Algorithm for the diagnosis of pulmonary arteriovenous malformations in adults

PAVM: pulmonary arteriovenous malformation; CT: computed tomography; TEE: transesophageal echocardiogram; HHT: hereditary hemorrhagic telangiectasia.

* Indications for diagnostic investigations include patients with one or more of the following: a suspicious nodule on chest radiography, stigmata of right-to-left shunt (eg, cyanosis, clubbing, history of cerebral stroke or abscess), unexplained hemoptysis, hemothorax, hypoxemia or dyspnea, patients with platypnea, orthodeoxia, and adults with a personal or family history of HHT.

¶ 100 percent oxygen method or radionuclide scanning for shunt assessment may be supplementary or an alternative to saline bubble contrast echocardiogram but are not as sensitive or as specific as saline bubble contrast echocardiogram. However, we prefer to proceed directly to CT scanning when saline bubble contrast echocardiogram is unavailable.

Δ Some patients may warrant follow up with chest CT (eg, patients with a high clinical suspicion for PAVM: typical nodule on chest radiograph or history of stroke. Please refer to the UpToDate topic on pulmonary arteriovenous malformations: clinical features and diagnostic evaluation in adults).

◊ The evaluation in this population depends upon the reason for an indeterminate scan. Please refer to the UpToDate topic on pulmonary arteriovenous malformations: clinical features and diagnostic evaluation in adults.

§ Observation in this population involves yearly evaluation clinically and a repeat saline bubble contrast echocardiogram within 5 years. Please refer to the UpToDate topic on pulmonary arteriovenous malformations: clinical features and diagnostic evaluation in adults.

¥ For patients that present incidentally with a CT scan diagnostic of PAVM, transthoracic echocardiography is not necessary. However, when incidental CT scans are nondiagnostic, some experts perform saline bubble contrast echocardiogram and/or repeat the CT scan with contrast.

‡ Inclusive in this group are patients with nondiagnostic CT scans, including those with atypical nodules that do not have the classic features of an arteriovenous malformation (refer to UpToDate text for details). The evaluation should be individualized in this population. Some experts occasionally perform contrast pulmonary angiography in patients with high grade shunt and indeterminate CT scans in whom the clinical suspicion is high. However, observation with follow-up saline bubble contrast echocardiogram and/or CT is also appropriate (eg, those with minimal symptoms and/or a low grade shunt).

† This population may have small PAVMs that are missed on CT and may require yearly clinical evaluation and repeat CT within 3 to 5 years. Alternative causes of shunt should also be sought (eg, great vessel shunt, hepatopulmonary syndrome). Rarely is a pulmonary angiogram done for patients with symptoms suggestive of a treatable PAVM (eg, idiopathic stroke). Please refer to the UpToDate topic on pulmonary arteriovenous malformations: clinical features and diagnostic evaluation in adults.