Chronic mesenteric ischemia

Chronic mesenteric ischemia ("abdominal angina")

Slowly progressing for a long time, the obstruction of the visceral arteries can lead to the development of collateral circulation, not to be accompanied by pronounced disorders and not to be manifested by a clear symptomatology. This is confirmed by the data of pathologists.

There are two groups of factors leading to chronic impairment of the visceral circulation:

1. intravasal;
2. extravasation.

Among the intravasal causes, obliterating atherosclerosis and nonspecific aortoarteriitis are on the first place. Less often observed hypoplasia of the aorta and its branches, aneurysms of unpaired visceral vessels, fibromuscular dysplasia.

The extravasal cause is the compression of unpaired visceral branches with a sickle-like ligament of the diaphragm or its medial pedicle, the neuroganglionic tissue of the solar plexus, tumors of the tail of the pancreas, or retroperitoneal space. In this compression, the celiac trunk is most often subjected to compression.

Of all the reasons listed above, the main one is atherosclerosis.

Summing up numerous studies and own observations, A. Marston (1989) gives the following current idea of chronic intestinal ischemia:

1. the main cause is atherosclerosis of the visceral arteries.

The incidence of lesions increases with age. In most cases, such lesions are poorly expressed, and "critical stenosis" is rare, in about 6% of cases;

2. the incidence of the defeat of the celiac trunk and the upper brachial artery is approximately the same, whereas the lesion of the inferior mesenteric artery is less frequent;
3. the macroscopic form of the intestine does not depend on the presence of arterial obstruction;
4. there is no correlation between the degree of arterial occlusion detected during autopsy and the symptoms of the gastrointestinal tract noted during life.

Thus, stenosis and occlusion of the visceral arteries in their chronic lesions is a more frequent finding of a pathoanatomical, rather than clinical, study. The difficulties of early detection of chronic intestinal ischemia can be explained by the fact that due to compensatory mechanisms that redistribute the blood flow in the intestinal wall, intestinal functions, including absorption, remain normal almost until the moment when the damage becomes irreversible. Collateral blood circulation contributes to the fact that even with complete occlusion of the visceral arteries in the gut, there is no symptomatic of vascular insufficiency. However, as the arterial inflow is further reduced, ischemia of the muscular gut layer occurs and the associated pain, as the blood flow becomes insufficient to provide enhanced peristalsis caused by ingestion. Circulation in the mucosa remains for some time normal and the absorption-excretory function of the intestine is not disturbed. With further progression of the process, the blood flow decreases below the level required to protect the mucous membrane from bacterial damage, and a focal or massive heart attack develops.

Of great practical importance is the classification of chronic mesenteric ischemia BV Petrovsky et al. (1985), according to which three stages are distinguished:

• / stage - relative compensation. At this stage, the dysfunction of the gastrointestinal tract is insignificant and the disease is detected accidentally when examining patients on some other occasion;
• // stage (subcompensation) - characterized by severe bowel dysfunction, abdominal pain after eating;
• /// stage (decompensation) - manifested by dysfunction of the intestine, constant pain in the abdomen, progressive weight loss.

A. Marston distinguishes the following stages of development of intestinal ischemia:

• 0 is the normal state;
• I - compensatory lesion of the arteries, in which there is no disturbance of blood flow at rest and after eating and there is no symptomatology;
• II - the defeat of the arteries progresses to such an extent that the blood flow at rest remains normal, but reactive hyperemia is absent. This is indicated by pain after eating;
• III - lack of blood supply with a decrease in blood flow at rest. A condition similar to pain in rest with limb ischemia;
• IV - intestinal infarction.

Symptoms of bowel ischemia:

The first clinical manifestations of chronic mesenteric ischemia appear in the II stage according to Petrovsky's classification.

The leading clinical symptoms are:

1. Abdominal pain. Pain in chronic mesenteric ischemia is often referred to as "abdominal toad", "abdominal intermittent claudication". Its main features are:

• is clearly associated with food intake, occurs 20-40 minutes after eating;
• does not have a clear localization (it can be felt in the epigastrium, around the navel, in the projection of the large intestine);
• has a cramping, spastic character;
• it is stopped by nitrates and antispasmodics in the initial period;
• significantly increases with the progression of the pathological process in the mesenteric arteries.

2. Dysfunction of the intestine. Chronic ischemia of the intestine leads to its dysfunction, which is manifested by pronounced flatulence and rumbling in the stomach after eating, constipated; with a prolonged course of the disease, diarrhea appears.
3. Auscultative signs of abdominal ischemia. The characteristic signs of mesenteric ischemia are found in the belly auscultation:

• systolic murmur at the point located midway between the xiphoid process and the navel (projection of the superior mesenteric artery);
• increased intestinal peristaltic noise after eating.

4. Progressive weight loss patients. With pronounced mesenteric ischemia, there is a decrease in the body weight of patients.
   This is due to the refusal of patients to eat (since eating causes significant pain in the abdomen) and a violation of the absorption capacity of the intestine.
5. Data of aortoangiography. Aortoangiography makes it possible to verify the diagnosis of mesenteric ischemia (constriction and pre-stenotic enlargement, deformation of the upper or lower mesenteric artery).

When auscultation of the abdomen, it is often possible to identify symptoms characteristic of chronic ischemia: systolic noise, determined at a point located at the middle of the distance between the xiphoid process and the navel, which corresponds to the localization of the upper brachial artery, and increased intestinal noises after eating.

Findings of aortoangiography for this pathology include stenosis and pre-stenotic enlargement, occlusion and deformation of the visceral arteries.

There is no effective conservative treatment that can stop the progression of the disease. Consequently, there is a constant threat of acute impairment of the visceral circulation. Given this, surgeons dealing with the problem of chronic ischemia in our country, recommend surgical treatment in II (subcompensation) and III (decompensation) stage of the disease. As for stage I (compensation), the correlation of blood flow across the visceral branches is recommended only in cases when patients are operated for the lesion of the abdominal aorta or other branches, since in this case the hemodynamic conditions in the visceral branches may be aggravated. With well-developed collateral blood flow against the background of angiographically revealed lesions of the visceral arteries, it is advisable to postpone the operation.

Surgical intervention is used only in those cases when patients have pain syndrome in the presence of established arterial obstruction, and also when a complete clinical examination excludes any other genesis of the symptomatology.

[1], [2], [3], [4], [5]