多电极射频治疗肿瘤的体外实验研究

目的 了解射频消融灶的大小与功率及时间的关系。超声与肉眼病理测值的关系。消融灶与周围组织的关系。方法 新鲜离体牛肝5只，电极置于距肝表面1cm,4cm处，用不同功率和时间实验，牛肾2只，将肾放在肝上，电极置于距肾表面1cm深处，观察肾和肝脏表面的变化。结果 消融灶超声表现为强回声，肉眼病理为椭圆灰白色区，时间相同，功率不同或时间不同，功率相同时，消融灶的肉眼解剖测值之间差别无显著性意义，但与超声测值相比差别有极显著性意义。距肝表面1cm消融时可见肝表面局部呈灰白色，4cm消融肝表面局部无变化，肝肾重叠放置时，可见肾脏前后两表面，与肾脏接触的肝表面呈灰白色改变。结论 射频消融灶大小不随时间和功率的增加而增加，超声化肉眼解剖测值大，近表面处的消融灶可伤及表面结构及临近组织。     

多因素影响冷循环射频消融疗效的体外实验研究

目的探讨冷循环射频初始功率、射频时间、射频针等因素对消融效果的影响,评价超声判断消融区的价值。方法超声全程监控下对新鲜离体牛肝进行冷循环射频消融,单电极针作用下观察不同初始功率(80W、120W)和不同射频时间(5min、8min、10min)消融灶的实时演变过程,此外进行5min射频时间下不同初始功率(80W、120W)的集束针实验。实验结束后纵剖开标本,肉眼观察消融灶形态,并测量其大小,光学显微镜下观察消融灶病理学变化。结果肉眼测量消融灶显示:初始功率80W组消融灶随时间延长而增大,但扩展速度呈减缓趋势,初始功率120W组消融灶随时间扩大不明显;在射频时间较短的情况下初始功率120W组消融灶大于初始功率80W组,时间延长后两者差别缩小,射频时间达10min后两者形成大小相似的消融灶。集束针所形成消融灶的纵横比小于单电极针,剖面更接近圆形。超声显示强回声区范围与实际消融区有一定误差,纵径多大于实际,横径受声影遮盖难以测定,在大消融灶中往往小于实际。光学显微镜下消融区细胞形态、结构无明显变化。结论不同的射频时间和初始功率对冷循环射频消融能力有一定影响,高初始功率在增加产热的同时也降低热能传导,实际应用中应综合考虑。与单电极针相比,集束针形成的消融灶更接近实体肝肿瘤形态,对2cm左右的小肝癌疗效更可靠。超声可用于引导射频定位,但不能准确判定消融区边界。     

离、活体对比实验探讨微波消融肾组织的研究

目的 通过对比观察植入式微波对正常离、活体猪肾实质的消融作用,为肾癌微波消融提供基础实验依据.方法 采用水冷式微波针,发射频率为2 450 MHz,输出功率范围为50～80 W,作用时间范围为300～900 s,选择不同能量组合对离、活体猪肾实质消融,观测消融形态、大小、温度变化等数据.结果 消融灶的形态在离、活体均为类圆形;随微波输出能量的增加,消融体积均呈非线性增加;当功率大于60 W后,长径和炭化区增加明显(P<0.05);增加作用时间,宽径增幅大于长径增幅,消融形状逐渐接近球形.活体状态下消融体积、宽径、长径均显著小于离体(P<0.05).活体实验病理证实微波消融区为凝固性坏死表现.结论 植入式微波可在猪肾实质内形成可控范围的类圆形消融坏死灶,但范围和形态均与血流状态有关.     

植入式微波消融离体猪肾实验研究

目的探讨植入式微波对离体状态下正常猪肾实质的消融作用。方法采用水循环内冷式硬质微波天线,微波频率为2450MHz,分别应用不同作用功率和作用时间对离体猪肾进行消融。结果植入式微波在不同条件下消融形态稳定,均为椭球形,统计了消融的体积、最大长径和宽径等参数。结论植入式微波消融离体猪肾实质凝固形态较满意,凝固范围随功率和时间增加而有程度不同的增大,微波消融有望在肾脏肿瘤微创治疗中发挥重要的作用。     

体外肝组织微波消融范围的研究

目的 研究微波消融治疗在离体人肝组织的消融灶形态及范围.方法 通过在不同初始功率、作用时间下对离体人肝组织进行单针微波消融,超声及大体解剖观察消融灶的形态及范围,镜下观察消融灶病理学变化.结果 相同初始功率组消融灶随作用时间延长而增大;在相同作用时间下初始功率70 W组消融灶大于初始功率50 W组,其差异均有统计学意义（P＜0.05）.超声显示消融灶范围较大体解剖测量范围大,两者比较差异具有统计学意义（P＜0.05）.病理检查见消融灶中心凝固区肝组织均凝固坏死,距凝固区边缘0.5 cm处有1例可见残存水肿肝细胞、1 cm处有17例可见残存肝细胞组织.结论 微波消融灶呈椭圆形,其范围随初始功率及作用时间增加而扩大,超声测量比大体解剖消融范围大,消融灶与周围组织间有移行带.     

新型内冷微波天线消融肝组织的实验研究——凝固灶短轴径与功率的关系

目的 探讨微波消融肝组织凝固灶短轴径(SD)与微波功率的关系.方法 应用新型内冷微波天线,取10 min和20 min两个时间段与不同功率条件组合,凝固离体猪肝和活体狗肝,完成后分别测量凝固灶的SD和长轴径(LD),比较相同时间与功率条件下离体猪肝与活体狗肝消融灶SD、LD和SD/LD(其值越接近1.0凝固灶形念越接近球形),并分析SD与功率的关系.结果 相同条件下,活体狗肝凝同灶SD和LD均较离体猪肝小(P<0.01);而SD/LD值的差异无统计学意义(P>0.05).同离体肝相似,活体肝凝固灶SD与功率的关系表现为高度近似的线性关系(r界于0.96～0.99之间,P<0.01),其线性拟合方程截距减小,斜率增大.结论 离体肝和活体肝组织的微波凝固灶SD大小在一定条件下与功率呈高度近似的正线性关系.     

新型腔内射频消融导管消融离体猪肝

目的 观察新型腔内射频消融导管对离体猪肝(肝实质、栓子模型)的消融效果。方法 应用EMcision Habib腔内射频消融导管及RITA射频发生器对新鲜离体猪肝肝实质及栓子模型进行消融,输出功率分别为5 W、10 W、15 W和20 W,消融时间分别为60 s、90 s和120 s,观察消融灶组织凝固形态及范围。结果 消融肝实质时,输出功率为10 W、延长消融时间(90 s延长至120 s),输出功率为15 W、延长消融时间(60 s延长至90 s)以及消融时间为60 s和90 s、增加输出功率(15 W增加至20 W)获得的消融灶长径增加(P均<0.05),而宽径增加不明显(P均>0.05)。消融栓子模型时,输出功率为10 W、延长消融时间(90 s延长至120 s),以及消融时间为60 s、增加输出功率(15 W增加至20 W)均可增加消融灶长径(P均<0.05),而宽径增加不明显(P均>0.05)。肉眼见所有消融灶附着处血管管壁颜色均与邻近血管管壁无差异。结论 采用EMcision Habib腔内射频导管消融离体猪肝可出现明确的消融范围,且对管道壁无明显损伤。     

冷循环射频消融输出功率及作用时间与凝固灶大小的关系

目的:分析冷循环射频消融输出功率及作用时间与牛肝组织凝固灶大小的关系。方法:实验于2006-11/2007-01在中山大学附属第二医院超声科治疗室完成。对新鲜离体牛肝组织进行冷循环射频消融,测量在不同作用时间(6,8,10,12,14min)和输出功率(50,60,70,80,90W)组合条件下凝固灶纵径(Dv)及横径()大小,并Dt分析凝固灶大小与作用时间、输出功率的关系。结果:在作用时间(14min)和输出功率(90W)范围内,凝固灶大小与作用时间和输出功率有高度线性相关关系,凝固灶纵径与作用时间、输出功率的相关系数r=0.951,P<0.001,二元线性回归方程为Dv=11.986 0.833T 0.172P(T为消融时间,P为输出功率);凝固灶横径与作用时间、输出功率的相关系数r=0.977,P<0.001,二元线性回归方程为Dt=9.246 0.907T 0.102P。结论:冷循环射频消融输出功率及作用时间与牛肝组织凝固灶大小呈正相关。     

超声引导激光消融实验兔肾的有效性评估

目的初步评估超声引导激光消融实验兔肾的有效性。方法超声引导下对4只正常新西兰兔肾进行单针或多针激光消融(每根光纤设定功率5W,持续6min,总能量1800J),观察消融过程中和消融结束后二维超声表现及消融结束后消融灶超声造影表现,并观察消融灶大体及镜下病理表现。结果二维超声上消融灶大体呈椭圆形,其中央部分为高回声,周边部分为稍低回声,与周围肾实质分界模糊,内未见血流信号;超声造影示消融灶整体呈无增强;双针消融灶(30mm×15mm)比单针消融灶(13mm×12mm)范围大。大体标本示消融灶中央为碳化区,周边呈粉红色区,与未消融区分界清晰。镜下可见消融灶中央凝固性坏死,周边变性伴间质出血,未消融区组织形态正常且与消融灶分界清晰。结论超声可引导激光对肾脏进行有效消融。结合超声造影,可进一步评估消融效果。多针消融可扩大消融范围。     

羊胸腺微波消融的实验研究

目的探讨微波消融技术对羊胸腺组织的影响。方法利用微波消融治疗仪和发射段长5 mm、直径2mm的电极,分别以不同功率和时间对离体羊胸腺组织进行超声引导下消融,测量气化范围及消融灶大小,并进行病理学检查。分析消融灶大小与消融功率、时间的关系;观察微波消融后羊胸腺组织的病理变化,以及超声下气化范围和实际热损伤范围的大小关系。结果随着消融时间和功率的增加,气化区长径、短径和气化范围及消融灶长径、短径和消融灶面积均呈现增大趋势;同一消融功率、时间下,气化范围小于消融灶面积(P0.05);消融灶质地变硬,边界清晰,光学显微镜下,消融灶内胸腺组织形态失常,其内淋巴细胞难以辨认。结论微波消融功率、时间越大,超声气化范围和消融灶大小往往越大;微波消融羊胸腺组织的热损伤范围大于超声观察的气化范围,临床通过气化范围评估消融范围并不可靠。     

射频消融猪甲状腺毁损灶形成的实验研究及意义初探

目的:探讨射频消融技术对猪甲状腺组织的影响,以了解毁损灶的形成大小与时间、功率的关系以及射频消融猪甲状腺组织的病理变化。方法:利用射频仪和外裸长5mm、直径2mm电极,分别予不同功率和时间对离体猪甲状腺组织进行消融,测量毁损灶的大小以及进行病理学检查。结果:单电极毁损灶为类圆形,在射频功率为60W时,随时间的延长,毁损坏死灶明显增加;当功率为70W时随时间的延长,毁损坏死灶范围虽增加但量有限;当功率为80W时,毁损坏死灶大小与时间没有明显相关性,大小趋于稳定。毁损区域甲状腺组织变硬,呈灰白色,与周围组织分界清楚;光学显微镜下消融区组织细胞形态和正常甲状腺组织无明显差别。结论:单根电极对甲状腺组织射频消融可形成最大直径为10.1mm的类圆形消融灶。当功率小于70W时,其射频毁损的范围大小是可以调节的,其大小与功率、时间呈正相关。     

超声引导下微波凝固离体猪肾的实验研究

目的 通过研究超声引导下微波对离体猪肾的凝固作用,为超声引导下微波凝固治疗肾脏病变的可行性及安全性提供依据.方法 在超声引导下,采用KY-2000型微波治疗仪和水循环内冷式微波天线以不同作用功率、时间对离体猪肾进行微波凝固,观察微波凝固过程,分析凝固灶范围与功率和时间的关系.结果 超声可清晰显示微波针在肾实质内的位置....     

Percutaneous tissue ablation by radiofrequency thermal energy as a prelim to tumour ablation

Porcine hepatic tissue was ablated in vitro and in vivo with radiofrequency (RF) energy applied through various percutaneous probes. Ultrasound was used for guidance. The technique was assessed for potential use to ablate tumours percutaneously. Tissue ablation was performed in two porcine cadaver and six live piglet livers in various experiments, three RF generators with either bipolar gold probes, 18–22 gauge modified angiocath needles, titanium curved and spiral 0.018″ guidewires, three-pronged grabber baskets, and/or a thermistor (temperature-controlled) probe were used to induce the RF effect with simultaneous assessment by real-time ultrasound. Gross and microscopic analysis of the liver was undertaken after acute sacrifice of the animals. The hepatic tissue that surrounded the probe after RF energy application became increasingly echogenic sonographically. The size of the echogenic area on ultrasound corresponded to the size of the thermal lesion on gross and microscopic examination. Thermal lesions up to 2 cm were created. The size of the thermal lesion was proportional to the surface area of the probe, the shape of the probe, the generator power, and the length of time that the RF energy was applied. The thermistor probe permitted improved contact and control by preventing central charring, cavitation, and boiling of the tissue that occasionally was observed with other probes. Percutaneously applied radiofrequency energy using US-guidance and monitoring is a feasible method to ablate hepatic tissue.     

植入式微波消融活体猪肾实验研究

目的通过研究植入式微波对正常活体猪肾实质的消融作用,为微波消融肾脏肿瘤的临床应用提供实验依据。方法采用水循环内冷式硬质微波针,微波发射频率为2450 MHz,能量输出50～80 W/600 s,观察不同能量条件下微波对活体猪肾实质的消融作用。结果植入式微波在不同能量条件下消融灶的形态均为椭球形,由消融中心向外周依次分别为组织炭化区、消融凝固区、充血反应区和正常组织区。不同区域病理表现各异。实验中分别统计了不同能量状态下消融范围（最大长径、宽径和体积）和天线周围温度变化。结论植入式微波消融技术可在活体猪肾实质形成类圆形消融坏死区,消融范围可随能量改变而变化。     

Simultaneous Multipolar Radiofrequency Ablation in the Monopolar Mode Increases Lesion Size

Delivery of radiofrequency (RF) energy from the distal tip of electrophysiology catheters produces lesions that may be too small to ablate arrhythmogenic sites during a single application of RF energy. To produce larger lesions, we delivered RF energy via a quadripolar catheter in which all four electrodes were connected in unipolar fashion. The catheter (Webster Labs) had a 4-mm tip, 2-mm ring electrodes, and 2-mm intereiectrode distance. Lesion size was compared using RF energy delivered in a multipolar configuration with that delivered only to the distal tip using fresh bovine ventricular tissue. In vivo, RF lesions were made in dogs using the distal tip as well as all four poles of the same catheter inserted percutaneously. RF energy was delivered using a constant voltage at a frequency of 400 kHz. Preliminary experiments were conducted to determine the maximum power deliverable without coagulation using each electrode configuration. The use of simultaneous muitipolar RF ablation produced significantly larger lesions both in vitro and in vivo. The length of the lesion was increased by a factor of approximately 2 in both the in vitro and in vivo experiments. There was a trend toward an increasing depth of the lesion by simultaneously applying RF energy to all four electrodes. Lesion width was significantly increased in the in vivo studies. We concluded that simultaneous muitipolar delivery of RF energy produces larger lesions than can be obtained with delivery of RF energy to the distal tip alone. This technique may offer a means of increasing lesion size, leading to a decrease in the number of applications of RF energy necessary for ablation of arrhythmias.     

超声引导下扩大微波消融活体犬脑组织安全性和可行性的实验研究

目的 探讨扩大超声引导下实验家犬脑组织微波消融灶的可行性和安全性,为超声引导微波消融脑肿瘤的临床应用提供实验依据.方法 以不同微波功率(20 W、30 W、40 W)及不同消融时间(60 s、90 s、120 s、150 s、180 s)随机作用于20只家犬脑组织,术中监测颅内压并应用电生理监测仪监测脑电图变化,术后1 h超声探测消融灶声像图变化,术后4~5 h取实验犬脑组织观察消融灶大体及镜下病理变化并测量水肿带宽度.应用多元线性回归分析消融灶长径、宽径与微波输出功率及时间的关系,并建立回归方程.结果 (1)20只实验家犬中10只完成颅内压监测,其中8只从消融开始至消融结束30 min内颅内压未见明显变化;2只颅内压显著升高.(2)脑电图监测结果显示消融灶波形平直,平均波幅(5.7±1.61)μV,消融灶旁开0.3 cm处以弥散性δ和θ波为主,消融灶旁开0.6 cm处以δ波为主.(3)病理大体标本显示微波消融灶呈椭圆形,随着消融时间及功率增加,消融灶长径(L)及宽径(W)均呈线性增加,消融灶长径、宽径与微波输出功率及时间建立的多元线性回归方程分别为L＝0.038P+0.009T,W＝0.012P+0.007T.结论 实验研究结果初步表明,在20 W×60 s~40 W×150 s时间功率组合范围内,消融灶随微波输出功率及消融时间增加而消融范围增大,在此时间功率组合范围内增加脑组织微波消融范围安全、可行.     

Early Assessment of Biophysical Parameters Predicts Lesion Formation During RF Energy Delivery In Vitro

Background: There is no currently available technology to accurately predict ablation lesion size within seconds of onset of delivery of radiofrequency (RF) energy. Methods: Changes in several biophysical characteristics of cardiac tissue in vitro within 5–15 seconds of the onset of RF energy were evaluated to predict lesion formation at 120 seconds. RF energy was applied with a 50% duty cycle to measure heating and cooling behavior of the electrode temperature sensor. Changes in impedance, phase angle, and the resulting resistance and capacitance, power, and electrode temperature variation during RF ablation were analyzed. Results: A combination of electrical‐based parameters measured online as early as 5, 10, and 15 seconds after onset of RF energy in vitro was found to explain 63, 75, and 76% of variability (R²) of lesion volume. These correlations were better than any single parameter, particularly impedance and target temperature. Conclusions: A combination of electrical‐based parameters provides better correlation with lesion formation than a single parameter and may be useful to predict lesion size during RF ablation in vivo. These parameters appear to represent changes in the tissue during heating. (PACE 2010; 33:1082–1088)     

实时谐波灰阶超声造影评价犬前列腺射频消融灶

目的应用实时谐波灰阶超声造影技术观察实验犬前列腺射频消融灶,并与常规二维超声检查、彩色能量多普勒超声检查及病理学结果进行比较,以评估实时谐波灰阶超声造影评价前列腺射频消融灶的有效性。方法对5条犬前列腺两侧叶行射频消融,术后即刻行经直肠二维超声检查、能量多普勒超声检查和超声造影。超声造影下测量消融灶体积,并与病理学标本大体测量的结果相比较。结果常规二维超声在射频消融后即刻无法准确地观测消融灶的范围。彩色能量多普勒超声虽然不能准确评价消融灶的体积,但对消融灶的血流变化比较敏感,能及时反映消融灶血流状态的改变。超声造影则能准确评价消融灶的范围,其测量结果与病理学结果比较没有统计学差异,且超声造影能够实时观察消融灶内部及周边血流灌注的情况。结论常规二维超声和彩色能量多普勒超声能实时反映消融灶回声的变化和血流情况的改变。实时谐波灰阶超声造影技术能准确地评价前列腺射频消融灶的范围。     

Segment by Segment Linear Ablation with an Articulated Bilimb Catheter: Initial Experimental Results

Transcatheter radiofrequency (RF) ablation of atrial fibrillation or flutter requires the creation of linear lesions. However, conventional catheters are not predictably effective because of poor endocardial contact, and limited lesion size and penetration. The purpose of the study was to assess, in the right atrium, the efficacy and safety of a new catheter designed to create long myocardial tissue lesions using RF energy. The main characteristics of this 8 Fr deflectable RF ablation catheter were: (1) a perpendicularly contacting articulated bilimb electrodes ensuring stable and firm endocardial firm contact; and (2) an irrigated planar interface. Three different electrode prototypes were tested. Fourteen anesthetized sheep weighing 61 ± 7 kg underwent RF ablation in the right atrium using three incremental power levels (25 to 45, 50, 55 to 75 W) with the aim of creating fully transmural (FT) lesions, defined as continuous and complete epicardial and endocardial lesion imprints. The animals were euthanized 1 hour later for macroscopic and histologic examinations. Forty-three of the 80 right atrial lesions created, in smooth as well as in trabeculated areas, were FT. The percentage of FT lesions increased with the applied power from 37% with 25–45 W, to 49% with 50 W, and up to 86% for 55–75 W. In all but two cases, histologic examination showed no discontinuity between FT lesions produced by both limbs resulting in 19 coalescent linear lesions with an average size of 25 × 6 × 4 mm (length × width × depth). In situ bipolar electrograms after ablation in the FT group showed split potentials and/or a marked decrease in amplitude from 2.85 ± 1.79 to 0.33 ± 0.14 mV (P = 0.001) accompanied by near complete disappearance of unipolar electrograms. There was no perforation due to RF ablation. In conclusion, continuous and FT lesions can be achieved in various areas of sheep atria, including the trabecular right atrium, with a perpendicularly contacting bilimb electrode catheter. It represents a promising tool for catheter ablation of atrial fibrillation and flutter.