The Chapter addresses congenital heart disease observed in adults, such as bicuspid aortic valve, atrial septal defects, and repaired or unrepaired complex lesions, stressing the importance of lifelong surveillance and multidisciplinary care. Diagnostic tools such as echocardiography (including TEE), cardiac MRI, and CT are reviewed alongside indications for surgical or transcatheter interventions. Special considerations are given to anticoagulation, heart failure management, and endocarditis prophylaxis, ensuring that hospitalists and generalists can recognize, risk-stratify, and co-manage these patients in acute and chronic care settings.