Pulmonary arteriovenous fistulas are rare, usually related to the
Rendu-Osler-Weber syndrome, and are detected by chest CT scan or
pulmonary angiography. In a 14-year-old boy without Rendu-Osler-Weber
syndrome, but with clinical evidence of a right-to-left shunt,
ancillary diagnostic studies were negative for pulmonary arteriovenous
fistulas, and the final diagnosis was made by contrast transesophageal
echocardiography. Saline echo-contrast medium injected peripherally was
seen emerging from each pulmonary vein and filling the left chambers.
These findings, in light of other negative test results, established
the diagnosis of diffuse telangiectasias at the capillary level in both
lungs. After 6 years of medical therapy, the patient remains cyanotic
but functions well.