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 Printable version |
Biological effects of ultrasound |
Sang Thrombose Vaisseaux. Volume 11, Number 1, 38-44, Janvier 1999, Mini-revues
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 Résumé
Article gratuit
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Author(s) : Gérard Drobinski |
Summary : Ultrasound is used in medicine for diagnosis and treatment. Ultrasound waves propagate in biological tissues and have mechanical effects which, in absorbing conditions, result in increase in temperature and, in aqueous conditions, in phenomena of cavitation and the production of local microcurrents. Biological effects have been
looked for in different organs of the body to determine whether ultrasound scans during pregnancy could be harmful to the foetus. Biological effects have been observed experimentally at molecular and cellular levels and in certain animals, but there have not been any well documented deleterious biological effects during diagnostic usage of ultrasound in clinical medicine. Parameters of intensity and exposition to ultrasound and thermal and mechanical indices have been established to define safety limits. When ultrasound is used therapeutically, the problem is quite different because the intensities used are voluntarily much higher. Potentially deleterious effects on the blood cells or cellular functions are not well known: relaxation of smooth muscle and thrombolysis are usually beneficial and are used for percutaneous ultrasonic angioplasty. Transcutaneous ultrasound seems to increase the availability of drugs at the sites of thrombosis and to facilitate the rupture of fibrin bridges, the fragmentation of thrombi and the circulation of drugs within the thrombus, cavitation being increased by the use of ultrasound contrast agents. Intracoronary usage of ultrasonic contrast could be a solution for improv-ing the results of ultrasonic angioplasty systems in the treatment of thrombotic occlusions, especially in the acute phase of myocardial infarction. |
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