Initial Approach to Pulmonary Arteriovenous Malformations
Percutaneous transcatheter embolization is the first-line treatment for pulmonary arteriovenous malformations (PAVMs), regardless of feeding artery size, due to the significant risk of paradoxical embolic complications including stroke (>25% lifetime risk), brain abscess, and myocardial infarction. 1, 2
Diagnostic Confirmation Before Treatment
Before proceeding with intervention, confirm the diagnosis and characterize the anatomy:
- CT chest with IV contrast is the preferred imaging modality to accurately detect the number, size, location, and distribution of PAVMs for treatment planning 1, 2
- Transthoracic contrast echocardiography (TTCE) is highly sensitive for detecting intrapulmonary shunts and confirming PAVM presence, though less sensitive for post-treatment surveillance 2, 3
- Perform positional oxygen saturation testing (supine and upright) as 65-83% of PAVMs are in the lower lobes, causing orthodeoxia and platypnea that standard single-position pulse oximetry may miss 2, 4
- Digital subtraction angiography provides definitive anatomic definition of the feeding arteries, nidus, and draining veins, typically performed at the time of embolization 1
Treatment Algorithm
Primary Intervention: Transcatheter Embolization
All PAVMs detected by CT or catheter angiography should be considered for treatment regardless of feeding artery size due to paradoxical embolism risk 2. The procedure involves:
- Deploy embolic devices (coils or plugs) in the feeding artery as close to the arteriovenous communication as possible 2
- Choice of embolic material impacts persistence rates:
Alternative: Surgical Resection
Conservative surgical excision (segmentectomy or lobectomy) is reserved for patients who are not candidates for embolization 3, 5. Surgical resection remains definitive with no postoperative recurrence in treated patients, and relieves dyspnea while increasing arterial oxygen tension after excision of large or solitary PAVMs 5.
Screening for Hereditary Hemorrhagic Telangiectasia
70-90% of PAVM patients have hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant disorder 1. Evaluate for:
- Recurrent epistaxis (especially when associated with anemia) 6
- Mucocutaneous telangiectasias 1
- Family history of HHT 1
- Visceral involvement (hepatic, cerebral AVMs) 1
- Apply Curacao criteria for clinical HHT diagnosis 1
Post-Treatment Surveillance
Follow-up CT angiography is mandatory:
- Initial follow-up at 6-12 months after embolization 2
- Subsequent imaging every 3-5 years to detect persistence, recanalization, or new lesions 2, 6
- Persistent perfusion carries continued paradoxical embolism risk and may require retreatment 2
Adjunctive Medical Management
- Antibiotic prophylaxis for all dental and invasive procedures is recommended in all PAVM patients due to cerebral abscess risk 3
- Meticulous intravenous line care to avoid air embolism to systemic circulation 1
- Oxygen supplementation for hypoxemia (present in 27-71% of patients) 1, 2
Critical Pitfalls to Avoid
- Never dismiss small PAVMs as insignificant—even feeding arteries <3mm pose paradoxical embolism risk 2
- Do not rely on blood pressure measurements in extremities with prior Blalock-Taussig shunts, as readings will be falsely low 1
- Avoid central line placement without detailed knowledge of complex venous anatomy in post-Fontan patients with PAVMs 1
- Pregnancy causes rapid PAVM growth due to hormonal and hemodynamic changes, with life-threatening hemorrhage affecting 1 in 100 pregnant women with PAVMs 1, 2
Special Considerations
In patients with Glenn shunts or Fontan circulation, conversion to modified Fontan procedure may be indicated when venous collateral channels or arteriovenous malformations develop in the right lung, as hepatic venous blood perfusion often causes PAVM regression 1. Clinically significant persistent venous collaterals or systemic aortopulmonary collaterals are usually treated with transcatheter occlusion 1.