Experimental investigation of the determination for the safe operating regime of ultrasound tube-shaped waveguide wire for internal blood vessel debulking.

BACKGROUND: Majority of limb amputations are caused by circulatory disturbances such as vascular occlusions and strictures. Discovery of modern and more advanced ultrasonic interventional vascular debulking methodology would likely save limbs of CVD patients and their lives in an economical way. However, there is a lack of researches regarding the ultrasound's effect on physiological functions of human blood cells. The tube-shaped ultrasound waveguide wire with orifices at its operational end was offered as the alternative to some currently patented interventional thrombosis treatment solutions. OBJECTIVE: To establish the safe operating regime of the proposed device. METHODS: The temperature rise induced by the cavitation process and friction between the waveguide and surrounding fluids was measured and microscopic pictures of human blood were made. RESULTS: Blood insonation lasting 15 seconds, leads to blood clot formation. If insonation continues for 30 seconds some cells are totally destroyed. In addition, the safe operating regime was established. To avoid heating of the environment to the temperature harmful for the medium (blood) and surrounding tissues, is achieved when the system should be on for 40%, and of for 60% of the period of 1 second. CONCLUSIONS: The safe operating regime of the proposed device was established.

Effect of Low-Intensity Cavitation on the Isolated Human Thoracic Artery In Vitro.

Reported here are the results of an experimental study on the response to low-intensity cavitation induced by low-frequency (4-6 W/cm2, 20 kHz and 32.6 kHz) ultrasound of isolated human arterial samples taken during conventional myocardial revascularization operations. Studies have found that low-frequency ultrasound results in a significant (48%-54%) increase in isometric contraction force and does not depend on the number of exposures (10 or 20) or the time passed since the start of ultrasound (0, 10 and 20 min), but does depend on the frequency and location (internal or external) of the blood vessels for the application of ultrasound. Diltiazem (an inhibitor of slow calcium channels) and carbachol (an agonist of muscarinic receptors) used in a concentration-dependent manner did not modify the relaxation dynamics of smooth muscle affected by ultrasound. Thus, ultrasound conditioned to the augmentation of the isometric contraction force the smooth muscle of blood vessels and did not improve endothelial- and calcium channel blocker-dependent relaxation.