Modification of the characteristics of regurgitant jets when impinging upon a surface: an in-vitro investigation...

Free jets were compared in vitro by colour Doppler flow mapping with jets striking a flat and a hemispherical surface, located 3 and 6 cm from a circular orifice (5 mm in diameter). The angles of the impinging jets were 45 degrees and 90 degrees. Flow rates from 6-52 ml.s-1 were tested (pulsatile jets, 0.5 s duration). Free jet areas (21.7 +/- 9.6 cm2) were larger (P less than 0.01) than that of impinging jets (14.3 +/- 5.6 cm2). The distance of the target was a significant factor for reducing areas of striking jets (P less than 0.001). The angle of incidence of the striking jet and the shape of the target surface were not independent factors, but they were important when interacting with flow rate (P less than 0.001). The percentage of total jet area of impinging jets occupied by swirling flow was larger for targets located at 3 cm (P less than 0.01), for a 90 degrees angle of incidence (P less than 0.01), for a flat target surface (P less than 0.05). We conclude that jets visualized in vitro by colour Doppler flow mapping are significantly modified when impinging a surface, with the interplay of several factors. This can be of importance in clinical settings.