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.     

Radiofrequency Catheter Ablation for Wolff-Parkinson-White Syndrome Associated with a Coronary Sinus Diverticulum

The case of a patient with Wolff-Parkinson-White syndrome undergoing attempted radiofrequency catheter ablation of a left posterior paraseptal accessory pathway is described. Coronary sinus venography revealed the presence of a large diverticulum attaching near the os. The electrogram recorded from a catheter placed in the narrow neck of the diverticulum revealed a very short atrioventricular time during sinus rhythm. The pathway was easily ablated using radiofrequency energy applied in the neck of the diverticulum, after multiple failed attempts at catheter ablation from the endocardial surface of the mitral annulus. Our report emphasizes the importance of searching for a coronary sinus diverticulum in all patients with posterior accessory pathways undergoing catheter ablation.     

The effect of ibutilide on retrograde accessory pathway conduction

Ibutilide is a compound with Class III effects marketed for rapid conversion of atrial fibrillation and atrial flutter. The Class III effect is primarily mediated by blockade of the rapid component of the cardiac delayed rectifier of potassium current, Ikr. Ibutilide was used in three patients with concealed accessory pathways during electrophysiological evaluation for ablation of symptomatic atrioventricular reentry tachycardia. Each pathway (mid-septal, left posterior, and left lateral) exhibited a mean retrograde effective refractory period of 240 +/- 20 ms. Each patient had atrioventricular reentry tachycardia that consistently degenerated to recurrent sustained atrial fibrillation. One to two milligrams of intravenous ibutilide converted atrial fibrillation to sinus rhythm and maintained sinus rhythm throughout the procedure. Retrograde accessory pathway conduction was unchanged. Maintenance of sinus rhythm allowed for successful mapping and catheter ablation of the concealed accessory pathways. No direct current cardioversion was needed. In these patients, ibutilide was effective in converting and controlling atrial fibrillation induced by atrioventricular reentry tachycardia without masking retrograde pathway conduction. Antegrade accessory pathway conduction could not be assessed in this study.     

Atrioventricular nodal reentry tachycardia: slow pathway ablation using the transseptal approach

Four hundred twenty consecutive patients with symptomatic slow/fast atrioventricular nodal reentry tachycardia had attempted slow pathway radiofrequency ablation. All patients had successful slow pathway ablation and no inducible tachycardia after ablation using the standard right-sided approach except for three patients. The three unsuccessful patients had inducible slow/fast atrioventricular nodal tachycardia after attempted right-sided posterior and inferoposterior anatomic ablative techniques and with slow pathway potential electrogram guidance. Lesions were also delivered linearly in the triangle of Koch and within the coronary sinus ostium. A transseptal puncture was performed and slow pathway ablation was obtained in each of these patients. Ablation was performed from the septal mitral valve annulus, anterior to the os of the coronary sinus and inferior to the His-bundle catheter with elimination of slow pathway conduction. Prior to the ablation, two of the three patients exhibited initiation of tachycardia with a double fast/slow antegrade response, and all three patients had long AH intervals (mean 378 ms) during slow pathway conduction. These electrophysiological findings may be consistent with a large area of slow pathway conduction that may include the left atrial septum not approachable by conventional right-sided ablative techniques. Slow pathway ablation to eliminate atrioventricular nodal reentry tachycardia at times may require a left atrial/transseptal approach when conventional right-sided techniques are ineffective.     

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.     

Radiofrequency Catheter Ablation of Septal Accessory Pathways within the Triangle of Koch: Importance of Energy Titration Testing Other than the Local Electrogram Characteristics for Identifying the Successful Target Site

Radiofrequency (RF) catheter ablation of accessory atrioventricular (AV) connections in the proximity of His bundle or AV node is at high risk of developing complete heart block. A safe and effective protocol has not been well established. Nineteen consecutive patients with 19 septal accessory pathways within the triangle of Koch underwent a protocol with power-titrated RF energy testing to identify the target site for successful catheter ablation. At every potential target site preselected by local electrogram characteristics, RF energy was started at 5 W for 10 seconds, with an increment of 5 W (duration remained at 10 s) until maximally 30 W or the observation of transient interruption of accessory pathway conduction. By this stepwise RF energy testing, we successfully localized and ablated 18 (94.7%) of the 19 septal accessory pathways, 10 close to His bundle (zone I) and 8 away from it (zone II). The test-effective RF power was 20 W or less in 9 of all 11 septal accessory pathways in zone I, and 5 of the 8 in zone II (P = 0.68). Meanwhile, the final RF power for successful ablation was 30 W or less in 9 of the 10 zone I and 6 of the 8 zone II septal accessory pathways (P = 0.83). One patient with an accessory pathway in zone I was complicated with complete AV block after final ablation at 30 W. None of the local electrogram characteristics except continuous electrical activity during retrograde mapping was helpful in the prediction of ablation outcome. Careful RF energy titration testing could effectively help identify the target site for successful RF catheter ablation of septal accessory pathways within the triangle of Koch. The dependence on local electrogram manifestations could be frustrated by a low probability of success.     

Catheter Atrioventricular Junctional Ablation in Patients with Accessory Pathways

Seven patients with accessory pathway and symptomatic alrioventricular reciprocating tachycardia underwent catheter ablution of the atrioventricular junction (AVJ). Four patients had the Wolff-Park inson White syndrome, two had concealed left free-wall accessory pathways, and one patient had a nodoventriculor connection. All patients failed multiple antiarrhythmic drugs and one failed attempted surgical ablation of a posteroseptal accessory pathway. Chronic interruption of atrioventricular node-His conduction was achieved in all patients. Over a mean follow-up period of 21 ± 14 months, four patients remained asymptomatic without antiarrhythmic therapy. One patient developed atrial fibrillation after magnet application to her VVI pacemaker, another developed atrial gutter, and a third had nonparoxysmal sinus or atrial tachycardia. Two patients required chronic quinidine therapy. Two patients with concealed accessory pathways had pacemaker-mediated tachycardia which was controlled by pacemaker reprogramming. Atrioventricular junctional ablation in patients with accessory pathways proved elective in that all are currently controlled without need for surgical intervention. On follow-up, a relatively high incidence of atrial arrhythmias requiring antiarrhythmic therapy was found.     

Mechanism of Double Ventricular Response to a Single Atrial Extrastimulus in Patients with Wolff-Parkinson-White Syndrome

The purpose of this study is to elucidate electrophysiological determinants of double ventricular response (DVR) to a single atrial extrastimulus in Wolff-Parkinson-White (WPW) syndrome. DVR was observed in 5 (3.4%) out of 146 consecutive patients with WPW syndrome. The site of accessory pathway was located in left lateral free wall in four patients and posterior septum in one. DVR was induced by extrastimulus from coronary sinus in four patients with left-sided accessory pathway, and from both coronary sinus and high right atrium in a patient with septal accessory pathway. However, it was not possible to induce DVR from high right atrium in patients with left-sided accessory pathway, because 50 to 80 ms are needed for intra-atrial conduction from high right atrium to coronary sinus. Critical prolongation of normal AV conduction allowing DVR was seen in the slow pathway of AV node in four patients. In the remaining patients requisite conduction delay occurred in both AV node and His-Purkinje system. Single right ventricular extrastimulus could easily elicit orthodromic AV reciprocating tachycardia or echo beat in four out of five patients and incremental ventricular stimulation induced it in the remaining patient, indicating the presence of retrograde block in the normal AV pathway. As requisites of DVR to a single atrial extrastimulus in WPW syndrome: (1) slow antegrade conduction and retrograde block in the normal AV pathway; and (2) stimulation site in the vicinity of accessory pathway, are needed.     

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.     

Ablation of a Left-Sided Free-Wall Accessory Pathway by Percutaneous Catheter Application of Radiofrequency Current in a Patient with the Wolff-Parkinson-White Syndrome

A case is presented of a 20-year-old woman with a history of three episodes of syncope within the last 4 years, which was caused by a rapid ventricular response to atrial fibrillation via a left-sided posterior accessory pathway. A variety of antiarrhythmic agents had failed to control the arrhythmia. Using a novel dual catheter approach, with one catheter in the coronary sinus and an adjacent catheter in the left ventricle close to the mitral annulus, accessory pathway conduction was successfully interrupted by two radio-frequency current applications between the tip electrodes of the two catheters. During follow-up, 12-lead electrocardiograms have been normal and the patient has been asymptomatic.     

Successful ablation of a left anterior accessory pathway from the left coronary sinus of Valsalva near the aortic–mitral continuity

Catheter ablation of accessory pathways can be challenging depending on the location of these pathways, and accessory pathways are rare through the aortic cusps. We report a patient who underwent radiofrequency catheter ablation for manifestation of a left anterior accessory pathway from the left coronary sinus of Valsalva near the aortic–mitral continuity. Anterior accessory pathways can be safely and effectively ablated from the aortic cusps with favorable long-term outcomes.     

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 for AV Nodal Reentrant Tachycardia Associated with Persistent Left Superior Vena Cava

Slow A V nodal pathway ablation using RF is highly effective for patients with refractory A V nodal reentrant tachycardia (AVNRT). We report three catheter ablation cases using RF current in patients associated with persistent left superior vena cava (PLSVC). Three patients with drug refractory AVNHT of common variety were involved in this study. An electrode catheter introduced through the left subclavian vein inserted directly into the coronary sinus, a typical anatomical finding of PLSVC. The ablation procedure was initially performed at the posteroinferior region of Koch's triangle. A slow pathway potential could not be found from that area; nonsustained junctional tachycardia (NSJT) did not occur during the delivery of RF current; there was failure to eliminate slow AV nodal pathway conduction. The catheter then was moved into the bed of the proximal portion of the markedly enlarged coronary sinus. A slow AV nodal pathway potential was recorded through the ablation catheter, and the delivery of RF current caused NSJT in two patients. Complete elimination of slow AV nodal pathway conduction was accomplished in these two patients by this method. No adverse effects were provoked by this procedure. Catheter ablation of the slow A V nodal pathway guided by a slow pathway potential and the appearance of NSJT was feasible and safe in the area of the coronary sinus ostium in patients associated with PLSVC.     

The annular fat stripe as a fluoroscopic guide to anatomic sites during diagnostic and interventional electrophysiology studies

Few radiographic landmarks are visible during electrophysiology procedures to aid in catheter positioning other than the catheters themselves. In the 35 degrees -45 degrees RAO projection, a linear radio-opacity corresponding to the rings of fat surrounding both annuli can be easily identified. This "fat stripe" can serve as a useful landmark for several important anatomic sites. Intracardiac catheters positioned left of (posterior) the fat stripe lie within an atrial cavity while those positioned to the right (anterior) lie within a ventricular cavity. The superior third of the stripe corresponds to the region of the right and left atrial appendages while the inferior end identifies the site of the coronary sinus os. The middle third serves as a reference for the fast AV nodal pathway and compact AV node. The region corresponding to the slow AV nodal pathway superimposes on the lower third of the fat stripe. Electrophysiological recordings from catheters positioned along the fat stripe always exhibit both an atrial and ventricular component consistent with an annular recording, whether the catheter is septal or free wall in its location. Coronary sinus os engagement and catheterization can be simplified by using the fat stripe as an anatomic guide. In addition to facilitating catheter positioning for evaluating normal AV conduction, the fat stripe can serve as an excellent guide for targeting the majority of structures intended for ablation because of their annular location. These include the compact AV node, the slow AV nodal pathway, the subeustachian isthmus and any accessory pathway. Good ablation catheter tip contact with annular structures is confirmed by observing its movement in unison with the fat stripe.     

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 Left-Sided Accessory Atrioventricular Pathways in Patients with Unusual Coronary Sinus

Four patients with left-sided accessory pathways (APs)and unusual coronary sinus (CS)received radiofrequency ablation. Unusual CS included occlusion of CS (patient 1), acute anguJation of proximal CS (patients 2 and 3), and narrowing of CS orifice and proximal segment (patient 4). CS catheterization and AP mapping along the CS could not be performed in the four patients. Radiofrequency ablation by left ventricular retrograde technique for the manifest left posteroseptal AP (patient 1), concealed left posterior AP (patient 2), and transseptai left atrial technique for the manifest left posteroseptal AP (patient 3)and manifest left posterior AP (patient 4)were performed successfully without CS catheter guidance. This study suggests that radiofrequency ablation of left-sided AP with unusual CS is feasible by some special techniques.     

Catheter Induced Mechanical Stunning of Accessory Pathway Conduction: Useful Guide to Successful Transcatheter Ablation of Accessory Pathways

Established electrophysiological criteria indicating anatomical proximity to an accessory pathway include early ventricular or atrial activation during antegrade or retrograde accessory pathway conduction, recording of accessory pathway potentials, and pace map concordance. This article describes two cases of RF catheter ablation of accessory pathways, during which positioning of the mapping catheter at specific sites on the endocardial aspect of the atrioventricular annulus led to prolongation of accessory pathway refractoriness and/or slowing of conduction. HF energy application at these sites successfully abolished accessory pathway conduction. When observed on an "intentional" basis during catheter mapping, catheter induced stunning of accessory pathway conduction provides evidence of satisfactory electrode-tissue contact in addition to anatomical proximity, and may give additional predictive value to successful transcatheter accessory pathway ablation.     

Atrial Flutter Ablation using a Technique for Detection of Conduction Block within the Posterior Isthmus

Catheter ablation orientated on the induction of a functional intraatrial block within the posterior isthmus of the tricuspid annulus has been shown to effectively abolish atrial flutter. In order to improve and simplify the current technique, a strategy based on an electrode catheter for combined right atrial and coronary sinus mapping and stimulation was explored prospectively. Twenty-four consecutive patients referred for catheter ablation of recurrent type I atrial flutter were included. A steerable 7 Fr catheter (Medtronic/Cardiorhythm) composed of two segments with 20 electrodes was used for right atrial and coronary sinus activation mapping and stimulation. Multiple steering mechanisms allowing intubation and positioning of the distal part within the coronary sinus were incorporated into the device. Adequate positioning of the mapping catheter was achieved solely via a transfemoral approach in all patients after 7.7 +/- 4.6 minutes, providing stable electrogram recordings during the entire ablation procedure. Radiofrequency current ablation (16.3 +/- 9.6 pulses) caused a significant bidirectional increase of the mean intraatrial conduction times via the posterior isthmus irrespective to the stimulation interval. Significant changes of intraatrial conduction properties were induced during ablation in 22 of 24 patients (bidirectional block: n = 18, unidirectional block: n = 3, conduction delay: n = 1, unchanged conduction: n = 2). Following ablation atrial flutter was noninducible in all patients. Twenty-two of 24 patients (92%) remained free of atrial flutter episodes during a follow-up of 12.5 +/- 5.7 months. Two of six patients without a bidirectional conduction block had a recurrence of atrial flutter. Atrial flutter ablation guided by the induction of an intraatrial conduction block can be effectively performed with this novel strategy for combined mapping of the posterior tricuspid isthmus, including coronary sinus and right atrial free wall. This transfemoral approach has a high accuracy with respect to the detection of radiofrequency current-induced changes of intraatrial conduction patterns.     

Acquired arteriovenous fistula and chronic occlusion of the left anterior descending coronary artery in a patient with previous ablation of a left-sided accessory pathway

Endocardial catheter ablation of accessory pathways is now considered as therapy of first choice in symptomatic patients. Success rates depend on the location of the accessory pathway itself and the operators experience in catheter ablation procedures. In patients with a left-sided pathway the retrograde transaortic catheter approach is used routinely in most centers. Besides occasional injuries of the vessels used for catheter placement and perforation of the cardiac chambers, there have been only a few case reports in the literature reporting rare procedure-specific complications such as catheter entrapment within the mitral valve apparatus and occlusion of the left circumflex coronary artery. We report a case of primary successful endocardial catheter ablation of a left lateral accessory pathway in a patient with normal coronary arteries at that time. Many years later progressive deterioration of systolic left ventricular function was observed. Coronary angiography revealed occlusion of LAD next to a arteriovenous (AV) fistula between the LAD and the anterior right ventricle.Endocardial catheter ablation was the only known cardiac manipulation in this patient raising the possibility that unintended catheter manipulations within the LAD had led to this rare and severe complication.     

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.