CCT with contrast injection in Fontan patients can be misleading; therefore, it should be done only when clinically indicated and when it can be appropriately protocoled and interpreted. If CCT is used instead of CMR imaging, the frequency should be weighed against radiation exposure. 6-minute walk test or CPET, depending on clinical indication. ACHD indicates adult congenital heart disease; CCT, cardiac computed tomography; CMR, cardiovascular magnetic resonance imaging; CPET, cardiopulmonary exercise test; ECG, electrocardiogram; and TTE, transthoracic echocardiogram. CLINICAL STATEMENTS AND GUIDELINES may have a role in identifying and addressing problems early. 8. Because of both the anatomic and physiological complexities of these patients, and the potential for concurrent intervention, hemodynamic and interventional cardiac catheterization of the adult with single ventricle/Fontan palliation should be performed only by persons with expertise in CHD in coordination with an ACHD cardiologist. Recognizing that it is difficult to accurately assess Fontan hemodynamics by clinical examination or noninvasive imaging, cardiac catheterization may be needed in these scenarios and others: a. Interval hemodynamic assessment, as filling pressures, mean PA pressure, and pulmonary vascular resistance may change over timeS4.4.2-8 b. Creation or closure of a fenestration or veno- veno collaterals, although with uncertain ben- efit of either interventionS4.4.2-54 S4.4.2-56 c. Treatment of baffle obstruction, even in the setting of low or no pressure gradientS4.4.2-57 d. Assessment of protein-losing enteropathy or ascites, because elevated Fontan pressure cor- relates with such complications, and lowering pressures may offer the potential for clinical e. Facilitation of transvenous liver biopsy for monitoring liver function including as part of a pretransplantation assessment f. Preoperative assessment before Fontan 9. Protein-losing enteropathy and plastic bronchitis contribute substantially to perioperative mortality, yet transplantation may be curative.S4.4.2-9,S4.4.2-11 Medical therapy options are often ineffective. Therefore, consideration of transplantation early in the course of PLE may be warranted. 