【作者】 朱悫；

【导师】 黄晶；

【作者基本信息】 重庆医科大学 ， 内科学， 2012， 博士

【摘要】 第一部分高强度聚焦超声经胸无创消融活体犬右房峡部的可行性研究背景：右房峡部是典型房扑的关键传导部位，是导管射频消融典型房扑的首选靶点。右房峡部解剖变异较大，射频能量的消融深度有限；目前导管介入操作多需要X射线引导，但X射线存在对人体的辐射危害，介入操作方式可能对血管及心腔内结构形成损伤，因此有必要探索不依赖X射线非导管化的消融能量及途径。在声通道适宜时，高强度聚焦超声可以直接从体外向体内聚焦对活体肿瘤实现消融，同时对消融靶点外组织结构不造成损伤。前期研究证实高强度聚焦超声对离体心肌组织和开胸状态下活体心脏内结构组织可以实现有效点状和线样损伤，由此推测，高强度聚焦超声有望在不开胸条件下，实现经胸消融心脏内特定结构。目的：改善心脏透声环境，在二维超声下实现右房峡部准确定位，探索高强度聚焦超声经胸消融活体犬右房峡部的可行性。方法：10只健康成年杂种犬，3%戊巴比妥麻醉后，常规脱毛、脱脂、脱气处理，建立双侧人工胸水模型；选择海扶JC200聚焦超声肿瘤治疗仪，在二维超声引导及适时监控下，在经三尖瓣后瓣的短轴切面，将HIFU焦点定位于右房峡部，从三尖瓣环侧向下腔静脉方向，在呼气末以450W×2s进行点消融叠加，超声监控图像呈现持续高灰度线性影像时停止消融，观察平均灰度变化。消融全程实时监控体表肢体导联心电图。1周后处死获取心脏标本进行大体观察，同时观察声通道结构有无损伤，剪取右房峡部消融标本用于HE染色组织学观察。结果：通过对实验犬的皮肤脱毛、建立人工胸水以及常规脱脂脱气等操作，对10只犬均完成了右房峡部的二维超声影像定位及HIFU消融，平均灰度值增加28.6±7.2,消融过程中右房外侧壁与右肺保持1.5个焦点的距离。单只犬从开始消融到结束消融累计平均时间为(54.5±12.0)s，去除等待时间，平均实际消融时间为（17.0±3.4）s。经大体观察及组织学评价，在8只犬中实现了右房峡部的全程透壁坏死，未达成全程透壁坏死的2只犬中，1例出现了肺损伤；共有2只犬在消融中出现了单发室性早搏和交界性早搏。所有动物未见皮肤、胸肋骨及心包损伤，未见右冠脉损伤，未见胸腔积液及心包积液。结论：通过改善超声透入条件，二维超声实现了对活体犬右房峡部的准确定位，引导高强度聚焦超声首次实现了以经胸方式对右房峡部的全程透壁消融，短期观察证实该方法安全可行。第二部分高强度聚焦超声经胸无创消融活体犬右房峡部的电生理验证和中期安全性评价背景：通过消融实现右房峡部的全程透壁损伤是根治典型房扑的解剖终点，这在动物实验和临床尸检报告中已得到证实。临床上无法通过解剖证实右房峡部的全程透壁坏死，因而选择经右房峡部的双向电传导阻滞作为消融终点，因右房峡部的解剖变异和射频能量的消融深度有限，约10%的患者在达成右房峡部双向电阻滞的终点后房扑复发。在声环境适宜时，聚焦超声的消融深度和消融效能优于射频能量。因此，在前期高强度聚焦超声以经胸方式实现右房峡部定位及消融的基础上，进一步通过心内电生理试验验证是否达成双向电传导阻滞，并评价中期安全性。目的：通过检测高强度聚焦超声经胸消融活体犬右房峡部后中期的右房内电传导时间，验证是否存在经右房峡部的电传导阻滞，并评价安全性。方法：8只健康成年杂种犬，分为消融组（n=4）和对照组（n=4）,两组间性别、体型和体重两两匹配。消融组按照第一部分实验方法准备方式及消融策略行HIFU消融右房峡部，对照组仅接受常规脱毛、脱脂、脱气处理及建立双侧人工胸水，不消融，和消融组相同条件饲养至术后30天，饲养过程中监测体重保持两组间体重匹配。术后第30天在气管插管、人工气囊辅助呼吸下行开胸电生理检查，穿刺双侧颈静脉及右股静脉，分别放入冠状窦电极、高位右房普通电极和低位右房普通电极，开胸后剪开心包，制作心包吊篮，电极放置到位后分别从低位右房释放电刺激，记录传导至高位右房和冠状窦口的时间，再从冠状窦口释放电刺激，记录传导至高位右房和低位右房的时间。电生理检查结束后，获取心脏标本进行大体观察及组织学检查，包括HE染色，内皮细胞钙粘蛋白和心房肌缝隙连接蛋白免疫组化测定。结果：消融组顺利完成右房峡部消融及观察终点的开胸电生理检查。消融组平均总消融时间为(61.4±9.0)s，去除等待时间，实际消融时间平均为（19.0±2.6）s，消融前平均心率（93.2±5.4）bpm，消融后平均心率（87.5±2.9）bpm,实时二维超声监控图像清晰，消融前后平均灰度下降（30.5±3.0）。电生理检查发现消融组右房内低位右房刺激向冠状窦口传导时间较对照组显著增加，虽然冠状窦口刺激向低位右房传导时间无明显增加，但传导途径经由高位右房，证实右房峡部在消融术后30天仍具有双向电阻滞效应。大体观察消融CTI内外膜结构光滑完整，HE染色提示消融区心肌在全程透壁坏死的基础上出现慢性纤维化，免疫组化提示消融组内皮细胞钙粘蛋白表达较对照组下降，提示内皮细胞功能受到部分抑制，对照组峡部心肌缝隙连接蛋白表达丰富，在消融组未见缝隙连接蛋白表达。结论：高强度聚焦超声经胸成像定位及消融策略，在消融后30天内仍然存在经右房峡部的双向电传导阻滞及全程透壁损伤，证实了此消融术式在中期观察期内安全有效更多还原

【Abstract】 PART1THE FEASIBILITY OF CLOSED-CHEST ABLATION OFTHE CAVOTRICUSPID ISTHMUS USINGHIGTH-INTENSITY ULTRASOUND INBackgrounds: Cavotricuspid isthmus(CTI) as the critical conductionarea for typical atrial flutter, is the first choice of treatment targets withradiofrequency ablation via catheter. However, the anatomic differences ofCTI and the limited injury depth of radiofrequency ablation requires newenergies as an alternative strategy. Moreover, the catheter manipulationneeds X-ray induction, and both the catheterization and X-ray have someside-effect for body, especially the radioactive injuries for doctors andpatients, so it requires new strategies independent of catheterization andX-ray. High-intensity focused ultrasound(HIFU) can ablate tumor inside thebody via extracorporeal method in the previous studies, and it also caninduce point and linear injuries on cardiac tissue in vitro. Furthermore, it hasbeen identified to induce atrial septum injury via open-chest way in vivo. Based on these, HIFU is chose to explore the feasibility of cardiac ablation invivo via closed-chest ways.Aims: To study the feasibility of CTI ablation using HIFU viaimprovement of cardiac acoustic environments.Methods: Ten healthy mongrel dogs, anesthesized, removing hair,degreased and degassed skin, constructing bilateral pleural effusion model,then using JC-200HIFU apparatus to localize the CTI and performingablation strategy as400W X2s from the TV to IVC. The average grey-scaledifference was observed, and ECG monitoring the process. One week afterablation, the experimental animal was sacrificed and the structure during theacoustic process was observed, the CTI specimen was observed on theaspects of morphology and histology. Meanwhile, the side-effect wasobserved. Results: Eight of ten reached the ablation termination of wholetransmural necrosis of CTI via closed-chest using HIFU. The average valueof total ablation time was (54.5±12.0)s，and the actual average time was17.0±3.4s except the waiting interval time. Occasional single premature beatwas observed on two animals and one lung injury was observed in oneanimal which could be ablation to the whole transmural necrosis oftermination. No injuries of pleural effusion and pericardial effusion wasobserved one week after ablation. No injuries of RCA was observed in thesection.Conclusions: Through improvement of cardiac acoustic environment, it can acquire clear ultrasonic image of CTI. Furthermore, this studyindicates the feasibility of CTI ablation using transthoracic HIFU and themethod is safe and effective. PART2THE ELECTROCONDUCTION INSIDE THE RIGHTATRIUM VIA CAVOTRICUSPID ISTHMUS AND SAFTEYOF ABLATION DURING THE MID-TERM PERSPECTIVEINTERVALS USING HIGH-INTENSITY FOCUSEDULTRASOUNDBackgrounds: The whole transmural necrosis of Cavotricuspidisthmus(CTI) is usually the anatomic ablation target for treatment of typicalatrial flutter, as a result, bilateral conduction block(BCB) is the alternativeoptimal ablation target for clinical treatment instead. Because of anatomicdifferences of CTI and the limited injury depth of radiofrequency energy,about10%patients cannot be cured via classic radiofrequency ablation.Based on the findings from experiments in part one, the safety andeffectiveness should be identified for further study.Aims: To study the electric conduction characteristics inside the rightatrium after CTI ablation using transthoracic HIFU and to estimate the safetyof the method at the30d.Methods: Eight canines were divided into two groups, four in theablation group and four in the control group. The ablation group followed the strategy of preparation and ablation as in the first section. And30d later, thetwo groups received open-chest cardiac electricity conduction test undertracheal tube and artificial breath. The bilateral jungular veins and rightfemoral vein were centesised for putting into electrodes, one into coronarysinus, one at the superior RA and one at the inferior RA. And the conductiontime inside the RA from the inferior RA to CS was recorded. The animalswere sacrificed after the test. The CTI specimen was preserved formorphology and histology observation including immunohistochemical testfor cadherin and connexin expression in the ablation area and the controlgroup. Results:The average value of total ablation time was (61.4±9.0)s，andthe actual average time was （19.0±2.6）s. The average difference ofgrey-scale value was30.5±3.0. All of the animals survived during theperspective interval time30d. The electricity conduction test identified theBCB of CTI, indicating the effectiveness of ablation. And little expression ofconnexin in the ablated CTI identified the deadly necrosis of atrial myocytes,but the decreasing level of endothelial cadhesin indicated the weakenfunction of endothelial cells inspite of its contact structures.Conclusions: The accurate location for canine CTI in vivo could beperformed under two-dimensional ultrasonography integrated in the HIFUapparatus. Based on this, the study demonstrated it could ablate canine CTIto the termination of whole transmural necrosis in vivo by closed-chest wayusing HIFU for the first time, via non-catheter and without X-ray inducing, and the security and effectiveness was indentified during the30d afterablation.更多还原