射频消蚀术前后血清心肌酶变化的研究

对３３例患者射频消蚀术（简称ＲＦＣＡ）前后的血清心肌酶（ＣＫ、ＣＫ－ＭＢ．ＡＳＴ、ＬＤＨ、ＬＤＨ１）进行动态观察。结果表明：ＲＦＣＡ后血清心肌酶活性均有不同程度的升高（Ｐ＜０．０１）；ＣＫ及ＣＫ－ＭＢ于术后６小时达到峰值，２４小时恢复至正常水平，ＡＳＴ于术后１２小时达峰值、时达峰值，７２小时恢复正常，ＬＤＨ及ＬＤＨ，的达峰及恢复时间分别为２４小时和１２０小时；多元线性相关分析显示心肌酶活性的升高程度与消蚀靶点个数呈高度正相关（ｒ＝０．８１３６，Ｐ＜０．００１）．揭示ＲＦＣＡ对心肌组织有不同程度的损伤，影响心肌损伤范围的主要因素是消蚀靶点的多少。因此，在ＲＦＣＡ中，应力求标测定位准确，尽量减少试探性放电，以最大限度地减少心肌损伤。     

Creating continuous linear lesions in the atria: a comparison of the multipolar ablation technique versus the conventional drag-and-burn

INTRODUCTION: Catheter-based treatment of atrial fibrillation (AF) requires the isolation of the triggering foci as well as modification of the atria with substrate that sustains AF. The creation of linear lesions in the left atrium with standard radiofrequency ablative methods requires long procedural times with unpredictable results. METHODS: The simultaneous delivery of phase-shifted radiofrequency energy from a multipolar catheter was compared to the conventional drag-and-burn technique for creating linear lesions in 10 dogs. Four atrial sites were targeted under intracardiac ultrasound and fluoroscopic guidance in each of 10 dogs. The conventional drag-and-burn technique or the multipolar phase-shifted ablation catheter was randomly applied for 60 seconds and compared. RESULTS: Creating linear lesions using the simultaneous multipolar phase-shifted ablation catheter was on average 11.0 minutes faster (33.6 minutes vs 44.6 minutes, P < 0.01) than the drag-and-burn method. The fraction of the lesion length achieved using phase-shifted ablation compared to that intended was 23% greater (76% vs 53%, P < 0.01), and has less discontinuities (0.1 compared to 0.8 discontinuities/line, P < 0.003). There was no significant difference in either the lesion transmurality, or fluoroscopy times. CONCLUSION: The simultaneous delivery of phase-shifted, radiofrequency energy using a multipolar catheter is more effective and efficient in producing linear lesions than the traditional drag-and-burn technique. Using the multipolar ablative method to create linear lesions may be a useful technique in the treatment of patients with substrate-mediated atrial fibrillation.     

A novel hybrid transcatheter ablation system that combines radiofrequency and cryoenergy

Introduction: Radiofrequency (RF) and cryoenergy are largely considered independent modalities for the transcatheter ablation of cardiac arrhythmias. There are numerous theoretical advantages to engineering a system capable of delivering both energy forms.
Methods and Results: We designed a hybrid steerable catheter capable of delivering RF and cryoenergy independently, sequentially, and simultaneously. The novel catheter system was tested pre-clinically by creating a total of 180 ablation lesions in 20 mongrel dogs. Right atrial and right and left ventricular sites were preselected by a randomized factorial design devised to compare sequential and simultaneous RF and cryoenergy applications to standard RF, irrigated RF, and standard cryoablation. A steerable 4-mm electrode-tip hybrid catheter ("Fire and Ice") was created by modifying a 7 F cryocatheter (Freezor™, CryoCath Technologies, Montreal, Canada). RF energy was injected via a copper wire, thermocouples were isolated to reduce RF interference, and 100 KHz band pass filters and RF chokes were added. Sequential low-dose RF (20 W, 60 seconds) preceding or following cryoablation resulted in larger lesions (P = 0.0010). The addition of RF energy did, however, produce more thrombus than cryoenergy alone, with clot detected on 82.4% versus 12.1% of ablation lesions, P < 0.0001. Simultaneously applying the two energy modalities (45 W, 10 or 30°C, 60 seconds) created more voluminous lesions than standard RF ablation (median 288.1 vs 126.1 mm³, P = 0.0333) of similar dimension to irrigated RF ablation.
Conclusion: A versatile catheter system was fashioned capable of creating standard cryoablation lesions, standard RF lesions, and simultaneous lesions of similar dimension to irrigated RF.     

EFFICACY OF LAPAROSCOPIC RADIOFREQUENCY ABLATION FOR HEPATOCELLULAR CARCINOMA COMPARED TO PERCUTANEOUS RADIOFREQUENCY ABLATION WITH ARTIFICIAL ASCITES

Aim: Hepatocellular carcinoma (HCC) nodules close to the liver surface exhibit high recurrence compared to those in distal parts of the liver. Moreover, when nodules remain adjacent to the gastrointestinal tract or gallbladder, severe complications such as perforation of those organs may occur due to invasive therapy. Percutaneous radiofrequency ablation (PRFA) with artificial ascites or laparoscopic radiofrequency ablation (LRFA) are used to treat these patients to avoid complications. The purpose of the present study was to assess the efficacy and safety of these two methods. Methods: Subjects comprised 74 patients (48 men, 26 women; mean age, 68.5 ± 8.0 years; range, 46–89 years) with 86 HCC nodules. PRFA with artificial ascites was carried out for 37 patients (44 nodules) and LRFA was used for 37 patients (42 nodules). Clinical profiles were compared between groups. Results: No significant differences in clinical profiles were found between patients treated by PRFA or LRFA. Mean number of treatments was significantly lower for LRFA (1.0 ± 0.0) than for PRFA (2.1 ± 1.0, P < 0.001). Mean number of PRFA treatments was 2.2 ± 1.0 in patients with HCC nodules >2 cm in diameter, whereas all tumors were completely ablated with only one session of LRFA. The safety margin was significantly wider for LRFA than for PRFA. Conclusion: LRFA is a better treatment option for ablation of HCC nodules >2.0 cm in diameter.     

Pediatric radiofrequency catheter ablation registry success,fluoroscopy time,and complication rate for supraventricular tachycardia: comparison of early and recent eras

INTRODUCTION: To assess changes of success rate, fluoroscopy time, and complication rate for six supraventricular tachycardia pathways/ mechanisms, data from the Pediatric Radiofrequency Catheter Ablation Registry were grouped into two eras (1991-1995; 1996-1999). METHODS AND RESULTS: Data from the early era and the late era were compared using the Chi-square test for the outcomes of success rate and complication rate and using the Student's t-test for the outcome of mean fluoroscopy time. In the Registry as a whole, ablation failure rates fell from 9.6% in the early era to 4.8% in the recent era, a reduction of 50% overall. Improved success rates were found for posterior septal, right free-wall, and left free-wall pathways and for AV nodal reentry, whereas anterior septal pathways and atrial ectopic-focus tachycardia did not show improvement. Mean fluoroscopy time overall decreased 21% from 50.9 +/- 39.9 minutes to 40.1 +/- 35.1 minutes. Individually, the improvement in fluoroscopy time was found for all but the atrial ectopic-focus tachycardia mechanism. The complication rate decreased from 4.2% to 3.0%, with significant decreases for left free-wall and posterior septal pathways. CONCLUSION: Patient selection strategies to optimize radiofrequency ablation outcomes in children, which have been based on the previously published Registry data, should be reconsidered in light of these new, updated data. The lack of uniform improvement provides the impetus for further research and development of new approaches and technologic advances so that further improvement can be achieved.     

Pace mapping of Koch's triangle reduces risk of atrioventricular block during ablation of atrioventricular nodal reentrant tachycardia

INTRODUCTION: Slow pathway (SP) ablation of AV nodal reentrant tachycardia (AVNRT) can be complicated by second- to third-degree AV block. We assessed the usefulness of pace mapping of Koch's triangle in preventing this complication. METHODS AND RESULTS: Nine hundred nine consecutive patients undergoing radiofrequency ablation of AVNRT were analyzed. Group 1 (n=487) underwent conventional slow pathway ablation. Group 2 (n=422) underwent ablation guided by pace mapping of Koch's triangle, which located the anterogradely conducting fast pathway (AFP) based on the shortest St-H interval obtained by stimulating the anteroseptal, midseptal, and posteroseptal aspects of Koch's triangle. In group 2, AFP was anteroseptal in 384 (91%), midseptal in 33 (7.8%), and posteroseptal or absent in 5 (1.2%). In 32 of 33 patients with midseptal AFP, slow pathway ablation was performed strictly in the posteroseptal area. In 4 of 5 patients with posteroseptal or no AFP, retrograde fast pathway was ablated. Two patients refused ablation. Persistent second- to third-degree AV block was induced in 7 (1.4%) of 487 group 1 patients versus 0 (0%) of 422 group 2 patients (P=0.038). Ablation was successful in all patients in whom ablation was performed. CONCLUSION: Pace mapping of Koch's triangle identifies patients in whom the AFP is absent or is abnormally close to the slow pathway. In these cases, guiding ablation helps to avoid AV block.     

Percutaneous microwave and radiofrequency ablation for hepatocellular carcinoma: a retrospective comparative study

Background Percutaneous microwave ablation and radiofrequency ablation are two commonly used modalities for the treatment of hepatocellular carcinoma; however, comparisons of them have not been documented adequately. Methods Of 102 patients with biopsy-proved hepatocellular carcinoma, 49 (98 nodules) were treated percutaneously with microwave ablation and 53 (72 nodules) with radiofrequency ablation. The local tumor control, complications related to treatment, and long-term results of the two modalities were compared retrospectively. Results The complete ablation rates were 94.9% (93/98) using microwave ablation vs 93.1% (67/72) using radiofrequency ablation (P = 0.75), and no significant differences were found either in the ablation of tumors of 3.0 cm or less (P = 1.00) or in those of more than 3.0 cm (P = 1.00) between the two modalities. The local recurrence rates were 11.8% (11/93) using microwave ablation vs 20.9% (14/67) using radiofrequency ablation (P = 0.12), and there were no significant differences between the two modalities either in tumors of 3.0 cm or less (P = 0.36) or in those of more than 3.0 cm (P = 0.82). The rates of major complications associated with microwave ablation and radiofrequency ablation were 8.2% (4/49) vs 5.7% (3/53; P = 0.71). The disease-free survival rates in the microwave ablation group were 45.9%, 26.9%, 26.9%, and 13.4% at 1, 2, 3, and 4 years, respectively, and those in the radiofrequency ablation group were 37.2%, 20.7%, and 15.5% at 1, 2 and 3 years, respectively (P = 0.53). The 1-, 2-, 3-, and 4-year cumulative survival rates for patients who underwent microwave ablation were 81.6%, 61.2%, 50.5%, and 36.8%, respectively, and for patients who underwent radiofrequency ablation the rates were 71.7%, 47.2%, 37.6%, and 24.2%, respectively (P = 0.12). Conclusions Percutaneous microwave ablation and radiofrequency ablation are both effective methods in treating hepatocellular carcinomas. The local tumor control, complications related to treatment, and long-term survivals were equivalent for the two modalities.     

Radiofrequency induced lesion characteristics according to force–time integral in experimental model

Contact force (CF)-sensing technology has enabled accurate real-time CF measurement in tissue. Average CF, which is quantified by the force–time integral (FTI), correlates with lesion volume.Little is known about which of the time and force factors that compose FTI plays a more important role and which is a better index for predicting lesion size, FTI, or force–power–time index (FPTI). Investigators sought to identify a better index for predicting radiofrequency ablation lesion formation with experimental model.Radiofrequency current was delivered to the swine skeletal muscle at radiofrequency energy current was delivered at 4 fixed power settings (15, 25, 30, and 40 W) for 6 variable time durations (5, 10, 20, 30, 40, and 50 s) with 6 variable CF settings (5, 10, 20, 30, 40, and 50 g). At each setting, the following parameters were evaluated:

• (1)transmural lesion depth,
• (2)lesion width, and
• (3)lesion volume.

Between FTI factors, the time factor was more important than the force factor for lesion formation. The area under the curve was greater for FPTI (0.943) than for FTI (0.870). On univariate linear regression analysis, the explanatory power of the linear regression model was better explained by FPTI (56.4%) than FTI (32.1%).Under the same FTI condition, the time factor had a greater effect on lesion formation. When power was included, the power factor had a greater effect on lesion formation and steam pop.     

Transvenous Cold Mapping and Cryoablation of the AV Node in Dogs: Observations of Chronic Lesions and Comparison to Those Obtained Using Radiofrequency Ablation

Cryoablation of the Proximal AV Node. Introduction: Radiofrequency (RF) is the most commonly used energy source for the treatment of cardiac arrhythmias. Surgical experience has shown that cryoablation also is effective for ablating arrhythmias. The aims of this study were to (I) investigate the feasibility of inducing permanent complete AV block (CAVB). (2) investigate the value of cold mapping to select the cryoablation site to produce permanent CAVB, (3) study the macro- and microscopic lesion characteristics 6 weeks later, and (4) compare them to those produced with RF energy. Methods and Results: A new steerable 8.5-French bipolar electrode catheter having a thermocouple with a 3-mm tip using N₂O as the refrigerant controlled by a cryoconsole was used. Six mongrel dogs were anesthetized, and the catheter was positioned via the femoral vein across the tricuspid valve to record a large low right atrial and a small His-bundle potential. After cold mapping (-15° to -20°C tip temperature) resulted in ECG modifications, cryothermia (-70°C) was given twice, lasting 5 minutes each, to create permanent CAVB (Cryo group). Additionally, RF catheter ablation of the AV node was performed in two anesthetized mongrel dogs (RF group). In the Cryo group, a permanent proximal CAVB was created in four dogs (block occurred within 10 to 20 sec of cryothermia). Permanent right bundle branch block was obtained in one dog and transient CAVB in the remaining dog. In both dogs of the RF group, permanent CAVB was obtained. The cryolesions consisted of well-circumscribed, homogeneous areas of fibrotic tissue without viable cardiomyocytes. Lesions produced with RF were less circumscribed and inhomogeneous, with clear evidence of viable cardiomyocytes and cartilage formation (patchy lesions). Conclusions: (1) Permanent CAVB can he created by using a steerable cryoablation catheter. (2) Histologically, cryoablated sites were homogeneous and showed fibrotic tissue without signs of chronic inflammation and no evidence of viable myocytes. (3) Lesions created with RF were less homogenous and still contained viable myocytes within the lesion and cartilage formation. (4) The arrhythmogenic significance of these differences requires further study. (5) The technology of using reversible cold mapping has the potential to identify the successful ablation site and warrants further clinical study.     

室性期前收缩的射频消融治疗的效果

目的:观察室性期前收缩（VE）射频消融治疗的临床效果。方法:对连续36例频发、药物难治性、症状明显的顽固性单源性VE进行导管射频消融治疗,术中标测方法采用联合起搏标测和激动顺序标测,同时结合试消融法指导标测,术后1月进行随访。结果:即刻成功率为86%,无严重并发症发生。术后1月时成功率为83%。结论:对于顽固性单源性VE导管射频消融治疗是一种安全、有效的治疗方法。     

Accessory Pathway with Two Conduction Times

A 48-year old man was referred for frequent paroxysmal narrow QRS tachycardias. Either a rapid orthodromic tachycardia (220 b/min) using a fast-conducting left lateral concealed atrioventricular (AV) accessory pathway (AP) for its retrograde conduction or a slow orthodromic tachycardia (125 b/min) using the same concealed AP which was slow-conducting, were induced. One application of radiofrequency energy at the earliest site of retrograde conduction suppressed both forms of tachycardias. Reciprocating tachycardias presenting with different retrograde conduction times were related to a single reentrant circuit.     

Symptomatic improvement after radiofrequency catheter ablation for typical atrial flutter

OBJECTIVE—To assess the changes in quality of life, arrhythmia symptoms, and hospital resource utilisation following catheter ablation of typical atrial flutter.
DESIGN—Patient questionnaire to compare the time interval following ablation with a similar time interval before ablation.
SETTING—Tertiary referral centre.
PATIENTS—63 consecutive patients were studied. Four patients subsequently underwent an ablate and pace procedure, two died of co-morbid illnesses, and two were lost to follow up. The remaining 55 patients form the basis of the report.
RESULTS—Patients were followed for a mean (SD) of 12 (9.5) months. Atrial flutter ablation resulted in an improvement in quality of life (3.8 v 2.5, p < 0.001) and reductions in symptom frequency score (2.0 v 3.5, p < 0.001) and symptom severity score (2.0 v 3.8, p < 0.001) compared with preablation values. There was a reduction in the number of patients visiting accident and emergency departments (11% v 53%, p < 0.001), requiring cardioversion (7% v 51%, p < 0.001), or being admitted to hospital for a rhythm problem (11% v 56%, p < 0.001). Subgroup analysis confirmed that patients with atrial flutter and concomitant atrial fibrillation before ablation and those with atrial flutter alone both derived significant benefit from atrial flutter ablation. Patients with concomitant atrial fibrillation had an improvement in quality of life (3.5 v 2.5, p < 0.001) and reductions in symptom frequency score (2.3 v 3.5, p < 0.001) and symptom severity score (2.2 v 3.7, p < 0.001) compared with preablation values.
CONCLUSIONS—Ablation of atrial flutter is recommended both in patients with atrial flutter alone and in those with concomitant atrial fibrillation.


Keywords: atrial flutter; radiofrequency ablation; quality of life     

Radiofrequency Modification of the Atrioventricular Node in Patients with Chronic Atrial Fibrillation:

RF Modification of AVN in AF. Introduction : We compared, in a prospective and randomized fashion with a cross-over design, the anterior and posterior approaches to radiofrequency (RF) modification of the AV node in patients with chronic atrial fibrillation.
Methods and Results : Thirty-three patients were randomized to receive first an anterior (group I) or posterior (group II) approach for RF modification of AV nodal conduction. Patients who did not fill the endpoint ventricular rate (< 90 beats/min) were crossed over to the alternative approach. After the anterior approach in group I patients, mean ventricular rate was significantly lower than in group II patients after the posterior approach (79.6 ± 18.8 beats/min vs 110.8 ± 16.2 beats/min, P < 0.001). In group I, 14 (82%) of 17 patients fulfilled the endpoint, 1 (6%) had complete AV block, and 2 (12%) were crossed over to the posterior approach fulfilling the endpoint. In group II, 4 (25%) of 16 patients fulfilled the endpoint. No transient or permanent high-degree AV block was observed. Among the 12 patients who were crossed over to the anterior approach, 8 fulfilled the endpoint, whereas 4 had permanent high-degree AV block. RF ablation carried out only in the anterior region was safer than a stepwise approach (6% vs 33% incidence of AV block), even though the difference did not reach statistical significance (P = 0.09).
Conclusion : Posterior AV nodal modification is less effective but safer than anterior AV nodal modification. However, to reduce the incidence of AV block, the anterior approach is preferable to a stepwise approach from the posterior to the anterior zone.     

Critical Atrial Site for Ablation of Pacing-Induced Atrial Fibrillation in the Normal Dog Heart

Site for Ablation of AF in Dogs. Introduction: Radiofrequency catheter ablation (RFA) has been used recently to treat atrial fibrillation (AF). The purpose of this study was to investigate a new approach to preventing AF by RFA.
Methods and Results: In open chest, anesthetized dogs, AF (lasting > 30 sec) was induced after burst stimulation, and electrophysiologic parameters were recorded before and after RFA. In group 1 (9 dogs) we performed selective and combined slow and fast pathway RFA, whereas in group 2(11 dogs) RFA was applied as a linear lesion at the mid-atrial septum between the inferior vena cava and the fossa ovalis. After ablation, the Wenckebach cycle length was significantly prolonged only in group 1 (194 ± 23 vs 282 ± 35 msec, P = 0.002). whereas the interval between the stimulus (S) artifact applied at the high right atrium to the His hundle (H) (SH interval) prolonged to the same extent in both groups (162 ± 14 vs 146 ± 45 msec. P = NS); group 1 due to an A-H prolongation whereas in group 2 it was due to an intra-atrial conduction delay. In group 1 AF still remained inducible, although with a longer mean R-R interval (215 ± 16 vs 433 ± 88 msec, P < 0.05). No instance of complete AV block developed. In group 2, sustained AF was noninducible in 10 dogs and its duration was markedly shorter in the remaining one (8 sec). Gross anatomy and histology did not reveal any damage inside of Koch's triangle, and particularly to the compact AV node.
Conclusion: These findings suggest that RFA at the mid-atrial septum prevents AF in the normal dog heart. This approach might also be successful in those clinical settings in which the atrial septum plays a critical role in the maintenance of sustained AF.     

高龄原发性肝癌射频治疗疗效分析

目的观察高龄原发性肝细胞癌(HCC)患者射频消融治疗(RFA)疗效及RFA对肝功能及生命质量的影响.方法超声引导RFA治疗的225例HCC患者为本文研究对象;非老年组(年龄≤60岁)109例;老年组(年龄＞60岁)116例中,年龄≥70岁者50例,52.6%(61人)合并其他疾病.治疗前两组病灶大小,肝功能分级均无显著差异.比较两组RFA疗效、生存期、生存率、生命质量变化及对肝功能的影响.结果两组消融成功率,局部肿瘤进展率均无明显差异.平均生存期非老年组为(43.31±3.16)个月,老年组为(41.07±2.50)个月,两组无统计学差异.老年组RFA治疗前后生命质量得分无显著差异;治疗后,老年组社会功能领域得分高于非老年组,两组生命质量总得分及其他领域得分均无显著差异.两组患者治疗前与治疗后1个月的谷丙转氨酶、谷草转氨酶、总胆红素水平均无明显差异.结论RFA对不适合手术治疗的高龄HCC患者,可获得良好疗效,并保持患者较高的生命质量;对高龄患者可作为首选治疗方法之一.     

Acute and chronic electrophysiologic changes surrounding radiofrequency lesions

INTRODUCTION: Arrhythmia recurrences may occur after acutely successful radiofrequency (RF) ablation, suggesting reversible electrophysiologic effects on myocardial tissue. The aim of this study was to examine the electrophysiologic changes occurring in myocardium surrounding acute and chronic RF lesions. METHODS AND RESULTS: RF lesions (60 degrees C for 30 sec) were produced on the epicardial left ventricular surface of 35 isolated perfused rabbit hearts. Microelectrode transmembrane action potential recordings were made at 0.25-mm intervals along the epicardial (n = 20) or intramural (n = 6) aspects of the lesions for up to 3.5 mm from the lesion edge at baseline and after acute RF lesion formation. In nine hearts, chronic lesions were studied with epicardial recordings made 22 +/- 13 days after RF lesion formation. In the acute hearts at 600-msec paced cycle length, action potential duration at 50% repolarization (APD50) and 90% repolarization (APD90) were reduced by up to 41% and 19%, respectively, within 2.5 mm from the lesion edge (all P < 0.05). Maximal action potential amplitude (APDmax) was reduced by 16% at 0.25 mm from the lesion edge (P = 0.009) but dV/dt was not changed. Conduction time (CT) from the outermost recording site to the lesion edge (3.5-mm distance) was reduced from 16 +/- 3 msec at baseline to 13 +/- 4 msec post ablation (P = 0.006). Qualitatively similar findings occurred at 200-msec cycle lengths. There were no changes in APD, CT, APDmax, or dV/dt surrounding the chronic lesions at 22 +/- 13 days after lesion formation. CONCLUSION: Acutely following RF energy delivery, APD, APDmax, and CT are reduced in the tissue surrounding the lesion. These electrophysiologic changes resolve within 22 +/- 13 days of lesion formation.