However, in the absence of an associated ASD, a- nomalous pulmonary venous connection differs in that there is no potential for right-to-left shunting, and the magnitude of the left-to-right shunt is not exacerbated by the development of acquired left heart disease. The most common anomalous pulmonary venous connec- tion is of the right upper pulmonary vein to the superior which may be associated with a sinus venosus defect. Other abnormal connections include right pulmonary vein(s) to the inferior vena cava (often via a so-called scimitar vein and associated with se- questration of the right lower lobe), left upper pulmo- nary vein(s) to the left innominate vein, and right upper Recommendations for Anomalous Pulmonary Venous Connections (Continued) COR LOE Recommendations CLINICAL STATEMENTS AND GUIDELINES pulmonary vein(s) connecting high on the superior vena cava. Long-term sequelae of anomalous pulmonary ve- nous connections reflect the impact of right heart vol- ume overload and are similar to the sequelae of ASDs. Surgical repair can be challenging as low-velocity ve- nous flow imparts risk of thrombosis of the surgically operated vein. See Section 3.3 for recommendations on who should perform surgeries, cardiac catheterization, and other procedures in these patients; Section 3.4 for rec- ommendations on diagnostic evaluation; and Section 4.4.6 for evaluation and management of severe PAH and Eisenmenger syndrome. Recommendation-Specific Supportive Text 1. Cross-sectional imaging with CMR or CTA is ideal for delineating pulmonary venous connections. CMR has the advantage of not using ionizing radiation and may also quantify the degree of shunting. Echocardiography is an important part of the evaluation and may identify the anomalous particularly in patients with excel- lent acoustic windows; however, CMR and CTA are superior for evaluating extracardiac vascular anatomy. 2. 