Blood Clots, Thrombolytics, and the Emerging Role of the EndoWave Catheter

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US Cardiology - Volume 5 Issue 1;2008:5(1):46-48

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Treatment for blood clots and their life-threatening sequelae has expanded significantly over the past 50 years. Thrombolytic therapy has gained widespread acceptance and use. Advances in technology have led to experiments with catheter-directed thrombolytic therapy in combination with other physical modality delivery systems, such as ultrasound, to improve the efficacy of thrombolytic therapy. One such thrombolytic ultrasound-guided therapy, the EKOS catheter system, will be reviewed in this article.

Thrombolytic Therapy

All available thrombolytic agents in clinical use today are plasminogen activators. These trypsin-like serine proteases have high specific activity directed at the cleavage of a single peptide bond in the plasminogen zymogen, converting it to plasmin. Plasmin is the active molecule that divides the fibrin polymer to thrombus dissolution. Due to the instability of plasmin at physiological pH, effective thrombolysis requires fibrinbound plasminogen converted to its active form, plasmin, at the site of the thrombus.1
The origin of thrombolytic therapy was the discovery by Tillet and Garner at Johns Hopkins Medical School in 1933 that certain strains of hemolytic streptococcal bacteria contained fibrinolytic properties.2 Approximately 20 years later, Tillet first reported the intravascular administration of a thrombolytic agent, purified streptokinase. The experiment was performed to obtain data on the safety of the administration of a thrombolytic agent in humans and was not used for the treatment of pathological thrombi. In 1957, Clifton at Cornell University Medical College in New York published his results of the first intravascular thrombolytic administration to treat occlusive thrombi. His study on the clinical effectiveness of a streptokinase–plasminogen combination in treating a wide range of pathological thrombi had frequent bleeding complications and inconsistent recanalization of blood vessels.3 Despite these results, however, Clifton is recognized as the first to use thrombolytic agents to treat pathological thrombi, as well as the first to use a catheter-directed administration for thrombolytic agents.

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