From a management perspective, most adults with AVSD will have had surgical repair as children. If those with complete AVSD (with large ASD and VSD) are not repaired early in life (typically <6 months of age), ir- reversible pulmonary vascular disease usually develops resulting in Eisenmenger physiology, precluding com- plete repair. For those who underwent a surgical repair, long-term follow-up is required to monitor for left atri- oventricular valve regurgitation and stenosis, left ven- tricular outflow tract (LVOT) obstruction attributable to the abnormal shape of the LVOT, and tachyarrhythmias and bradyarrhythmias. Left atrioventricular valve regur- gitation is the most common reason for later surgical reintervention. There are few long-term follow-up stud- ies of patients after AVSD repair in childhood, so the most effective and efficient timing and type of surveil- lance are still being evaluated. The atrioventricular node is typically displaced infe- riorly in AVSD and is associated with relative hypopla- sia of the left anterior fascicle.S4.1.4-9 Late-onset com- plete heart block (as late as 15 years after surgery) has been noted after surgery in patients operated on for AVSD who were discharged from the hospital with normal conduction, although more commonly seen in those patients with transient postoperative heart block. Regular monitoring for symptoms and screening with an ECG are important to evaluate for conduction See Section 3.3 for recommendations on who should perform surgeries, cardiac catheterization, and other procedures in these patients; Section 3.4 for recommendations on diagnostic evaluation; Sec- tion 4.1.1 for recommendations on primum ASD; Section 4.4.6 for evaluation and management of se- vere PAH and Eisenmenger syndrome associated with AVSD; and Table 15 for routine testing and follow-up intervals. Recommendation-Specific Supportive Text 1. 