| In recent years, thrombus disease has become threat of human health and life with rising of life rhythm and level. It has brought heavy burden to patients and society because quantity increases obviously and age also tends to middle gradually. Thrombus disease is now still a very difficult problem in clinical treatment. Most medicine treatment of use has side effects and the possibility of bleeding complication. It also has long treatment period and easy to occur dissolve bolt failure or again block etc. The wound of the general reconstruction operation of blood vessel has much complication and certain possibility of occluding again. The clinical application of artery rotational ablation and laser angioplasty developed in recent years were restricted in some degree for which could cause the membrane damage in the blood vessel.After 1990's, along with the synthesis application development of ultrasonics and electronics and advanced science, the application of biological medical ultrasound has much attracted. Ultrasonic technology show increasingly wide prospect in thrombus disease field, which melt thrombus for its own choice. A lot of developed countries already made ultrasonic technical application in body ultrasonic thrombolysis. It has little application in our country. The study of fundamentally application of ultrasonic thrombolysis has less and less. Now, study of the influence of ultrasonic thrombus focused on single frequency. It take on thrombus organization with the high-energy low frequency ultrasonic and high-strength ultrasound has the latent danger of damaged normal organization for which can make organization cell harm. It is not clear for the parameter optimization of strength and frequency and its mechanisms, though it is observed a series of advantage of thrombolysis. It is still need to carry out some more extensive research in this field.In this paper, the study of interventional ultrasonic thrombolysis has developed. A series of interventional ultrasonic transducer was designed, initial study of influence on the thrombolysis of different ultrasonic preferences also developed. Through experiment we get:(1) A series of intervene ultrasonic transducers were designed and tested, The theoretical design value of transducers accorded with experiment measured value as well as the ANSYS finite element simulating value, the error of harmonic frequency in the scope that can be allowed. Speed ratio of transducer of the former and the latter is equal to 3 (Fig.3-1), it is raised 50% than the ratio of pure exponent amplitude transformer horn under the same conditions (about 2). In the whole experiment, all the transducers works well and has a normal output without overheat, which met the requirements of experiment. (2) With the same acting time and ultrasonic frequency, influence of different transducer input power was studied. The results shows increased with the rise of ultrasonic power.(3) In order to get the relationship of ultrasonic frequency and thrombolysis, 7 different frequencies have selected( 20kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz and 100kHz ), the input power and ultrasonic frequency of ultrasonic is constant value for every sample. Experiment results lists, in the frequency range of our experiment, the effects of frequency to thrombolysis is low frequency efficient than high frequency. Because design restriction of transducer, frequency has small range (20kHz~100kHz), this tendency seems not very outstanding, in which rise and fall may be caused by conversion efficiency for different transducer. Synthesized experiment results and theoretical analysis, acoustic cavitation effect leads to thrombolysis mainly, but in the high frequency, it is mainly mechanical effect.(4) Keeping the input power of transducer and the frequency of ultrasonic as constant, the thrombolysis versus acting time of ultrasonic was studied. It is shown that usually more time, higher thrombus.(5) Keeping the frequency and acting time of ultrasonic and the input power of transducer as constant, the influence of thrombus age to thrombolysis is investigated (the time that thrombus forms). The results shows: longer thrombus age is, lower thrombolysis. Thrombus age is the shorter, higher thrombolysis will be.(6) Condensation and precipitation of is not observed after 72 hours stewing in the experiment. There are no any particles can be observed with eyes. The diameter of the biggest particle in liquid is approximately 1 micrometer. It is also observed fiber scraps. In the normal human body, the diameter of red blood cell is approximately 7.5 micrometer; the average diameter of blood vessel is about 7～9 micrometer. Thrombus melt scrap can not cause block of blood vessel again. |
