Study of the acoustic cavitation phenomenon of microbubbles for myocardial revascularization

Abstract

Ischemic heart diseases, in particular, acute myocardial infarction (AMI), represent one of the major causes of death, both national and worldwide, and have the potential of damaging the health of those who survive such events. Existing treatments, such as angioplasty and the use of thrombolytics, are not sufficient to mitigate the situation and present risks and disadvantages. Thus, as an alternative method, sonothrombolysis with microbubbles is studied. It consists of applying ultrasound to the region where the clots are and, in the presence of microbubbles injected into the bloodstream, it causes mechanical disturbances around the thrombus, unclogging the vessels and restoring circulation. This process relies on the phenomenon of cavitation, volumetric deformations and/or destruction of microbubbles as a result of the pressure variation generated by the ultrasound. Cavitation can be either inertial or stable, depending on the characteristics of the waves emitted during the treatment. Currently, adaptations of diagnostic ultrasound equipment are commonly made to perform sonothrombolysis, therefore there is no optimization of the process, especially regarding the regime of cavitation. Hence, it is necessary to understand the ideal settings for implementing the treatment and how to properly execute it. This work, through experimental studies, seeks to comprehend the influence of parameters such as frequency and amplitude of ultrasound on the cavitation of microbubbles, contributing with the development of portable devices for the treatment of AMI, as well as other applications of acoustic cavitation, such as localized administration of drugs.