Robert J. Sammartano

On the Nature and Etiology of Vascular Ectasias of the Colon: Degenerative lesions of aging

Vascular lesions of the right colon are being diagnosed increasingly as a cause of lower intestinal bleeding, but their nature and occurrence, primarily in the elderly, remains unexplained. Colons from patients with clinical and angiographic diagnoses of cecal vascular lesions were studied by injection and clearing, and by histological sections. In all injected specimens one or more mucosal vascular ectasias were identified. The mucosal lesions appeared to be secondary to dilated tortuous submucosal veins which were the more prominent feature and were often present without the mucosal ectasia. This suggests that ectasias are caused by chronic, intermittent, low grade obstruction to submucosal veins with dilation and tortuosity initially of submucosal veins, then of venules, capillaries, and arteries of the mucosal vascular unit. Ultimately, precapillary sphincters lose their competency, producing small arteriovenous communications. The concept that ectasias are degenerative lesions was evaluated by studying 15 right colons resected for carcinoma with no history of bleeding. Mucosal ectasias were identified in four colons and submucosal ectasias in eight. These investigations suggested that these lesions: (1) are vascular ectasias developing as a degenerative process of aging, (2) are present with or without bleeding in a significant portion of the population over 60 years of age, (3) are multiple more often than single, and (4) may represent the commonest cause of major lower intestinal bleeding in the elderly.

Lower intestinal bleeding in the elderly

Lower intestinal bleeding in the elderly is a common problem with numerous and varied causes. Its diagnosis and treatment require a careful, systematic approach by physicians with special expertise. Under the proper circumstances, elderly patients with lower intestinal bleeding do well, even when surgery is required. An individuals age, by itself, should not preclude aggressive medical care.

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.

Vascular ectasias of the right colon in the elderly: A distinct pathologic entity

Vascular ectasias (angiodysplasias, arteriovenous malformations) of the cecum and ascending colon are a frequent cause of lower intestinal bleeding in the elderly that has been overlooked by clinicians and pathologists. Their nature and etiology have been poorly understood until recently. This article reviews the previous literature and presents a complete and detailed description of these lesions based on the examination of 87 areas showing vascular ectasia from 26 colons. Their morphology spans a spectrum from small focal early lesions to multiple large late lesions. The early lesions are characterized by markedly dilated, large, tortuous submucosal veins with minimal dilatation of their tributaries in the mucosa. The late lesions showed further dilatation of submucosal veins and venules and extensive replacement of the overlying mucosa by racemose collections of dilated and thin walled venules and capillaries, three of which demonstrated rupture into the colonic lumen. The pathology of these lesions is considered to be specific enough to establish vascular ectasias of the colon as a distinct entity.

Qualitative and quantitative fluorescein fluorescence in determining intestinal viability.

Clinical evaluation and qualitative (visual) and quantitative (fluorometric) fluorescence for predicting intestinal viability were compared in an animal model of temporary arterial occlusion with early revascularization. Quantitative fluorescence was determined with a perfusion fluorometer after an intravenous bolus of fluorescein. Qualitative fluorescence was determined by examination under a Woods lamp in a darkened room. The effectiveness of each diagnostic technique in determining nonviability was expressed in terms of sensitivity, specificity, and accuracy. All three methods had 100 percent specificity; only bowel deemed nonviable proved to be so. Quantitative fluorescence also had a 100 percent sensitivity, but clinical evaluation and qualitative fluorescence had only a 33 and 11 percent sensitivity, respectively (some segments of bowel that were ultimately nonviable were not correctly predicted to be so). The inaccuracy of qualitative fluorescence was due to the fact that ischemic intestine with a hyperfluorescent pattern often progressed to necrosis. Fluorometric quantitation identified those hyperfluorescent segments that were viable. This study suggests that visual fluorescence is not reliable in assessing intestinal viability after early revascularization after arterial occlusion, but quantitative fluorometric fluorescence is reliable in almost all instances.

Hemodynamic basis of the pain of chronic mesenteric ischemia.

Tonometry, a new technique to indirectly assess intestinal blood flow, was used to determine the hemodynamic changes produced by a simulated meal in animals with a fixed, decreased splanchnic blood flow. In experiments on 14 dogs, celiac artery and superior mesenteric artery blood flow was maintained at 50 percent of normal flow by occluders and flow probes, and tonometers were placed in the stomach and small bowel to measure intramural pH, a metabolic marker of intestinal perfusion. Intramural pH was determined at 100 percent and 50 percent splanchnic blood flow, at 50 percent flow after instillation of cream into the stomach, and again when cream was placed into the small bowel. Intestinal intramural pH decreased significantly when blood flow was decreased to 50 percent, as expected, but decreased significantly again when cream was placed in the stomach. The hemodynamic explanation of the decrease when cream was placed in the stomach is a steal from the intestinal to the gastric circulation stimulated by food in the stomach. Such a steal could explain the temporal nature of the pain experienced by patients with chronic mesenteric ischemia.

Scintigraphic diagnosis of ischemic intestine with technetium 99m sulfur colloid labeled leukocytes

Positive scintigrams were obtained in 13 of 15 dogs injected with technetium-99m sulfur colloid-labeled leukocytes following the experimental production of intestinal ischemia. The radioactivity of the ischemic intestines averaged 5.9 times that found in normal control segments of intestine from the same animal. Labeled leukocytes may be used as a rapid noninvasive technique for the early identification of ischemic intestine.