The chronic reduction of the flow in the splanchnic area, linked to stenoostructive lesions of the arteries, which irrigate the digestive system, determines a picture of functional insufficiency of blood flow, which manifests itself during the phases of greater demand for blood, such as in to digestion. It is a not very frequent condition, also called "angina abdominis", which consists of pains of varying severity, which arise after hours from meals. It can also precede a long time an intestinal infarction or the evolution in ischemic colitis. Patients are generally between the ages of 40 and 70, smokers and with a history of peripheral vascular disease. Celiac-mesenteric insufficiency is caused by intrinsic lesions of the main visceral arteries, celiac trunk, superior and inferior mesenteric arteries, or more rarely from extrinsic compressions. In most cases it is due to an atherosclerotic plaque at the origin of the vessels, which rarely extends for more than 1-2 cm, often associated with polydistrict atherosclerosis.
Other possible causes can be dissections of visceral arteries, post-actinic lesions, fibromuscular hyperplasia, Buerger's disease, rheumatoid arthritis, systemic lupus erythematosus, nodular polyarthritis, correction of a coarctation, ergotamine poisoning, cocaine abuse. The arched ligament of the diaphragm can cause an extrinsic stenosis on the celiac tripod, when this originates more cranially than the upper margin of the first lumbar vertebra. Very rarely, even the nerve fibers of the celiac ganglion, ganglioneuromas, fibrosis and retroperitoneal neoplasms can cause compression of the vessel.
Important anastomoses exist between the visceral blood vessels and between these and
the hypogastric blood vessels:
- upper and lower pancreatic-duodenal arches between celiac
trunk and superior
mesenteric artery;
- arc of Riolan and the marginal artery of Drummond between this and the
inferior mesenteric artery;
- branches of the hypogastric and lumbar arteries with mesenteric branches;
- inferior and middle rectal arteries with superior
rectal arteries belonging to the inferior
mesenteric.
The Arcade of Riolan or Riolan Arc indicates an anastomosis
between the ascending branch of the middle colic artery which is the first
branch of the superior mesenteric artery and the ascending branch of the
left
colic artery, which is upper branch of the inferior mesenteric artery. It then connects
two different arterial systems, ensuring optimal spraying to the transverse
colon and the first part of the descending one.
As a result, symptoms only become apparent when at least two of the three
splanchnic arteries are affected by significant stenosis or obstruction. In some
patients, mainly those already undergoing abdominal surgery, which involved the
interruption of collateral circulation (colic resections, for example), the
symptoms may become apparent already with the obstruction of a single vessel,
usually the upper mesenteric artery.
On the other hand, isolated stenoses of the celiac trunk or inferior mesenteric artery, often obstructed in aortic aneurysms or in severe aortic ateromasias, are usually well tolerated. In general, intestinal spraying at rest r i requires less than 20% of the cardiac output, but in the post-prandial phase it can exceed 30%. Postprandial hyperemia, regulated by humoral, metabolic and possibly nervous factors, varies in duration and entity in relation to the quantity and quality of food. Most of the flow is distributed to the small intestine, of which 70% to the mucosa, and to the pancreas. Hyperemia is maximum after 30-90 minutes that the food has reached the intestine and lasts 4-6 hours. Thanks to the remarkable self-regulation of the splanchnic flow, pressure variations are well tolerated if the systemic pressure remains above 60-70 mmHg. If the perfusion pressure falls below this threshold, a progressive ischemia is established and consequently the metabolism tends to become anaerobic.
The main symptom is pain, which seems to correlate with the discrepancy between oxygen supply and metabolic demands during absorption. The pain is located in mesogastrium q epigastrium and is sometimes irradiated posteriorly. It is described as colic or as persistent, deep and intense; occurs within 15-30 minutes from the meal, lasts 1-3 hours and is not associated with signs of peritonitis. Initially the patient manages to feed in the pain free intervals, and as the pathological condition is often underestimated due to its relative rarity, the symptoms are attributed to peptic ulcer or to cholelithiasis. It is associated with the reduction in frequency and quantity of meals resulting in weight loss, and malabsorption diarrhea. They often associate nausea, vomiting, alterations of the abdomen in a constipated sense, rare diarrhea, constipation and flatulence. At the physical examination there are no signs of peritonitis or intestinal infarction, while an epi-mesogastric breath is often perceived, which is not particularly specific.
The diagnosis is first of all clinical, based on a correct collection of the
anamnestic data and on a correct interpretation of the objective examination,
but also of exclusion after thorough evaluation of the gastro-intestinal, liver
or pancreas. There are several clinical situations in which the differential
diagnosis is made with mesenteric ischemia: cholelithiasis, gastroduodenal ulcer,
neoplasia of the gastro-enteric apparatus and in particular of the pancreas,
chronic gastritis, hiatal hernia, complicated diverticulosis, chronic
pyelonephritis, nephrolithiasis.
The stigmata of weight loss, with the abdomen dug and treatable even during the
exacerbation of pain, and signs of peripheral vascular disease, mainly occlusive
to the aortoiliac axes, are detectable. At the bio-oral level, in addition to
the malnutrition indices, the increase in amylase and lipase is an indication of
ischemic pancreatitis. Tests of intestinal absorption and excretion, such as the
measurement of urinary D-xylose levels after oral administration of Dxylose,
have not proven to be useful in the diagnosis of chronic intestinal ischemia,
being simple malabsorption indices. At endoscopy, the presence of duodenal ulcer
or ischemic colitis can sometimes be detected. The color-Doppler echo of the
celiac trunk and of the superior mesenteric can detect steno-occlusions, with
acceleration of the flow and inversion of the direction in the hepatic and
splenic arteries; the post-prandial flow increase at the AMS level is typical.
angioTC and angioRM can provide very representative pictures of steno-occlusions,
but arteriography is still the benchmark test in patients with suspected chronic
intestinal ischemia. The location of atherosclerotic lesions is usually at the
level of the ostium of the main vessels, therefore, in order to better evaluate
the severity of the stenosis, it is necessary, in addition to the
anterior-posterior projection, also the lateral one.
There is no effective and decisive medical therapy. Therefore the symptomatic chronic
mesenteric insufficiency always imposes a correction treatment of the
atheromatous lesion, also to prevent prolongation towards an intestinal
infarction. In elderly, atherosclerotic, malnourished and defiled patients,
major surgical interventions are indicated but at high risk, so a preparatory
phase with total parenteral nutrition is appropriate for about 7-10 days.
Asymptomatic obstructions of individual vessels do not require almost any
correction, except in anticipation of other aortic interventions. Multiple and
symptomatic obstructions are usually solved by revascularizing a single vessel,
almost always the superior mesentery.
Percutaneous angioplasties are excellent and provide acceptable results over
time. Surgically, revascularization is easily achieved by retrograde bypass
between the suborenal and superior mesenteric aorta (aorto-mesenteric bypass),
and more complexly by endarterectomy. Monitoring with an ecodoppler is difficult,
so angio-CT or angio-MR is preferable. Particular cases of ab extrinsic stenosis
rarely require correction, as they are well compensated; eventually the removal
of the cause is necessary.
see >> Ischemic
colitis
It is a particular picture, which results in diminished perfusion due to reduced
cardiac out-put in serious cardiopathies or in prolonged shock, or to
celiac-mesenteric insufficiency and embolism with inadequate collateral
compensation. It is rare before the age of 60, in which case it is associated
with vasculopathies, coagulopathies or diseases induced by drugs. It affects
mainly two segments placed as a watershed between two vascular systems: the
splenic flexure, between the upper mesenteric artery and the inferior; the
distal sigma, between the inferior mesenteric artery and the hypogastric artery.
Insufficient and prolonged spraying can lead to ischemic necrosis of such
magnitude as to affect the mucosal lining up to the muscular. At endoscopy the
mucosa appears edematous, dark red or purpura result of hemorrhages, thickened
and with superficial ulcerations. Histologically, vasal dilation is observed
associated with hemorrhagic necrosis confined in the superficial layers of the
mucosa, but sometimes extended to the submucosa and to the superficial layer of
the muscular tissue. When the mucosal barrier disappears, bacterial
contamination occurs. Morphological changes, therefore, are similar to
pseudomembranous colitis or other inflammatory and / or infectious processes,
with which it can be confused, as well as with carcinomas and lymphomas.
Patients report various episodes of abdominal pain in the left quadrants,
associated with blood diarrhea and which resolve over several days. Severe
ischemia can lead to intestinal necrosis and perforation with an acute abdomen
and 10% mortality. In some cases intestinal stenosis can develop with consequent
occlusion. A realistic diagnosis of ischemic colitis can only be achieved when
radiological signs are related to clinical data. The direct radiograph of the
abdomen can detect a dilation of the colonic loops, flattening of the haustra,
edema of the wall. the opaque opacity is abnormal in 90% of cases and shows
irregularities of the polypoid mucosa, up to true ulcerations; in the late
phases appear parietal rigidity up to real stenosis. CT is the best
investigation to rule out other causes of abdominal pain and to diagnose
ischemic colitis, as it detects alterations of blood vessels and blood flow to
the intestine. AngioRM is reserved for individuals with renal impairment. The
therapy is of medical type and based on antiplatelet and hemorrhoids and
antibiotics in the acute phases. In severe or complicated cases only a
revascularization of the main vessels or a resection of the affected colon tract
can resolve the situation.