Learning from the pulmonary veins.

The purpose of this article is to review the basic embryology and anatomy of the pulmonary veins and the various imaging techniques used to evaluate the pulmonary veins, as well as the radiologic findings in diseases affecting these structures. Specific cases highlight the clinical importance of the imaging features, particularly the findings obtained with multidetector computed tomography (CT). Pulmonary vein disease can be broadly classified into congenital or acquired conditions. Congenital disease, which often goes unnoticed until patients are adults, mainly includes (a) anomalies in the number or diameter of the vessels and (b) abnormal drainage or connection with the pulmonary arterial tree. Acquired disease can be grouped into (a) stenosis and obstruction, (b) hypertension, (c) thrombosis, (d) calcifications, and (e) collateral circulation. Pulmonary vein stenosis or obstruction, which often has important clinical repercussions, is frequently a result of radiofrequency ablation complications, neoplastic infiltration, or fibrosing mediastinitis. The most common cause of pulmonary venous hypertension is chronic left ventricular failure. This condition is difficult to differentiate from veno-occlusive pulmonary disease, which requires a completely different treatment. Pulmonary vein thrombosis is a rare, potentially severe condition that can have a local or distant cause. Calcifications have been described in rheumatic mitral valve disease and chronic renal failure. Finally, the pulmonary veins can act as conduits for collateral circulation in cases of obstruction of the superior vena cava. Multidetector CT is an excellent modality for imaging evaluation of the pulmonary veins, even when the examination is not specifically tailored for their assessment.