Global Thrombosis Test: Occlusion by Coagulation or SIPA?

Figures

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  Fig. 1. Schematic of the GTT cartridge. Blood is injected at the top of the GTT test tube and flows passing the gaps of two ceramic beads. Occlusion happens due to several stages of activation and aggregation. 1 GTT, global thrombosis test; OT, occlusion time.

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  Fig. 2. Histology of the GTT clot using Carstairs' stain. Red indicates fibrin and blue platelets. GTT, global thrombosis test.

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  Fig. 3. Box charts of LT obtained from the blood samples treated with PBS or tPA in PBS through the GTT device after clot formation. GTT, global thrombosis test; PBS, phosphate buffered saline; tPA, tissue plasminogen activator.

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  Fig. 4. Box charts of OT obtained for GTT for fresh blood and blood with the anticoagulant heparin. The star in the plot is the predicted value for OT obtained for SIPA using the model developed by Mehrabadi et al for SIPA in heparin. 20 GTT, global thrombosis test; OT, occlusion time; SIPA, shear-induced platelet aggregation.

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  Fig. 5. Box charts of OT obtained flowing fresh blood through GTT and mGTT. mGTT adds a collagen surface, higher shear stress, and eliminates the low shear zone between the beads. mGTT, modified global thrombosis test; OT, occlusion time.

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  Fig. 6. Histology of the mGTT clot using Carstairs' stain. The thrombus is composed primarily of platelets are stained blue, and the tinge of red indicates small amounts of fibrin. Few RBC are present in this white clot. mGTT, modified global thrombosis test; RBC, red blood cell.

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  Fig. 7. Box charts of OT obtained for GTT and mGTT for non-anticoagulated blood (“none” in the graph) and anticoagulated blood with heparin for both GTT and mGTT and citrate for the mGTT. mGTT, modified global thrombosis test; OT, occlusion time.

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  Fig. 8. Box charts of OT obtained for three different bead surfaces: ceramic, glass, and collagen coated. GTT and mGTT were tested with blood samples without anticoagulants ( none in graph) and with heparin as an anticoagulant. OT, occlusion time.

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  Fig. 9. Micro-CT scan of a 4 mm and 3 mm beads ( a ) and ( b ), respectively. The gaps are the dark lines in between the ceramic bead ( in white ) and the test tube ( gray ) and indicated by red arrows. Yellow arrows indicate the places where the bead and the test tube touch their surfaces.

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  Fig. 10. The gap geometry is approximate to be a rectangle of length L using Eq. (2), where α is the gap arc angle and R the bead radius, as shown as an example in the image, and width w , which is obtained from roughly the middle of the gap indicated by the blue arrow in the image. The gap area is then calculated as A = L × w .

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  Fig. 11. Examples of the readout from the SD stored data versus the data shown in the display. The x axis of the graphs should be cumulative running time, and the y axis should display the time, d, between two consecutive drops. In ( a ) the stored values increase smoothly and monotonically, as it is expected from the measurements. In contrast, other traces are shown in ( b ) and ( c ), where the stored values had jumps back and forth in time ( x and y axis), even showing negative time points. In ( b ), the displayed data was OT 612 and LT 1925, but the readout from the SD card is OT 317 and LT 2167. Also, there is a long time-delay for the first drop to register. The x-axis records time in a nonstandard unit that is not in seconds. In ( c ), it is difficult to understand this output. LT, lysis time; OT, occlusion time; SD, standard deviation.