Positive Chronotropic Effect Caused By Transthoracic Ultrasound In Heart Of Rats

Pulsed ultrasound can produce chronotropic and inotropic effects on the heart with potential therapeutic applications. Fourteen 3-month-old female rats were exposed transthoracically to 3.5-MHz 2.0-MPa peak rarefactional pressure amplitude ultrasonic pulses of increasing 5-s duration pulse repetition frequency (PRF) sequences. An increase in the heart rate was observed following each PRF sequence: an similar to 50% increase after the 4-5-6Hz sequence, an similar to 57% increase after the 5-6-7Hz sequence, and an similar to 48% increase after the 6-7-8Hz sequence. Other cardiac parameters showed a normal or indicated a compensatory decrease at 3 and 15 min post-ultrasound compared to control.