Reversible increase in the EKG of rats using transthoracic pulsed ultrasound

• Published in: The Journal of the Acoustical Society of America 2021-10, Vol.150 (4), p.A56-A56
• Main Authors: Coiado, Olivia, Yerrabelli, Rahul, Lucas, Alex, Christensen, Anton, Wozniak, Marcin, O'Brien, William D.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/10.0007611

This study showed the ability to increase inotropy in a rat heart while maintaining hemodynamic stability. A total of fourteen rats were used in this experiment. They were divided into four group including a control group (no ultrasound exposure). 3-month-old female rats were transthoracically to 3.5 MHz ultrasonic pulses of 2.0-MPa peak rarefactional pressure amplitude, ∼0.5% duty cycle and an increase pulse repetition frequency (PRF) sequence (4–5–6, 5–6–7, and 6–7–8 Hz). All rats underwent the same anesthesia, preparation, measurement, and positioning with only experimental rats being exposed to the turned-on transthoracic ultrasound. Rats were positioned in dorsal recruitment position and cardiac parameters were monitored using EKG and echocardiography. An increase in the heart rate was observed followed by each PRF sequence with increased heart rates. A mean of 550 + -50, 563 ± 45, and 712 ± 61 bpm at the conclusion of ultrasound for 4–5–6 Hz, 5–6–7 Hz, and 6–7–8 Hz sequences versus the control baseline of 248 ± 19 bpm was achieved. Other cardiac parameters were normal or had a compensatory decrease by 3- and 15-min post-ultrasound compared to control. EKG data of the experimental group of rats showed areas of rapid peaks outside of sinus rhythm during ultrasound pulsing while the control group-maintained sinus rhythm throughout the experiment.