Elaine Belassiano, Flávio Buiochi, Rosana A. Bassani, and Eduardo T. Costa
biosensors and transducers, ultrasound, therapy, cardiology
In cardiology, diagnostic ultrasound is well established, whereas there is an unexplored potential for therapeutic applications. Searching for alternative devices that do not apply high intensity electric fields to the heart is interesting because these fields can damage myocytes due to electroporation, generating Ca2+ overload and even cell death. Power ultrasonic transducers, capable of generating high intensity acoustic fields, might be able to interfere with the cardiac activity. Modeling, construction and characterization of a 66-kHz ultrasound transducer are described. Experimental and theoretical acoustic impedance curves show good agreement. Power characterization confirmed the transducer stable behavior upon high electric drive. The transducer starts to produce cavitation when excited by an input voltage of 37VPP. The ultrasonic transducer driven by a 25Vpp electric voltage (peak negative pressure of approximately 2.1kPa) was used to apply 66-kHz bursts to a perfused isolated rat heart, generating proarrhythmic effects. This is promising when it comes to therapeutic applications of ultrasound in cardiology, since arrhythmia-inducing agents might as well be antiarrhythmic. The developed transducer will be used for further investigation aiming to find a specific set of acoustical parameters able to interfere in the heart rate without damaging the cardiac tissue.
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