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The effect of ultrasound on the rate of fibrinolysis has been investigated using an in vitro system. Plasma or blood clots containing a trace label of 125I fibrin were suspended in plasma containing plasminogen activator and intermittently exposed to continuous wave 1-MHz ultrasound at intensities up to 8 W/cm2. Plasma clot lysis at 1 h with 1 microgram/ml(More)
BACKGROUND The outcome of percutaneous transluminal angioplasty (PTA) of peripheral arterial lesions is influenced by several factors, including the haemodynamic conditions. Our study tested: (a) whether infrapopliteal run-off after completed PTA influenced the time course of restenosis/reocclusion of the femoropopliteal arterial segment, and (b) whether(More)
Fibrinolysis is accelerated in vitro in an ultrasound field, and externally applied high frequency ultrasound also accelerates thrombolysis in animal models. Although the mechanism of this effect is not known, ultrasound does not cause mechanical disruption of clots but rather accelerates enzymatic fibrinolysis. To determine if accelerated fibrinolysis(More)
Fresh retracted clots are known to be poorly lysable by fibrinolytic agents. We have studied whether lysis of retracted clots could be enhanced by bulk transport in comparison to pure diffusion of plasma containing urokinase (400 IU/ml) into the clots. Cylindrical retracted blood clots were occlusively glued by a polyester into plastic tubes and put in(More)
Thrombolytic therapy depends on penetration of plasminogen activator into clots which occurs through diffusion and flow. An in vitro system has been developed to characterize the rate and pattern of fibrinolysis in relation to flow through occlusive clots exposed to a pressure gradient. Whole blood clots formed in plastic tubes were perfused with plasma(More)
We have studied how pharmacological dissolution of blood clots was affected by clot retraction, the mode of transport of fibrinolytic agents into the clot and the thickness of the composite fibrin fibers. Retracted clots were resistant to fibrinolysis in a milieu without dissolved plasminogen, because the amount of fibrin-bound plasminogen in retracted(More)
We have characterized the effects of ultrasound on fibrinolysis in vitro to investigate the mechanism of ultrasonic potentiation of fibrinolysis and to identify potentially useful ultrasound parameters for therapeutic application. Radiolabeled clots in thin walled tubes were exposed to ultrasound fields in a water bath at 37 degrees C, and lysis was(More)
Transport of fibrinolytic agents into thrombi represents a rate limiting step in therapeutic thrombolysis. Mathematical modeling predicts and in vitro experiments demonstrate that effective delivery of fibrinolytic agents into clots is the most important determinant of fibrinolytic rate. Transport by diffusion is slow and limited by the need for a high(More)
INTRODUCTION Although fibrinolytic treatment has been used for decades, the interactions between the biochemical mechanisms and the mechanical forces of the streaming blood remain incompletely understood. Analysis of the blood clot surface in vitro was employed to study the concomitant effect of blood plasma flow and recombinant tissue plasminogen activator(More)
Axially directed blood plasma flow can significantly accelerate thrombolysis of non-occlusive blood clots. Viscous forces caused by shearing of blood play an essential role in this process, in addition to biochemical fibrinolytic reactions. An analytical mathematical model based on the hypothesis that clot dissolution dynamics is proportional to the power(More)