After a patient has a pulmonary embolism, the body activates the fibrinolytic system, and the doctor takes thrombolytic anticoagulant therapy according to the patient’s risk classification. In high-risk patients, the thrombus dissolves after thrombolytic therapy. After anticoagulant treatment, no new thrombus is formed in patients with intermediate or low risk. The body starts the fibrinolytic system, which will gradually dissolve the thrombus. However, some patients have incomplete thrombus dissolution, thrombus mechanization or arteritis, resulting in vascular repair and reconstruction, stenosis, increased resistance of the pulmonary artery, and the formation of thromboembolic pulmonary hypertension. This is a sequela that occurs when thrombolytic therapy is not ideal.