Correlation of in vivo clot deposition with the flow characteristics in the 50 cc penn state artificial heart: a preliminary study

Flow stasis in an artificial heart may provide a situation where thrombus develops. Should part, or all, of the clot dislodge, a thromboembolism may lead to stroke(s), neurologic deficits, or even death. In an effort to determine if the regime of low shear or stasis exists, a two-dimensional particle image velocimetry (PIV) system was implemented to measure the velocity field within the 50 cc Penn State Artificial Heart. The velocity measurements were decomposed nearest the wall to obtain wall shear rates along the bottom of the chamber. The PIV measurements were made in three image planes across the depth of the chamber to reconstruct a surface distribution of the wall shear rates at the bottom over the entire heart cycle. The wall shear rate is shown to be spatially nonuniform, with persistently low wall shear rates. An area near the front edge of the chamber at the bottom showed wall shear rates not exceeding 250 s(-1). This was an area of clot formation seen in vivo, suggesting a link may exist between the low wall shear rate zone and thrombus formation.