Platelet Aggregation Induced in Vitro by Therapeutic Ultrasound

Abstract

SummaryPlatelets were found to aggregate spontaneously when exposed to ultrasound generated by a commercial therapeutic device. At a given frequency, aggregation was found to be a dose-related phenomenon, increasing intensities of ultrasound inducing more extensive and more rapid aggregation. At any single intensity, the extent aggregation was increased as the frequency of the applied ultrasound was decreased (from 3.0 to 0.75 MHz).Ultrasound-induced platelet aggregation was found to be related to overall platelet sensitivity to adenosine diphosphate. More sensitive platelets were found to aggregate spontaneously at lower intensities of sound, and also the maximum extent of aggregation was found to be greater. Examination of ultrasound-induced platelet aggregates by electron microscopy demonstrated that the platelets had undergone the release reaction.The observation that haemoglobin was released from erythrocytes in whole blood irradiated under identical physical conditions suggests that the platelets are being distrupted by ultrasonic cavitation (violent gas/bubble oscillation).It is postulated that overall platelet aggregation is the result of two distinct effects. Firstly, the direct action of ultrasonic cavitation disrupts a small proportion of the platelet population, resulting in the liberation of active substances. These substances produce aggregation, both directly and indirectly by inducing the physiological release reaction in adjacent undamaged platelets.

Endothelial Cell Injury and Platelet Aggregation Induced by Contrast Ultrasonography in the Rat Hepatic Sinusoid

“…19 Damage to the platelet membrane does not always produce A B C platelet lysis, however, although it may affect platelet function. 20,21 We previously reported that expression of CD62P by contrast ultrasound on the platelet surface indicates platelet activation in vitro. 18 Hepatocytes have been reported to show karyorrhexis and disappearance of the cytoplasmic ultrastructure on exposure to highpower ultrasound in the treatment of tumors.…”

In Vitro Platelet Activation by an Echo Contrast Agent

“…17 Moreover, damage to the platelet membrane does not result in platelet lysis but may affect platelet function. 18,19 Recently, several monoclonal antibodies that recognize platelet surface antigens have been developed. [20][21][22][23] Activated platelets express activationspecific antigens on the platelet surface, for example, PAC-1, and CD62P.…”

Ultrasound thrombolysis in stent thrombosis

“…Meltzer et al have shown in vitro that high-power ultrasound can cause platelet lysis through the mechanism of inertial cavitation [18]. Thus, it can be hypothesized that in these cases platelet-rich clots were lysed by a cavitation-induced mechanism, leading to a successful procedure [19,20]. More data are necessary to establish the safety and efficacy of intravascular ultrasound thrombolysis as a treatment of stent thrombosis.…”