Pulmonary arteriosclerosis and cor pulmonale due to recurrent thromboembolism.

EVIDENCE has now accumulated that incorporation of blood clot into arterial intima might as well be a cause as a result of arteriosclerosis. Those who have studied large human systemic arteries from this thrombogenic viewpoint agree that all aspects of intimal arteriosclerosis including atheroma can follow incorporation of blood clot.1-4 Because red cell envelopes are rich in lipoid, it is suggested that their breakdown supplies much of the fatty material in arteriosclerosis.1' 5 Experiments on the effects of blood clot emboli in pulmonary arteries, though showing that fibrous and elastic tissue form intimally, have not produced atheroma.6-9 It is, however, possible that pulmonary arteries might differ from systemic arteries in their response to blood clot. (Pulmonary artery pressure is much lower than systemic pressure and pulmonary arteries transport venous blood.) Also, atheroma is exceedingly rare in veins. Furthermore, because atheroma both in pulmonary and systemic arteries is mostly limited to large elastic branches, this disease was perhaps not to be expected because the blood clot emboli used experimentally were far too small to lodge in vessels the size of elastic arteries. The following experiments were undertaken to study afresh the effects of blood clot on the pulmonary arteries, and it is argued that thromboembolism could account for some human cases in which arteriosclerosis largely confined to pulmonary arteries is associated with cor pulmonale.