Abstract

A unique and novel method to study thromboembolism by direct observation was developed. High-definition videos of thrombus formation and embolization were successfully obtained in miniature flow cells using in-vitro, non-invasive, real-time techniques. Critical parameters of thromboembolism such as thrombus growth rate, thrombus growth direction, shear force on the thrombus at embolization, and adhesion strength of the thrombus to the foreign surface were determined. Thrombus growth was found predominantly in two locations: 1) in the flow recirculation zone just after the trailing edge of the small tubes (53%) and 2) at the leading edge of the small tubes (47%). In the small tubes, thrombus volume and shear force acting on the thrombus increased in a power-law like function of time. In the large tubes, thrombus volume and shear force acting on the thrombus increased in a linear like function of time. The slope of thrombus growth rate in the small tubes was significantly greater than that in the large tubes. Thrombus growth direction was also estimated by tracking the thrombus center of mass with respect to time and typically ranged from 15 to 35 degrees from the direction of flow. According to observations, embolization seems to occur via two possible mechanisms: 1) complete detachment of the thrombus by sliding off the foreign surface or 2) partial embolization of the thrombus by internal tearing. The estimated shear force on the thrombus at embolization was determined and was significantly greater in the small tubes than in the large tubes. The adhesion strengths of thrombi were calculated for the small tubes using the shear force at embolization and the estimated thrombus attachment area and ranged from 9.63 to 28.83 N/m2 (mean = 16.24 ± 2.59 N/m2 95% confidence), which was in good agreement with published results of platelet retention experiments. An experimental series demonstrated that the developed method could be used to study the effects of controlled variables on thromboembolism parameters. In that series, heparin concentration in blood, blood flow rate, and device design were studied one variable at a time to test their effects on thrombus growth parameters and adhesion strength. Because of the small number of data, these preliminary results were statistically insignificant but pointed the way for future studies.

Degree

MS

College and Department

Ira A. Fulton College of Engineering and Technology; Chemical Engineering

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2012-08-09

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd5622

Keywords

thrombosis, thromboembolism, blood-contacting devices

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