SPIRAL LAMINAR-FLOW IN-VIVO

1. Blood flow patterns are poorly understood despite their impact on a rterial disease. There have been few measurements in vivo of the three -dimensional blood flow patterns; we present the results of such studi es using a new non-invasive in-vivo method of examining biplanar arter ial blood flow patterns. 2. Multiple colour Doppler ultrasound directi onal velocity images were obtained at two different beam target angles from the artery in the plane perpendicular to its axis. Ensemble aver age images were constructed; the absolute velocity and direction were calculated by compounding the left and right averaged images. Simple d irectional, non-directional velocity and vector maps were constructed. 3. Flow patterns were sampled in 11 healthy male volunteers at four p oints of the pulse cycle; peak systole, systolic downswing, diastolic reverse flow and diastolic forward flow and at three sites; the right common and distal superficial femoral and the left common femoral arte ries. 4. Stable rotational flow was observed in all subjects, the dire ction of rotation varying between sides and individuals. 5. There are theoretical advantages to spiral laminar blood flow; the forward-direc ted, rotationally induced stability and reduction of laterally directe d forces may reduce turbulence in the tapering branching arterial tree and at stenoses and have a beneficial effect on mechanisms of endothe lial damage and repair.