Acute and chronic ischemia
Occlusive diseases of the mesenteric vessels are classified into acute and chronic.
Acute mesenteric ischaemia (Acute mesenteric ischaemia, AMI) in modern clinical practice is diagnosed predominantly using computed tomography, which has replaced diagnostic laparotomy. If intestinal viability is preserved, a potential treatment method is targeted thrombolysis (targeted thrombolysis). However, it is important to understand that the evidence base for this method is still limited and relies on small case series and reports.
Chronic mesenteric ischaemia (Chronic mesenteric ischaemia, CMI) is insidious due to its asymptomatic nature. According to autopsy data, atherosclerotic lesions of the mesenteric arteries are detected in 35–70% of unselected patients. Despite such high prevalence, thanks to a powerful collateral circulation system between the mesenteric arteries, the clinical picture rarely unfolds.
Manifestation of classical symptoms—postprandial pain (abdominal pain after eating) and weight loss—requires significant stenosis of at least two of the three main mesenteric arteries. The main treatments for CMI are surgery and arterial stenting.
Diagnostic imaging and MALC syndrome
Doppler ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) serve as the basic and primary tools for non-invasive diagnosis. Catheter angiography today is used exclusively for intraoperative confirmation of the diagnosis directly during the intervention. Lateral aortography is recognized as the optimal method for assessing anatomical features before surgery.
The most crucial step in the imaging evaluation is the exclusion of extravasation compression of the coeliac axis (coeliac axis) by the median arcuate ligament of the diaphragm. This condition is known as median arcuate ligament syndrome, or MALC (median arcuate ligament of the diaphragm compression).
Detection of MALC radically changes the management: such patients are indicated for surgical treatment, as endovascular techniques are not applicable here.
Angiographic signs of MALC:
- Asymmetric narrowing along the superior surface of the coeliac axis.
- The narrowing is non-ostial (non-ostial) in nature.
- The pathological pattern is accentuated (maximized) on angiograms performed in the expiratory phase.
Endovascular intervention (Angioplasty)
The main method of endovascular correction of ischemia is primary stenting (primary stenting). The intervention is performed via femoral (femoral) or brachial (brachial) access. Atherosclerotic lesions are most frequently localized at the vessel origins (vessel origins). Technical success of the procedure in most observational series reaches 80–100%.
Revascularization strategy:
- To relieve clinical symptoms, stenting of a single vessel is usually sufficient.
- Restoring blood flow in multiple arteries (if technically feasible) improves long-term outcomes.
- If the surgeon is forced to limit treatment to only one artery, the superior mesenteric artery (SMA / superior mesenteric artery, SMA) becomes the optimal choice.
When choosing instruments, preference is given to covered stents or stent-grafts (covered stents). They demonstrate higher long-term patency compared to bare metal stents (bare metal stents).
Clinical case review: A typical endovascular treatment algorithm can be traced using SMA stenting as an example. At the preoperative stage, sagittal CT angiography is performed, visualizing critical stenosis. Intraoperative fluoroscopy allows monitoring of guidewire (guidewire) advancement into the SMA and positioning of a balloon-expandable stent (e.g., 7 mm) using proximal and distal radiopaque markers. Finally, post-procedural control in the left lateral projection is performed, confirming the restoration of arterial patency.
Briefly: answers to topical questions
What are the main causes of acute mesenteric ischemia?
The main causes of acute mesenteric ischemia are:
- Arterial embolism.
- Arterial thrombosis.
- Venous occlusion.
- Low-flow states (low-flow states).
Which arteries are considered the main mesenteric arteries?
The main mesenteric arteries supplying blood to the intestine include three primary sources. The following vessels are distinguished:
- Coeliac trunk (coeliac trunk / coeliac axis) — supplies derivatives of the foregut, including the stomach and duodenum up to the duodenojejunal flexure.
- Superior mesenteric artery (SMA) — supplies derivatives of the midgut from the duodenojejunal flexure usually to the splenic flexure of the colon.
- Inferior mesenteric artery (IMA) — supplies derivatives of the hindgut, covering the rest of the colon down to the lower part of the rectum.
For symptoms of chronic ischemia to appear, remember the "two-out-of-three" rule: due to rich collaterals, clinical manifestations (pain after eating and weight loss) occur only with stenosis of at least two of the three main mesenteric arteries.
Class and exam questions
Which imaging modality is preferred in acute mesenteric ischemia?
Currently, computed tomography (CT) is the method of choice, diagnosing acute ischemia more frequently and accurately than diagnostic laparotomy.
What to do if it is technically feasible to stent only one artery?
If multi-vessel intervention is impossible, the superior mesenteric artery (SMA) is the priority target for stenting.
How to distinguish celiac axis compression by the median arcuate ligament (MALC) on an angiogram?
A non-ostial, asymmetric narrowing along the superior surface of the coeliac axis is visualized, the severity of which increases on images taken during expiration.
Which stents show the best results in mesenteric angioplasty?
Covered stents (stent-grafts) are preferable to bare metal ones because they provide higher long-term vessel patency.
What else to study on this topic
- Rationale and patient selection criteria for targeted thrombolysis in acute mesenteric ischemia.
- Anatomy of the gastrointestinal collateral circulation (Riolan's arch, Drummond's artery).
- Comparative characteristics of covered and bare metal stents in vascular surgery.
- Technique of intraoperative fluoroscopy and radiopaque marker positioning during stenting.
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