Pulmonary arterial hypertension is an important cause of pulmonary artery aneurysm. In patients with pulmonary artery aneurysms, severe RV dysfunction occurs. Large pulmonary artery aneurysm and right ventricular dilation occur in left ventricular diastolic dysfunction. Pulmonary artery aneurysm causes several complications. Three-dimensional echocardiography is useful to detect pulmonary artery aneurysm.