Noninvasive diagnosis of partial anomalous left pulmonary artery

The branching patterns of the pulmonary arteries may vary, with one or more lobes of the left lung being supplied by a branch originating from the right pulmonary artery - a condition termed partial anomalous left pulmonary artery. If this anomalous branch courses anterior and inferior to the trachea, it is unlikely to result in airway obstruction. It is important that this anomaly not be confused with pulmonary artery sling, where the anomalous branch courses posterior to the trachea, encircling it almost completely. Partial anomalous left pulmonary artery has previously been diagnosed with angiography or by direct visualization during surgery. We present the first cases of noninvasive diagnosis of this anomaly with the use of echocardiography and magnetic resonance imaging. The complementary roles of these two modalities in detecting the anomaly and defining the spatial relationship of the anomalous pulmonary artery to the trachea are emphasized.