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.     

射频消融治疗快速性心律失常的体会

临床安全应用射频导管消融（ＲＦＣＡ）治疗各类快速性心律失常７８０例，总成功率９７．８％。其中房室折返性心动过速（ＡＶＲＴ）５５４例；房室结折返性心动过速（ＡＶＮＲＴ）１８２例；房扑１５例；房颤５例；特发性室速８例；右室流出道室速、室早１４例；致心律失常性右室心肌病（ＡＲＶＣ）２例。本组患者无一例发生血胸、气胸、心包填塞、动脉拴塞、３°房室传导阻滞、室颤等严重并发症。本文特别强调了术前充分准备、术中精确标测定位、细心轻巧操作、严谨控制消融能量和时间，术中与术后严密监护，可以最大程度地降低并发症的发生率。     

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).     

Radiofrequency Current Catheter Ablation for Control of Supraventricular Arrhythmias

Radiofrequency Catheter Ablation in SVT. With the advent of radiofrequency energy, catheter ablation techniques have become an accepted form of treatment for a variety of Supraventricular arrhythmias. The ablation of the atrioventricular (AV) node was performed first and is now widely used in patients with refractory atrial fibrillation or flutter. Ablation has also replaced surgery in patients with preexcitation syndromes, and as the complication rate in experienced centers is low, it has become the first line of treatment in these institutions. The results of catheter ablation in AV nodal reentrant tachycardia are excellent as well, although there is still debate about whether "slow" pathway ablation is superior to "fast" pathway ablation. Radiofrequency current ablation has also contributed to a better understanding of the pathophysiology of AV nodal reentrant tachycardia, as it has provided evidence for atrial participation in the reentrant circuit. Experience with atrial tachycardias and tachycardias due to Mahaim fibers remains limited. The ideal source of energy for specific arrhythmias is still unknown and improvement in catheter technology is needed.     

Radiofrequency catheter ablation in the treatment of supraventricular tachycardia in the elderly

Objectives. The purpose of this study was to evaluate the efficacy and safety of radiofrequency catheter ablation for the treatment of supraventricular tachycardias in an elderly (≥70 years of age) group of patients.Background. Supraventricular tachycardias are the most common form of cardiac arrhythmia and affect all age groups. Although usually well tolerated in youth, supraventricular tachycardias may be associated with disabling symptoms and have lifethreatening potential 10 the elderly. In addition, antiarrhythmic agents are less well tolerated and may be associated with a higher incidence of toxicity in the elderly.Methods. From May 1989 to March 1993, 454 patients underwent a radiofrequency catheter ablation procedure at the University of California, San Francisco, for the treatment of symptomatic supraventricular tachycardia. Sixty-seven of these patients were ≥70 years of age and constituted the study group. Patients underwent one of the following catheter ablation procedures: complete atrioventricular (AV) junctional ablation for ventricular rate control in patients with atrial fibrillation (37 patients), AV node modification for the treatment of AV node reentrant tachycardia (17 patients), accessory pathway ablation (9 patients), ablation of the “slow zone” to cure atrial flutter (4 patients) and atrial tachycardia ablation (1 patient). One patient underwent ablation for both AV node reentrant tachycardia and atrial flutter.Results. Success was achieved in 67 (98.5%) of 68 ablation procedures. There were no procedural or early deaths. The overall complication rate was 7.4%, and only one patient (1.5%) had long-term sequelze (permanent cardiac pacing for complete heart block). At a mean (±SD) follow-np of 22.1 ± 12.9 months, 63 (94%) of 67 patients were alive, with no antiarrhythmic agents for the treatment of their presenting arrhythmia.Conclusions. In this series radiofreqnency catheter ablation appears to be an effective and safe treatment option for elderly patients (≥70 yean of age) with a variety of symptomatic, drug-resistant supraventricular tachycardias. Because of the high incidence of severe symptoms associated with tachycardic episodes, the expense and the possible severe proarrhythmic problems associated with antiarrhythmic medications in this age group, catheter ablation may be considered an early rather than a “last resort” treatment option.     

Catheter Ablation for the Treatment of Paroxysmal Supraventricular Tachycardia

Catheter Ablation for PSVT. Radiofrequency catheter ablation has evolved into a front-line curative therapy for patients who have paroxysmal supraventricular tachycardia secondary to Wolff-Parkinson-White syndrome, AV nodal reentrant tachycardia, and atrial tachycardia. In patients with accessory pathways, cure rates exceed 90% in almost all anatomic locations. Equally high success rates are noted in patients with atriofascicular pathways and the permanent form of junctional reciprocating tachycardia. Complications secondary to catheter ablation of accessory pathways occur in 1% to 3% of patients and include cardiac perforation, tamponade, AV block, and stroke. In patients with AV nodal reentrant tachycardia, selective slow pathway ablation is curative in over 95% of patients with a very low risk of AV block. Atrial tachycardias originating in both the left and right atria can he successfully ablated in over 80% of patients. Given the overall effectiveness of this procedure, radiofrequency catheter ablation should be considered as front-line therapy in patients with recurrent or drug-refractory paroxysmal supraventricular tachycardia. Although an effective therapy, the risks and benefits of this procedure need to be assessed in all patients who are candidates for this procedure.     

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.     

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)     

Catheter ablation for cardiac arrhythmias

The clinical introduction of catheter ablation in 1981 revolutionized the treatment of cardiac arrhythmias. Implementation of radiofrequency as an alternative energy source, with the advantages of higher selectivity and less collateral damage, provided an expansion of catheter ablation therapy. Today the majority of arrhythmias can potentially be cured with catheter ablation therapy. The safety and efficacy of catheter ablation for treatment of AV nodal reentrant tachycardia, accessory pathway arrhythmias, focal atrial tachycardia, atrial flutter and idiopathic ventricular tachycardia, is well established. Catheter ablation for treatment of atrial fibrillation and ventricular tachycardia secondary to structural heart disease, remains an area of active research. In this article we will review the current state of knowledge about the technique, indications, and results of catheter ablation for the treatment of cardiac arrhythmias.     

Catheter ablation for cardiac arrhythmias

With the introduction of radiofrequency energy, catheter ablation has become an established technique for managing many cardiac rhythm disturbances. High efficacy and safety have been reported for accessory pathway ablation, selective fast and slow atrioventricular nodal pathway ablation to eliminate atrioventricular nodal reentrant tachycardia (while preserving atrioventricular conduction), atrioventricular junctional ablation to control the ventricular response to atrial tachyarrhythmias, ablation of the right bundle branch to eliminate bundle branch reentrant ventricular tachycardia, and ablation of the site of tachycardia origin in patients with ventricular tachycardia unassociated with structural heart disease. In addition, there has been active investigation into ablation techniques for more complex arrhythmias such as atrial tachycardia, atrial flutter, and ventricular tachycardia associated with structural heart disease.     

Regular supraventricular tachycardias associated with idiopathic atrial fibrillation

The present study analyzed the recurrence rate of idiopathic atrial fibrillation (AF) after elimination by radiofrequency ablation of the substrate for a regular tachycardia. Forty consecutive patients with idiopathic AF and a history of regular palpitations or documented regular tachyarrhythmias were prospectively included. Regular tachyarrhythmias were induced in 82.5% of patients: atrial flutter (42.4% of the inducible arrhythmias), atrial tachycardia (24.2%), atrioventricular (AV) nodal reentry (18.2%), AV reentry through a concealed accessory pathway (9.1%), and AV nodal reentry associated with right atrial tachycardia (6.1%). Dual AV node physiology with single or dual AV node echoes was demonstrated in 6.1% of patients without inducible arrhythmias. During follow-up (92 +/- 11 months), AF recurred in 19.2% of patients after successful radiofrequency ablation and in 69.2% after unsuccessful or not performed procedures (p <0.05). Left atrial diameter did not change after successful ablation but increased significantly in the population without elimination of the substrate (initial diameter 37.5 +/- 2 mm, final diameter 46.4 +/- 3.2 mm; p <0.05). In conclusion, the systematic search for the substrate of regular tachyarrhythmias followed by their elimination by catheter ablation reduces the recurrence of idiopathic AF in patients with a history of regular palpitations or documented regular tachyarrhythmias.     

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.     

From bedside to bench: entrainment and other stories.

The concepts of transient entrainment of reentrant rhythms started with studies of overdrive pacing of atrial flutter (AFL) in patients in the immediate period after open heart surgery. Initial studies demonstrated the need to achieve a critical pacing rate and a critical duration of pacing at the critical pacing rate to interrupt AFL. Further pacing studies of AFL, ventricular tachycardia, atrioventricular (AV) reentrant tachycardia, AV nodal reentrant tachycardia, and atrial tachycardia refined the understanding of what occurs during overdrive pacing of reentrant tachycardias, and permitted a mechanistic understanding of transient entrainment as continuous resetting of a reentrant tachycardia to a pacing rate that is faster than the rate of the tachycardia, but which fails to interrupt it. The demonstration of transient entrainment of a tachycardia provides a reliable clinical tool to establish the presence of a reentrant rhythm. Moreover, the principles of entrainment have also been applied clinically to assist in effective application of antitachycardia pacing and catheter ablation techniques.     

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.     

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.     

Surgical alternatives for supraventricular tachycardias

Since Sealy's pioneering surgical intervention for Wolff-Parkinson-White syndrome, surgical electro-physiologic interventions have been developed for all supraventricular arrhythmias. The surgical rationales are based on the site of origin of the arrhythmic mechanism and the associated pathology that characterizes the “arrhythmogenic substrate.”

The Wolff-Parkinson-White syndrome is characterized by an accessory atrioventricrdar (AV) connection distinct from the AV node—His bundle system. It is associated with AV reentrant tachycardia or atrial fibrillation, or both, with fast ventricular responses through the accessory pathway. The current surgical management involves ablation of the accessory pathway using either an endocardial or an epicardial approach. Surgical ablation is associated with high efficiency and low morbidity. Epicardial dissection of the accessory pathway on the beating heart has helped to localize variant accessory pathways associated with Coumel's tachycardia or the Mahaim fiber.

AV nodal reentrant tachycardia can be cured using direct AV nodal dissection (or perinodal cryoablation). Atrial flutter can be interrupted by cryoabladon of the arrhythmogenic substrate located in the coronary sinus orifice region. The chronotropic atrial function, abolished by incessant or paroxysmal idiopathic atrial fibrillation, can be restored using the corridor operation (sinus node-AV node insulation). The success of surgical intervention in atrial tachycardias is uncertain, but it may be an option in selected patients with resistant atrial tachycardias.     

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 with Radiofrequency Energy: Biophysical Aspects and Clinical Applications

Radiofrequency Catheter Ablation. Radiofrequency catheter ablation techniques are becoming increasingly accepted as the therapy of choice for selected patients with symptomatic arrhythmias. The ability to titrate the power output using radiofrequency current has allowed these ablative techniques to be applied safely in a variety of arrhythmias. In many institutions, radiofrequency catheter ablation has now become standard therapy for controlling medically refractory atrial arrhythmias using atrioventricular (AV) junction ablation and for curing AV nodal reentrant tachycardia and supra ventricular tachycardia due to accessory AV connections. This technology is also being used to treat some forms of ventricular tachycardia such as bundle branch reentry ventricular tachycardia, ventricular tachycardia in structurally normal hearts, and with limited success in patients with ventricular tachycardia and coronary artery disease. Advancements in catheter design and energy delivery systems may further expand the use of this form of therapy. (J Cardiovasc Electrophysiol, Vol. 3, pp. 173–186, April 1992)     

Transcatheter ablation of cardiac tissue: advantages and disadvantages of different ablative techniques.

Transcatheter ablation techniques are emerging as an alternative therapeutical tool in the management of cardiac arrhythmias. Catheter ablation was initially introduced as the last resort to ablate the atrioventricular nodal conduction in patients with atrial fibrillation and uncontrolled ventricular response and in patients with drug refractory ventricular tachycardias. Direct current energy was used as the sole source of energy, but because of potential significant complications and early and late mortality, presumably mostly due to ventricular tachyarrhythmias, other sources of energy were sought. Radiofrequency current which does not produce barotrauma and does not require general anesthesia rapidly replaced direct current ablation in many centers. Early results with radiofrequency current ablation of the atrioventricular node and accessory atrioventricular pathways are very encouraging. The results of radiofrequency as well as direct current ablation for atrial flutter, atrial tachycardia and ventricular tachycardia, where the components of reentry circuit are less defined, are not as favorable as those of AV junctional tachycardias. However, improvement of catheter and generatory technology and better understanding of the mechanisms of ventricular tachycardias and characteristics of the target site will enhance the results of catheter ablation in ventricular tachcardias. The procedures are still considered investigational, and mostly done by very experienced groups at tertiary referral hospitals with surgical teams available in case of serious complications. Larger patient populations and longer follow-up periods are required before these techniques expand to community hospitals and to patients with minimal symptoms or asymptomatic individuals as a prophylaxis therapy.     

Intravenous flecainide acetate for supraventricular tachycardias

Flecainide acetate, 2 mg/kg body weight, given intravenously at 10 mg/min was administered to 128 (74 male and 54 female) patients whose ages ranged from 11 to 86 years (mean 44). All patients had supraventricular tachycardias (SVT) that developed spontaneously or were induced during electrophysiologic study. There were 26 patients with atrial flutter, 34 with atrial fibrillation, 7 with ectopic atrial tachycardia, 41 with atrioventricular (AV) reentrant tachycardia and 40 with AV nodal reentrant tachycardia. Twenty patients had more than 1 variety of SVT. Flecainide was administered during SVT to 9 patients with atrial flutter, 11 with atrial fibrillation, 7 with atrial tachycardia, 38 with AV reentrant tachycardia and 34 with AV nodal reentrant tachycardia. In the remaining 31 patients with inducible SVT at electrophysiologic study, flecainide was administered during sinus rhythm. Reinitiation of SVT was attempted in these patients after completion of flecainide administration. Flecainide successfully terminated atrial flutter in 2 patients (22%), atrial fibrillation in 9 (82%), atrial tachycardia in 5 (71%), AV reentrant tachycardia in 32 (84%) and AV nodal reentrant tachycardia in 30 (88%). Reinitiation of SVT was possible in 10 of 26 patients with atrial flutter (38%), 5 of 34 with atrial fibrillation (15%), 3 of 7 with atrial tachycardia (43%), 14 of 41 with AV reentrant tachycardia (34%) and 11 of 40 with AV nodal reentrant tachycardia (27%). In patients with AV reentrant tachycardia and AV nodal reentrant tachycardia, reinitiation occurred when retrograde anomalous pathway refractoriness was not significantly prolonged by intravenous flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)