Aspirin and other blood thinners are often prescribed to help prevent formation of thrombi that can lead to strokes and heart attacks. While these can be very effective, their benefit seems to vary greatly patient to patient. The reasons are still not well understood, but having a handy tool to evaluate how a drug affects the coagulation of the patient’s own blood before making a prescription would significantly improve antiplatelet therapy.
Researchers at Georgia Tech have developed and tested a new device that puts blood through mechanical stresses, such as found within narrow dynamic vasculature, while seeing how various drugs help resist clotting. The device has four tubes, each replicating a coronary artery, through which blood premixed with a drug is pumped through. Each tube has a different “shear rate,” or stress applied to the blood due to the pressure inside the tube, which allows blood to be tested as though it’s moving through a variety of arteries, from atherosclerosic to more healthy ones.
Some details from the study abstract:
In this work we measured occlusion times and thrombus detachment for a range of initial shear rates (500, 1500, 4000, and 10000 s−1) and therapy concentrations (0–2.4 µM for eptifibatide, 0–2 mM for acetyl-salicylic acid (ASA), 3.5–40 Units/L for heparin) using a microfluidic device. We also measured complete blood counts (CBC) and platelet activity using whole blood impedance aggregometry. Effects of shear rate and dose were analyzed using general linear models, logistic regressions, and Cox proportional hazards models.
Shear rates have significant effects on thrombosis/dose-response curves for all tested therapies. ASA has little effect on high shear occlusion times, even at very high doses (up to 20 times the recommended dose). Under ASA therapy, thrombi formed at high shear rates were 4 times more prone to detachment compared to those formed under control conditions. Eptifibatide reduced occlusion when controlling for shear rate and its efficacy increased with dose concentration. In contrast, the hazard of occlusion from ASA was several orders of magnitude higher than that of eptifibatide. Our results show similar dose efficacy to our low shear measurements using whole blood aggregometry. This quantitative and statistically validated study of the effects of a wide range of shear rate and antiplatelet therapy doses on occlusive thrombosis contributes to more accurate understanding of thrombosis and to models for optimizing patient treatment.
Flashbacks: Blood Coagulation Testing Using Smartphone Touchscreens…; Mass General Researchers Use Laser Speckle Rheology to Measure Coagulation of Blood…; Gold Nanoparticles For the Precise Measurement of Clotting Agents in the Bloodstream…; Point-of-Care Clotting Analyzer from HemoSonics and Cambridge Consultants…; CoaguSense’s Home-Use Blood Coagulation System Gets FDA OK…