The pre-stenotic Doppler shift signature.

In two series of measurements the Doppler shift signatures of 10 healthy volunteers were studied at varying distances proximal to a total reflection site, in order to describe parameters which are predictive for downstream lesions. Characteristic changes both in amplitude and time parameters were found; the most marked changes being the abolishment of a DC-component for monophasic signatures, the development or the augmentation of early diastolic reverse flow amplitudes together with a highly significant reduction in the signatures' systolic deceleration time. Maximum changes however tended to be localized at 2 to 4 centimeters upstream from the reflection site. Further upstream propagation was limited. Hence the time course of a Doppler signature and particularly its systolic deceleration should be taken into account in addition to the known resistance indices, if downstream lesions shall be predicted from upstream Doppler signatures. The limited upstream propagation of pre-stenotic Doppler signature changes restricts its diagnostic value to vascular segments where the region adjacent to a lesion is routinely scanned; thus diagnostic benefit can be expected for extracranial carotid artery disease but hardly for peripheral (lower limb) lesions.

[Changes in the ultrasound power spectrum due to concentric stenoses of the femoral artery of the dog]. / Veränderungen des Ultraschall Power-Spektrums durch konzentrische Stenosen in der Femoralarterie des Hundes.

An artificial stenosis model consisting of a revolving centric cylinder with six boreholes (10-60% diameter reduction) was implanted in the superficial femoral artery of anaesthezised beagles (n = 10). Range gated pulsed Doppler signals were recorded at 7 sites between three diameters upstream to ten diameters downstream the Angle corrected parameters derived from the contour of spectral lines between 3 and 21dB on both sides of mode frequency were calculated for different time windows. Two groups of dogs could be distinguished. Group A showed marked downstream power spectrum changes which did not correlate to the degree of stenosis. In Group B, in contrast, the degree of power spectral disturbances correlated to the degree of stenosis. It was suggested that partial thrombosis of the stenoses during measurement provides an acceptable explanation for the missing correlation in Group A.