Background: The present study aimed to investigate the effect of low-level combined dual- frequency of 1 MHz and 150 kHz ultrasonication on fibro-lipid plaque with neovascularization in the rabbit common carotid artery.

Materials and Methods: In this experimental study, the common carotid arteries in 17 rabbits were injured perivascularly by liquid nitrogen, followed by a 1.5% cholesterol-rich diet for eight weeks. The animals were randomly divided into three groups including A: a cholesterol-rich diet (n=7) and evaluation at eighth week, B: control and discontinuation of cholesterol-rich diet (n=5) and evaluation at twelfth week and C: low-level combined dual- frequency ultrasonication and discontinuation of cholesterol-rich diet (n=7) and evaluation at twelfth week. Blood volume flow and blood mean velocity were measured by color Doppler ultrasonography. Moreover, mean wall thickness and percentage of luminal cross-sectional area of stenosis were measured by B-mode ultrasonographic and histological methods in the stenotic region of the common carotid artery.

Results: Results showed a significant reduction in the mean value for blood peak systolic pressure, blood mean pressure, blood mean velocity, mean wall thickness and percentage of luminal cross-sectional area of stenosis and a significant increase in the mean value for blood peak diastolic pressure and blood volume flow in group C compared with the other groups (P<0.05).

Conclusion: Enhanced inertial cavitation effect of low-level combined dual- frequency ultrasonication can cause the degradation of the microvessels and the fibro-lipid content, lipolysis and thrombolysis in the plaque and significantly dilate the luminal cross-sectional area of stenosis.