Abstract
Objective
To compare the effects of different waveforms of 1 MHz and 3 MHz therapeutic ultrasound on endothelial function in healthy subjects.
Design
Randomised placebo-controlled, crossover study with concealed allocation and assessor blinding.
Setting
Imaging Centre of the University Hospital.
Participants
Thirty volunteers aged between 18 and 35 years were divided into two homogeneous groups (1 MHz and 3 MHz).
Interventions
Continuous (CUT; 0.4 W/cm2SATA), pulsed (PUT; 20% duty cycle, 0.08 W/cm2SATA) and placebo waveforms (equipment off) of ultrasound (1 MHz and 3 MHz) were randomized and applied over the brachial artery for 5 minutes.
Main outcome measures
Endothelial function was evaluated using the flow-mediated dilation (FMD) technique.
Results
Both 1 MHz [CUT: mean difference 4%, 95% confidence interval (CI) 2 to 6%, P < 0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P < 0.001] and 3 MHz (CUT: mean difference 4%, 95% CI 2 to 6%, P < 0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P < 0.001) of therapeutic ultrasound increased %FMD by approximately 4% compared with the placebo waveforms. The endothelium-dependent vasodilator responses were the same for both types of waves and frequencies. No differences in baseline diameter, hyperaemic flow, and nitroglycerin-mediated diameter and vasodilation were observed between groups.
Conclusion
Both CUT and PUT ultrasound waveforms improved endothelial function. The 1 MHz and 3 MHz frequencies of therapeutic ultrasound led to similar improvement in endothelial function in healthy volunteers.
Clinical trial registration number RBR-4z5z3t.
Citation
Comparison of the effects of 1 MHz and 3 MHz therapeutic ultrasound on endothelium-dependent vasodilation of humans: a randomised clinical trial