Preliminary Study Of Percutaneous Transluminal Angioplasty By Heat-Balloons And Freezing-Balloons

BackgroundPercutanous transluminal angioplasty (PTA) is one of the most importanttreatments to manage stenosis or occlusion of blood vessels, however, the highrestenosis rate somewhat limits its application. Recent study showed that thesub-hyperthermia and the hypothermia could restrain the migration and proliferation ofthe vascular smooth muscle cells(VSMC), resulting in decreasing in the restenosis rate.However, further study about this subject is needed.ObjectiveTo investigate if cryoplasty and heat-balloon therapy could inhibit re-stenosis afterPTA in animal model, and to investigate the proper thermal parameters.Materials and methodsPartⅠ To establish the animal model of atherosclerosis stenosis. Ten Landraceswere fed with high fat diet for two months after their internal iliac arteries were treatedby hot-air. Angiographics were performed in all Landraces and the pathology ofinternal iliac arteries was examined for histology in two animals.Part Ⅱ6Landraces（weight75Kg) were randomly divided into three groups：group I (42℃-50℃,10minutes); group II (42℃-50℃,20minutes); group III (-10℃,2minutes). The thermal energy were inducted into the target vessels by using balloonwith liquid medium and nitrous oxide gas under the monitored under X-rayfluoroscopy and high sensitive intra-cavity temperature. Angiography and histologywere performed before and after the animal was executed. The response anddevelopment of the vessel to sub-hyperthermia and hypothermia were observed. Theoptimal approach was seeked to gain the inactivation or the restraining of local VSMC.ResultsPartⅠThe iliac artery was occluded in one animal and the model was thought to be failed. One animal was died after the procedure. The angiographies of the other8Landraces showed the formation of iliac artery stenosis two months after theintervention by hot-air.2pigs were satisfied and the pathology of iliac artery showedthe formation of atherosclerotic plaque.PartⅡ Lumen area was larger in group II than in the other groups(263653.76±251422.46um2,348123.68±199871.47um2,260960.68±141244.12um2,respectively; P=0.0037); Smooth muscle cell numbers of intimal (high magnification)(289±34,330±105,232±66, respectively; P=0.0001） and lumina stenosis index(0.492±0.184,0.779±0.173,0.565±0.185, respectively; P=0.0001) were higher ingroup II than in the other groups; media area (545198.09±64574.07um2,543880.64±66129.98um2,640743.85±262858.74um2, respectively; P=0.0001) andneointimal area (178497.16±83903.75um2,84640.09±55330.06um2,263897.40±268037.66um2, respectively; P=0.0001) were larger in group III than inthe other groups. intima/media area ratio (0.344±0.186,0.156±0.098,0.419±0.495,respectively; P=0.0001) and intima hyperplasia index (0.246±0.109,0.130±0.067,0.235±0.188, respectively; P=0.0001) were lower in group II than in the other groups.ConclusionⅠ. The combination of vascular intima by hot-air and long-term high fat diet isfeasible to establish the animal model of atherosclerosis stenosisⅡ. The sub-hyperthermia and the hypothermia can restrain the migration andproliferation of the VSMC.III. The best dialation effect was achieved in the condition of: the temperatiureranged between40℃to45℃and the20mins dialation duration.