/labelled solution concentration ratio. Transmural profiles of these ratios revealed no difference between the aorta of the RCDA patient with non-specific aortic dystrophy, and that of a 70-year-old man undergoing aortocoronary bypass. However, in the patient with aortic histology compatible with Marfan's syndrome, the average media concentration ratio was 5-fold less (4% vs. 20%).