Pulmonary arteriovenous malformation embolisation

Embolization of pulmonary arteriovenous malformation (PAVM) is a minimally invasive procedure aimed at treating abnormal connections between pulmonary arteries and veins within the lungs. 

Indications

1. Symptomatic PAVM: When patients with PAVM experience symptoms such as shortness of breath, fatigue, cyanosis (bluish skin), clubbing of fingers, or brain abscesses due to paradoxical embolism.
2. Risk of Complications: To prevent complications like stroke, brain abscess, or bleeding from ruptured PAVMs.
3. High-Flow PAVM: When PAVMs are identified with a significant shunt fraction or high-flow characteristics on imaging studies.

Pre-procedure Preparation

1. Patient Assessment:
   • Evaluation of symptoms, medical history, and imaging studies (CT angiography, pulmonary angiography, or MRI) to confirm the presence, location, and characteristics of PAVMs.
   • Assessment of lung function and cardiac status to ensure the patient’s suitability for the procedure.
2. Imaging and Planning:
   • CT angiography or other imaging modalities are used to visualise the PAVMs, assess their size, location, and blood flow characteristics, and plan the embolization procedure.
3. Laboratory Tests:
   • Routine laboratory tests are conducted, including coagulation profile, complete blood count, and renal function tests.
4. Informed Consent:
   • Explanation of the procedure, its purpose, potential risks, benefits, and alternatives to the patient or their caregivers. Informed consent is obtained.

Procedure Steps

1. Patient Positioning:
   • The patient is positioned on the angiography table, typically lying flat on their back.
   • Access sites (usually the femoral vein and sometimes the radial artery) are prepared and draped in a sterile fashion.
2. Local Anaesthesia:
   • Local anesthesia is administered at the access site(s) to numb the skin and underlying tissues.
3.  

4. 

   Catheter Insertion:
   • Under fluoroscopic guidance, a catheter is inserted into the femoral vein and guided through the venous system toward the pulmonary arteries.
   • Contrast dye is injected through the catheter to visualize the pulmonary vasculature and identify the PAVMs.
5. Selective Catheterization:
   • Using a combination of angiography and fluoroscopy, the catheter is advanced into the feeding arteries supplying the PAVMs.
   • Superselective catheterization is performed to selectively access each PAVM to be embolized.
6. Embolization:
   • Embolic materials, such as coils, vascular plugs, or liquid embolic agents, are delivered through the catheter into the feeding arteries of the PAVM.
   • These embolic agents block the abnormal blood flow and cause the PAVM to thrombose (form a clot), leading to its closure over time.
7. Confirmation:
   • Angiography is repeated to confirm successful embolization of the PAVMs and assess for any residual flow or complications.
8. Closure:
   • After completing the embolization procedure, the catheter is removed, and pressure is applied to the access site to achieve hemostasis.
   • Sterile dressings are applied to the access site(s), and the patient is monitored in a recovery area.

Post-procedure Care

1. Monitoring:
   • The patient is monitored for a few hours post-procedure for vital signs, oxygen saturation, and signs of complications such as bleeding or vascular injury.
   • Neurological assessment may be performed in cases of PAVMs related to brain abscess or stroke risk.
2. Pain Management:
   • Pain or discomfort at the access site(s) is managed with appropriate analgesics as needed.
3. Follow-up:
   • Follow-up appointments are scheduled to assess the effectiveness of the embolization, monitor for any recurrent symptoms, and perform imaging studies (CT angiography) to confirm PAVM closure.

Benefits of PAVM Embolization

• Symptom Relief: Improves symptoms related to PAVMs such as shortness of breath, fatigue, and cyanosis.
• Prevention of Complications: Reduces the risk of complications like stroke, brain abscess, or bleeding from ruptured PAVMs.
• Preservation of Lung Function: Maintains lung function by redirecting blood flow away from the PAVMs and improving oxygenation.
• Minimally Invasive: Compared to surgery, embolization is minimally invasive with shorter recovery times and fewer complications.

Risks and Considerations

• Vascular Injury: Risk of inadvertent embolization to normal lung tissue, pulmonary infarction, or vascular injury during the procedure.
• Recurrence: Although rare, PAVMs may recur or new PAVMs may develop over time, necessitating regular follow-up.
• Complications: Potential risks include infection, bleeding, allergic reactions to contrast dye, or rare complications such as pulmonary hypertension post-embolization syndrome.

Conclusion

Embolization of pulmonary arteriovenous malformation (PAVM) is an effective and minimally invasive procedure for treating abnormal lung blood vessel connections. It aims to relieve symptoms, prevent complications, and preserve lung function by closing off the abnormal vessels. Close monitoring and follow-up are essential to assess treatment efficacy, detect any recurrence or new PAVMs, and ensure optimal patient outcomes.