Optimising miller cuff dimensions: the influence of geometry on anastomotic flow patterns.
OBJECTIVE
since cuff dimensions are variable, we studied the influence of cuff geometry on flow mechanics, in an attempt to identify the optimum configuration.


METHODS
bench studies involved the manufacture of anatomically accurate models of varying cuff dimensions, perfused in a specifically designed flow rig, simulating physiological conditions. Flow visualisation studies incorporating laser illumination of tracer particles enabled accurate analysis of flow patterns.


RESULTS
the vortex created within the proximal cuff of each model during the deceleration phase of the cardiac cycle was strongly influenced by the aspect ratio (AR=cuff height:length). The standard and high cuffs (AR=1.63 and 1.18, respectively) demonstrated cohesive vortices and stable flow patterns. Low and long cuffs (AR=2.6 and 2.25, respectively) created more complex vortices with large areas of flow separation and low velocities.


CONCLUSIONS
aspect ratio has an important influence on flow within the distal anastomosis, with cuff dimensions of 13 mm long and 8-11 mm high (standard and high cuffs) creating beneficial flow patterns anticipated to optimise wall shear stress and inhibit myointimal hyperplasia.
Fisher
R K
RK
Regional Vascular Unit and Department of Clinical Engineering, Royal Liverpool University Hospital, Daulby Street, Liverpool L69 3GA, U.K.
How
T V
TV
Carpenter
T
T
Brennan
J A
JA
Harris
P L
PL
D000714:Anastomosis, Surgical; D001783:Blood Flow Velocity / Q000502:physiology; D019917:Blood Vessel Prosthesis Implantation; D003198:Computer Simulation; D005263:Femoral Artery / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D012212:Rheology; D013314:Stress, Mechanical