The Effect of Plasma Fibrinogen Levels on Measures of Fibrinolytic Activity

Haemostatic function, arterial disease and the prevention of arterial thrombosis

Recent years have seen the expansion of information linking raised plasma levels of individual clotting factors and evidence of disturbances of fibrinolytic activity with the risk of thrombotic manifestations of arterial disease, both in community-based, apparently healthy populations and in patients with known atherosclerosis. Some of these prothrombotic changes in the haemostatic system may result partly from underlying chronic inflammation or acute infection and may, in turn, contribute substantially to the thrombotic risk which accompanies these underlying processes. The importance of the coagulation system in the pathogenesis of arterial thrombosis is further illustrated by the benefit in the Thrombosis Prevention Trial of low-intensity, dose-adjusted warfarin in the primary prevention of ischaemic heart disease. Clinical trials of bezafibrate, which is being used for its fibrinogen-lowering as well as lipid-modifying properties, are in progress.

Exhaustion of arm fibrinolytic potential after repeated venous occlusions and local exercise

The effect of repeated venous occlusions of the arm combined with local exercise was assessed in 10 healthy volunteers. The blood was drawn before and after three venous occlusions of 20 minutes. Between occlusions I - II, and II - III, twelve occlusions of 10 minutes were performed on the same arm while a small rubber ball was compressed 30 times per minute. Plasminogen activator (PA) activity was measured on plasminogen rich fibrin plates and by the euglobulin clot lysis time. A high increase in PA activity after venous occlusion (fibrinolytic potential) was present in all three occlusions on the first day, but fell to a very low level on the fourth day. The restitution of potential followed, but was not complete even on fifteenth day. These results indicate that PA continues to be released even after the termination of stimulation and can be temporarily depleted some days afterwards. An increase of fibrin(ogen) degradation products together with a slight decrease of alpha-2-antiplasmin in postocclusion samples, but no change in fibrinogen concentration speak in favour of a small fibrin(ogen)olysis during venous occlusion.

Etiologic aspects of coagulopathy in Takayasu's aortitis

Sixteen patients with Takayasu's aortitis were studied to evaluate the significance of coagulopathy in the etiology. In the initial stage of the disease (three cases) characterized by severe inflammatory symptoms with aortic lesions localized in the thoracic portion, marked hyperfibrinogenemia, and hypofibrinolytic activity of the plasma were observed. In the intermediate stage (five cases) characterized by moderate inflammation and aortic lesions expanded into thoracic and abdominal portions, hyperfibrinogenemia and hypofibrinolytic activity were also seen; in three of these cases, hypercoagulability was evident because of the presence of fibrinogen derivatives having gamma-gamma-diads in the plasma. When the inflammation subsided after the establishment of aortic lesions, the end-stage (eight cases), hyperfibrinolytic activity with normal plasma fibrinogen was observed. It is suggested that hypercoagulability may be in response to the arterial disease and may possibly play a part in the development of this disorder.