Activation, aggregation and adhesion of platelets exposed to high intensity focused ultrasound

High intensity focused ultrasound (HIFU) is being considered as a noninvasive method to halt internal bleeding, thus we investigated the capability of HIFU to produce "acoustic primary hemostasis", including platelet activation, aggregation and adhesion to a collagen-coated surface. Various HIFU doses were applied to platelet rich plasma (PRP) with and without ultrasound contrast agents. Flow cytometry, laser aggregometry, environmental scanning electron microscopy and passive cavitation detection were used to quantify platelet activation, aggregation, adhesion and associated cavitation. HIFU can activate platelets and cause them to adhere to a collagen-coated surface. Cavitation was monitored during aggregation trials and was quantified to provide a relative measure of the amount of cavitation that occurred in each aggregation trial. Regression analysis shows weak correlation between aggregation and intensity, and a strong correlation between aggregation and cavitation occurrence.