Arterial
Procedure Guide
Indications
Symptomatic pulmonary arteriovenous malformation (AVM) or AVM with feeding artery >2-3 mm.
Associated with shortness of breath/hypoxia in 40-50%, TIA/stroke/brain abscess 30-40%, migraines 40-50%, bleeding with hemoptysis or hemothorax ~10%, particularly during pregnancy (up to 3% risk of death).
Presence of multiple or complex pulmonary AVM should prompt working up for hereditary hemorrhagic telangiectasia (HHT), more common with type 1 (46-76%) than type 2 (5-48%).
Screening with echo bubble study - positive if echogenic bubbles injected intravenously are visualized in the left heart.
Grade 1 = 30 bubbles, Grade 2 = 30-100 bubbles, Grade 3 = >100 bubbles
Further assessment with CT indicated for Grade 2 or 3 (~28% normal individuals will have a grade 1 positive study). Noncon CT is sufficient and avoids risk of air embolism from IV contrast.
Types of PAVMs
Simple: 1 feeding artery
Complex: >1 feeding artery
Diffuse: 1+ lung segments diffusely involved with AVMs
Telangiectatic: predominant ground glass lesion
Contraindications
Uncorrected coagulopathy (INR >1.5, Plt <50K)
Bacteremia
Unfavorable anatomy
Efficacy and alternatives
Technical success of embolization is 88-100%. Often pursued rather than surgery to preserve lung function.
Recurrence rates
18% secondary enlargement of previously small AVMs
7% with recanalization
Pre-procedure care
CT to characterize anatomy and for procedure planning. Non-contrast CT is often sufficient and avoids risk of air embolism with IV contrast injection.
Some give prophylactic antibiotics.
Caution nurses to avoid air bubbles in IV, can apply a filter to IV.
procedure
Internal jugular or common femoral vein access. Some believe femoral access gives more favorable angles for catheterization.
Access the right or left pulmonary artery pending location of the AVM.
People use various catheter/wire combinations. Examples include a Kumpe and glidewire or pigtail catheter. If coming from IJ access, can bend the backend of a Bentson wire and used it to curve the pigtail in the right ventricle.
(Optional) Pulmonary artery pressure measurement to ensure angiography is safe.
(Optional) 3000-5000 IU heparin to avoid thrombus formation.
Pulmonary angiogram (e.g. 20 mL for 40 mL), often in multiple projections to lay out vascular anatomy.
Advance a working wire, e.g., Rosen, and use it to advance a 7-8 Fr sheath.
Use a short, angled, 5 Fr catheter (e.g. H1, Kumpe, White-Lumax catheter set, angled glidecath, JR-4) with an angled glidewire to select the feeding artery.
Sometime embolization can be performed via the 5 Fr catheter. Otherwise, a microcatheter and microwire system (e.g. ProGreat and Fathom) can be used for more distal access.
Often coils or plugs are used embolizing the nidus sac or as close to the sac as possible. Important to have a dense coil pack to prevent recanalization (some say to add one more coil when you think you’re done). Recanalization is often secondary to embolizing too proximal in the feeding artery or failure to embolize all feeding arteries.
Recanalization rates are lower for plugs in studies but this may be due to not packing the coils tight or distal enough. However, another advantage of plugs is less artifact on follow up imaging.
Repeat angiography to ensure complete embolization and identify any residual feeding arteries to embolization.
Obtain hemostasis.
Complications
Pleurisy in 5-15%, which often improves with NSAIDs).
TIA/CVA and paradoxical coil embolization are rare.
Post-procedure care & Follow Up
CT in 6 months with serial monitoring every 2 years
Other recommend CTA chest in 1-6 months and at 5 years