A blockage in the arteries supplying the stomach and intestines is known as Mesenteric Ischemia. This serious medical event occurs when blood flow to the intestines is restricted or completely cut off, leading to rapid tissue damage. The condition is categorized by the speed of its onset: acute (sudden) or chronic (long-term). If blood flow is not quickly restored, the lack of oxygen and nutrients can lead to irreversible damage.
Recognizing the Warning Signs
The symptoms depend heavily on whether the blockage is acute or chronic, with the acute form representing an immediate medical emergency. Acute mesenteric ischemia presents with a sudden onset of severe abdominal pain. This pain is often described as disproportionate to the physical examination findings, meaning the patient is in agonizing pain, yet the abdomen may feel soft when pressed.
Patients frequently experience other signs of distress, including nausea and vomiting, alongside the sudden pain. Some individuals may also note an urgent need to pass stool. In later stages, bloody stool or rectal bleeding can occur as the intestinal lining becomes damaged. As the condition progresses rapidly, the patient can quickly show signs of shock, such as a rapid heart rate, low blood pressure, and fever.
Chronic mesenteric ischemia, often called “abdominal angina,” has a more subtle, long-term presentation linked directly to eating. The hallmark symptom is pain that consistently begins 15 to 60 minutes after a meal, when the intestines require increased blood flow for digestion. This postprandial pain lasts for one to three hours and is described as a dull or crampy ache in the middle of the abdomen.
Because eating causes pain, patients often develop a fear of food, limiting their intake to very small portions. This food avoidance commonly results in significant, unexplained weight loss, a feature seen in over 60% of chronic cases. Other changes in digestive function, such as persistent diarrhea, constipation, or altered bowel habits, may also be present. Chronic symptoms can worsen over time, and in about 40% of cases, narrowed vessels suddenly become completely blocked, progressing the condition into the life-threatening acute form.
Underlying Causes of Blockage
The restriction of blood flow to the intestines can be caused by three primary mechanisms involving the mesenteric arteries. Arterial embolism is a frequent cause, accounting for approximately 50% of acute cases. This occurs when a blood clot, often originating in the heart due to conditions like atrial fibrillation, breaks free and travels through the bloodstream. The traveling clot then lodges in and obstructs a smaller mesenteric artery, most commonly the superior mesenteric artery, causing a lack of blood flow.
Arterial thrombosis is another cause, occurring when a clot forms directly within an already narrowed mesenteric artery. This narrowing is due to severe atherosclerosis, where fatty deposits build up on the vessel walls. Thrombosis often happens in patients with a history of chronic mesenteric ischemia and is seen in about 15% to 25% of acute cases. The third category is non-occlusive mesenteric ischemia (NOMI), meaning the arteries are not physically blocked by a clot or plaque.
NOMI is caused by a severe reduction in overall blood flow and a subsequent spasm of the intestinal blood vessels, often due to shock or severe low blood pressure. This type of ischemia is seen in critically ill patients with severe heart failure, septic shock, or those receiving vasoconstricting medications. In these scenarios, the body prioritizes blood flow to the brain and heart, leading to insufficient perfusion of the intestines without a physical obstruction.
When to Seek Emergency Care
Any sudden, severe abdominal pain, especially if it seems disproportionate to physical findings, warrants immediate emergency care. Individuals with a history of postprandial pain or unexplained weight loss, suggesting chronic ischemia, should seek urgent medical attention if symptoms suddenly intensify or if they notice bloody stool. Prompt diagnosis is necessary because the mortality rate can be as high as 60% to 80% if treatment is delayed.
Upon arrival at the hospital, the diagnostic process begins with laboratory tests, though initial blood work is not definitive. Blood tests may reveal a high white blood cell count and elevated lactate levels. Lactate is a byproduct of tissue starved of oxygen and is associated with irreversible intestinal damage. The most reliable diagnostic tool is a Computed Tomography Angiography (CTA), which uses contrast dye to create detailed images of the arteries.
The CTA can pinpoint the exact location and type of blockage, showing whether it is an embolism, a thrombosis, or NOMI. Immediate treatment focuses on stabilizing the patient and restoring blood flow to the intestines quickly. Revascularization may involve endovascular techniques, using a catheter to deliver clot-dissolving drugs or place a stent to open the artery. Open surgery may also be necessary to directly remove a clot (embolectomy) or to bypass the blocked section of the artery.
Potential Severe Outcomes
If the blood supply is not restored quickly, the lack of oxygen leads to complications within the intestinal tissue. The most direct consequence is intestinal tissue death, known as necrosis or infarction. When the cells of the bowel wall die off, the tissue can no longer function, leading to a breakdown of the intestinal wall’s integrity.
Tissue death can result in a bowel perforation, where a hole forms in the intestine, spilling contents into the abdominal cavity. This leads to peritonitis, a widespread infection of the abdominal lining. If the infection spreads throughout the body, the patient develops sepsis, a life-threatening complication and a major predictor of mortality.
To manage these severe outcomes, surgeons often perform a bowel resection, removing the necrotic sections of the intestine. If a large portion of the small intestine is removed, the patient may develop short bowel syndrome, a chronic condition characterized by the inability to properly absorb nutrients. The high mortality rate, ranging from 50% to 80%, underscores the need for immediate medical intervention when a blocked artery is suspected.