In vitro flow loop for generating a SIPA clot. (A) A constant-pressure closed loop circuit with a roller pump was developed to generate a clot in (B) a collagen-coated glass stenosis that has a throat diameter of ∼2.5 mm. A total volume of 400 mL of blood was circulated through the flow loop. (C) To maintain a constant 30-mm Hg pressure head, the roller pump flow rate was reduced as the clot grew over time (red, mean of 8 with standard deviation, shown by vertical lines) as compared with the simulated flow rate in an empirical model of SIPA thrombus growth rate (blue, upper and lower limit displayed in the bars). (D) The initial maximum shear rate in the throat was greater than 10 000 s−1. The area of high shear is consistent with the thrombus location in the stenosis. (E) The SIPA clot occluded the stenosis with a trumpet-like shape. The boundary of the SIPA clot is highlighted by the yellow dotted line. (F) The glass tube with the SIPA clot after blood was drained, showing the extension of the thrombus at the wall both upstream and downstream of the throat.