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.     

Single Radiofrequency Application to Cure Atrioventricular Nodal Reentry: Arguments for the Slow Pathway Origin of the High-Low Frequency Slow Potentials

Background: High-low frequency slow potentials are thought to be related to the slow AV pathway conduction. Their use was proposed to guide radiofrequency (RF) ablation of atrioventricular nodal reentrant tachycardia (AVNRT). The present study was designed to determine the prospective value of these high-low frequency slow potentials to guide AVNRT ablation using a single RF application. Single RF application could indeed reduce the size of the lesion created in the viciny of the specialized AV conduction system and shorten the radiation exposure and the overall duration of the procedure.Results: Forty-one patients (14 men, 27 women, 45±16 years old) with AVNRT underwent slow pathway RF ablation guided by high-low frequency slow potentials. High-low frequency slow potentials were found in all patients along the tricuspid annulus and above the coronary sinus. Ablation was always performed in the posterior part of Koch's triangle. The mean A/V amplitude ratio of the successful site was 0.43±0.59. In 32 patients (78%) AVNRT was no longer inducible after a single RF application. Procedure and radiation times were 35±31 and 13±12 min respectively. Five patients required 2, 3 patients 3, and 1 patient 6 RF applications. The mean number of RF applications was 1.4±0.9 (median = 1). In the 32 patients who required only one RF application, 24 (75%) had an obvious dual AV nodal pathways with a jump before ablation, wich completely disappeared in 18 of them (75%) after ablation. In the 6 remaining patients, who still had a jump after 1 RF application, there was no significant change in either conduction times or refractory periods concerning both the anterograde and retrograde AV conduction. No patient had PR interval purlongation. After a mean follow up of 11±5 months, recurrence was observed in a single patient who received 2 discontinued RF applications.Conclusion: Catheter-mediated ablation of AVNRT using high-low frequency slow potentials to localize the slow AV pathway is feasible and safe. Using this technique, a single RF application was successfull in 78% of patients, and slow pathway characteristics were completely eliminated in 75% of patients. The radiation time and the procedure duration were short. This suggest that, in patients with AVNRT, the choice of an appropriate RF target can reduce procedural duration.     

阈下刺激定位慢径消融靶点的临床应用研究

目的 :探讨利用阈下刺激 (STS)定位房室结折返性心动过速 (AVNRT)的慢径消融靶点的临床应用价值。方法 :选择AVNRT患者 6例 ,经常规电生理检查明确诊断后 ,将大头电极放在冠状窦口下缘与希氏束之间的中下区域进行标测 ,测定该点的起搏阈值后 ,诱发AVNRT ,然后发放STS终止AVNRT ,在终止位点处试消融 ,观察STS标测消融的有效性 ;在非终止位点处 ,结合局部心内电图判断是否进行试消融 ,如在非终止位点处试消融 ,观察STS标测的可靠性。同时观察STS标测定位的安全性。结果 :在 6例患者中 ,有 3例STS终止了持续性AVNRT ,且在终止位点处试消融并获得成功 ;有 5例共在 10个位点处发放了STS ,其中在 9个位点未终止心动过速 ,在这些非终止位点处试消融均未获得成功 ,非 1个位点出现了心房夺获。所有患者在STS标测过程中 ,未出现心房颤动、心动过速的加速或心室颤动等现象。结论 :STS终止AVNRT的位点是判断消融靶点的一个良好的电生理学指标。STS标测定位是安全、有效和可靠的一种方法 ,值得进一步地深入研究     

Intracardiac Echocardiography Guided Radiofrequency Catheter Ablation of the Slow Pathway in Atrioventricular Nodal Reentrant Tachycardia

Background: ICE has demonstrated its utility in imaging right atrial structures but its utility in slow pathway (SP) ablation has not been documented in a randomized trial. Methods: The feasibility of using ICE as a imaging modality to identify the effective site of SP ablation was done in part one of the study comprising 10 patients of typical AVNRT. Subsequently, a prospective randomized study was done comparing the conventional (group A) and ICE guided (group B) ablation of the SP. Each group had 20 patients of typical AVNRT. Ablation in the conventional arm was guided by intracardiac electrograms and fluoroscopy. Group B patients underwent SP ablation guided primarily by ICE imaging; fluoroscopy was used mainly for initial placement of catheters. Results: Reliable & stable ICE images were obtained in all patients. Part I of the study showed that RF pulses given when the ablation catheter was seen to cross the atrioventricular muscular septum (AVMS), always resulted in junctional rhythm. In Group B, RF pulse was delivered only when the ablation catheter was at the AVMS making an obtuse angle with the image of the His-bundle catheter. Consistent junctional rhythm and abolition of SP resulted at this site. Compared to group A, patients in group B required fewer pulses (mean 1.4±0.6 vs. 4.4±3.0; p < 0.05, median 1 vs. 5; p < 0.01), achieved a higher temperature (56±4 °C vs. 50±6 °C) and had more frequent junctional rhythm (100% vs. 70%) during RF pulse. Conclusions: A critical portion of SP exists adjacent to Tricuspid valve overlying the AVMS. ICE imaging consistently and reliably localizes this site and RF applications here result in interruption of antegrade SP conduction.     

Standard right atrial ablation is effective for atrioventricular nodal reentry with earliest activation in the coronary sinus

INTRODUCTION: Reports suggest that coronary sinus (CS) or left atrial ablations may be necessary for treatment of AV nodal reentrant tachycardia (AVNRT) with earliest retrograde atrial activation in the CS. We assessed the efficacy of standard right atrial catheter ablation approaches in these tachycardias and determined the incidence of earliest activation in the CS in AVNRT. METHODS AND RESULTS: We retrospectively evaluated intracardiac recordings from 225 consecutive patients who underwent electrophysiologic studies and radiofrequency (RF) ablation for AVNRT in two institutions. Atrial activation during AVNRT was evaluated using multiple catheters according to standard protocol used in our laboratories. RF ablations in the triangle of Koch were performed in all patients. Eighteen of 225 patients (8%) had earliest activation in one of the CS poles. The demographics and AVNRT characteristics of these 18 patients were similar to those of the other 207 patients who did not have CS as earliest activation site and included both typical and atypical AVNRT. Following RF ablation, none of the 18 patients had inducible AVNRT. CONCLUSION: Successful RF ablation can be performed at standard sites in the triangle of Koch regardless of earliest site of atrial activation. The incidence of CS as earliest retrograde atrial activation site in AVNRT is 8%.     

Left atrionodal connections in typical and atypical atrioventricular nodal reentrant tachycardias: activation sequence in the coronary sinus and results of radiofrequency catheter ablation

INTRODUCTION: The presence of atrionodal connections and coronary sinus (CS) breakthrough in atrioventricular nodal reentrant tachycardia (AVNRT) has been suggested. However, the incidence, anatomic relationship with reentrant circuit, and results of catheter ablation are unknown. METHODS AND RESULTS: Fifty-two patients with typical slow/fast AVNRT and 10 patients with atypical slow/intermediate or fast/slow AVNRT were included. Eccentric activation of the CS (EACS) was observed in 3 of 52 patients with typical and 8 of 10 patients with atypical AVNRT. The earliest CS activation in patients with an EACS was recorded at a site 10-20 mm inside the CS ostium. The postpacing interval after transient entrainment at the proximal CS in patients with EACS was 23 +/- 21 msec longer than the pacing cycle length. Modification or ablation of the slow pathway was successful in all patients with typical slow/fast AVNRT and in 7 of 9 patients with atypical AVNRT by RF energy delivered at the right septal tricuspid annulus (TA). In 2 patients with atypical AVNRT and an EACS, RF delivery inside the CS targeting the earliest CS activation eliminated the sustained AVNRT. CONCLUSION: Eccentric coronary sinus activation is observed in some rare cases of typical AVNRT, and in a majority of atypical AVNRT. Entrainment results suggest that the proximal coronary sinus may be part of the reentrant circuit. RF ablation of atypical AVNRT, if it fails from the standard right-side approach, can be targeted at the site of earliest retrograde atrial activation inside the CS.     

Transmembraneous Irrigation of Multipolar Radiofrequency Ablation Catheters: Induction of Linear Lesions Encircling the Pulmonary Vein Ostium Without the Risk of Coagulum Formation?

INTRODUCTION: Pulmonary vein (PV) isolation for the curative treatment of atrial fibrillation using conventional radiofrequency ablation (RF) catheters with the point by point technique is time consuming and carries a remaining risk for thrombembolic complications. AIMS OF THE STUDY: Aim of the present in vivo study was to evaluate feasibility and safety of a novel multipolar irrigated ablation catheter designed to create contiguous lesions encircling the PV ostium in a single ablation position. METHODS: The entire ablation section (tripolar, length of each electrode 22 mm, interelectrode distance 2 mm, helix radius: 9 and 10 mm) of the 7F RF catheter (Encirclr, Medtronic, MN, USA) was covered by a porous membrane (pore size 30 micron) providing continuous irrigation. The helical formed catheter was used in two different experimental settings. Initially, a thigh muscle preparation has been performed in 7 anesthetized sheep in order to evaluate the development of lesions at different power level (40-80 W) and RF duration (30-90 sec). The ablation catheter was placed at the surface of the thigh muscle in a perpendicular position (0.1 N contact pressure) and perfused with heparinized blood (250 ml/min, 37C degrees ). Irrigation was provided with a flow rate of 10 ml/min. The resulted lesion morphology was evaluated with regard to coagulum or crater formation and lesion depth and diameter. Subsequently in 9 anesthetized sheep intracardiac ablation has been achieved with 50 W and an irrigation flow of 10 ml/min. Transseptal puncture and RF ablations were guided using fluoroscopy and intracardiac echocardiography (ICE, Acuson, USA). Endpoint of the intracardiac RF applications was the reduction of local electrogram amplitude >50%. RF applications were achieved at both atrial appendages and in the orifices of the coronary sinus (CS), the vena cava inferior (VCI) and PV. Following RF ablation all animals were sacrificed and following in vivo staining (2% TTC) macroscopically and histologically investigations of the lesions were performed. RESULTS: At the thigh muscle preparation 57 RF applications have been performed. The lesion depth was homogeneous without gaps between the ablation electrodes. There was a significant increase comparing 30 with 90 sec of RF duration for 40, 50 and 60 W applications respectively: 40 W: 1.1 +/- 0.4 vs. 3.6 +/- 0.5; 50 W: 1.2 +/- 0.3 vs. 4.6 +/- 0.4 mm and 60 W: 2.6 +/- 0.6 vs. 4.8 +/- 0.5 mm. All applications with 80 W (n = 3) had to be terminated due to immediate increase of impedance >150 omega. Late impedance rises (>60 sec) without occurrence of coagulum formation have been observed in 1 out of 4 RF applications with 60 W.A total of 85 RF applications could be achieved intracardiacally in the right atrium (right atrial appendage n = 18, ostium of the coronary sinus n = 12, ostium of the inferior caval vein: n = 12) and in the left atrium (left atrial appendage: n = 15, ostium of the PV: n = 28). ICE guided positioning of the catheter and showed during all applications no coagulum formation at the electrode or impedance rise (>150 Omega). Reduction of local electrograms (>50%) were observed following 48 out 85 (56%) RF applications. The lesions showed a homogeneous depth of 4 +/- 2 mm and a width 5 +/- 2 mm at the surface. No charring or crater formation could be observed in any of the lesions. CONCLUSIONS: In the present in vivo studies it could be demonstrated that long irrigated ablation electrodes induce continuous lesions without the risk of thrombus formation at the electrode. Increase of RF duration from 30 to 90 seconds with power setting of 40-60 W, respectively, created deeper lesions without the risk of thrombus formation. Thus, the helical formed irrigated ablation catheter appears to be appropriate for simplified PV isolation.     

Prospective evaluation of the coronary sinus anatomy in patients undergoing electrophysiologic study.

BACKGROUND: Previous retrospective studies could find a predominant incidence of coronary sinus (CS) anomalies in patients with accessory pathways and a characteristic anatomy of the CS ostium in patients with atrioventricular nodal reentrant tachycardias (AVNRT). HYPOTHESIS: In the present prospective study, CS angiograms were prospectively performed to analyze the incidence of CS anomalies and to measure the diameters of the CS ostium. METHODS: The study included patients referred for electrophysiologic study and catheter ablation of various tachyarrhythmias. The anatomy of the CS and its side branches was visualized [left anterior oblique (LAO) 30 degrees, right anterior oblique (RAO) 30 degrees] by retrograde angiography in 204 consecutive patients (82 women, 122 men, age 45 +/- 15 years); of these, 120 presented with 123 accessory pathways (45 left-sided, 33 right-sided, 45 septal). The diagnosis in the remaining patients was atrioventricular nodal reentrant tachycardia in 43 cases, atrial tachycardia or atrial fibrillation in 12, and ventricular tachycardia in 15. In 14 patients, the indication for the electrophysiologic study was an unexplained syncope. The CS angiogram was evaluated for anomalies and the size of the CS ostium was manually measured in both projections. RESULTS: Anomalies of the CS defined as diverticula, persistent left superior vena cava, or enlarged CS ostia were found in 18 patients (9%). Of those, CS diverticula were found in nine patients, all with a posteroseptal or left posterior manifest accessory pathway, which was abolished within the neck of the diverticulum in seven patients and at the posteroseptal tricuspid annulus in two patients. Persistence of the left superior vena cava was found in five patients, four had atrioventricular reentrant tachycardia secondary to five accessory pathways (left free wall in four, right midseptal in one), and one patient had atrioventricular nodal reentrant tachycardia (AVNRT). Enlargement of the CS ostium of > 25 mm width was detected in nine patients (5%), of whom four had AVNRT. However, the width of the CS ostium generally did not differ significantly between patients with AVNRT (LAO: 14.4 +/- 5.6; RAO 9.3 +/- 2.4 mm) compared with the control group (LAO 13.4 +/- 4.1; 8.2 +/- 1.9 mm). CONCLUSIONS: Anomalies of the CS as diverticula, persistent superior vena cava, or enlargement of the CS ostium are predominantly found in patients with accessory pathway-related tachycardias. Diverticula of the proximal CS were found in 7% of patients with accessory pathways; in these cases, ablation succeeded mostly by radiofrequency (RF) current delivery in the neck of the diverticulum. Enlargement of the CS ostium was more often seen in patients with AVNRT than in all other patients. However, in general the measurements of the coronary sinus ostium did not significantly differ in patients with AVNRT compared with the control group.     

Radiofrequency Catheter Ablation of AtypicalAtrioventricular Nodal Reentrant Tachycardia

Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia, Introduction: Published reports of radiofrequency ablation of atypical atrioventricular nodal reentranttacbycardia (AVNRT) have been limited. We present our experience in 10 consecutive patientswith atypical AVNRT wbo underwent radiofrequency ablation of the "slow" AV nodal pathway.
Methods and Resttlts: there were 9 females and 1 male; their mean age was 44 ± 19 years (± SD), the mean AVNRT cycle length and ventriculoatrial (VA) interval at the His positionduring AVNRT were 340 ± 50 msec and 200 ± 70 msec, respectively. the slow pathway wassuccessfully ablated in all patients with a mean of 10 ± 7 radiofrequency energy applications inthe posteroseptal right atritim near the coronary sinus os. The mean procedure duration was 100 ± 35 minutes. There were no complications. In 4 patients, target sites were identified during sinus rhythm by mapping for possible slow pathway potentials, In the other 6 patients, target sites were identified by mapping retrograde atrial activation during AVNRT or ventricularpacing, The VA times at successful target sites were a mean of 45 ± 30 msec less tban the VAtime at the His cathetcr during AVNRT, There were no differences in success rate, number ofradiofrequency energy applications, or procedure duration between patients in whom mappingwas guided by possible slow pathway potentials or by retrograde atrial activation, During 6 ± 3 months of followup, 1 patient bad a recurrence of atypical AVNRT and underwent a secondablation procedure, which was successful.
Conclusion: Radiofrequency ablation of atypical AVNRT can be safely and effectivelyaccomplisbed when target sites are identified based either on possible slow pathway potentialsduring sinus rbytbm or retrograde atrial activation times during tachycardia.     

Successful catheter ablation of a slow AV-nodal pathway from the left posteroseptal region

Summary We present the case of a 44 year old woman with recurrent episodes of supraventricular tachycardia due to AV-nodal reentry (AVNRT). She was refractory to conventional medical treatment and referred to our hospital with the view to catheter ablation of the slow AV-nodal pathway. AVNRT of the common type was easily induced performing stimulation from the high right atrium and proximal coronary sinus. Other forms of supraventricular tachycardia were definitely ruled out during further electrophysiologic study. Repetitive RF applications around the right posteroseptal region failed to cure the tachycardia which remained inducible with a typical jump in the AH interval. Extensive RF applications from posteroinferior to the midseptum including the area of the proximal coronary sinus and its os were ineffective as well.AVNRT was transiently but reproducibly eliminated while burns were applied to the high midseptum but AVNRT reoccured within 20 minutes. Finally after retrograde passage of the aortic valve with a 4 mm tip ablation catheter, RF was applied to the left postero to midseptal region. An accelerated junctional rhythm was immediately observed and AVNRT remained non-inducible from that time onwards.It is concluded that an atypical posterior extension of the AV node with predominant leftatrial course might be responsible for this unusual success of slow pathway elimination from left posteroseptal.     

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in children aided by the LocaLisa mapping system.

AIMS: In young patients, slow pathway ablation for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) carries a small but definite risk of permanent AV block. The aim was to assess the efficacy of slow pathway ablation aided by the LocaLisa mapping system. PATIENTS AND METHODS: Radiofrequency (RF) modification of the slow AV nodal pathway was performed in 26 children < 19 years of age (median age 9.8 years, range 3-18.9). Three measures to limit the risk of AV block were applied: (1) use of LocaLisa, a non-fluoroscopic mapping system, to determine and mark the location of the AV node/His bundle axis, and monitor ablation catheter position, (2) continuous atrial stimulation during RF delivery to monitor AV conduction, and (3) gradual increase of RF power during RF ablation. RESULTS: AVNRT was rendered non-inducible in all patients. Dual AV physiology was abolished in 24/26 patients; 2 patients had single atrial echoes at the end of the procedure. At follow-up, AVNRT recurred in 3 patients (including the above 2), necessitating a second procedure. The median number of RF applications was 4 (3-8); median fluoroscopy time was 16 (7-33)min. One patient developed transient second-degree AV block, with full recovery within 6 weeks of the procedure. CONCLUSIONS: RF modification of the slow AV nodal pathway in children can be safely accomplished, achieving the ideal end-point of abolishing dual AV physiology, aided by use of the LocaLisa mapping system.     

CARTO与常规X线指导下射频消融房室结折返性心动过速的对比观察

目的 对比研究三维电解剖标测系统（CARTO）指导下和常规X线指导下射频消融房室结折返性心动过速的不同特点及优势,探讨CARTO指导下行房室结折返性心动过速射频消融的优势及可行性.方法 将60例房室结折返性心动过速的患者随机分为2组：CARTO系统指导下射频消融组和常规X线指导下射频消融组,对比两组的手术时间、X线曝光时间、放电时间、并发症的发生率、复发率、成功率.结果 CARTO系统指导下射频消融组患者30例,即刻成功率达100％,无1例发生并发症,随访半年以上均未复发,X线曝光时间较常规组明显缩短,手术时间较常规组无明显缩短.常规X线指导下射频消融组30例,1例并发Ⅲ.房室传导阻滞,2例复发改为CARTO指导下再次行射频消融后成功,随访半年未再复发.结论 在房室结折返性心动过速患者的射频消融中,三维电解剖标测系统指导与传统X线指导相比,增加了手术的安全性,提高了手术成功率,减少复发,且明显减少了X线的曝光时间.     

Functional Disconnection of Arrhythmogenic Pulmonary Veins in Patients with Paroxysmal Atrial Fibrillation Guided by Combined Electroanatomical (CARTO®) and Conventional Mapping

Background: Isolation of arrhythmogenic pulmonary veins (PVs) by radiofrequency current (RF) application has been introduced as a curative treatment for patients (pts) with paroxysmal atrial fibrillation (AF). The present study sought to investigate the feasibility and efficacy of this approach guided by conventional and electroanatomical mapping (CARTO^®). Methods: Twenty pts (13 male; 57 ± 8 years) with recurrent documented focally triggered idiopathic AF refractory to multiple antiarrhythmic drugs were prospectively included. Atrial premature beats were present at baseline in 9 pts and could be provoked in further 8 pts. Empirical ablation of both superior PVs was performed in 3 pts with no focal activity. After transseptal puncture selective angiography of all PVs was obtained. Thirty-six PVs (left superior: n = 18, right superior: n = 10, left inferior: n = 8) were targeted for RF ablation. A complete left atrial CARTO^®—map including the left atrial (LA) to pulmonary vein (PV) junction was obtained during sinus rhythm and/or coronary sinus pacing. RF was initially applied at the PV-LA junction at areas with the shortest left atrial- to PV potential interval (target 50°C, max. 30 W, duration 60 sec). Isolation was confirmed by the complete disappearance of specific PV potentials. RF lesions were analyzed with respect to the number of segment-quarters covering the PV ostium. Results: Functional isolation could be achieved in 35 out of 36 PVs following 10 ± 5 RF applications for each PV. RF applications covered 2 or less quarter segments of the overall PV circumference in 29 (80%) PVs. Total session duration was 6.5 ± 1.6 h with a mean fluoro-time of 54 ± 18 minutes. For CARTO^® mapping and ablation a mean fluoro time of 34 ± 6 min was required. During a mean follow up period of 8.3 ± 2.5 months AF relapsed in 9 pts (46%). A second approach was performed in 5 pts. and demonstrated either new foci (n = 2) or recurrence of previously isolated PV (n = 8). The second RF ablation procedure led to stable sinus rhythm in 3 out 5 pts. Thus, the overall successrate including the second procedure was 70%. Conclusions: CARTO^® guided functional isolation of presumed arrhythmogenic PVs by RF lesions covering 2 or less segments of the PV ostium in most patients is feasible. However, repeat procedures are often warranted to permanently treat paroxysmal atrial fibrillation.     

Radiofrequency catheter ablation within the coronary sinus eliminates a macro-reentrant atrial tachycardia: Importance of mapping in the coronary sinus

We describe a patient who underwent radiofrequency (RF) catheter ablation of symptomatic atrial fibrillation. After left atrial (LA) catheter ablation and pulmonary vein isolation, a macro-reentrant atrial tachycardia (AT) with a critical isthmus at the mitral isthmus was induced by incremental atrial pacing from the coronary sinus. Extensive RF energy applications from endocardial sites using ablation catheters with 4 mm- and 8 mm- tips resulted in no discrete potentials being recorded from the endocardial sites of the isthmus, but the tachycardia could not be terminated. However, discrete potentials were recorded within the CS, and epicardial RF energy applications from the CS eliminated the tachycardia. Thus, mapping in the CS is useful for detecting residual conduction at epicardial sites along the mitral isthmus. RF catheter ablation within the CS should be considered when no distinct electrograms are recorded after extensive ablation from the endocardial sites and when distinct electrograms are recorded within the CS.     

以冠状静脉窦壁心肌为心房插入点的后间隔旁路

目的介绍５例经导管标测和射频消融证实的以冠状静脉窦（ＣＳ）壁心肌为心房插入点的后间隔旁路。方法常规电生理检查定位旁路在后间隔,以７Ｆ大头导管标测左、右后间隔和二尖瓣环左心房侧（房间隔穿刺）,均找不到比ＣＳ电极处更理想的标测电图,多次高能量消融不成功。经右心房将大头电极送至ＣＳ口或ＣＳ内,标测到典型靶点图,低能量消融成功。结果５例患者男性３例,女性２例,年龄３８±１７岁。旁路以ＣＳ口１ｃｍ内为插入点者３例,２ｃｍ内者２例。心动过速中放电３例,右室起搏时放电２例,能量１０～２０Ｗ,旁路均在２ｓ内阻断。随访１４±６个月无心动过速复发。结论ＣＳ壁全程都可成为房室旁路的心房插入点。这种旁路走行偏心外膜,如果在左、右后间隔心内膜难以有效标测和消融,应仔细标测ＣＳ壁,准确定位后以低能量或温控方式在ＣＳ壁上消融。     

Ablation of pulmonary vein foci for the treatment of atrial fibrillation; percutaneous electroanatomical guided approach.

AIMS: To evaluate the usefulness of three-dimensional (3D) electroanatomical mapping of the pulmonary veins (PV) for guiding radiofrequency (RF) ablation of focal atrial fibrillation (AF) in a single session and to correlate the electrophysiological results with the six month clinical outcome. METHODS AND RESULTS: Sixteen consecutive patients with idiopathic paroxysmal AF (more than 1 episode/month) were studied. A non-fluoroscopic mapping system was used to generate 3D electroanatomic maps of the left atrium and deliver RF energy. In patients with frequent ectopies, mapping was performed using the 'hot-cold' approach (looking for the earliest electrogram in the 3D reconstruction). In patients with infrequent/no ectopies, double/ multiple potentials recorded at the PV were tagged. Pacing at these sites to test for inducibility of ectopy or atrial fibrillation was used to define PV foci. The therapeutic endpoint was defined as suppression of premature beats, dissociation of PV potentials and inability to induce AF. Twenty-five foci were identified (multiple foci in 38%). In the 4 pts with frequent ectopies, Group A, these were suppressed by 4 +/- 4.7 applications. In the 12 pts with infrequent/no ectopies, Group B, an average 4.7 +/- 1.8 applications were delivered per focus; the endpoint was achieved in eight of the patients (13 of 21 foci). By 180 days follow-up, 11 patients were free of symptoms and in sinus rhythm, two had paroxysmal AF episodes and 3 have symptomatic ectopies and are receiving antiarrhythmic drugs. The overall success rate at six months was thus 69%, 100% for group A and 58% for group B. CONCLUSION: Electroanatomic guided RF ablation of paroxysmal AF was highly successful in patients with frequent ectopies. The use of electroanatomical mapping for precise anatomical localization of multiple potentials and for guiding the PV ostia isolation allowed successful RF ablation in 50% of pts with infrequent/no ectopies.     

Anatomical and electrophysiological variations of Koch’s triangle and the impact on the slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia: a study using 3D mapping

Objective

This study aimed to reveal individual variations in Koch’s triangle using NavX and to evaluate the efficacy of the NavX-guided slow pathway ablation.

Methods

A regional geometry around Koch’s triangle was constructed in 42 consecutive patients with atrioventricular nodal reentrant tachycardia (AVNRT), and a bipolar electrogram map was created with 72?±?30 sampling points during sinus rhythm to identify sites with Haissaguerre’s slow potentials (SPs) and His bundle electrograms (HBEs) to examine the anatomical and electrical variations. Radiofrequency ablation was performed at the most prominent SP recording site. The acute results and long-term outcome were examined in comparison to another 42 consecutive patients who underwent a conventional fluoroscopy-guided slow pathway ablation in the previous months.

Results

The size of Koch’s triangle and the coronary sinus ostium varied over a wide range of 132 to 490 and 69 to 346 mm², respectively. HBEs were recorded linearly along the antero-septal right atrium (n?=?29) or deviated downward toward the midseptum (n?=?13, 31 %). The SPs were always distributed below the lowest HBE recording site. The NavX-guided ablation eliminated AVNRT with a median of 1 radiofrequency pulse, 9.1?±?4.6 min of fluoroscopy, and 49?±?14 min of procedure time, all of which were significantly smaller than those in fluoroscopy-guided ablation. No procedure-related complications or long-term recurrence was noted in either group.

Conclusion

Koch’s triangle varies in terms of the size and electrogram distribution, and the NavX-guided slow pathway ablation overcomes the diversity and seems more effective than fluoroscopy-guided ablation.     

Anatomical variations of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia: usefulness of the left anterior oblique view

OBJECTIVES: Several anatomical distances of Koch's triangle including the ablation site were measured and correlated with clinical features and slow pathway potentials in patients with atrioventricular nodal reentrant tachycardia to improve the avoidance of complete atrioventricular block. METHODS: Sixty consecutive patients (24 males and 36 females, mean age 47 +/- 12 years) with successfully eliminated atrioventricular nodal reentrat tachycardia were studied. The distances between the His-bundle area and the base of the coronary sinus ostium (Dis HBE-CS) and the distances between the successful ablation site and the base of the CS ostium (Dis SP-CS) were measured in both right anterior oblique and left anterior oblique views, and used to define the dimensions of Koch's triangle. The relationship between the slow pathway potentials at the successful ablation site and anatomical distances was estimated. RESULTS: The Dis HBE-CS in the right anterior oblique view was negatively correlated with patient age (r = -0.759, p < 0.001) and body mass index. In contrast, the Dis HBE-CS in the left anterior oblique view had only weak correlations with patient age and body mass index. The mechanism of the short Dis HBE-CS in the right anterior oblique view in elderly obese patients tended to change the shape of the tricuspid annulus from a circle to an ellipse, compressed by the ascending aorta and diaphragma. The Dis SP-CS in the right anterior oblique view associated with the low frequency potential (Haissaguerre's slow pathway potential) was longer than that associated with the high frequency potential (Jackman's slow pathway potential). CONCLUSIONS: Elderly obese patients had shorter distances between the proximal His-bundle area and the base of the coronary sinus ostium in the right anterior oblique view. In contrast, the Dis HBE-CS in the left anterior oblique view was not so narrow. Therefore, slow pathway ablation can be performed safely without complicated complete atrioventricular block, using both the slow pathway potential guided approach and the anatomical guided approach, especially in the left anterior oblique view.     

Identification of successful catheter ablation sites in patients with ventricular tachycardia based on electrogram characteristics during sinus rhythm

BACKGROUND: Zones of slow conduction facilitate reentry, the major mechanism of ventricular tachycardia (VT) after myocardial infarction (MI). Identification of these zones during sinus rhythm (SR) is desirable for radiofrequency (RF) catheter ablation of VT. Local conduction velocity may correlate with electrogram duration. OBJECTIVES: The purpose of this study was to revise the definition of normal electrogram characteristics and to reevaluate the significance of low-amplitude, long-duration electrograms recorded during SR to select RF catheter ablation sites in patients with VT. METHODS: Electroanatomic mapping was performed during SR in 10 control patients with normal left ventricles (LVs) and in 10 patients with stable VT after MI. From the controls, reference values for electrogram amplitude, duration (first peak to last peak distance), and fragmentation (positive deflection) were derived. In patients after MI, areas with signals exceeding these values were annotated and related to successful ablation sites. RESULTS: Ninety-five percent of normal LV electrograms were > or =1.0 mV and < or =28 ms (range 5-39 ms) and all had < or =4 deflections. Based on these results, cutoff values were set at 1 mV, four deflections, and 40 ms. In infarcted hearts, 653 electrograms (44%) were <1.0 mV and of these, 303 were > or =40 ms with >4 deflections and restricted to circumscribed areas. Twenty-seven of 28 targeted VTs remained noninducible after RF catheter ablation within these areas, resulting in 86% sensitivity and 94% specificity for low-amplitude, long-duration electrograms predicting successful ablation sites. CONCLUSION: Identification of successful RF target areas during SR in patients with VT is feasible with high sensitivity and specificity using a mapping strategy based on voltage and duration criteria.     

Distal end of the atrioventricular nodal artery predicts the risk of atrioventricular block during slow pathway catheter ablation of atrioventricular nodal re-entrant tachycardia

OBJECTIVE—To search for a reliable anatomical landmark within Koch's triangle to predict the risk of atrioventricular (AV) block during radiofrequency slow pathway catheter ablation of AV nodal re-entrant tachycardia (AVNRT).
PATIENTS AND METHODS—To test the hypothesis that the distal end of the AV nodal artery represents the anatomical location of the AV node, and thus could be a useful landmark for predicting the risk of AV block, 128 consecutive patients with AVNRT receiving slow pathway catheter ablation were prospectively studied in two phases. In phase I (77 patients), angiographic demonstration of the AV nodal artery and its ending was performed at the end of the ablation procedure, whereas in the subsequent phase II study (51 patients), the angiography was performed immediately before catheter ablation to assess the value of identifying this new landmark in reducing the risk of AV block. Multiple electrophysiologic and anatomical parameters were analysed. The former included the atrial activation sequence between the His bundle recording site (HBE) and the coronary sinus orifice or the catheter ablation site, either during AVNRT or during sinus rhythm. The latter included the spatial distances between the distal end of the AV nodal artery and the HBE and the final catheter ablation site, and the distance between the HBE and the tricuspid border at the coronary sinus orifice floor.
RESULTS—In phase I, nine of the 77 patients had complications of transient (seven patients) or permanent (two patients) complete AV block during stepwise, anatomy guided slow pathway catheter ablation. These nine patients had a wider distance between the HBE and the distal end of the AV nodal artery, and a closer approximation of the catheter ablation site to the distal end of the AV nodal artery, which independently predicted the risk of AV block. In contrast, none of the available electrophysiologic parameters were shown to be reliable. When the distance between the distal end of the AV nodal artery and the ablation target site was more than 2 mm, the complication of AV block virtually never occurred. In phase II, all 51 patients had successful elimination of the slow pathways without complication when the ablation procedure was guided by preceding angiography with identification of the distal end of the AV nodal artery.
CONCLUSIONS—The distal end of the AV nodal artery shown by angiography serves as a useful landmark for the prediction of the risk of AV block during slow pathway catheter ablation of AVNRT.


Keywords: atrioventricular nodal artery; atrioventricular nodal re-entrant tachycardia; catheter ablation; heart block.