COR LOE Recommendation I B-NR Strategies to limit and monitor radiation exposure are recommended during imaging of patients with ACHD, with studies not involving ionizing radiation chosen whenever Recommendation-Specific Supportive Text 1. Low-dose ionizing radiation is a known carcin- ogen, and certain levels of exposure similar to medical exposure have been associated with later Patients with ACHD have multiple potential exposures to low-dose ionizing radiation throughout their lifetimes from cardiac catheterizations, computed tomographic (CT) scans, nuclear perfusion scans, stress tests, and chest x-rays. It remains unclear whether there is an increased risk of malignancy among patients with ACHD, but the exposure levels from multiple pro- cedures are in the range of concern. Every effort should be made to use tests without radiation whenever possible or to select protocols with the lowest possible doses of radiation compatible with securing the needed clinical information. Recommendations for Echocardiography Referenced studies that support recommendations are summarized in Online Data Supplement 7. COR LOE Recommendations I B-NR Intraoperative TEE is recommended to guide surgical repair of CHD in adults.S3.4.3-1 I C-EO Patients with ACHD should undergo transthoracic echocardiography (TTE) for initial assessment, with timing of serial assessment based on anatomic and physiological severity and clinical status. Recommendation-Specific Supportive Text 1. A large retrospective study has shown that the routine use of intraoperative TEE has a substantial impact on patient care, leading to alteration of planned procedure or revision of the initial repair in 14% of cases and was also determined to be CLINICAL STATEMENTS AND GUIDELINES 2. For patients with ACHD in whom abnormalities and changes that may be identified on echocar- diography (eg, valvular or ventricular function or pulmonary pressures) commonly influence man- agement decisions; echocardiography is an indis- pensable tool in the initial and serial follow-up evaluation. 