DOPPLER COLOR-FLOW IMAGES OF ILIOFEMORAL GRAFT END-TO-SIDE DISTAL ANASTOMOTIC MODELS

Hemodynamics within the distal anastomoses of iliofemoral bypass graft s were simulated using Plexiglas models (2.5 cm ID) within a pulsatile flow loop system (Re(mean) = 92, Re(peak) = 459 and alpha = 3.56). En d-to-side distal anastomoses were constructed with angles of 30-degree s, 45-degrees and 60-degrees to bypass proximal artery segments with s tenoses of 60% and 100% diameter reduction. Velocities were obtained o ver a two-dimensional field within the artery using an ultrasonic Dopp ler color flow imager operating at 5 MHz at positions from 1.5 diamete rs upstream to 3 diameters downstream of the anastomosis. Flow pattern s downstream of an occlusion demonstrated definite skewing effects tow ard the outer wall with resultant flow separation along the inner wall . Presence of a partial (60% diameter reduction) arterial stenosis ups tream of the anastomosis produced flow separation along both artery wa lls and a more symmetric profile downstream. Measurement of a separati on area index (SAI) along each arterial wall demonstrated a minimum ar ea exposed to low velocities for the 30-degrees anastomotic angle comp ared to the 45-degrees and 60-degrees anastomotic angles and for the o ccluded proximal artery cases compared to corresponding stenotic arter y cases. The SAI values were minimal at peak systole compared to succe ssive quarter cycle intervals. The findings of this study provide furt her information regarding the relationship between local fluid mechani cs and predominant sites for intimal hyperplasia formation.