Current Status of Thromboendarterectomy for Chronic Pulmonary Embolism

Summary

Chronic pulmonary hypertension due to unresolved major vessel pulmonary emboli occurs infrequently but is extremely debilitating. The embolic material may be highly organized and thus resistant to fibrinolysis. A defect in the fibrinolytic system may also play a role in unresolved pulmonary emboli. Several embolic episodes may be necessary to cause chronic pulmonary vascular obstruction. The possibility of chronic pulmonary embolism should be considered in patients who present with chronic pulmonary hypertension. The definitive diagnosis depends on pulmonary arteriography. When pulmonary arteriography confirms the presence of proximally located major vascular obstruction, significant functional disability and pulmonary vascular resistance of at least 300 dynes·s·cm ⁻⁵ are prerequisites for surgical consideration. Features of pulmonary thromboendarterectomy include median sternotomy, cardiopulmonary bypass with deep hypothermia and circulatory arrest, distal exposure of the orifices all the bronchopulmonary segmental arteries, and endarterectomy for areas of obstruction. Endarterectomy techniques are necessary because ingrowth of collagen and elastic tissue cause the organizing embolic material to adhere firmly to the pulmonary arterial wall within several weeks after acute embolization. The most recent data suggest that hospital mortality for pulmonary thromboendarterectomy is approximately 6% in the last 300 patients undergoing pulmonary thromboendarterectomy at the University of California, San Diego. In this group, over 90% of survivors were in New York Heart Functional Class I. In the next largest series published in the last 5 years, hospital mortality was 23% in 34 patients. Consequently, it is apparent that optimal results are based upon a highly experienced, multidisciplinary team dedicated to the management of these patients.