Anomalous pulmonary venous drainage: a pictorial essay with a CT focus

The imaging of pulmonary venous anatomy has traditionally been performed with echocardiography and catheter pulmonary angiography. Magnetic resonance imaging (MRI) and notably multi-detector row computed tomography (CT) have refined the usual imaging techniques. Anomalous pulmonary venous drainage (APVD) is the drainage of one or more pulmonary veins outside the left atrium. Its detection is critical due to the strong association with congenital heart disease as well as other cardiac and respiratory anomalies, which have significant implications for patient management. The pervasive application of CT combined with the relatively non-specific clinical presentation of APVD has resulted in the increased incidental detection of these anomalies. Knowledge is hence vital as the imaging specialist is now usually the first person to make such a diagnosis. Furthermore, pulmonary veins are an important site for arrhythmogenic foci and radiofrequency ablation of such sites is used in the treatment of refractory atrial fibrillation. Hence an imaging road map of these veins is crucial before any management can take place. This pictorial review will illustrate embryology, normal and variant pulmonary vein anatomy, and varied patterns of APVD. Finally, we discuss the implications in the treatment of atrial fibrillation.