Inducción de taquicardia reentrante nodal aurículo-ventricular por aplicación de radiofrecuencia / Induction of atrioventricular nodal reentrant tachycardia by radiofrequency application

La taquicardia reentrante nodal aurículo ventricular es la forma más común de taquicardia sostenida, regular con QRS angostos. Fisiopatológicamente está determinada por una anatomía y fisiología nodal aurículo ventricular dual, con una vía rápida y otra lenta que forman el sustrato de la reentrada. El estudio electrofisiológico determina el diagnóstico de certeza si es inducida, aunque en algunos casos no es posible. Presentamos nuestra casuística donde la aplicación de radiofrecuencia indujo taquicardia reentrante nodal aurículo ventricular cuando el estudio electrofisiológico no pudo hacerlo, y explicamos su mecanismo electrofisiológico.

Atrioventricular nodal reentrant tachycardia is the most common form of sustained regular narrow QRS complex tachycardia. It is caused by the presence of a dual atrioventricular nodal anatomy and physiology, with a fast and a slow pathway forming a substrate for re-entry. Electrophysiology study confirms the diagnosis when the tachycardia is induced, although in some cases this is not possible. Casuistry is here presented where the application of radiofrequency induced atrioventricular nodal reentrant tachycardia, when the electrophysiological study could not do it; we explain here its electrophysiological mechanism.

Comparison of cryoablation catheter and radiofrequency ablation for treating atrioventricular nodal reentrant tachycardia / 中国介入心脏病学杂志

Objective By comparing the efficacy and complication rates of the 8-mm-tip cryoablation catheter with the normal electrode ablation catheter in the treatment of atrioventricular nodal reentrant tachycardia,this study investigated the efficacy and feasibility of ablation with the 8-mm-tip cryoablation catheter.Methods This is a retrospective case-control study including 122 patients with AVNRT treated with CRYO (n =56) using an 8-mm-tip cryoablation catheter or RF ablation (n =66) from June 2014 to May 2016.The procedure success rate,the recurrence rate,atrioventricular block incidence,procedure time and the difference between the X-ray fluoroscopy dose were compared between the 2 groups.Results The procedure success rate was comparable between the 2 groups(100％ for CRYO vs.98.5％ for RF,P ＞0.999)and no AVB was found in both groups.The CRYO group needed shorter procedural time [(66.29±4.72)min vs.(70.00 ± 7.50) min,P =0.001] and less X-ray exposure [(674.14 ± 126.12) mSv vs.(837.52 ± 138.38) mSv,P ＞ 0.001] than the RF group.Conclusions 8-mm-tip cryoablation catheter cryoablation for atrioventricular nodal reentrant tachycardia is as safe and effective as compared to conventional radiofrequency ablation with potential advantages.

Comparison Between Cryoablation and Radiofrequency Catheter Ablation for Treating the Patients With Atrio-ventricular Nodal Reentrant Tachycardia by Meta-analysis / 中国循环杂志

Objective: The compare the safety and efficacy between cryoablation (CRYO) and radiofrequency catheter ablation (RFCA) for treating the patients with atrio-ventricular nodal reentrant tachycardia (AVNRT) by meta-analysis. Methods: We systemically searched the Medline, Cochrane library and Embase database to fulifll our pre-deifned criteria until the publication of May 2014. Results: There were 5 randomized controlled trials (RCTs) and 14 retrospective trials enrolled in our study with 2900 patients. The patients were allocated into 2 groups:CRYO group, n=1384 and RFCA group, n=1516. The overall pool-analysis demonstrated that compared with RFCA group, CRYO group had the lower risk of permanent atrio-ventricular nodal block (OR:0.27, 95%CI 0.11 to 0.62, P Conclusion: Although CRYO could decrease the risk of permanent atrio-ventricular nodal block, while its effectiveness was lower than RFCA for AVNRT treatment in relevant patients.

Taquicardia por reentrada nodal recurrente en paciente con transposición congénita corregida de grandes vasos. Utilización de mapeo no fluoroscópico / Use of non-fluoroscopic mapping in recurrent atrioventricular nodal reentrant tachycardia in a patient with corrected transposition of the great arteries

La complejidad anatómica y la variabilidad en el sistema de conducción en la transposición congénita corregida de los grandes vasos plantean intervenciones con el uso de recursos tecnológicos que faciliten un desenlace favorable. Describimos un caso de ablación de taquicardia por reentrada intranodal en donde el mapeo no fluoroscópico facilitó una intervención compleja.

The anatomy in congenital corrected transposition of the great arteries is complex and the conduction system may experience large degrees of variation. Invasive procedures should be done with the use of the highest possible technological sources to warrant success. We describe here, a patient with recurrent atrioventricular node reentry tachycardia where non-fluoroscopic navigation system helped in a complex ablation.

Transvenous Cryoablation Versus Radiofrequency Catheter Ablation for Treatment of Atrioventricular Nodal Reentrant Rachycardia / 中国循环杂志

Objective:To compare the efficacy and safety between cryoablation(Cryo)and radiofrequency (RF)ablation in patients with atrioventricular nodal reentrant tachycardia(AVNRT). Methods: A total of 83 patients with AVNRT underwent electrophysiological treatment in our hospital from October 2006 to March 2009 were studied. Patients were divided into two groups according to their own choices. Cryo group (n=41) and RF group (n=42). The clinical characteristics,success rate,procedural time and ablative time were compared between two groups. Results:The procedural time and ablative time in Cryo group was significantly longer than those in RF group (119.14±40.16 min vs.85.86±28.24 min,P=0.001; 1118.91±620.62 s vs.370.97±279.23 s,P<0.001). The acute success rate was achieved in 40/41(97.6%)patients in Cryo group,and 42/42(100.0%) in RF group. Transient AV-block was encountered in 6 (15%) patients in the Cryo group and 5 (11.9%) in RF group (P=0.681). There was no complete atrial-ventricular(AV)conduction block at the end of procedures. There was no recurrence of AVNRT in either Cryo group nor in RF group during 11.6±5.5 months of follow up period.Conclusion:Cryoablation was as effective and safe as RF ablation for AVNRT. Cryo-energy was one kind of alternative ablation energy for AVNRT.

Impact of slow pathway ablation on AV conduction in atrioventricular nodal reentrant tachycardia

Introduction: Atrioventricular nodal reentrant tachycardia is quite common in clinical. The use of radiofrequency for this condition is more common. However, there are few studies on the impact of slow pathway ablation on AV conduction.Objectives: To investigate the impact of slow pathway ablation on AV conduction in atrioventricular nodal reentrant tachycardia. Subjects and method: Between Jul 2003 to Jul 2006, 27 patients with typical atrioventricular nodal reentrant tachycardia underwent the slow pathway eradication using radiofrequency. Some AV conduction measurements before and after ablation were compared. Results: There is a significant difference in sinus interval before and after ablation (745.81 +/- 136.63ms vs. 634.61+/-148.82ms, p<0.05). The differences in PA interval (32.03+/-8.71ms vs. 34.15+/-9.36ms), AH interval (67.72+/-18.66ms vs. 69.31+/-25.92ms), Wenckebach AV nodal block (316.32+/-52.13ms vs. 338.16+/-65.52ms), 2:1 AV block (245.95+/-78.46ms vs. 251.62+/-65.31ms) were all not significant. . The fast pathway refractory periods before and after ablation was 358.31+/-68.67ms and 362.48+/-92.11ms, respectively. Conclusion: The slow pathway eradication by radiofrequency for atrioventricular nodal reentrant tachycardia has no impact on the AV conduction.

Radiofrequency catheter ablation for the refractory atrioventricular nodal reentrant tachycardia / 医学研究生学报

Objective: To analyze the elcctrophysiological and clinical features of 68 common and 9 refractory atrioventricular nodal reentrant tachycardia(AVNRT) cases,thereby to seek safe and effective strategies for the treatment of refractory AVNRT with radiofrequency catheter ablation(RFCA). Methods: Ablation at lower zone is customarily applied in AVNRT,if noneffective,ablation electrode can be gradually moved upward,and radiofrequency energy can be delivered at a midpoint or upper position of His Bundle even with small H waves.The movement of the ablation electrode must be carefully monitored lest His bundle be eroded mistakenly.For those both atrioventricular nodal dual pathways(AVNDP) and atrioventricular accessory pathways(AVAP) are present,we always ablate AVAP first. Results: All 68 common AVNRT cases are simple slow-fast type.Among the 9 cases of refractory AVNRT,2 cases were combined with concealed left postseptal AVAP and concealed right AVAP respectively,while 1 case with atrioventricular nodal three pathways. Conclusion: X-ray anatomical position and intraventricular local mapping should be analyzed for the use of RFCA in refractory AVNRT.Safe and effective mapping should be: small A wave and big V wave,shattered A wave with width≥68 ms,A/V= 0.1-0.25,no H or H≤(0.02?0.03) mV.If lower position and middle position method are noneffective,linear ablation at mid-level of Koch's triangle seems to be a satisfactory alternative,which could avoid complications of atrioventricular block in the upper position ablation.

Taquicardia por reentrada nodal atrioventricular: Ablación con radiofrecuencia / Atrioventricular nodal reentrant tachycardia: radiofrequency ablation

La taquicardia por reentrada nodal atrioventricular, es una de las causas más frecuentes de taquicardia supraventricular. Es generalmente una arritmia benigna y usualmente no está asociado a cardiopatía estructural, se presenta más frecuentemente en mujeres de media edad, pero no es infrecuente encontrarlo en personas jóvenes y en ancianos. El desarrollo de la ablación con radiofrecuencia a través de un catéter facilita la cura definitiva de la arritmia y permite una mejor compresión del sustrato anatómico electrofisiológico.

Atrioventricular nodal reentrant tachycardia is the most frequent regular supraventricular tachycardia. It is generally a benign arrhythmia and usually it is no associated with heart disease. It is more often seen in middle-aged women but it is no infrequent in younger and older patients. The development of radiofrequency with catheter ablation has provided the possibility to definitely cure the arrhythmia and moreover permit a better comprehension of the underlying electrophysiologic and anatomic substrate. (Arch Cardiol Mex 2003; 73:143-154).

Study on safety of radiofrequency catheter ablation in treatment of AV nodal reentrant tachycardia / 医学研究生学报

Objective:To investigate the couse of 24 cases AVB during RFCA and 5 cases after RFCA in total 94 AVNRT patients. Methods:94 AVNRT patients received RFCA in which time, the energy and power were gradually discussed. The correlation among AVB and both different anatomical positions (upper, middle and lower zone) and A/V, H-value in intraventricular ablation mapping were studied respectively. Results: With the elevation of ablation zone, the AVB risk was also increased. The intraventricular ablation mapping showed that:①Increase of A/V and H-value means higher AVB risk;② Simultaneous increase of A/V and H-value would lead to the most dangerous result. Conclusion:It is of great importance to perform RFCA under such situation:middle and lower zone as ablation positions multiple-peak A wave, A/V(0.1-0.25) and no H or slightest H(≤0.02?0.03)mV are present in intraventricular ablation mapping, which could significantly lower the risk of RFCA-related AVB.

Effects of different radiofrequency ablation methods on atrioventricular block in patients with atrioventricular nodal reentrant tachycardia / 医学研究生学报

Objective:Atrioventricular nodal reentrant tachycardia(AVNRT) is a common type of arrhythmia,for which radiofrequency ablation(RFCA) is the first therapeutic option.This study is to investigate the causes of 16 cases of temporary atrioventricular block(AVB) during RFCA and 2 cases of permanent AVB after RFCA in common and refractory AVNRT.Methods: We performed RFCA for 77 AVNRT patients by gradually increasing the ablation time,energy and frequency.Generally we chose the lower zone as the first position of ablation and,if invalid,moved the catheter gradually up to the middle or upper zone.Then we analyzed the correlation of AVB with A/V and H-wave in different positions.Results: The AVB risk was increased with the upward movement of the ablation zone and increase of A/V or H-wave(P 0.05). Conclusion: The method of gradually increasing the ablation time,energy and frequency can prevent temporary from permanent AVB.In the common AVNRT group,the middle and lower zone ablation,the multiple-peak A wave,small A wave and big V wave(A/V ≤ 0.45?0.37) with no H wave or H≤0.003?0.01 mV could significantly decrease the risk of RFCA related AVB,but the risk of AVB remains among the refractory AVNRT patients with CSO abnormality or expansion,even if with ablation in the lower zone.

Predictors of successful catheter ablation of AV nodal reentrant tachycardia / 대한내과학회지

Catheter ablation of the AV nodal slow pathway using radiofrequency (RF) energy has been established as the first-line curative therapeutic modality of recurrent symptomatic AV nodal reentrant tachycardia (AVNRT). In contrast to catheter ablation of the AV bypass tract, there was no useful marker to localize succesful site of the pathway. This study was performed to determine predictors of successful catheter ablation of the AV nodal slow pathway in patients with AVNRT. METHODS: Forty patients (18 men, 22 women; 47.9+/-13.3 years) with AVNRT undergoing successful catheter ablation of the AV nodal slow pathway were included in this study, in which 217 attempts were tried to ablate the AV nodal slow pathway. Characteristics of local atrial electrogram, anatomical site at each attempt, junctional rhythm during RF delivery were analyzed (40 successful, 177 failed). Maximum difference and duration of atrial electrograms were measured and local atrial electrograms were classified into 5 types (A1, A2, B1, B2 and C type) according to the type and the degree of fragmentation. Finally, the occurrence of junctional rhythm during RF discharge and its onset time were compared between successful and failed attempts. RESULTS: There was no significant difference in the maximum difference of amplitude and duration of atrial electrograms between successful and failed attempts. The success rate in each type of atrial electrogram was significantly different. And, the success rate in non-C type atrial electrograms (A1, A2, B1, and B2) was significantly higher than that in type C atrial electrograms (25.0% vs 10.3%, p<0.01). No significant difference was noted in success rates according to attempted sites. Junctional rhythms during radiofrequency application occured significantly more frequent in successful attempts than in failed attempts (87.5% vs 47.5%, p<0.001). The time to onset of junctional rhythm was not different between successful and failed attempts (5.2+/-4.9 sec vs 6.1+/-5.5 sec). CONCLUSION: Fragmented local atrial electrogram and junctional rhythm during RF energy delivery may be used to predict successful catheter ablation of AVNRT. It is recommended that RF energy should be applied to the site where fragmented atrial electrogram is recorded and terminated if junctional rhythm does not develop within 15 seconds after starting RF energy delivery.

Predictors of successful catheter ablation of AV nodal reentrant tachycardia / 대한내과학회지

Catheter ablation of the AV nodal slow pathway using radiofrequency (RF) energy has been established as the first-line curative therapeutic modality of recurrent symptomatic AV nodal reentrant tachycardia (AVNRT). In contrast to catheter ablation of the AV bypass tract, there was no useful marker to localize succesful site of the pathway. This study was performed to determine predictors of successful catheter ablation of the AV nodal slow pathway in patients with AVNRT. METHODS: Forty patients (18 men, 22 women; 47.9+/-13.3 years) with AVNRT undergoing successful catheter ablation of the AV nodal slow pathway were included in this study, in which 217 attempts were tried to ablate the AV nodal slow pathway. Characteristics of local atrial electrogram, anatomical site at each attempt, junctional rhythm during RF delivery were analyzed (40 successful, 177 failed). Maximum difference and duration of atrial electrograms were measured and local atrial electrograms were classified into 5 types (A1, A2, B1, B2 and C type) according to the type and the degree of fragmentation. Finally, the occurrence of junctional rhythm during RF discharge and its onset time were compared between successful and failed attempts. RESULTS: There was no significant difference in the maximum difference of amplitude and duration of atrial electrograms between successful and failed attempts. The success rate in each type of atrial electrogram was significantly different. And, the success rate in non-C type atrial electrograms (A1, A2, B1, and B2) was significantly higher than that in type C atrial electrograms (25.0% vs 10.3%, p<0.01). No significant difference was noted in success rates according to attempted sites. Junctional rhythms during radiofrequency application occured significantly more frequent in successful attempts than in failed attempts (87.5% vs 47.5%, p<0.001). The time to onset of junctional rhythm was not different between successful and failed attempts (5.2+/-4.9 sec vs 6.1+/-5.5 sec). CONCLUSION: Fragmented local atrial electrogram and junctional rhythm during RF energy delivery may be used to predict successful catheter ablation of AVNRT. It is recommended that RF energy should be applied to the site where fragmented atrial electrogram is recorded and terminated if junctional rhythm does not develop within 15 seconds after starting RF energy delivery.

Anatomical Sites of the Successful Catheter Ablation Using the Anatomic Approach in Patients with AV Nodal Reentrant Tachycardia

BACKGROUND AND OBJECTIVES: Intracardiac electrocardiographic finding using as a guide for selective catheter ablation in patients with AV nodal reentrant tachycardia (AVNRT) is not specific. Therefore, we evaluated the efficacy and safety of the anatomical approach for catheter ablation in patients with AVNRT. MATERIALS AND METHOD: Among the patients diagnosed as AVNRT by electrophysiologic study, total 66 patients (M:F=26:40) were included in this study. In the right anterior oblique radiographic view, the septal annulus of tricuspid valve, extending from the most posterior region of the annulus adjacent to coronary sinus ostium (posterior) to His bundle recording site (anterior), was divided into posterior (P), mid (M), and anterior (A) sites. Radiofrequency (RF) energies were applied from the posterior part to the anterior part sequentially along the septal annulus of tricuspid valve until successful ablation. RESULTS: Successful anatomical sites were located in posterior (11 patients), mid (48 patients), and anterior (7 patients) sites. The most patients (62 patients) were treated with slow pathway ablation except 4 patients in whom fast pathway was ablated. Probable slow potentials were observed in 8 patients (12%, 3 in posterior sites and 5 in mid sites). Transient complete AV block followed by first degree AV block and delayed complete AV block was occured in one case whose ablation site was A1. And another 3 patients had postablation first degree AV block. CONCLUSION: In patients with AVNRT, the ablated pathway were different according to successful anatomical site. And RF catheter ablation of atrioventricular nodal reentrant circuit guided by anatomical landmark is safe and efficacious.

Intracardiac Electrogram at Successful Site of Radiofrequency Catheter Ablation in Patients with Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND AND OBJECTIVES: Ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) can be performed by using a specific intracardiac electrogram findings predicting a successful radiofrequency catheter ablation. The purpose of the present study is to recognize a specific intracardiac electrogram findings predicting a successful sites of radiofrequency catheter ablation in patients with AVNRT. MATERIALS AND METHODS: The study population consisted of the 18 patients (7 males, mean age:46 yr) to undergo successful catheter ablation using radiofrequency current in order to eliminate AVNRT from January 1993 to september 1994. We have analyzed local intracardiac electrogram at successful and unsuccessful sites of radiofrequency catheter ablation before the radiofrequency application: Atrial electrogram amplitude, duration, number of peaks in atrial electrogram, atrial/ventricular (A/V) electrogram amplitude ratio, and presence of His potential and/or slow potential. RESULTS: Of 18 patients, 16 patients underwent a slow pathway ablation, the other 2 patients a fast pathway ablation. The mean A/V electrogram amplitude ratio at successful and unsuccessful sites was 0.69+/-0.91 and 1.86+/-2.03, respectively. The mean atrial electrogram duration and number of peaks at successful and unsuccessful sites was 57+/-16 msec vs 69+/-16 msec and 1.7+/-0.5 vs 2.2+/-0.7, respectively. His bundle electrogram was seen in one slow pathway ablated and one fast pathway ablated patient. No slow potential could be identified in any of these 18 patients. CONCLUSION: We think that A/V electrocardiogram amplitude ratio below 0.5 at posterior interatrial septum along tricuspid annulus is important marker indicating a successful ablation sites.

Análise das características do ritmo juncional em pacientes com taquicardia por reentrada nodal submetidos a ablação da via lenta por radiofreqüência / Characteristics of Junctional Rhythm During Radiofrequency Catheter Ablation of Slow Pathway in Atrioventricular Nodal Reentrant Tachycardia

PURPOSE--To study the quantitative and qualitative aspects of junctional rhythm (JR) during radiofrequency (RF) catheter ablation of slow pathway in atrioventricular nodal reentrant tachycardia. METHODS--Twenty five patients, 5 males, ages ranging from 15 to 76 years, with recurrent atrioventricular nodal reentrant tachycardia, underwent to RF catheter ablation of slow pathway. During RF applications (40V, duration 60s) electrocardiographic was continuously recorded. The recordings were posteriorly used to study the presence and characteristics of JR (number of episodes, frequency and time of onset) at the effective and ineffective RF sessions. All variables were expressed as median and mean +/- SD. Univariate analysis of the effects of each variable on success or failure of ablation were performed using x2 test. A p value < 0.05 was considered significant. RESULTS--One hundred forty nine RF sessions were performed, 25 effective and 124 ineffective (mean per patient 6, range 1 to 22). JR was present in 18 of 25 effective and 44 of 124 ineffective sessions (p < 0.05). Mean time of appearance was 12s, occurring later this time in 9 of 18 effective and in 10 of 44 ineffective sessions (p < 0.05). Mean number of episodes was 3, occurring higher number in 7 of 18 effective and in 4 of 44 ineffective sessions (p < 0.05). Median of frequency of JR was 100bpm; 11 of 18 effective and 15 of 44 ineffective sessions presented higher frequencies (p < 0.05). CONCLUSION--JR during slow pathway ablation is a sensitive marker of ablation success. JR predictor of success has higher number of episodes, higher frequency and later time of appearance than that one of ineffective sessions.

Objetivo - Estudar quantitativa e qualitativamente as características do ritmo juncional (RJ) ocorrido durante o procedimento de ablação por cateter da via lenta, em pacientes com taquicardia por reentrada nodal. Métodos - Vinte e cinco pacientes (5 homens, 15 a 76 anos) foram submetidos a ablação por cateter da via lenta, utilizando radiofreqüência (RF). Durante as sessões de RF de 40V, com 1min de duração, foi realizado o registro eletrocardiográfico contínuo, na velocidade de 25mm/s. Os registros serviram, posteriormente, para análise da presença e das características do RJ (número de episódios, freqüência e tempo de aparecimento após o início da RF), nas sessões eficazes e ineficazes. As variáveis estudadas foram expressas em mediana, média e desvio-padrão. A análise univariada do efeito das mesmas no sucesso da ablação foi realizada, utilizando-se o teste do qui-quadrado. Valor de p<0,05 foi considerado significante. Resultados - Foram realizadas 149 sessões de RF (média de 6/paciente, variando de 1 a 22), sendo 25 eficazes e 124 ineficazes. O RJ esteve presente em 18 de 25 sessões eficazes e em 44 de 124 ineficazes (p<0,05). A média do tempo de aparecimento do RJ após o início da RF foi de 12s, aparecendo em tempo superior à média em 9 de 18 sessões eficazes e em 10 de 44 ineficazes (p<0,05). A média do número de episódios de RJ foi 3, sendo maior que a média em 7 de 18 sessões eficazes e em 4 de 44 ineficazes (p<0,05). A mediana da freqüência do RJ foi de 100bpm, sendo maior que esse valor em 11 de 18 sessões eficazes e em 15 de 44 ineficazes (p<0,05). Conclusão - O RJ durante ablação com RF é um marcador sensível do sucesso do procedimento. O RJ preditor de sucesso apresenta número maior de episódios, freqüência cardíaca mais elevada e aparece mais tardiamente durante o pulso de RF, quando comparado ao que resulta ineficaz

The Selective Radiofrequency Catheter Ablation in Patients with AV Nodal Reentrant Tachycardia

BACKGROUND: The catheter ablation using radiofrequency(RF) energy in patients with AV nodal reentrant tachycardia(AVNRT) has been proved as a safe and effective nonpharmacologic therapeutic modality. The selective ablation of slow pathway is now becomming a standard treatment in patients with AVNRT because of its high success rate and negligible AV block risk. In our study, we demonstrated the feasibility, success rate and complications of selective radiofrequency catheter ablation of fast pathway or slow pathway for the treatment of AV nodal reentrant tachycardia. METHODS: Among patients diagnosed as AVNRT by electrophysiologic study, total 21 patients (M : F=11 :10, mean age ; 39 years old) were included in this study. Selective RF ablation of fast pathway was performed in 9 patients and selective RF ablation of slow pathway in 12 patients. The RF generator used in this study was Osypka HAT 200 model and catheters were 6F or 7F steerable catheters with 4 mm distal tip. RESULTS: The successful selective abation was achieved in 18 of 21 patient(86%). The success rate of selective ablation of fast pathway was 67%(6/9 patients) and that of slow pathway was 100%(12/12). The complication(complete AV block) was occurred in one patient in slective ablation of fast pathway but there was no AV block in selective ablation of slow pathway. During follow-up, there was one recurrence in patients treated by selective ablation of fast pathway(mean F/U : 17 months) but there has been no recurrence yet in patients treated by selective ablation of slow pathway(mean F/U : 6 months). The procedural feasibility between two ablation methods in terms of total procedure time, fluoroscopic time and number of RF applications was not differrent significantly. CONCLUSION: The RF ablation in patients with AV nodal reentrant tachycardia is a safe and a effective nonpharmacologic therapeutic modality. Especially, the selective RF ablation of slow pathway is a promising therapeutic modality in patients with AV nodal reentrant tachy cardia.

AV Nodal Reentrant Tachycardia with 2:1 AV Block

BACKGROUND: Second degree AV block is occasionally induced during AV nodal reentrant tachycardia by programmed electrical stimulation. This study was performed to determine the incidence, the block site, and the mechanism of AV block during AV nodal reentrant tachycardia. METHODS AND RESULTS: The study population was 67 consecutive patients with AV nodal reentrant tachycardia studied by programmed electrical stimulation. Among these patients, common types(slow pathway for anterograde and fast pathway for retrograde conduction) were 64 patients and uncommon types(fast pathway for anterograde and slow pathway for retrograde conduction) were 3 patients. Among 67 patients with AV nodal reentrant tachycardia 10 patients developed 2:1 AV block during tachycardia. The block site of AV block was infrai bundle in 9 patients and supraHis bundle in patient. There were intermittent aberrancies of RBBB and/or LBBB form during tachycardia in 5 patients with infraHis AV block. CONCLUSION: The occurrence of AV block during AV nodal reentrant tachycardia is not rare and might be related to the prematurity of atrial extrastimulation. The block sites of AV block were infraHis bundle in most cases and this finding suggests that distal common pathway of the reentry circuit is present in the AV node.

Tratamento cirúrgico da taquicardia por reentrada nodal: resultados tardios / Long-term Results of Surgical Treatment of Atrioventricular Nodol Reentrant Tachycardia

Métodos - No período de março de 1987 a março de 1990, 20 portadores de TRN foram submetidos a tratamento cirúrgico, 14 do sexo feminino, com idades variando entre 12 e 70 (média 42,8 ± 17,1) anos. Apresentavam crises recorrentes de TRN de 6 meses a 60 anos (média de 18,4 15,9 anos ). Dez apresentaram síncopes ou présíncopes durante as crises e dois foram ressuscitados durante tentativa de reversão com drogas antiarrítmicas. Fizeram uso de 1 a 6 (média de 3,75 ± 1,45) drogas antiarrítmicas, sem sucesso. Todos foram submetidos a estudo eletrofisiológico que caracterizou a forma comum de TRN. O procedimento cirúrgico foi semelhante em todos os casos, com dissecção profunda da região perinodal posterior. Seis pacientes submeteram-se a procedimentos cirúrgicos associados. Dezoito pacientes foram submetidos a estimulação atrial programada antes da alta hospitalar. A avaliação tardia resultou de observação clínica ambulatorial e de EEF e Holter quando necessários. Resultados - A estimulação atrial programada realizada em 18 pacientes não reproduziu a TRN, mesmo após administração de atropina IV. A média do intervalo PR variou de 153 ± 50,36 ms no pré, para 152 ± 38 ms no pós-operatório (p>0,05). Nenhum paciente apresentou recorrência da TRN no seguimento de 26,3 ± 10 m. Dois pacientes evoluíram para FA crônica após 24 meses da cirurgia. Conclusão - A técnica de dissecção perinodal empregada foi eficaz e segura a longo prazo, preservando a condução AV

Purpose - To analyze the long term results of surgical treatment of atrioventricular nodal reentrant tachycardia (AVNT). Methods - From March 1987 to March 1990, 20 patients with AVNT were submitted to surgical therapy, 14 female, aged 12 to 70 (42.8 ± 17) years. All presented crisis of AVNT from 6 months to 60 (18.4 ± 15.9) years. Ten of them had syncope or near syncope and two with cardiac arrest during reversion of AVNT with antiarrythmic drugs. They used 1 to 6 (3.75 ± 1.45) antiarrythmic drays before surgery. The electrophysiologic study (EPS) showed the commom form of AVNT in all cases. The surgical procedure was anatomically directed to the posterior area of the AV node. Programmed atrial stimulation (PAS) were applied on 18 patients after surgery. The longterm results were analysed by clinical evaluation, EPS andHolter when they were necessary. Results - The pos-operative PAS was done in 18 patients and did not induce any AVNT, even after atropine IV. The PR interval was 153 ± 50 ms before and 152 ± 38 ms after surgery (p > 0.05). During follow up (26 ± 10 m) there were not AVNT reccurence. Two patients developed chronic atrial fibrillation after 24 months of surgery. Conclusion - The perinodal dissection technique used was safe and successful to treat AVNT, preserving AV nodal conduction

Transcatheter Modification of Atrioventricular Junction With Radiofrequency Energy for Control of Atrioventricular Nodal Reentrant Tachycardia / 中国介入心脏病学杂志

Transcatheter atrioventricular (AV) junction ablation with radiofrequency energy was performed in five patients with AV nodal reentrant tachycardia. Disappearance of ventriculoa-trial condcution in all patients was showed and no dual pathway was observed in four patients, in whom three patients occurred first degree AV block after ablation. No tachycardia was showed in all patients in the electrophysiology test and in follow-up of 1. 5-12. 5 months. The results sug-gested that the application of radiofrequency energy may be a suitable and safe therapeutic mothed for modification of AV nodal conduction in patients with AV nodal reentrant tachycardia.