Thus, CHD expertise is helpful for optimal quality and interpretation of cardiac imaging studies. Although imaging of a patient with TOF may seem straightforward because many have familiar chamber and great vessel relationships, there are nuances to echocardiographic imaging of RV size and function, PR severity, and/or location of right ventricular outflow tract obstruction that affect clinical care and are thus best carried out by sonographers and echocardiographers with appropriate expertise. Similarly, expertise in congenital CMR is important in evaluating patients with TOF, as RV volumes and function are key components in evaluation for timing of pulmonary valve replacement.S3.3-15,S3.3-16 Use of a multimodality cardiac imaging approach can be used for patients with ACHD, accounting for patient-specific considerations, strengths and weaknesses of each modality, institutional resources, and expertise. ACHD programs need a dedicated CMR service, and CMR expertise is integral to an ACHD program, as is expertise in ACHD Electrophysiological care of patients with ACHD Perform procedures in electrophysiology laboratories equipped for 3D mapping and ablation and involve specialists experienced in the management of arrhythmias in patients with ACHD. Examples of diagnostic questions best answered by electrophysiological study: a) evaluation of the conduction system in cases of suspected postsurgical conduction abnormalities b) evaluation of syncope c) diagnosis of the mechanism of supraventricular tachycardia or wide complex tachycardia d) programmed ventricular stimulation particularly in patients following repair of TOF and its variants (Section 4.4.1.) as well as preoperative assessment of arrhythmia substrates that may be amenable to operative intervention, such as an atrial maze procedure for atrial arrhythmias. 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. 