Visceral arterial ischemia

Visceral arterial ischemia  is caused by a sudden or slowly incoming closure of the a. mesenterica sup. and at the same time by stenosis or closure of the a. coeliaca or a. mesenterica inferior. This acute closure causes severe intestinal ischemia. If the artery closure arises slowly, sufficient collateral circulation develops due to the anatomical arrangement of the vessels of the gastrointestinal tract.

Chronic closure of the mesenteric artery
Causes

The main causes include atherosclerosis, rarely arteritis, fibromuscular dysplasia, (congenital anomalies). Anatomical causes may be atherosclerosis, fibromuscular dysplasia or external compression. The main functional cause is iliofemoral (aorto-ilic) steal syndrome (closure of the lower aorta or common pelvic artery); blood goes the inferior mesenteric artery – a. rectalis sup. - a. rectalis media - a.  Iliaca interna - a.  iliaca communis - a. iliaca externa - a. femoralis.

Clinical picture

The main symptoms are abdominal pain occurring 10-60 minutes after a meal (angina abdominis), diarrhoea or constipation, sometimes a murmur is heard, progressive cachexia. The diagnostic methods can be used to test the patient orally – the patient is given cream and then his pH is monitored in the jejunum - a steal phenomenon is created with reversal of blood flow to the stomach, in patients with intestinal ischemia the pH in the jejunum decreases.

The differential diagnosis  is pancreatic cancer, stomach cancer or peptic ulcer.

Therapy

In severe abdominal angina with cachexia, the therapy is surgical. Another therapy is transaortic endarterectomy. A significant proportion of patients are generally at risk, which is why bypass - from the infrarenal aorta is preferred. If this part of the aorta is sclerotic, the supraceliac section of the aorta is used, thus the bypass is behind the pancreas. In PTA (percutaneous transluminal angioplasty), there is a risk of acute thrombotic closure with a fatal outcome.

Acute mesenteric ischemia
It is most often caused by embolism in the a. mesenterica superior, less by plaque thrombosis, aneurysm or aortic dissection. Another cause may be venous thrombosis.

Mesenteric artery embolism
Clinical picture

Sudden severe abdominal pain with poor physical findings. It may cause vomiting and blood in the stool. After a few hours, the pain eases a bit, peristalsis ceases, vascular ileus develops until diffuse peritonitis.

The progress
 * 1) up to 6 hours - initial stage with pain and shock, early intervention can preserve the intestine
 * 2) 6–12 hours - pain calms down, overall condition worsens, paralytic ileus with wall gangrene develops
 * 3) after 12 hours - intestinal perforation and peritonitis
 * laboratory - leukocytosis, may be higher lactate and amylase

Dianosis – angiography, but usually the fastest possible laparotomy is more effective

The time factor is very important - the ischemic intestine is necrotic within 8 hours.

Therapy

With early surgery - embolectomy with a Fogarty catheter, after 24 hours it is appropriate to perform a second laparotomy and revise the intestine, resect any necrosis. In case of clear necrosis, resection after small emboli - segmental resection, trunk closure - up to the colon is necessary. Previously, it was considered incompatible with life, today it is possible to consider maintaining on parenteral nutrition.

Closure of the a. mesenterica inferior
Thrombosis on the atherosclerotic plaque most often occurs. Clinically there is pain in the left lower quadrant, the stool is usually mixed with blood and detached mucosa, later signs of low ileus. Surgical treatment is resection of the affected segment.

Mesenteric artery thrombosis
It manifests itself similarly to embolism, but the symptoms may begin slower. There may be an abdominal angina in the anamnesis. Thrombectomy is usually insufficient, a bypass should be established.

Non-occlusive mesenteric ischemia
Causes

The causes can be insufficient perfusion - in case of the cardiac failure, arrhytmia, acute Myocardial Infarction, hypovolemia, after burns, polytrauma. Arteriography shows spastic segments of the a. mesenterica.

Therapy

Already during angiography, we can apply a vasodilator localy (eg 30 mg papaverine). Then we continue the infusion of the substance. It is necessary to address the causes.

Mesenteric venous thrombosis
Causes

The cause is a coagulation disorder, which often occurs after infections (viral and bacterial) - such as salmonellosis.

Clinical picture

It is manifested by abdominal pain, nausea, vomiting, fever. There are progressive signs of peritoneal irritation.

Diagnostics

It is usually diagnosed during a laparotomy. The problem can be detected even without surgery - duplex ultrasound and CT with contrast.

Therapy

The therapy is complete heparinization.

Renovascular hypertension
Pathogenesis

It can be either an atherosclerotic atherosclerotic slice at the place of artery separation (in 2/3 of patients) or fibromuscular dysplasia (especially young women). Insufficient perfusion pressure leads to activation of the renin-angiotensin-aldosterone system. It is the cause of about 5-10 % of all hypertensions (in large hypertension they account for 30-40%).

Examination

Examinations include renal duplex sono, arteriography, isotope renography or renin vein sampling (RIA).

Therapy

The therapy is preferably surgical - we reduce the pressure and prevent the progression of kidney damage. Today, much of the stenoses can be treated with PTA.

Surgical therapies can be:
 * 1) aortorenal bypass by autologous vein
 * 2) renal artery endarterectomy
 * 3) in case of severe changes (mainly fibromuscular) - ex vivo reconstruction on the kidney, perfused with preservative solution
 * 4) in the worst case - nephrectomy

Related articles

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 * Ischemic heart disease
 * Chronic ischemic disease of the lower limbs
 * Large vein closures