Pulmonary thromboembolic disease, also called chronic thromboembolic pulmonary hypertension, occurs in patients with one or more clots in the wall of the pulmonary artery. These clots do not respond to drug treatment and can only be removed surgically through the complex procedure of endarterectomy. About 350 thromboendarterectomies are performed each year worldwide.

Dr. Rubin explained that patients with this disease present with signs and symptoms that resemble pulmonary hypertension and include unexplained dyspnea and signs of right-sided heart failure. Previous signs of acute pulmonary embolism or discrete episodes of acute pulmonary embolism are usually absent.

The techniques used to diagnose chronic thromboembolic pulmonary hypertension are chest radiograph, echocardiogram, ventilation perfusion scan, computer tomographic scan and pulmonary angiography. Echocardiogram determines the presence of pulmonary hypertension. The ventilation perfusion scan is always abnormal in patients with this disease and suggests its presence. Chest radiographs provide the best picture of the main pulmonary arteries and chronic clots. Pulmonary angiography shows fibrotic connections between clots; marked hypoperfusion of the lung and filling defects. These characteristics determine whether the disease is amenable to surgery.

Endarterectomy is an option for patients with surgically accessible chronic organized thrombosis. This means that the majority of the thromboses are in the branches of the pulmonary arterial tree. Distal disease is not operable. The site of the clot can be identified using balloon occlusion. This technique is used to evaluate vascular resistance and allows separation of upstream vascular resistance from downstream vascular resistance. Only patients with upstream vascular resistance benefit from this procedure.

The best patients for this procedure have symptomatic chronic disease for at least 6 months, systemic pulmonary hypertension with pulmonary resistance of 4 to 5 units and no inoperable concurrent cardiac disease. Surgery for those of advanced age is not contraindicated, but its risk should be considered.

The best outcome is obtained with complete endarterectomy and is measured by near normal pulmonary vascular resistance, pulmonary arterial pressure, improved cardiac output, improved right ventricular function, and systemic pulmonary arterial pressure. With carefully selected patients, surgery is curative. The most common complication from endarterectomy is reperfusion pulmonary edema, which appears 24 hours after surgery and lasts several days. Mortality from endarterectomy ranges from 6 to 8% for all patients at experienced centers.