Multiple Pulmonary Arteriovenous Fistulas Demonstrated by Dynamic Radionuclide Pulmonary Perfusion Scanning

Dynamic radionuclide perfusion scintigraphy performed with 99mTc-labeled microspheres was instrumental in establishing the diagnosis of multiple, small-vessel, pulmonary arteriovenous fistulas in a 14-month-old patient with cyanosis. Computer analysis of the sequential distribution of tagged microspheres in the pulmonary parenchyma normally demonstrates a curve that rises rapidly to a plateau as the particles microembolize. In the case reported here, the pulmonary flow curve rose rapidly to a maximum and then fell within 2 sec to a plateau of less than 50% of the maximum count, indicating that a large proportion of the microsophers passed through the pulmonary circulation. Conventional pulmonary contrast angiography did not demonstrate any intracardiac shunting but did confirm the presence of multiple pulmonary arteriovenous fistulas.