Pulmonary thromboendarterectomy (PTE) is a surgical procedure performed to remove organized blood clots (thrombi) and scar tissue from the pulmonary arteries, which carry blood from the heart to the lungs. This procedure is typically done to treat chronic thromboembolic pulmonary hypertension (CTEPH), a condition where blood clots obstruct the pulmonary arteries, leading to increased pressure in these vessels and reduced blood flow to the lungs.