Surgical and catheter ablative techniques for treating supraventricular tachycardia.

Although antiarrhythmic drugs are commonly used in patients with supraventricular tachycardia, their use is limited due to inefficacy, side effects and patient compliance problems. Nonpharmacologic therapies used in the treatment of supraventricular tachycardia include: antitachycardia pacing, DC and radiofrequency catheter ablation and surgical therapy. Although certain pacing techniques can prevent the initiation of tachycardia, antitachycardia pacing is primarily used to terminate the supraventricular tachycardia once it has occurred. In patients with primary atrial tachycardias that are refractory to treatment, DC or radiofrequency catheter ablation can be used to modify or completely ablate the AV junction with resultant complete heart block. With DC AV junction ablation, 65% of patients will have resultant third degree AV block and 20% of patients will have modification of AV condition. Results with radiofrequency ablation have shown efficacy rates ranging from 56-9470 and can be used without the need for general anesthesia. Both forms of catheter ablation can be used to selectively alter the retrograde limb of an AV node reentrant circuit. Catheter ablation has been successful in ablating accessory pathways. DC catheter ablation has been predominantly used in posterior paraseptal pathways. More recently, radiofrequency catheter ablation of the ventricular insertion site of accessory pathways has demonstrated usefulness in selective laboratories. Surgical therapy for supraventricular tachycardia has been used for excision and/or ablation of an atrial ectopic focus, surgical ablation of the AV node in patients with refractory atrial tachyarrhythmias and microsurgery of the AV node in patients with AV node reentrant tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Radiofrequency catheter ablation of both atrial ventricular nodal reentrant and atrial ventricular reentrant tachycardia in a single session

Radiofrequency catheter ablation is a new therapeutic approach to treat patients with symptomatic drug-resistant paroxysmal supraventricular tachycardia. Ablation of two accessory atrioventricular pathways in a single session has been frequently described previously. However, ablation in a single session of both the fast pathway, involved in atrial ventricular nodal reentrant tachycardia, and a concealed atrioventricular accessory pathway involved in a circus movement tachycardia has rarely been reported. A 57-year-old man with a grade III aortic incompetence had the infrequent association of atrial ventricular nodal reentrant tachycardia and orthodromic circus movement tachycardia due to a concealed accessory pathway. He presented with drug-resistant reentrant supraventricular tachycardia and, in a single session, underwent a successful radiofrequency catheter ablation of the fast atrial ventricular nodal pathway and a concealed posteroseptal accessory pathway. During a 10-month follow-up he was free of palpitations without any antiarrhythmic therapy and underwent elective aortic valve replacement.     

Catheter ablation of accessory pathways and atrioventricular nodal reentry tachycardia

Radiofrequency current catheter ablation has gained acceptance as primary long-term therapy for patients with symptomatic accessory pathways and symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) with frequent recurrences. In both arrhythmias, curative treatment is possible in more than 90% of cases at a low complication rate although an incidence of about 1% complete AV block after slow pathway ablation has to be taken into account when this therapy is considered. The recurrence rate is 3-10% for accessory pathways and 0-15% for AVNRT. The high success rate of catheter ablation has already led to a shift in the indications for the procedure where the percentage of patients with accessory pathways is decreasing and there is an increase of patients with AVNRT and newer indications (atrial flutter, focal atrial tachycardias).     

Experience in 1,500 patients undergoing radiofrequency ablation in the treatment of tachycardias

Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular and ventricular tachycardias. This report details the results of radiofrequency catheter ablation in 1500 consecutive patients with a wide variety of supraventricular and ventricular tachycardias treated in the Instituto Nacional de Cardiología "Ignacio Chavez", between April 22, 1992 until December of 1999. Tachycardias were associated with the presence of an accessory pathway in 987 patients (65.8%). Dual accessory pathways were present in 24 patients giving a total of 1,012 accessory pathways. The mechanism of the arrhythmia was atrioventricular nodal reentrant tachycardia in 321 patients (21.4%). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 109 (7.2%) patients and a primary atrial tachycardia in 13 patients (0.8%). Atrioventricular node ablation and permanent pacemaker implantation were performed in 26 patients (1.7%). Finally we performed radiofrequency catheter ablation in 37 (2.4%) patients with ventricular tachycardia. Radiofrequency catheter ablation was successful in 908 of 1012 (89.7%) patients with accessory pathways with a complication rate of 10 (0.98%) and a recurrence rate of 92 (9%). AV nodal reentry was successfully abolished in 319 of 321 patients by selective ablation of the slow pathway in 297/321 (92.5%) patients and the fast pathway in 22/24 (92%) patients. The complication rate of this group was 8/321 (2.4%) with a recurrence rate of 34 patients (10.5%). The reentrant circuit of atrial flutter was ablated successfully in 86 of 109 (76.8%) patients with a recurrence flutter in 14 (12.8%) patients. Five of 13 (38.4%) cases of primary atrial tachycardia were successfully ablated. Complete AV block was achieved in 26 of 26 (100%) patients with atrial fibrillation or flutter treated by AV nodal ablation. The procedure was successful in 28 of 37 (75.6%) patients with fascicular ventricular tachycardia. The results of this series of patients demonstrates the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of taquicardias with high rate of success 1375 of 1500 patients (91.6%), with 142 recurrences (9.4%), 15 complications (1%), and no mortality.     

Percutaneous radiofrequency catheter ablation for supraventricular arrhythmias in children

Nineteen procedures were performed in 17 children, aged 10 months to 17 years, using catheter radiofrequency applications for the management of malignant or drug-resistant supraventricular tachyarrhythmias. Diagnoses were junctional ectopic tachycardia in 1 patient, atrioventricular (AV) node reentrant tachycardia in 4 and accessory pathway-mediated tachycardia in 12. Accessory pathway locations were left lateral (n = 4), posteroseptal (n = 3), left posterior (n = 2), right posterolateral (n = 1), right posterior paraseptal (n = 1), right intermediate septal (n = 1) and right anterior (n = 1). Ablation of accessory pathways was performed using 20 to 40 W of energy. The catheter was passed retrograde to the left ventricle in patients with a left-sided pathway and anterograde to the right atrium in those with a right-sided or posteroseptal pathway. In the 12 patients with an accessory pathway, radiofrequency applications were successful in 11 pathways and failed in 2. There were no recurrences of accessory pathway-mediated tachycardia. Atrioventricular node reentrant tachycardia was treated by AV node modification using 15 W of energy applied until first degree AV block occurred. After radiofrequency catheter ablation, there was a prolonged AH interval, tachycardia was not inducible and tachycardia recurred in one patient. For the patient with junctional ectopic tachycardia, 15 to 18 W of energy was delivered at the site of the maximal His bundle electrogram until sinus rhythm and normal AV conduction appeared. After a recurrence, a second procedure abolished tachycardia and AV conduction. In summary, radiofrequency catheter ablation was initially successful in 17 of 19 procedures and ultimately curative in 14 (82%) of 17 patients with no serious complications. Radiofrequency catheter ablation appears to be a safe and effective method for the management of supraventricular tachyarrhythmias in children.     

Usefulness of the pre-excitation index to determine the mechanism of supraventricular paroxysmal tachycardia and the location of the anomalous pathway

To evaluate the preexcitation index in determinate the mechanism of paroxysmal supraventricular tachycardia and localize accessory pathway, fifty nine patients with clinical and electrocardiographic supraventricular tachycardia were analyzed. There were thirty eight patients (64.4%) with orthodromic AV reentry using an accessory pathway for retrograde conduction and 21 patients (35.6%) with typical AV nodal reentrant tachycardia. Preexcitation of the atrium during tachycardia by premature ventricular complex at a time when anterograde His bundle activation was present in 30 o 38 (79%) patients with AV reentry while only 8 of 21 (38%) patients with AV nodal reentry demonstrated preexcitation during tachycardia. There was no significant difference between left and right accessory pathways and in mean tachycardia cycle length between the two groups. However, atrioventricular reentry demonstrated atrial preexcitation during tachycardia more frequently than AV nodal reentry. In conclusion, our findings show that the preexcitation index is a useful method for determinate the mechanism of supraventricular tachycardia and to localize accessory pathways.     

Temperature-controlled Radiofrequency Catheter Ablation of Accessory Pathways and Atrioventricular Nodal Reentrant Tachycardia: The 5-French Catheter Approach

Ablation with Temperature-Controlled 5-French Catheters. Introduction: In the present study, we assessed the feasibility of radiofrequency (RF) ablation of accessory pathways and AV nodal reentrant tachycardias with novel 5-French catheters with 4-mm tip electrodes using established mapping criteria and temperature-controlled power output control. Methods and Results: In this prospective study, 60 consecutive adult patients (mean age 36 ± 20 years) with accessory pathways (n = 37; 24 left-sided) or AV nodal reentrant tachycardia (n = 23) underwent RF catheter ablation. A 5-French catheter with a 4-mm tip electrode and an embedded thermistor was used for RF application. The surface of the tip electrodes was 26 mm2 compared to 38 mm² of 7-French catheters with 4-mm tip electrodes from the same catheter series. Power output was automatically and continuously adjusted according to the preset catheter tip temperature of 60° to 70°C. Pulse duration was 90 seconds. For left-sided accessory pathways, the retrograde route via the femoral artery was used. After removing the 5-French sheaths, only 4 hours of bed rest were advised. For ablation of AV nodal reentrant tachycardia, the so-called slow pathway was targeted for ablation. Acute success was achieved in 34 (92%) of 37 patients with accessory pathways and 23 (100%) of 23 patients with AV nodal reentrant tachycardia. A mean of 3 ± 4 RF pulses (median 2 pulses; range 1 to 20 pulses) was applied. The mean fluoroscopy time was 26 ± 21 minutes. No complete AV block or other procedure-related complications were observed. Recurrences occurred in 2 patients with accessory pathways and in 2 patients with AV nodal reentrant tachycardia during a follow-up of 9 ± 4 months. Conclusions: Temperature-controlled RF ablation of accessory pathways and AV nodal reentrant tachycardia in adults using 5-French catheters is feasible, effective, and safe. Ablation with 5-French catheters might help to reduce the complication rate of catheter ablation techniques.     

Catheter Ablation of the Atrial Origin of a Decrementally Conducting Atriofascicular Accessory Pathway by Radiofrequency Current

Radiofrequency Ablation of Pseudo-Mahaim Fibers. Introduction: A young woman with refractory recurrent supraventricular tachycardia was referred for catheter ablation. Methods and Results: Electrophysiologic studies revealed the mechanism of tachycardia to be atrioventricular (AV) reentry, utilizing a decrementally conducting atriofascicular accessory pathway as the anterograde limb of the circuit and the normal intraventricular conducting system as the retrograde limb. Pace mapping in the right atrium during sinus rhythm suggested an atrial origin of the accessory pathway several centimeters distant from the AV node. Multiple radiofrequency lesions at the distal insertion of the accessory pathway in or near the right bundle branch failed to abolish preexcitation. In contrast, radiofrequency current applied to the ventricular side of the anterolateral tricuspid ring, adjacent to the atrial origin of the accessory pathway, was successful in abolishing preexcitation and inducible supraventricular tachycardia without affecting AV nodal conduction. Conclusion: Radiofrequency ablation can provide curative therapy for intractable supraventricular tachycardia due to decrementally-conducting atriofascicular accessory pathways. The risk of AV block in such patients as a consequence of the procedure should be quite low.     

Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: Clinical features,electrophysiologic characteristics and results of radiofrequency ablation

Objectives. This study was designed to evaluate the clinical features, electrophysiologic characteristics and results of radio-frequency ablation in elderly patients with accessory atrioventricular (AV) pathways or AV node reentrant tachycardia. Background. Radiofrequency ablation in elderly patients with paroxysmal supraventricular tachycardia has not been well described, and comparative study between elderly and younger patients is limited.Methods. Electrophysiologic studies and radiofrequency ablation were performed in 92 elderly patients (45 with an accessory pathway, 47 with AV node reentrant tachycardia).Results. The elderly patients had poorer electrophysiologic properties in accessory pathways and dual AV node pathways than those of younger patients. The success rate of radiofrequency ablation was similar in elderly and younger patients. However, elderly patients had more complications (14%) in left-sided accessory pathways.Conclusions. Radiofrequency ablation in elderly patients with supraventricular tachycardia was effective. However, it must be performed cautiously in those patients with left-sided accessory pathways.     

Role of Radiofrequency Ablation in the Management of Supraventricular Arrhythmias:

Radiofrequency Ablation of Supraventricular Arrhythmias, Introduction: Several reports iiave demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular tachycardias. However, the efficacy, complications, risk of arrhythmia recurrence, and follou-up survival analysis have not been reported in a large series of consecutive patients with supraventricular arrhythmias with diverse electrophysiologic mechanisms. This report details the results of radiofrequency catheter ahiation in 760 consecutive patients (386 males, 374 females) with a wide variety of supraventricular tachycardias treated at one center. Methods and Results: Arrhythmias were associated with the presence of an accessory pathway i n 363 patients (384 accessory pathways), including four patients with Mahaim fibers and eight patients with the permanent form of junctional reciprocating tachycardia. The mechanism of the clinical arrhythmia was AV nodal reentrant tachycardia in 245 patients, and a primary atrial tachycardia in 20 patients (ectopic atrial tachycardia in 16 patients and sinus nodal reentry in 4 patients). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted i n 13 patients. AV node ahiation and permanent pacemaker implantation were performed in 119 patients with medically refractory atrial fihrillation or flutter. Radiofrequency catheter ahiation was successful in 346 of 363 patients (95.3%, CI 93.I%–97.5%) with accessory pathways (367 of 384 pathways, 95.6%, CI 93.5%–97.6%) with a complication rate of 1.1% and a recurrence rate of 5.5%. Successful accessory pathway ablation was achieved for 179 of the first 192 pathways treated (93.2%, CI 89.7%–96.6%) and increased to 188 of 192 pathways (97.9%, CI 95.9%–99.9%) over the second half of the series. AV nodal reentry was successfully abolished in 244 of 245 patients (99.6%, CI 98.8%–100%) by selective ablation of the slow pathway in 234 patients and the fast pathway in 10 patients. The complication rate in this group was 2.0% with a recurrence rate of 6.5%. All 20 primary atrial tachycardias were successfully ablated with no complications and a recurrence rate of 15%. The reentrant circuit of atrial flutter was ahlated successfully in 10 of 13 patients (77%) with recurrent atrial flutter in one additional patienl. Complete AV block was achieved in 117 of 119 (98.3%, CI 96.0%–100%) patients with atrial fibrillation or flutter treated hy AV nodal ablation with a complication rate of 0.8% and recurrence of AV conduction in 6%. The median duration of fluoroscopy exposure for the population was 23.4 minutes. The overall primary success rate for the entire population was 97.0% (737 of 760 patients, CI 95.8%–98.2%). Conclusion: Thus, the results of this large series of patients demonstrates the safety and efiicacy of radiofrequency ahiation for the treatment of a wide variety of supraventricular arrhythmias. It also appears that increasing experience with these procedures increases the rate of successful ahlation and decreases the risk of complications.     

Recurrence of Conduction Following Radiofrequency Catheter Ablation Procedures:

Recurrence of Conduction Following RF Catheter Ablation. Introduction : More than 1 in 10 patients may develop recurrence of conduction after undergoing a successful radiofrequency catheter ablation procedure. The physiologic basis for recurrence following successful ablation procedures remains uncertain. The purpose of this study was to evaluate the role of electrode temperature as a predictor of recurrence following radiofrequency catheter ablation procedures.
Methods and Results : The subjects of this study were 538 patients who underwent a successful attempt at radiofrequency catheter ablation of AV nodal reentrant tachycardia, an accessory pathway, and/or the AV junction. Patients were followed for a mean of 215 ± 138 days. Conduction recurred in 35 (6.5%) of the 538 patients. Recurrence of conduction occurred in 25 (9.3%) of 270 patients undergoing ablation of an accessory pathway, 7 (3.5%) of 201 patients undergoing ablation of AV nodal reentrant tachycardia, and in 3 (4.5%) of 67 patients undergoing ablation of the AV junction. The electrode temperature achieved at successful sites associated with recurrence was not different from the temperature achieved at successful sites without recurrence (61.1 ± 8.9 vs 61.6 ± 9.1; P = 0.8). The likelihood of developing a recurrence was higher following ablation of accessory pathways than following ablation of A V nodal reentrant tachycardia or the AV junction (P = 0.03). Patients experiencing a recurrence following ablation of an accessory pathway had longer procedure durations (P = 0.0001). Ablation of left free-wall pathways was associated with a lower incidence of recurrence as compared with all other locations (P = 0.008).
Conclusion : The results of this study suggest that electrode temperature at the successful ablation site cannot be used to identify patients at highest risk of recurrence.     

New Horizons in Catheter Ablation

Catheter ablation has evolved into the dominant therapeutic modality in the treatment of a variety of arrhythmias, particularly supraventricular arrhythmias with the mechanisms of atrioventricular (AV) nodal reentry and AV reciprocating tachycardia via an accessory pathway. The mode of catheter ablation used in the great majority of cases is radiofrequency (RF) catheter ablation. This technology is well-suited for the above arrhythmias because the targets and the RF lesions are both small and discrete. Using temperature monitoring may improve the outcome of these procedures by decreasing procedure time and incidence of coagulum formation on the catheter after a sudden rise in electrical impedance. New RF catheter designs and new modalities of creating catheter-induced focal myocardial injury will allow operators to have improved success with the ablation of less approachable arrhythmias, including atrial flutter and reentrant ventricular tachycardia. Studies are currently underway to create a catheter based "maze" procedure for the treatment of atrial fibrillation. As techniques and technologies evolve, a greater proportion of patients with symptomatic or threatening arrhythmias may be approached with catheter ablation as a curative or palliative procedure.     

Mechanisms and management of paroxysmal supraventricular tachycardia

Paroxysmal supraventricular tachycardia (PSVT) is defined as a regular rapid heart beat, which initiates and terminates suddenly. PSVT may have a variety of electrophysiologic mechanisms, including atrial tachycardia, atrioventricular (AV) nodal reentry, and tachycardia involving an accessory AV connection. Atrial tachycardia may be reentrant or may be caused by abnormal automaticity or triggered activity. AV nodal reentry, in which the reentrant circuit is confined to the AV node or the region around the AV node, is the most common type of PSVT in adults. Orthodromic supraventricular tachycardia is the most frequently found tachycardia in patients with accessory AV connections. During orthodromic supraventricular tachycardia, antegrade conduction occurs via the AV node, and retrograde conduction occurs via an accessory AV connection. Other types of PSVT, including junctional tachycardia, are less common. A definitive diagnosis of the PSVT mechanism usually requires electrophysiologic testing, but clinical and electrocardiographic clues may be present. Understanding the mechanism of PSVT can alter therapy because the response to antiarrhythmic drugs may be somewhat different depending on the PSVT type. In addition, the risks and efficacy of catheter ablation for curing PSVT may differ depending on the PSVT type. A better understanding of PSVT mechanisms, which has developed over the past 20 years, has led to dramatic improvements in therapy.     

Interventionelle Therapie tachykarder Herzrhythmusstörungen bei Kindern

Over the past decades, interventional therapy of tachyarrhythmias in children without structural heart disease has evolved as an alternative to chronic pharmacological treatment. Catheter ablation in children over 5 years with symptomatic tachycardia using radiofrequency- or cryoenergy is nowadays performed with high success and low complication rates at experienced centers. The use of modern technologies such as non-fluoroscopic 3-dimensional mapping has further increased efficacy and safety of catheter ablation, and has led to a significant reduction of fluoroscopy time and dose. Arrhythmia substrates treated most frequently by catheter ablation in children include accessory pathways (WPW syndrome) leading to atrioventricular reentrant tachycardia (AVRT) and dual AV nodal pathways causing atrioventricular nodal reentrant tachycardia (AVNRT). Success rates of catheter ablation for these substrates during long-term follow up are over 90?%. Less common forms of tachycardias in children, such as focal atrial tachycardia, ventricular outflow tachycardias or idiopathic left ventricular tachycardia, are also amenable to catheter ablation with good long-term results. In asymptomatic children with preexcitation on the surface ECG (accessory pathway with the risk of rapid antegrade conduction during atrial fibrillation) the indication for catheter ablation of the accessory pathway for the prevention of sudden cardiac death should already be evaluated during childhood.     

Ablation of Atrioventricular nodal “slow pathway” for simultaneous treatment of coexisting atrioventricular and nodal reciprocating tachycardias

Introduction We report the case of a 49-year-old male patient with recurrent palpitations and two different supraventricular reciprocating tachycardias due to atrioventricular (AV) nodal reentry and orthodromic AV reentry sustained by a left-sided, concealed AV accessory pathway (AP). Methods and results During the baseline electrophysiological study, dual AV nodal conduction (90 ms jump) and non-decremental, eccentric, ventriculo-atrial conduction due to a left-sided, unidirectional, postero-septal AP were documented. Both typical AV nodal reentrant and orthodromic AV reentrant tachycardias were induced by programmed electrical stimulation. In both cases, shift and sustained conduction over the AV “slow pathway” were required for tachycardia induction and maintenance, respectively. Accordingly, catheter ablation was performed by targeting the AV nodal “slow pathway” first with radiofrequency current applications delivered at the inferior portion of the Koch’s triangle. Irritative, slow-rate junctional rhythm was observed during ablation. Afterward, programmed electrical stimulation demonstrated a continuous AV nodal conduction curve, persistent conduction over the AP, and only single orthodromic AV echo beat inducible under baseline condition and pharmacological stress (atropine 0.02 mg/kg i.v. bolus and continuous isoprenaline i.v. administration). Sustained reentrant tachycardias were not inducible any more. For these reasons, the procedure was stopped without any attempt to ablate the AP. After a 4 years follow-up the patient is still asymptomatic without antiarrhythmic drug usage. Conclusion AV nodal “slow pathway” ablation may abolish both typical AV nodal reentry tachycardia and orthodromic AV reentry tachycardia induction when the latter arrhythmia is dependent from AV nodal “slow pathway” conduction for induction and maintenance. This ablation strategy could be considered, under some instances (e.g. right antero-septal accessory pathways, older patients, etc), in order to reduce the procedure risks due to multiple arrhythmia substrate ablations.     

射频消融术治疗三尖瓣下移畸形并房室折返性心动过速射频消融术治疗三尖瓣下移畸形并房室折返性心动过速

８例三尖瓣下移畸形并右侧旁路患者行射频消融，平均室上速发作病史１１年。成功消融７例共８条旁束。结果表明：射频消融术前先行右室造影有利于消融靶点定位，射频消融术是治疗三尖瓣下移畸形并房室折返性心动过速安全、有效的方法。     

Need for Fast Pathway Ablation in Typical Irregular AV Nodal Reentrant Tachycardia in a Patient with Multiple AV Nodal Pathways

A case of a 60-year-old male with irregular AV nodal reentrant tachycardia of the common type is reported. Electrophysiological study revealed multiple antegrade slowly conducting AV nodal pathways and one exclusively retrogradely conducting fast AV nodal pathway. Despite the recommendation for slow pathway ablation as the treatment of choice in patients with AVNRT, first pathway ablation was successfully performed in this case due to the risk of total A V block of ablating the slow pathways. The present report shows that there is the rare patient in whom fast pathway ablation is required for curative treatment of AV nodal reentrant tachycardia.     

Catheter ablation of retrograde fast pathway in patients with atrioventricular nodal reentrant supraventricular tachycardia.

Atrioventricular (AV) nodal reentrant tachycardia is a common cause of supraventricular tachycardia. The present study describes catheter ablation of this form of tachycardia in 23 patients using direct current shocks. The aim of ablation was to abolish conduction through the retrograde pathway while preserving the anterograde conduction. All patients had symptomatic, drug resistant, slow-fast variety of dual atrioventricular nodal reentrant tachycardia. Using the retrograde atrial activation in the His bundle catheter as the reference, the optimal ablation site was selected by positioning an electrode catheter to obtain atrial activation synchronous with or earlier than the atrial activation at the reference electrode. Shocks of 100-300 joules were delivered at this site resulting in blockade of retrograde conduction in all patients. Ventriculo-atrial conduction studied 24 hours after the procedure was still absent in 16, modified in 2 and resumed in 3 patients. Two patients developed permanent complete heart block and were given pacemakers. At repeat electrophysiologic study performed after 2-4 months in 10 patients, the supraventricular tachycardia could not be induced. The AH interval was 67 +/- 10 msec during control study and to 115 +/- 39 msec at restudy (p < 0.001). The ventriculo-atrial conduction was absent in 7 cases and had been modified in 1 case. Over a follow up period of 1-30 months (mean 10.8 +/- 7.1 mo) 17 patients (73%) remained free of the arrhythmia without medication or pacemaker. Three other patients were easily controlled with digoxin. Thus, catheter modification of AV node results in permanent cure of the AV nodal tachycardia in majority of patients.     

Posterior his bundle electrogram location in a patient with atrioventricular nodal reentrant tachycardia and structurally normal heart

Atrioventricular (AV) nodal reentrant tachycardia is the most common form of paroxysmal supraventricular tachycardia in adults, and slow AV nodal pathway ablation has evolved into first-line therapy. Variations in conduction system anatomy are occasionally found at electrophysiological study and may make this ablation procedure very challenging. Here, we present the case of a 69-year-old man with a structurally normal heart and posterior displaced His bundle who underwent successful slow pathway ablation. Demonstration of the characteristic slow pathway recording and His bundle electrogram is strongly recommended prior to radiofrequency energy application in the posterior septal region.     

Radiofrequenz-Katheterablation von Vorhofflattern und Vorhofflimmern

Radiofrequency catheter ablation is now considered as a curative approach in patients with typical atrial flutter. Typical atrial flutter is due to a macrore-entrant circuit within the right atrium and it can be eliminated by a linear lesion in the isthmus between the tricuspid annulus and the vena cava inferior. The electrophysiological criterion of a bidirectional isthmus block has been shown to reduce the recurrence rate of atrial flutter after catheter ablation, thus achieving long-term cure of typical atrial flutter. Acute success rates of 85 to 90% and recurrence rates of 10 to 15% have been reported. The risk of paroxysmal atrial fibrillation continues to be clinically relevant in patients who underwent successful ablation of atrial flutter, in particular in patients with previously documented atrial fibrillation. The incidence of a new onset of atrial fibrillation after ablation of atrial flutter seems to be approximately 20%. Isthmus ablation has also been shown to be beneficial for the majority of patients with typical atrial flutter and atrial fibrillation: In addition to an elimination of typical atrial flutter the isthmus ablation apparently reduces the incidence of paroxysmal atrial fibrillation. At present, atrial fibrillation can only be treated by catheter ablation as a curative approach in the rare cases where an accessory pathway, an AV nodal re-entrant tachycardia, typical atrial flutter or an ectopic atrial tachycardia is the induction mechanism of the atrial fibrillation. The majority of patients with atrial fibrillation is apparently not amenable to a curative local ablation. While AV junction ablation and AV node modification can palliate some of the symptoms of atrial fibrillation by a control of ventricular rate, the arrhythmia persists with the loss of AV synchrony and continued risk of thromboembolism. The surgical MAZE procedure implies a compartimentation of the atria by surgical incisions resulting in areas to small to sustain the arrhythmia. Based on this procedure experimental and clinical studies are currently performed in order to develop catheter ablation cure of atrial fibrillation.