UC San Diego Health System is the worldwide leader for pulmonary thromboendarterectomy (PTE). Developed here at UC San Diego, PTE is a complex surgery that removes deadly chronic blood clots from major blood vessels in the lungs that cannot be treated with medication. Without treatment, these clots block off blood flow to the lungs, cause damaging vascular changes and pulmonary hypertension. This condition can lead to heart failure and death.