Cardiac follow-up and imaging may include evaluation of RV pressure; quantifying relative pulmonary blood flow and imaging for evidence of residual lesions or PA obstruction or aneu- rysm at sites of prior intervention; and in-stent stenosis and/or stent fracture (the latter often best seen by fluoroscopy). Stenting of branch PA stenosis is effective in reducing the pressure gradients, but patients often require further In-stent stenosis with a re- duction in the ipsilateral pulmonary blood flow is seen in approximately 25% of patients after percutaneous PA angioplasty and stent place- ment, more common in patients with abnormal pulmonary arteries, such as those with TOF or Regular surveillance and imaging, with intervention as required, may prevent the development of RV hypertension and its sequelae.S4.3.2-1 2. Balloon angioplasty or stenting of a peripheral PA is effective in reducing pressure gradients and improving pulmonary blood flow. Indications for pulmonary angioplasty or stenting include symp- toms attributed to the decreased pulmonary blood flow, focal narrowing, abnormal differen- tial perfusion, and/or elevated RV pressure. The decision for intervention with PA angioplasty or stenting includes assessment of clinical symp- toms, imaging, and discussion with an ACHD in- terventional cardiologist. 4.3.3. Double-Chambered Right Ventricle Recommendations for Double-Chambered Right Ventricle Referenced studies that support recommendations are summarized in Online Data Supplement 41. COR LOE Recommendations I C-LD Surgical repair for adults with double- chambered right ventricle and moderate or greater outflow obstruction is recommended in patients with otherwise unexplained symptoms of HF, cyanosis, or exercise (Table 22). IIb C-LD Surgical repair for adults with double- chambered right ventricle with a severe gradient may be considered in asymptomatic (Table 22). Synopsis Double-chambered right ventricle is uncommon in adults. Hypertrophied muscle bundles develop in the RV cavity, creating RVOT obstruction.S4.3.3-5,S4.3.3-6 It is com- monly associated with a VSD. 