Jamiolkowski, Megan A
(2016)
Characterization of Real Time Platelet Deposition onto Opaque Surfaces under Clinically-Relevant Flow Conditions.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Although the thrombogenic nature of the surfaces of cardiovascular devices is an important aspect of blood biocompatibility, few studies have examined platelet deposition onto opaque materials used for these devices in real time. This is particularly true for the metallic surfaces used in current ventricular assist devices (VADs). Using hemoglobin depleted red blood cells (RBC ghosts) and long working distance optics to visualize platelet deposition, we sought to perform such an evaluation. A titanium alloy (Ti6Al4V) and 5 alternative opaque materials were examined. Ti6Al4V had significantly increased platelet deposition relative to the majority of alternative materials.
Blood flow patterns are of particular concern for devices such as blood pumps where shearing forces can be high, volumes are relatively large, and the flow fields can be complex. However, few studies have examined the effect of geometric irregularities on thrombus formation on clinically relevant opaque materials under flow. The second objective of this report was to quantify human platelet deposition onto titanium alloys, as well as positive and negative control surfaces, in the region of crevices (~50-150 µm in width) that might be encountered in many VADs. The results revealed that the largest crevice size was the least thrombogenic. At the higher shear rate, the most deposition occurred in the medium size crevice.
A third challenge in assessing the hemocompatibility of a blood-wetted device is understanding the functional relationship between shear stress, biochemical agonists, and artificial surfaces. The final objective of this report was to investigate the effect of sub-threshold concentrations of ADP in conjunction with flow on platelet deposition onto clinically relevant opaque materials. To achieve this aim, a membrane-based agonist delivery system was designed to evenly introduce specific concentrations of agonists into a flowing blood analog. The results showed that that the addition of a sub-threshold level of ADP to the system resulted in nearly a 2.5 fold increase in deposition on the titanium surface. The data generated from this report could be used to improve the accuracy of a predictive model of thrombotic deposition in VADs.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
25 January 2016 |
| Date Type: |
Publication |
| Defense Date: |
9 November 2015 |
| Approval Date: |
25 January 2016 |
| Submission Date: |
17 November 2015 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
136 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Bioengineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
platelets, thrombosis, red blood cell ghosts, opaque
biomaterials, ventricular assist device |
| Date Deposited: |
25 Jan 2016 18:18 |
| Last Modified: |
25 Jan 2017 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/26308 |
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