Journal of Ultrasound in Medicine, Vol 5, Issue 12 685-689, Copyright © 1986 by American Institute of Ultrasound in Medicine
Sonographic evaluation of platelet aggregate retention in a vortex within a simulated venous sinus
J. Machi, B. Sigel and J. R. Ramos
To examine the possible role of venous-valve pockets in enhancing platelet
aggregate retention and deposition, in vitro experiments using real-time
ultrasonography were performed in a venous-sinus flow model under
controlled flow conditions. In each of 10 experiments, adenosine
diphosphate (ADP)-induced platelet aggregates in plasma were circulated in
both test and control models at upstream shear rates from 60 to 0 sec-1.
High-resolution, real-time, B-mode ultrasonography was used to detect and
measure the platelet aggregates. Vortex flow was observed in all
poststenotic segments, particularly in the sinuses. With reduced shear
rates, platelet aggregates increased in size within the vortices and
subsequently deposited in the dependent poststenotic tube surface,
especially in the sinuses. In conclusion, this study using real-time
ultrasonography indicates that the presence of a venous sinus greatly
accentuates vortex formation, which, in turn, augments the retention and
deposition of platelet aggregates. This relation may provide an explanation
for mechanisms that would cause thrombosis to originate in venous-valve
pockets.
