Abstract
Little is known about the behavior of ultrasound contrast microbubbles in human capil laries. The evaluation of circulatory effects of echo contrast media may bring valuable information for the interpretation of echo contrast phenomena in the human myocardium. In 12 healthy volunteers (aged 31 ±6.7 years; five women), nailfold capil laries were examined by means of TV microscopy. The authors investigated acral micro circulation at rest and after local cold application with and without saccharide-based microbubbles (10 mL Levovist® 300 mg/mL IV). The mean blood flow velocity at rest was 1.18 ±0.18 mm/s (mean value ±1 SD) and 1.11 ±0.11 mm/s (mean value ±1 SD) after the injection of Levovist® (ns). One minute after local cold exposure a decrease of the blood flow velocity by 61% before and by 75% after intravenous Levovist® was found. In both groups the cold-induced decrease of blood flow velocity was statistically significant (p<0.01), whereas there was no significant difference in flow reaction between the two groups. No wall adhesion of blood cells or extravasation of contrast into the surrounding tissue was detected. After intravenous injection of a regular dose of saccharide-based microbubbles Levovist®, no change of blood cell flow velocity and no wall adhesion or extravasation could be found at rest and after cold application in human nailfold capil laries. Since microcirculatory flow characteristics in the finger nailfold capillaries are not influenced by Levovist®, it might be assumed also that myocardial blood flow behavior remains unchanged, so that this contrast agent may be used as a flow tracer for cardiac investigation.
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