Annals of Biomedical Engineering

, Volume 36, Issue 1, pp 1–13

Procoagulant Properties of Flow Fields in Stenotic and Expansive Orifices

  • Anna M. Fallon
  • Lakshmi Prasad Dasi
  • Ulla M. Marzec
  • Stephen R. Hanson
  • Ajit P. Yoganathan
Article

DOI: 10.1007/s10439-007-9398-3

Cite this article as:
Fallon, A.M., Dasi, L.P., Marzec, U.M. et al. Ann Biomed Eng (2008) 36: 1. doi:10.1007/s10439-007-9398-3

Abstract

In the United States, over 125,000 mechanical heart valves (MHVs) are implanted each year. Flow through the MHV hinge can cause thromboemboli formation. The purpose of this study was to examine various orifice geometries representing the MHV hinge region and how these geometries may contribute to platelet activation and thrombin generation. We also characterized these flow fields with digital particle image velocimetry (DPIV). Citrated human blood at room temperature was forced through the orifices (400 and 800 μm ID) with a centrifugal bypass pump, continuously infusing calcium chloride to partially reverse the citrate anticoagulant. Blood samples were tested for the presence of thrombin–antithrombin complex (TAT) and platelet factor 4 (PF4). Velocity and shear stress were measured with DPIV using a blood analog fluid seeded with fluorescent microbeads. The results indicate that small changes in geometry, although they do not affect the bulk flow, change the coagulation propensity as blood flows through the orifices. A more abrupt geometry allows more stagnation to occur resulting in more thrombin generation. PF4 measurements indicated similar levels of platelet activation for all orifices. DPIV showed differences in the jets with respect to entrainment of stagnant fluid. These results help to pinpoint the important parameters that lead to flow stasis and subsequent thrombus formation.

Keywords

Mechanical heart valves Shear-induced platelet activation Shear-induced platelet aggregation Thrombosis Blood Coagulation 

Abbreviations

MHV

mechanical heart valve

SJM

St. Jude medical

DPIV

digital particle image velocimetry

LDV

laser Doppler velocimetry

TAT

thrombin–antithrombin III

PF4

platelet factor 4

PReS

principle Reynolds stress

SIPAct

shear-induced platelet activation

SIPA

shear-induced platelet aggregation

Symbols

V

average centerline velocity

Y

location of velocity measurement in jet

Yo

jet origin (orifice plate location)

Vc

average centerline velocity at Yo

D

orifice diameter

a

a constant for the type of jet

Supplementary material

Copyright information

© Biomedical Engineering Society 2007

Authors and Affiliations

  • Anna M. Fallon
    • 1
  • Lakshmi Prasad Dasi
    • 1
  • Ulla M. Marzec
    • 2
  • Stephen R. Hanson
    • 2
  • Ajit P. Yoganathan
    • 1
  1. 1.Wallace H. Coulter School of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaUSA
  2. 2.Department of Biomedical EngineeringOregon Health and Science UniversityPortlandUSA

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