Pathophysiology of gastrointestinal circulation

Blood Pressure and the Risk of Death From Non-cardiovascular Diseases: A Population-based Cohort Study of Korean Adults

“…Intestinal ischemia is associated with acute or chronic low blood flow to the gut due to atherosclerosis, cardiac arrhythmias and other reasons. Although arterial hypertension is not a direct risk factor for intestinal ischemia in terms of gastrointestinal vascular pathology, several experimental results have shown that blood vessels in hypertensive animals are more sensitive to vasoconstrictors [28]. These results suggest that hypertension may induce intestinal ischemia and increase the risk of death in the presence of any stress conditions, although it is not a common mechanism of intestinal ischemia.…”

Intestinal Ischemic Disorders

“…The blood supply to the small intestine derives pri marily from the superior mesenteric artery (SMA) which is one of the two largest branches of the aorta. Resting SMA blood flow in a 70-kg adult person is about one tenth of the cardiac output [7,8], The proximal half of the colon is also perfused by branches of the SMA. whereas the distal large bowel receives its blood mainly from the inferior mesenteric artery whose blood flow is half that of the SMA.…”

“…Variations in intestinal parenchymal me tabolism normally alter mesenteric blood flow, such that the increased demand for blood leads to increased vascular perfusion [7,12], An elevated metabolism coupled with a pathological reduction in blood flow will, however, aggravate the ischemic insult and lead to hypoxic mucosal injury and necrosis. Local metabolic activity also generates chemi cals which protect parenchymal cells by their profound intestinal microcirculatory actions, e.g., increasing microcirculatory blood flow, relaxing precapillary sphincters, adjusting transcapillary exchange, etc.…”

“…The cardiovascular system external to the gut is responsible for the forces which are among the major determinants of normal blood flow to the intestine [7,12], The blood volume, the cardiac output, and systemic ar terial pressure are generated mostly outside the bowel, yet these parameters are essential ingredients for normal intestinal vascular re sistance and normal blood flow. Thus, for example, sudden severe hemorrhage from a vessel distant to the gut, say the femoral artery as a result of trauma, will trigger a cascade of cardiovascular abnormalities outside the bowel which will cause intestinal ischemia ( fig.…”

“…Furthermore, in a majority of elderly patients initially diagnosed with colonic inflammatory bowel disease, the ultimate diagnosis turned out to be ischemic colitis [6], One outcome of the prevailing medical view of intestinal isch emia is a low level of diagnostic suspicion which translates into a low frequency of timely diagnoses. Second, patients with severe intesti nal ischemia are usually already gravely ill with another life-threatening disorder, usually cardiovascular, such as heart failure, throm boembolic diseases, extensive atherosclerosis, cardiac arrhythmias, circulatory shock, exten sive bums, or recovery from major cardiac surgery [1,7]. The low flow state in the gut is masked by the preexistent cardiovascular dis ease, again precluding an early diagnosis of intestinal ischemia.…”