| An experimental and clinical study on angioplasty with lowfrequency and high-energy ultrasoundsUltrasonic angioplasty, as a new approach for reconstruction of blood supply, has attracted attention from researchers at home and abroad in recent years. For this technique, such effects as mechanical vibration and cavitation etc. exerted by low frequency and high-energy ultrasounds (LFHEU) are employed to restore potency of blood vessels by splitting atherosclerotic plaques and dissolving thrombi. Meanwhile, the technique does not damage normal vascular structure. This study was designed to investigate angioplasty with LFHEU. The purposes and brief procedures are as follows: 1) After vascular smooth muscle cells (VSMC) in an animal model were treated with LFHEU, expression of C-sis and platelet-derived growth factor (PDGF) and proliferation state of the cells were evaluated to determine effects of LFHEU on proliferation of smooth muscle cells. 2) LFHEU was used to dissolve panhematic thrombi formed in vitro and those in patients with acute myocardial infarction or old myocardial infarction to determine its safety and efficiency in dissolving thrombi. 3) LFHEU was used to treat serious stenosis of the coronary artery to investigate its dissolving effects on atherosclerotic plaques.In this study, rabbits were randomized into normal control group (group A), experimental control group (group B), balloon-injured group (group C) and ultrasonic dissolved group (group D). After the injury in carotid artery, the target segment of the common carotid artery with a length of 4 cm in rabbits in the latter two groups was extracted at 48, 72, 96, 120 hours and 1 and 2 weeks, respectively. The segment was divided into 4 parts with a length of approximately 1 cm in each. Expression of C-sis mRNA was determined by RT-PCR, synthesis and content of DNA in smooth muscle cells measured by 3H-TdR incorporation and positive indexes of PDGF-~ and PCNA by PDGF-~and PCNA immunohistochemical staining to determine effects of ballooninjury and LFHEU on proliferation of smooth mu5cle cel1s. It was fOund thatthere were no expression of C-sis and significant increase in the conteflt ofPDGF-0, PCNA staining and incorporation of 3H-TdR in Group A, Group Band Group D. In Group C, typical expression of C-sis of cytokines encodingPDGF-0 appeared and its peak was found in l week after the injury. Theexpression intensity was increased for 6.5 times. PDGF-positive smoothmuscle ce1ls began to aPpear at 48 hours and the number reached its peak at 1week after the injury. Incorporation value of tritium began to be continuouslyelevated in 72 hours and reached its peak at 1 week after the injury.Venous blood of 2 ml was collected from volunteers to prepare 20panhematic c1ots. Then the colt was weighed. Ultrasounds of 40 KHz and l8Wcm2 was used to dissolve the clots till its disaPpearance. After the dissolvedsubstance was made stationary, the supernatant was discarded and sedimentcol1ected for smear examination under the microscope. Microscopicexamination revealed that the diameter of 90% of pieces produced in dissolvewas smaller than that of red blood cells and prepared panhematic clots werecompletely dissolved in l5 seconds (dissolving speed = 0. 13 8 i 0.018g/s).LFHEU was introduced via catheterization to treat patients with acutemyocardial infarction, old myocardial infarction and those with old myocardialinfarction in whom PTCA failed. Degree of residual stenosis was measured andanalyzed with SHIMADZU Digitex a 2400 computerized analyzing system andchanges in blood flow in infarction-related arteries (IRA), CK-MB after thetreatment, ST segmeni in ECG and clinical manifestations were observed toevaluate feasibility of using angioplasty with LFHEU to treat myocardialinfarction. Safety of ultrasonic angioplasty was exp1ored by measuring contentsof PT, APTT t-PA and PAI in venous blood before and after the treatment todetermine whether there were imaging changes such as coron...
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