Abstract
In order to investigate the relationship between high-intensity transient signals (HITS) detected in midcerebral artery and cavitation bubble formation arround artificial valves, an in vitro experiment was conducted. A cavitation channel device mounted with bileaflet valve models was employed and cavitation formation was detected with high speed video and high speed strobe scope. The opening angle of the leaflets was restricted to 60°, 55°, 40°, 35°, respectively. Cavitation was incepted at 10.2 l/min of forward flow in the 60° model. The bubbles were 0.05-0.4 mm in diameter and disappeared within 15 cm downstream from the valve. However, with Coulter Counter methods, microbubble nuclei of 5-25 μm in diameter were detected at the 60 cm downstream from the valve. Both the diameter and the number density were increased with the flow rate. Our results suggest that etiology of HITS may be the microbubbles generated arround artificial valves.
