Eisenmenger’s syndrome (ES) is the most advanced form of pulmonary arterial hypertension (PAH) associated with congenital heart diseases (CHD). It is caused by simple or complex CHD with a large systemic-to-pulmonary shunt. When the pulmonary pressure exceeds the systemic pressure, the shunt reverses and central cyanosis appears. ES is a progressive and fatal condition, and it is accompanied by an increased risk of a range of potentially life-threatening complications. Patients with ES are both at risk for bleeding, due to damaged capillaries and high pressure, and for in situ pulmonary thrombosis, related to hyper-viscosity and slow blood flow in dilated pulmonary arteries. Moreover, the enlarged main pulmonary arteries and cardiac chambers may determine displacement or extrinsic compression on airways, pulmonary veins, coronary arteries, and other mediastinal structures. The clinical effects may be diverse, such as respiratory difficulties, localized pulmonary edema, cardiac dysfunction, or sudden death. Multidetector computed tomography (MDCT) allows to accurately assess in a single examination, pulmonary parenchyma and vessels, coronary artery origin, and heart chambers. The aim of this review was to illustrate the thoracic MDCT angiography findings and complications of adult patients with PAH-CHD and in particular of those with ES.