FACTORS INFLUENCING VORTEX DEVELOPMENT IN A MODEL OF A SKELETAL-MUSCLE VENTRICLE

A video technique was used to visualize flow patterns in a pulsatile m odel of a skeletal muscle ventricle (SMV). The shape and duration of S MV filling/emptying curves were determined by the stroke action of a c omputer-controlled piston pump. In this way we examined the effect of filling duration and injection volume on the now structures. To simula te the interaction between the Left ventricle and the SMV in the propo sed clinical application, two filling/emptying regimes were employed w ith the period of each SMV cycle being either equal to or twice that o f a typical cardiac cycle. Vortex formation at the inlet to the ventri cle was a feature of both flow cycles during filling for all the combi nations of injection volume and filling duration considered. When a pa cing ratio of 1:1 was simulated, SMV filling was immediately followed by ejection, and the formed vortex was expelled. Under this flow regim e, fluid in the apical end of the ventricle remained undisturbed. When the pacing ratio was 2:1, however, the quiescent period that followed filling allowed time for the formed vortex to travel a significant di stance toward the apical end of the ventricle. Under certain condition s of injection volume and flow rate, the vortex reached the apex by th e end of the quiescent period. We suggest that a ventricle connected t o the aorta by a single valveless conduit would require a flow regime that included a significant period of quiescence after filling. This w ould allow the vortex to reach and displace blood that would otherwise stagnate in the apex, thereby reducing the risk of thrombus formation .