Recommendations that are based on a body of evidence that includes the sys- tematic review conducted by the ERC are denoted by the superscript SR (eg, LOE B-RSR ). See Section 3.3 for recommendations on who should perform surgeries, cardiac catheterization, and other procedures in these patients; Section 3.4 for recom- mendations on diagnostic evaluation; Section 4.4.6 for evaluation and management of severe PAH and Eisen- menger syndrome; and Figure 1 for a diagnostic and treatment algorithm for secundum ASD. See Table 13 for routine follow-up and testing intervals. Recommendation-Specific Supportive Text 1. Pulse oximetry is useful in defining shunt direction at rest and with exercise, which will help guide deci- sions regarding therapeutic options. Pulse oximetry at rest and with exercise may identify patients with increased pulmonary arterial resistance and shunt reversal. In a subset of patients with resting sys- temic oxygen saturation >90%, a decrease in ox- ygen saturation with activity to <90% may occur, emphasizing the importance of performing resting and ambulatory pulse oximetry assessment. 2. TTE has limited use in assessment of anomalous pulmonary venous connections in adults with ASD. Moreover, the poor visualization of the su- perior and posterior atrial septum by TTE in adults may require testing with other imaging modalities to clearly define septal anatomy. TEE is excellent for visualization of the entire atrial septum as well as pulmonary venous connections. Anomalous right upper and middle lobe pulmonary venous connections often occur in combination with su- perior sinus venosus defect; TEE is excellent for visualization of this combination but may not vis- ualize other anomalous pulmonary venous con- nections. 