RESUMO
OBJECTIVE: Introduction: Chronic lung disease (WHO group 3) is the second leading cause of pulmonary hypertension (PH). In turn, the development of PH influences the course of lung disease, worsening the clinical symptoms and prognosis. The aim: To analyse the difficulties in the diagnosis of pulmonary hypertension due to chronic lung disease. PATIENTS AND METHODS: Review and Discussion: According to recent literature, PH in the course of lung diseases develops as a result of both "parenchymal" and vascular pathology in patients with a genetic predisposition. Prolonged infection (especially viral) may be an additional promoting factor. Elevation of pulmonary arterial pressure (PAP) is usually moderate and correlates with severity of lung disease. In a small minority, PAP may reach that seen in WHO group 1 pulmonary arterial hypertension (PAH). CONCLUSION: Conclusions: Echocardiography and right heart catheterization are the principal tools for the diagnosis of PH in chronic lung diseases. Unfortunately, current medications for treating PAH have not shown benefit in controlled trials of group 3 PH, hence their routine use is not recommended. Patients with severe group 3 PH should be considered for referral to expert centres or entry into clinical trials.