Vessel Embolization: Transcatheter Embolization of Pulmonary Arteriovenous Malformations and Aortopulmonary Collateral Arteries
Pulmonary arteriovenous malformations (PAVMs) are abnormal direct communications between the pulmonary artery and vein, allowing an intrapulmonary right-to-left shunt. Significant PAVMs can result in systemic hypoxemia with exertional dyspnea, paradoxical embolization with stroke, brain abscesses, and pulmonary hemorrhage with massive hemoptysis. Aortopulmonary collateral arteries (APCs) are frequently present in patients with cyanotic congenital heart disease and reduced pulmonary blood flow. Large or multiple collaterals can result in pulmonary overperfusion and symptomatic cardiac volume overload. Transcatheter embolization has been established as the preferred treatment for both PAVMs and APCs.
KeywordsPulmonary arteriovenous malformation Aortopulmonary collateral arteries Embolization Transcatheter therapy Vascular plug
22.1 Transcatheter Embolization of Pulmonary Arteriovenous Malformations
Pulmonary arteriovenous malformations (PAVMs) are direct communications between the pulmonary arteries and veins, bypassing the normal pulmonary capillary bed and resulting in an intrapulmonary right-to-left shunt. Large or diffuse PAVMs can cause systemic hypoxemia and cerebrovascular complications secondary to paradoxical embolism as well as pulmonary hemorrhage due to sac rupture. Transcatheter embolization has emerged as the preferred treatment for PAVMs with favorable long-term follow-up results.
22.1.1 Indications and Patient Selection
Evidence of significant systemic hypoxemia
Risk for paradoxical embolism or pulmonary hemorrhage
Having a documented history of a paradoxical embolic event
Discrete lesions with feeding arteries greater than 3 mm in diameter
Partial or staged closure may also be indicated in some patients with diffuse PAVMs in order to alleviate symptoms.
Although traditionally coils have been used to occlude PAVM, the size of the feeding vessels involved is usually more effectively occluded using the Amplatzer vascular plug (AVP) series (AGA Medical Corp., MN, USA) (Fig. 22.1). Transcatheter occlusion of a large PAVM in a 11-year-old female patient using the AVP I is shown in Figs. 22.2–22.6 and videos 1–3.
22.2 Transcatheter Embolization of Aortopulmonary Collateral Arteries
Aortopulmonary collateral arteries (APCs) can be detected frequently in patients with complex cyanotic CHDs such as tetralogy of Fallot, pulmonary atresia, and single ventricle with pulmonary stenosis, resulting in varying degrees of left-to-right shunting.
Large or multiple APCs can result in pulmonary overperfusion and symptomatic cardiac volume overload manifested as exertional dyspnea, recurrent pleural effusion, protein-losing enteropathy, frequent lower airway infection, and hemoptysis.
22.2.1 Indications and Patient Selection
Asymptomatic single ventricle patients with moderate-sized collaterals undergoing routine pre-Glenn or pre-Fontan cardiac catheterization
Patients with pulmonary atresia and APCs that have adequate dual supply from native pulmonary arteries
Transcatheter occlusion is not recommended for the presence of APCs of any size in patients who have significant cyanosis due to decreased pulmonary flow.
Transcatheter occlusion is not recommended for patients in whom the responsible collateral arteries directly supply a large area of pulmonary parenchyma, when embolization could result in infarction of the lung parenchyma.
Patient 1. The VER135° angiographic catheter was then exchanged for an 8 Fr, 80-cm long delivery sheath through which a 100 cm, 7 Fr Judkins Right 3.5 guide catheter was introduced. The guide catheter was then advanced as distally as possible within the feeding vessel beyond any branches to the normal lung (AVI 15365 kb)
Patient 1. A 12 mm AVP I (AGA Medical Corporation, Minnesota) was selected so as to be 50% larger than the target vessel and was delivered through the guide catheter to the feeding vessel. Selective arteriogram after deployment of the AVP in the feeding vessel showed near-complete occlusion of the left upper PAVM (AVI 23814 kb)
Patient 1. Repeated selective arteriogram a 5 min later after the device release documented the AVP I in good position with no residual flow into the left upper PAVM. Upon deployment of the AVP, her peripheral arterial oxygen saturation improved from 86 to 93% at rest. Due to the length of the procedure and the amount of contrast given, no further embolization attempts to another PAVM were performed (AVI 24070 kb)