超声与射频导管消融下腔静脉口的实验研究

目的 观察超声与射频导管消融下腔静脉口对其消融终点、狭窄的影响及组织学改变，探讨超声消融的临床应用价值。方法 健康成年杂种犬11只，随机分成2组：5只行下腔静脉口超声消融，6只行下腔静脉口射频导管消融（在同一个环状面上分别消融5－15个点，力求达到环状消融）。消融3个月后行下腔静脉造影，观察消融处管腔直径的变化，然后行电生理检查，观察消融终点（电隔离）情况，将狗处死，取消融处组织制成切片，行Masson三色染色法染色，在光镜下观察其组织学改变。结果 下腔静脉造影显示：行超声消融的5个下腔静脉口有1个出现轻度狭窄，行射频导管消融的6个下腔静脉口均出现程度不等的狭窄。电生理检查发现：超声消融易达到消融终点，且在3个月时仍保持电隔离状态；而射频消融不易达到电隔离，30min及3个月时均不存在电隔离。大体标本显示射频消融术后静脉管壁形成局限、僵硬、形状不规则的瘢痕，且瘢痕间有存活的心肌；而超声消融组在静脉壁形成光滑、均匀、连续的环状损伤。组织学证实射频消融与超声消融后均有不同程度的内膜损伤及增生，全层肌组织破坏并被纤维组织取代，管壁挛缩，但射频消融组更明显。结论 超声消融下腔静脉口成功率高，狭窄发生率低，且损作简单，是临床上行肺静脉口消融治疗局灶性心房颤动较射频消融更为理想的方法。

Animal experiment of ultrasound and radiofrequency catheter ablation on orifice of inferior vena cavas

Objective To observe and compare the long term effect (including electrical isolation,stenotic and pathological change) of ablation by using ultrasound and radiofrequency energy on orifice of inferior vena cava (IVC),then evaluate their clinical value.Methods Eleven canines were divided into two groups: five canines underwent circumferential isolation of IVC by using ultrasound energy, another six canines' IVC received radiofrequency ablation at the same position(five to fifteen points were selected at the IVC of one plane to ablate).The change of inner diameter of IVC by angiography and the endpoints of ablation (electrical isolation) were observed three months later.After examination,those canines were killed,sections of ablation were cut and stained by Masson methods,and examined under light microscope.Results It was easy to get electrical isolation in ultrasound ablation group and keep it three months later,but it was difficult in radiofrequency ablation group.By IVC angiography,only one in five IVC ablated by ultrasound displayed mild stenosis,but that ablated by radiofrequency showed mild to moderate narrowing.On gross examination,radiofrequency catheter ablation (RFCA) produced tissue necrosis and white,firm,irregularly contraction scars,while lesions caused by ultrasound energy were smooth,even,continuously and circumferential.Histological examination revealed that intimal injury and proliferation,necrotic myocardium,collage replacement,elastic lamina proliferation,and endovascular contraction were more serious in radiofrequency catheter ablation group.Conclusions Ultrasound ablation can successfully isolated inferior vena cava,and at three months following up,this approach seems to be more effective in preventing stenosis of veins after ablation than RFCA.