[Validation of a Doppler catheter for intravascular flow measurement in vivo. A comparison with simultaneous electromagnetic flow measurement].

A new 3-French Doppler catheter has recently been developed for direct measurement of blood flow velocity within the vessel. In in-vitro studies Doppler and real flow measurements correlated strongly. To validate this method in-vivo, phasic flow measurements in the aorta ascendens of 11 narcotized Wistar rats using Doppler and an external electromagnetic flowmeters were performed. The individual stroke volume was varied over a wide range. High intraindividual correlations were found (r = 0.92-0.99). However, a considerable variation of the slope a of the regression lines was noted (a = 0.42-1.47). Thus, qualitative registration of phasic flow is possible and relative changes of flow can be determined with sufficient accuracy through intravascular Doppler measurements. Probably due to interindividual differences of the catheter position within the vessel, however, measurements of absolute flow volumes are unreliable in this setting.