IntroductionEisenmenger syndrome was initially described in 18971, when Eisenmenger reported a patient with dyspnea and cyanosis since childhood that later developed heart failure and hemoptysis, dying. His autopsy revealed a ventricular septal defect. This syndrome represents the most severe phenotype of pulmonary arterial hypertension in patients with congenital heart disease. A left-to-right shunt triggers a severe growth of pulmonary vascular resistance, which with time results in shunt reversal and cyanosis. It can lead to multiorgan disease, with cardiac, hematological, neurological, respiratory, gastrointestinal, urinary, immunological, musculoskeletal and endocrinological manifestations2. A multidisciplinary approach is the best strategy to those patients3, with both prevention and management of complications at the core of treatment. The improvement of exercise tolerance, a better quality of life and longevity are the main goals and supportive measures, in order to reduce symptoms and prevent complications, have an extraordinary importance. Complications related to hypoxaemia, coagulation disorders and congestive heart failure are among the most common. However, anticoagulants and antiplatelets are not usually prescribed, unless in some cases (with specific indications). Diuretics and pulmonary hypertension therapies are the most commonly used - bosentan, macitentan, sildenafil and prostanoids are some examples. The definitive treatment for Eisenmenger syndrome is lung transplantation and shunt closure or heart-lung transplantation.Our case report aims to mark the importance of being aware of subtle signs of cardiorespiratory distress in young patients.