The pathophysiologic basis for the angiographic signs of vascular ectasias of the colon.

Three reliable diagnostic signs were identified on angiograms from 25 patients with ectasias of the right colon: (a) a slowly emptying dilated, tortuous, intramural vein; (b) a vascular tuft; and (c) an early filling vein. The frequency of these signs and the order of their occurrence reflect the different stages in the evolution of ectasias. The earliest and most frequent sign, the slowly emptying vein, reflects ectatic changes in a submocosal vein resulting from chronic intermittent partial obstruction. The vascular tuft represents more advanced lesions and corresponds to extension of the degenerative process to the venules in the mucosa. An early filling vein reflects an arteriovenous communication through a dilated arteriolar-capillary-venular unit-a mucosal ectasia.