Mesenteric arterial embolization for acute bleeding from gastrointestinal tract

Mesenteric artery embolization is a minimally invasive procedure used to treat gastrointestinal (GI) bleeding by selectively blocking abnormal blood vessels that supply the bowel that are the source of bleeding. Here’s an overview of how the procedure is typically performed:

Indications

1. Acute GI Bleeding: When conservative measures fail to control significant or recurrent bleeding from the gastrointestinal tract.
2. Source of Bleeding: Identified sources of GI bleeding may include arterial bleeding from ulcers, angiodysplasia, diverticula, tumors, or post-operative complications.
3. High-Risk Patients: Patients who are not suitable candidates for surgery or endoscopic interventions due to medical comorbidities or failed previous interventions.

Pre-procedure Preparation

1. Patient Assessment:
   • Comprehensive evaluation of the patient’s medical history, symptoms, underlying GI condition, coagulation profile, and imaging studies (CT angiography, mesenteric angiography) to identify the source of bleeding.
   • Assessment of vital signs, hemodynamic stability, and fluid resuscitation if necessary.
2. Imaging and Planning:
   • CT angiography or mesenteric angiography is used to localize the site of bleeding, identify abnormal vessels in the mesenteric arteries, and plan the embolization procedure.
   • Evaluation of the vascular anatomy, collateral circulation, and potential risks of embolization to non-target areas.
3. Informed Consent:
   • Explanation of the procedure, its purpose, potential risks (such as ischemia, infarction, or complications related to embolization), benefits, and alternatives. Informed consent is obtained.

Procedure Steps

1. Patient Positioning:
   • The patient is positioned on the angiography table, usually lying flat on their back.
2. Local Anaesthesia:
   • Local anaesthesia is administered at the puncture site (typically the femoral artery) for vascular access.
3. Catheterization:
   • A catheter is inserted into the femoral artery and guided under fluoroscopic guidance or angiography to selectively access the mesenteric arteries supplying the bleeding site(s).
   • Selective catheterization may be performed to reach the specific branches of the superior mesenteric artery (SMA) or inferior mesenteric artery (IMA) involved in the bleeding.
4. Angiography:
   • Contrast dye is injected through the catheter to visualise the mesenteric arteries and identify the abnormal vessels responsible for the bleeding.
   • Selective angiography helps determine the precise location, extent, and nature of the bleeding source.
5. Embolization:
   • Embolic agents, such as microspheres, coils, or gelfoam, are delivered through the catheter into the abnormal branches of the mesenteric arteries to block blood flow and induce vessel occlusion.
   • The embolic material is carefully selected based on the size, location, and characteristics of the target vessels to achieve effective hemostasis.
6. Post-Embolization Assessment:
   • Angiography or fluoroscopy is repeated to confirm successful embolization, assess for any residual blood flow, and ensure preservation of normal arterial supply to non-target areas.
   • Evaluation of collateral circulation and perfusion to vital organs, especially the bowel, to avoid ischemic complications.
7. Closure and Recovery:
   • After completing the embolization, the catheter is removed, and pressure is applied to the puncture site to achieve hemostasis.
   • The patient is monitored in a recovery area for a few hours and then transferred to a regular ward for observation.

Post-procedure Care

1. Monitoring:
   • Vital signs, hemodynamic stability, abdominal pain, and bowel function are closely monitored post-procedure.
   • Serial laboratory tests, including haemoglobin levels, are performed to assess for ongoing bleeding or complications.
2. Pain Management:
   • Pain or discomfort at the puncture site or abdominal discomfort is managed with analgesics as needed.
3. Nutritional Support:
   • Nutritional support and fluid resuscitation may be provided as necessary, especially if the patient is at risk of bowel ischemia or post-embolization syndrome.
4. Follow-up:
   • Follow-up appointments are scheduled to monitor the patient’s recovery, assess for recurrent bleeding, and perform imaging studies (CT angiography of mesenteric angiography) to evaluate embolization efficacy and detect any complications.

Benefits of Mesenteric Artery Embolization

• Control of GI Bleeding: Effectively stops or reduces bleeding from abnormal vessels in the mesenteric arteries, improving hemodynamic stability and preventing haemorrhage.
• Minimally Invasive: Compared to surgery, mesenteric artery embolization is minimally invasive with lower risks, shorter recovery times, and fewer complications.
• Preservation of Bowel Function: Targets the bleeding vessels while preserving blood flow to vital organs, avoiding the need for bowel resection in many cases.
• Suitable for High-Risk Patients: Provides a treatment option for patients who are not surgical candidates or have significant comorbidities.

Risks and Considerations

• Ischemia and Infarction: Risk of ischemia or infarction in non-target areas if embolic material inadvertently travels to normal bowel tissue.
• Recurrence: Some patients may experience recurrent bleeding and require repeat embolization or alternative interventions.
• Complications: Potential risks include bowel ischemia, non-target embolization, access site complications, allergic reactions to contrast dye, or rare complications such as pancreatitis if the pancreatic branches are embolized.

Conclusion

Mesenteric artery embolization is an effective and minimally invasive procedure for treating gastrointestinal bleeding by blocking abnormal vessels in the mesenteric arteries. It offers rapid control of bleeding, preserves bowel function, and is suitable for high-risk patients who may not be candidates for surgery. Close monitoring and follow-up are essential to assess treatment efficacy, detect any complications, and ensure optimal patient outcomes.