The latter procedure is commonly used at the time of conversion of atriopulmonary connection Fontan, and may also be useful in other forms of repaired CHD with postoperative atrial arrhythmias such as TOF. Bradyarrhythmia and tachyarrhythmias are common in TGA with atrial switch patients and may seem straightforward, but the altered anatomy adds complexity to the procedures and emphasizes the need for specialized equipment and expertise to ensure the best chance for procedural success. For example: 1) pacemaker placement in a patient with TGA with atrial switch can be challenging because of the altered atrial anatomy and interatrial baffle that will necessitate placement of an atrial lead in the anatomic left atrium, often scarred such that tissue amenable to pacing is difficult to find; and 2) atrial flutter is a common arrhythmia in TGA with atrial switch, but the flutter circuit may be on the systemic side of the interatrial baffle and thus may require baffle puncture or retrograde approach to effectively ablate the circuit. Diagnostic and interventional cardiac procedures, including electrophysiology procedures Perform procedure in a hospital with cardiologists, anesthesiologists, surgeons, and other providers with expertise in the management of patients with ACHD. Patients with ACHD often have complex underlying cardiac anatomy and physiology. In patients with CHD, the presence of anatomic and physiological complexity from the specific defect or surgical palliation, may change the overall care plan and procedural decision-making. Procedures that may seem straightforward, such as pacemaker implantation or ASD closure, may be more complex when accounting for the nuances imparted by CHD. The data obtained and the interventions performed during ACHD cardiac procedures are difficult to sort out without specialized knowledge of the CHD. Consultation with providers with ACHD expertise may be substituted if the procedure is urgent such that timely transfer is not feasible. 