INCREASED FIBRINOLYTIC-ACTIVITY IN THE INTIMA OF ATHEROMATOUS CORONARY-ARTERIES - PROTECTION AT A PRICE

Objective: The aim was to quantify and compare the fibrinolytic activi ty of normal blood vessels (saphenous vein, internal mammary artery, a nd aorta) and atheromatous arteries (coronary endarterectomy specimens ). Methods: Fibrinolytic activity was measured by fibrin plate and col orimetric assays on fresh samples of coronary endarterectomy core, int ernal mammary artery, human aorta, and saphenous vein from patients un dergoing coronary artery bypass surgery. Results: Fibrinolytic activit y on fibrin plates ranked in the order endarterectomy cores > internal mammary artery > saphenous vein. The increased activity of endarterec tomy cores was associated with an increased content of extractable tis sue plasminogen activator and was suppressed by monoclonal antibody to tissue plasmogen activator. Paired comparisons of tissues from the sa me patients confirmed this increased activity in endarterectomy specim ens relative to normal artery or vein. Urokinase activity was also inc reased in some endarterectomy specimens, but was more variable than ti ssue plasmogen activator. Conclusions: The increased fibrinolytic acti vity of endarterectomy cores may help preserve patency in atheromatous vessels, but at the possible price of increased intimal instability a nd fibrous proliferation.