Use of Adenosine to Identify Patients at Risk for Recurrence of Accessory Pathway Conduction After Initially Successful Radiofrequency Catheter Ablation

Objectives: The use of adenosine after radiofrequency catheter ablation of accessory pathways was prospectively studied to determine its utility for identifying patients at risk for recurrence of accessory pathway conduction and to guide therapy that might reduce late recurrence in this group. Background: Accessory pathway conduction recursin 5%–12% of patients following initially "successful" radiofrequency catheter ablation. Adenosine may facilitate conduction over accessory pathways that have been modified by radiofrequency delivery, thus identifying patients at risk for recurrence. Methods: Radiofrequency catheter ablation was performed in 109 patients. Prior to ablation, 12–18 mg of adenosine was administered. After ablation, when all evidence of accessory pathway conduction remained absent for at least 30 minutes, adenosine 12–18 mg was again administered. Results: Adenosine given prior to radiofrequency catheter ablation did not block accessory pathway conduction in any patient. Adenosine given after elimination of accessory pathway conduction induced complete atrioventricular and ventriculoatrial block in 95 patients; 11 (11.6%) subsequently had recurrence of accessory pathway function. Accessory pathway conduction was unmasked by adenosine in 12 patients (11.2%). After further deliveries of radiofrequency energy, 7 of these 12 patients subsequently demonstrated adenosine induced atrioventricular and ventriculoatrial block; 1 of these 7 patients experienced recurrence of accessory pathway conduction. The remaining 5 patients demonstrated persistent accessory pathway conduction only with adenosine; all experienced clinical recurrence of accessory pathway function. Conclusion: The use of adenosine after presumed successful radiofrequency catheter ablation may reveal persistent accessory pathway conduction. Elimination of this latent accessory pathway conduction reduces the risk for recurrence.     

Radiofrequency Ablation of Accessory Pathways: Characteristics of Transiently and Permanently Effective Pulses

The purpose of this study was to characterize and compare the radiofrequency current applications that produced permanent or transient accessory pathway conduction block. One hundred fifty-two radiofrequency energy applications that induced permanent (permanently effective pulses, n = 48) or transient (transiently effective pulses, n = 104) accessory pathway block in 57 patients with 60 accessory pathways were analyzed. The time from the onset of current application to disappearance of preexcitation or termination of supraventricular tachycardia by permanently effective pulses was 1-15 seconds (mean 3.6 +/- 3.8 sec) compared to 2-29 seconds (mean 11.5 +/- 7.5 sec) by transiently effective pulses (P less than 0.01). After transiently effective pulses that induced block in accessory pathway, conduction resumed within 5 minutes while induced block by permanently effective pulses persisted in 44 of 48 patients (92%) during follow-up of 11 +/- 12 months. The accessory pathway conduction returned in the remaining four patients after ablation 2 weeks to 7 months. After transiently effective pulses, 41 impulses were delivered to the same site using a higher power output (n = 32) and/or longer energy delivery duration (n = 20) without new mapping of accessory pathway location. Thirty-six of these impulses again resulted in transient accessory pathway block, four had no effect, only one impulse induced a permanent block in the accessory pathway. Pulses with higher power outputs tended to induce transient effects more frequently than pulses with lower energy.(ABSTRACT TRUNCATED AT 250 WORDS)     

New Observations on Decremental Atriofascicular and Nodofascicular Fibers: Implications for Catheter Ablation

Introduction: The purpose of this study was to characterize the anatomy and physiology of accessory pathways that exhibit anterograde decremental conduction. Results: Among 100 consecutive patients with an accessory pathway undergoing electrophysiological study, six individuals with decremental anterograde accessory pathway conduction were identified. Anterograde accessory pathway effective refractory periods and conduction curves were assessed by atrial extrastimulus testing. Atrial pace mapping and ventricular activation sequence mapping were used to define accessory pathway origin and insertion. Surgical ablation (N = 1) or radiofrequency catheter ablation (N = 3) was performed based on accessory pathway anatomy as determined during electrophysiological study. Four of 6 patients had gaps in anterograde accessory pathway conduction. Two patients had evidence of functional longitudinal dissociation in the accessory pathway. Five of 6 patients had atriofascicular fibers with an atrial rather than AV nodal site of origin of their decrementally conducting accessory pathway and with distal insertions in the right bundle branch. Among these five patients, a right posterior atrial origin was nearly as common as a right anterior atrial origin. One patient had a true nodofascicular fiber that arose from the AV node, inserting distally into the left bundle branch. Conclusion: Most accessory pathways with anterograde decremental conduction arise from the right anterior or right posterior atrium, not the AV node. A gap in anterograde accessory pathway conduction and functional longitudinal dissociation are common in such accessory pathways. Surgical or catheter ablation of such pathways is effective when directed at the atrial origin of the accessory pathway. True nodofascicular fibers arising from the AV node are rare. These may insert distally in the left ventricle. Catheter ablation of the proximal origin of such fibers is likely to result in complete AV block.     

Adenosine-dependent concealed accessory pathway

Adenosine is routinely used during ventricular pacing to exclude the persistence of retrograde accessory pathways conduction after radiofrequency (RF) ablation procedures by blocking conduction over the atrioventricular node. This is the first report of an adenosine-dependent concealed accessory pathway demonstrating transient conduction only after adenosine administration. Our findings may have potential clinical implications in reducing recurrence after accessory pathway ablation. Furthermore, it may add relevant information regarding the ability of adenosine to elicit dormant conduction after RF ablation, a phenomenon that has acquired considerable interest in the era of pulmonary vein isolation.     

Compensatory Accessory Pathway for Complete Atrioventricular Block: 28-Year Follow-Up

We report a case of atrioventricular (AV) block diagnosed 28 years ago compensated by a functional accessory pathway. During follow-up, the accessory pathway conduction properties at rest deteriorated while the refractory properties were unchanged. At 46 years, the patient became symptomatic from bradycardia and a dual-chamber pacemaker was implanted. Although rare, concealed AV block due to an accessory pathway has to be recognized before radiofrequency ablation.     

Delayed Effects of Radiofrequency Energy on Accessory Atrioventricular Connections

The purpose of this study was to determine the incidence and characteristics of delayed effects on conduction through accessory atrioventricular (AV) connections after apparently successful attempts at radiofrequency catheter ablation. Among 450 patients who had 471 accessory AV connections, the ablation procedure was unsuccessful in 26 patients (6%), as defined by persistent conduction through the accessory AV connection 60 minutes after the final application of radiofrequency energy. In 6/26 unsuccesfully treated patients (24%), conduction through the accessory AV connection disappeared on a delayed basis. At least once during the ablation procedure, conduction through each of these 6 accessory AV connections was transiently eliminated for 10 seconds to 60 minutes. Five of these accessory AV connections were left-sided and one was posteroseptal; one was concealed and five were manifest. Conduction through the accessory AV connection disappeared on a delayed basis 6–18 hours after the ablation procedure in 4 patients, and at some time between 1–5 days or 1–60 days in the other 2 patients. In 2 patients, the delayed effect was only transient, while in 4 patients, conduction through the accessory AV connections did not return during 5–23 months of follow-up. In conclusion, up to 15% of patients who undergo an apparently unsuccessful attempt at radiofrequency ablation of an accessory AV connection may later manifest a permanent loss of conduction through the accessory AV connection.     

Protected circumferential conduction in the posterior atrioventricular vestibule of the left atrium: electrophysiologic and anatomic correlates

BACKGROUND: The anatomic substrate for protected isthmus conduction in the right atrium has been well defined. Little is known of similar substrates in the left atrium (LA). METHODS: Patients (pts) with reentrant tachycardia (AVRT) supported by a single left-sided accessory pathway were studied retrospectively (n = 64) and prospectively (n = 31). Intracardiac electrograms were recorded from the His bundle position and coronary sinus (CS). The LA was mapped with a steerable catheter using the transseptal approach. LA anatomy was examined grossly and histologically in six cadaver hearts after removal of endocardium. RESULTS: A distal-to-proximal CS activation sequence during AVRT was seen in all patients with a left lateral accessory pathway before ablation. After one to three radiofrequency (RF) energy deliveries that did not interrupt accessory pathway conduction, the CS activation sequence was reversed in three patients in the retrospective group and bidirectional conduction block in the posterior atrioventricular vestibule of the LA (PAVV) was demonstrated in nine patients in the prospective group. Four of the six cadaver hearts showed a distinct circumferential inferoposterior myocardial bundle that coursed parallel to the CS in the PAVV. CONCLUSIONS: We described evidence of bidirectional intraatrial block in the PAVV after application of RF energy during accessory pathway ablation. Such conduction block may mimic the presence of a second accessory pathway. Our data suggest that circumferential conduction in the PAVV may be poorly coupled to the rest of the LA and may be involved in the macro-reentrant circuit around the mitral annulus. The circumferential inferoposterior myocardial bundle may serve as the underlying anatomic substrate.     

Radiofrequency catheter ablation of accessory pathways.

One hundred five patients with an accessory atrioventricular pathway underwent catheter ablation of the pathway using radiofrequency current. There were 79 accessory pathways located on the left and 32 on the right side of the heart. In patients with right-sided pathways ablation was attempted via a catheter positioned at the atrial aspect of the tricuspid annulus. In patients with a left-sided free-wall accessory pathway a novel approach was utilized in which the ablation catheter was positioned in the left ventricle directly below the mitral annulus. Accessory pathway conduction was permanently abolished in 93 patients (89%). Failures were mainly due to inadequate catheters used initially. It is concluded that catheter ablation of accessory atrioventricular pathways using radiofrequency current is an effective and safe therapeutic modality for patients with symptomatic tachyarrhythmias mediated by these pathways.     

A Wide Complex Tachycardia with Changing Atrial Activation Sequence

Change of the retrograde atrial activation sequence during radiofrequency (RF) ablation of left‐side accessory pathway can be due to another accessory pathway, another mechanism for the tachycardia, or due to intraatrial conduction block, partial or complete, caused by RF delivery to a site proximal to the site of insertion of the accessory pathway. In this case report, a temporary complete intraatrial conduction block was created by RF delivery proximal to the site of accessory pathway insertion, causing a change in the retrograde atrial activation sequence during ongoing tachycardia that was terminated by ablation at the insertion site of accessory pathway. (PACE 2013; 36:e23–e26)     

Radiofrequency Catheter Ablation of Accessory Pathways During Entrainment of AV Reentrant Tachycardia

Radiofrequency ablation of accessory pathways must sometimes be done during orthodromic atrioventricular reentrant tachycardia when manifest anterograde accessory pathway conduction is absent or retrograde fusion obscures accessory pathway location during ventricular pacing. Unfortunately, abrupt heart rate slowing upon radiofrequency induced termination of atrioventricular reentrant tachycardia often causes catheter dislodgment. We report our experience in circumventing this problem during radiofrequency ablation by using entrainment of atrioventricular reentrant tachycardia. The latter maintains retrograde activation pattern over the accessory pathway while preventing abrupt ventricular rate change. Eight patients (4 men and 4 women, mean age 37.3 ± 17.9) with eleven left-sided accessory pathways were included. Ablation during entrainment was used as the first approach in three patients with concealed accessory pathways and one patient with a bidirectional accessory pathway. In another four patients, ablation during entrainment was used after technical difficulties in ablating during tachycardia. Only 1–3 radiofrequency applications were required to eliminate the accessory pathway using the entrainment technique. The catheter remained stable when accessory pathway conduction was interrupted by radiofrequency current. In conclusion, entrainment of atrioventricular reentrant tachycardia during radiofrequency application is useful for maintaining catheter position for accessory pathway ablation during atrioventricular reentrant tachycardia.     

Radiofrequency Catheter Ablation of Atriofascicular Accessory Pathways Guided by Discrete Electrical Potentials Recorded at the Tricuspid Annulus

Background: The purpose of this study was to test the feasibility of using the recording of discrete electrical potentials to guide radiofrequency catheter ablation of atriofascicular accessory pathways with Mahaim-like properties. Methods and Results: Four patients (3 females, 1 male) who fulfilled criteria for having atriofascicular accessory pathways with Mahaim-like properties and preexcited reciprocating tachycardia underwent radiofrequency catheter ablation. The mean age was 35 years (range 27–47). Symptoms were present for a mean of 10.5 years (range 6–18). Recording of discrete electrical potentials of the atriofascicular pathway was attempted by mapping the tricuspid annulus in sinus rhythm, during atrial pacing, and during reciprocating tachycardia. During atrial pacing, a mean of seven radiofrequency pulses (range 1–14), delivered to the tricuspid annulua at the area where electrical potentials were recorded, eliminated conduction through the atriofascicular accessory pathway in all patients. No complications occurred. Tachycardia did not reoccur during a mean follow-up of 5 months (range 3–9). Conclusions: Recording of discrete electrical potentials at the tricuspid annulus identifies an optimal ablation site where radiofrequency current can safely eliminate conduction through atriofascicular accessory pathways with Mahaim-like properties.     

Transient Complete Atrioventricular Block During Transcatheter Ablation of a Left Inferoparaseptal Anomalous Pathway in a Patient with a History of Previous Surgical Repair of Ventricular Septal Defect

This case describes a young woman with a manifest left inferoparaseptal accessory pathway and previous history of surgical repair of a defect of the ventricular inlet septum in whom a transient complete AV block occurred during radiofrequency ablation performed from the coronary sinus. The presence of a preexisting surgery related AV block unmasked by anomalous pathway ablation is the more reliable explanation for this case.     

Curative Radiofrequency Catheter Ablation for Permanent Junctional Reciprocating Tachycardia

Two patients with the permanent form of junctional reciprocating tachycardia successfully treated with the radiofrequency catheter ablation technique are described. In both patients a reentrant tachycardia utilizing a conceoled slow conducting posterior septal accessory pathway for retrograde conduction was demonstrated. Radiofrequency current was delivered below the coronary sinus orifice. The procedure resulted in ablation of the accessory pathway conduction in both patients. During the follow-up, both patients remained free from tachycardia on no medication. This report demonstrates that the arrhythmogenic substrate of the permanent junctional reciprocating tachycardio can be easily suppressed by means of the radiofrequency catheter technique.     

Unexpected Complete AV Block Following Transcatheter Ablation of a Left Posteroseptal Accessory Pathway

Radiofrequency catheter ablation is the procedure of choice for the nonpharmacological treatment of AV connections that are responsible for debilitating tachycardia. This article describes a patient with a manifest left posteroseptal accessory pathway and recurrent syncopes in whom a transient complete AV block occurred after transcatheter radiofrequency ablation of the left posteroseptal pathway. Three electrical abnormalities were present in this patient: AV infra-Hisian block, a left posteroseptal accessory pathway, and an AV nodal reentry tachycardia. This case report reminds you that one should be prepared for all fall backs during catheter ablation.     

Catheter ablation for a right anteroseptal accessory pathway in a patient with an endocardial cushion defect

We report a radiofrequency catheter ablation for atrioventricular reentrant tachycardia in a patient with a right anteroseptal accessory pathway complicating an endocardial cushion defect. His bundle potential was recorded 20 mm posterior to the accessory pathway. In the presence of associated congenital heart disease, it is very important to understand the anatomy of the conduction system prior to radiofrequency catheter ablation.     

Atrioventricular conduction: a determinant for the manifestation of ventricular preexcitation in patients with Wolff–Parkinson–White syndrome

The relation between the atrioventricular conduction properties of the atrioventricular node and the anterograde conduction ability over the accessory pathway in the Wolff–Parkinson–White syndrome has never been studied. Atrioventricular nodal characteristics were studied in 285 patients with manifest and 204 with concealed accessory pathway who underwent radiofrequency ablation, and compared with 146 controls. First and second degree atrioventricular block was observed in 13 (5%) preexcitation patients after ablation, compared with none in concealed accessory pathway (P=0·001) and control patients (P=0·006). The atrial‐His intervals in preexcitation patients (88 ± 20 ms) was significantly longer than in concealed accessory pathway (76 ± 15 ms, P<0·0001) and control patients (77 ± 15 ms, P=0·0007), as was PR intervals (165 ± 25 versus 149 ± 20 and 150 ± 21 ms, P<0·0001, respectively) even after excluding those with atrioventricular block. Significant differences in PR and atrial‐His intervals were not observed between concealed accessory pathway and control patients. More preexcitation patients had ventriculoatrial dissociation than had patients in the other groups. The results indicate that atrioventricular block is not uncommon in preexcitation patients and a relatively long atrioventricular conduction time is an electrophysiological prerequisite for the manifestation of preexcitation in the Wolff–Parkinson–White syndrome.     

Delayed Response to Radiofrequency Ablation of Accessory Connections

This article summarizes delayed interruption in anomalous conduction through accessory connections following radiofrequency ablation attempts in three patients. The time course of the delayed interruption in accessory connection conduction suggests that such an effect is unlikely to occur after the first week following unsuccessful radiofrequency ablation.     

Catheter Ablation for Recurrent Tachyarrhythmias. Clinical Experience with Two Different Techniques of Ablation in 21 Patients

Between 1984 and 1988, 21 patients underwent catheter ablation for drug refractory arrhythmias. Nine patients presented atrial flutter, atrial fibrillation or atrial tachycardia, nine had supraventricular tachycardia (one AV nodal reentrant tachycardia, one reciprocating tachycardia due to concealed accessory pathway and seven XMPW syndrome). Three had ventricular tachycardia. Fourteen patients were treated with direct current shock ablation (DC) and seven patients with radiofrequency ablation (RF). Eight patients underwent ablation of the His bundle. In six patients permanent AV block could be induced and in two first-degree AV block. All became asymptomatic (two with additional antiarrhythmic drug therapy). In four patients with WPW syndrome DC ablation of the accessory pathway was attempted. In one patient a permanent block in the accessory pathway and in another an intermittent block were obtained. In the two remaining patients with accessory pathways the ablation failed to interrupt the retrograde conduction in one the retrograde conduction was modified: however, in the other no change could be demonstrated. Two patients underwent ventricular foci ablation, with one partial success (arrhythmia controlled with associated drug therapy) and one failure. Three patients had RF His bundle ablation (two for atrial flutter and one for atrial fibrillation). One complete atrioventricular block, one first degree AV block and one first degree AV block associated with right bundle branch block were induced. Recurrence of tachyarrhythmias was prevented only in the patient with complete atrioventricular block. RF ablation of accessory pathway was performed in three patients. It resulted in anterograde block in the accessory pathway in the first patient; a slight modification of the retrograde refractory period in the second and no change was noted in the last one. The first of these three patients could then be controlled with drug therapy. The other two patients underwent surgical dissection of the pathway. One patient underwent an unsuccessful attempt of ventricular focus ablation with RF energy. Complications were more common with DC than with RF ablation but serious ventricular arrhythmias were also observed during RF ablation. Thus, DC ablation was completely successful in eight of 14 patients (57%), partially successful with the addition of drug therapy in three patients (21%) and failed in 22%. HF ablation was successful in only one patient (14.5%) and partially successful in another one (14.5%). This relatively low success rate is due in part to the design of the device and the electrodes used in this study. With technical improvements of RF ablation it seems reasonable to expect that this method will play a significant role in the management of drug refractory arrhythmias, since RF ablation, when compared to DC ablation, has the major advantage not to require general anesthesia during the procedure.     

Fast pathway ablation in a patient with PR prolongation

The classical form of typical atrioventricular node reentrant tachycardia (AVNRT) is a “slow-fast” pathways tachycardia, and the usual therapy is an ablation of the slow pathway since it carries a low risk of atrioventricular (AV) block. In patients with long PR interval and/or living on the anterograde slow pathway, an alternative technique is required. We report a case of a 42-year-old lady with idiopathic restrictive cardiomyopathy, persistent atrial fibrillation status post pulmonary vein isolation, and premature ventricular complex ablation with a systolic dysfunction, who presented with incessant slow narrow complex tachycardia of 110 bpm that appeared to be an AVNRT. Her baseline EKG revealed a first-degree AV block with a PR of 320 ms. EP study showed no evidence of anterograde fast pathway conduction. Given this fact, the decision was to attempt an ablation of the retrograde fast pathway. The fast pathway was mapped during tachycardia to its usual location into the anteroseptal region, then radiofrequency ablation in this location terminated tachycardia. After ablation, she continued to have her usual anterograde conduction through slow pathway and the tachycardia became uninducible. In special populations with prolonged PR interval or poor anterograde fast pathway conduction, fast pathway ablation is the required ablation for typical AVNRT.     

射频消融的延迟效应对手术效果及并发症的影响

目的 :探讨射频消融延迟效应对手术效果及并发症的影响。方法 :回顾分析 1998～ 2 0 0 2年住院的室上速 4例 ,年龄 15～ 4 5岁 ,男女各 2例 ,其中房室结折返性心动过速 (AVNRT) 2例 ,右侧显性预激 (B- WPW) 2例 ,射频消融均未成功 ,在消融过程中 2例 B- WPW出现短暂旁路前传消失 ,2例 AVNRT出现短暂快速交界性心律及一过性 度房室传导阻滞。结果 :2例 B- WPW术后 1个月复查心电图预激消失 ,2例 AVNRT分别于术后 3d和 1周出现持续 度房室传导阻滞和 度 型房室传导阻滞 ,经激素治疗后房室传导均恢复正常。所有患者术后均未再发作室上速。结论 :射频消融术后组织及电学损伤范围可进一步加大从而产生延迟现象 ,它可对患者有益也可产生不利影响 ,因此射频消融时要密切注意可能产生延迟反应的电生理现象。