95: Pulmonary Arteriovenous Malformation

Introduction

The term pulmonary arteriovenous malformation (AVM) refers to lesions that have abnormal communications between the pulmonary arteries and pulmonary veins. Numerous other names have been used in the past to describe these lesions, such as pulmonary telangiectasias, aneurysms, fistulas, hemangiomas, and cavernous angiomas. These lesions can be congenital, usually as part of the hereditary hemorrhagic telangiectasia, also known as Rendu–Osler–Weber syndrome, or acquired from bronchiectasis, infections, hepatic cirrhosis, mitral stenosis, malignancies, or trauma. AVMs have been described based on number (single vs. multiple), location (unilateral vs. bilateral; parenchymal vs. pleural), and size or type of drainage (simple vs. complex).^1,2

Clinical Presentation

Clinical suspicion for the presence of pulmonary AVM should arise when there is the presence of nonspiculated pulmonary nodule suggestive of AVM; a family history of hereditary hemorrhagic telangiectasia; sequelae of right-to-left shunting such as hypoxemia, dyspnea, clubbing, cyanosis, and polycythemia; and systemic embolism such as cerebral stroke or cerebral abscess. Epistaxis can be reported in up to 85% of patients with hereditary hemorrhagic telangiectasia.¹ A continuous bruit can be auscultated over the lesion. The triad of cyanosis, clubbing, and polycythemia is seen in 20% of patients. Approximately 90% of AVMs are unilateral, and 50% to 67% of patients have a single AVM.^1,2 Rarely, patients may present with massive hemothorax under tension from acute hemorrhage secondary to rupture of the AVM.

Ideal Patient Characteristics and Preoperative Assessment

Workup should include a chest computed tomography (CT) scan, which is the most sensitive test, evaluation of the shunt fraction, and pulmonary angiography to assess the feasibility of embolization. Approximately 25% of AVMs tend to enlarge up to a rate of 2 mm per year, and patients who are not treated have a stroke rate of 13% and a brain abscess rate of 11%. Complications are more common in patients who have AVMs greater than 2 cm or afferent vessels greater than 3 mm.^1,2 At minimum, treatment should be offered to these patients, if not to all patients with angiographically accessible lesions.¹

Embolization of pulmonary AVMs was first described in 1977.^1,2 Pulmonary angiography is performed, and numerous techniques have been described, including coils, balloons, sclerosing agents, and Amplatzer occluding devices.³ Multiple AVMs may be embolized at a single session or a few weeks apart. Embolization is feasible in most patients with angiographically accessible lesions, although treating patients with multiple feeding vessels can be challenging. Complications after balloon occlusion include balloon migration with distal embolization, balloon deflation, and pulmonary infarction. Long-term follow-up after embolization procedures is sparse. Recurrence after embolization has been reported.

Surgery is reserved for patients who cannot be embolized or who have failed embolization. Surgical techniques used include thoracotomy and video-assisted thoracic surgery, and the extent of resection can range from fistulectomy and segmental resection to lobectomy ...