Catheter Ablation Of Accessory Pathways Research Articles

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.

Radiofrequency catheter ablation of accessory pathways in infants younger than nine months old

Radiofrequency catheter ablation of accessory pathways in infants younger than nine months old

Catheter Ablation for the Treatment of Paroxysmal Supraventricular Tachycardia

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 modal 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 be 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.

Radiofrequency catheter ablation of Mahaim tachycardia by targeting Mahaim potentials at the tricuspid annulus.

Reentrant tachycardias associated with Mahaim pathways are rare but potentially troublesome. Various electrophysiological substrates have been postulated and catheter ablation at several sites has been described. To assess the efficacy and feasibility of targeting discrete Mahaim potentials recorded on the tricuspid annulus for the delivery of radiofrequency energy in the treatment of Mahaim tachycardia. 21 patients out of a consecutive series of 579 patients referred to one of three tertiary centres for catheter ablation of accessory pathways causing tachycardia. All had symptoms and presented with tachycardia of left bundle branch block configuration or had this induced at electrophysiological study. In all cases, the tachycardia was antidromic with anterograde conduction over a Mahaim pathway. 6 patients had additional tachycardia substrates (4 had accessory atrioventricular connections and 2 had dual atrioventricular nodal pathways and atrioventricular nodal reentry). After ablation of the additional pathways, Mahaim potentials were identified in 16 (76%) associated with early activation of the distal right bundle branch and radiofrequency energy at this site on the tricuspid annulus abolished Mahaim conduction in all 16 cases. In 2 patients there was early ventricular activation at the annulus without a Mahaim potential but radiofrequency energy abolished pre-excitation. In the remaining patients no potential could be found (1 patient), no tachycardia could be induced after ablation of an additional pathway (1 patient), or no Mahaim conduction was evident during the study (1 patient). During follow up (1-29 months (median 9 months)) all but 1 patient remained symptom free without medication. Additional accessory pathways seem to be common in patients with Mahaim tachycardias. The identification of Mahaim potentials at the tricuspid annulus confirms that most of these pathways are in the right free wall and permits their successful ablation and the abolition of associated tachycardia.

Use of adenosine to identify patients at risk for recurrence of accessory pathway conduction after initially successful radiofrequency catheter ablation.

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. Accessory pathway conduction recurs in 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. 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. 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. 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.

1009-46 Does Reinnervation of Cardiac Sympathetic Nerves Occur in Regions Denervated by Catheter Ablation of Accessory Pathways?

Long term effects of radiofrequency (RF) ablation of accessory pathways are unknown. We hypothesized that defects in sympathetic innervation detected by 1-123 metaiodobenzylguanidine (MIBG) and myocardial perfusion detected bythallium-201 (TI) scintigraphy after RF ablation would not change in three years followup. Six pts were studied 6.8 +/-9.1 days (acute) and 3.1 +/-0.3 years (chronic) after RF. TI and MIBG images were scored: absent, decreased, or normal uptake in 13 cardiac segments. The mean numbers of segments with decreased uptake of TI and MIBG were compared for acute and chronic studies. Acute Chronic TI 0.2 ± 0.4 0.7 ± 0.8 (p = NS) MIBG 1.5 ± 1.5 2.5 ± 1.5 (p = NS) As expected, MIBG defects were larger than TI defects in 9 studies. Three studies had no MIBG defects: one of these had a TI defect. There was no difference in the number of segments with decreased TI or MIBG uptake between acute and chronic studies. No segments had absent TI uptake, and only one segment had absent MIBG uptake. Two chronic MIBG defects were smaller and four larger than the acute MIBG defects. Thus, focal MIBG defects after RF ablation of accessory pathways do not significantly change in three years follow-up, suggesting sympathetic reinnervation does not occur.

1025-100 Patients with WPW Syndrome and Paroxysmal Atrial Fibrillation Shows Prolonged Atrial Conduction Time by Signal-Averaged P-Wave Electrocardiogram

The purpose of this study was to establish a relationship between the atrial activation assessed by signal-averaged P wave ECG (SAPW) and episodes of paroxysmal atrial fibrillation (PAF) in patients (pts) with WPW syndrome (WPWS). fourteen pts with documented episodes of PAF, without underlying heart disease were selected (12 men: age = 35.2 ± 11.1 years) from a total of 70 consecutives pts successfully submitted to radiofrequency catheter ablation of accessory pathway (AP). All pts with anterograde conduction over the AP. left side AP in 9 pts and right side AP in 5 pts. The SAPW were recorded with the Corazonix Predictor II system from the X, Y, Z leads (40–250 Hz, least Square filter, final noise < 0.3 μV). The total filter P wave duration (PWD) was obtained manually from the vector-magnitude in ms. Recordings were performed between 7 th and 14 th day after the ablation. No pts showed left atrial larger than 4.0 cm on the echocardiogram. The results were compared with a control group of 12 pts matched in age (5 men; age = 33.0 ± 10.2 years) without heart disease. Values were given as mean and 1SO and compared using non-paired Student t test (significance < 0.05). Control Group In = 12): PWD ranged from 115.0 to 129.5 ms with a mean of 124.4 ± 4.4 ms. WPWS with PAF (n = 14): PWD ranged from 130.0 to 171.0 ms with a mean of 142.9 ± 1 0.1 ms (p < 0.000). Eleven pts (78.5%) showed PWD > 135.0 ms. There were no differences between PWD and AP location. Recurrent PAF after ablation was noted in 3 pts (21% – PWD: 171.0, 1505 and 139.0 ms for each patient). With a cutoff < 135.0 ms for a normal PWD, the sensitivity was 78.5%, the specificity was 100%; the positive predictive value was 100% and the negative was 75% for SAPW to identify pts with WPWS and PAF. In the current study, pts with WPWS and PAF showed prolonged intra-atrial conduction time when compared with a control group. This may contribute to the development of PAF.

Localization and radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation Feasibility and electrogram criteria for identification of appropriate target sites

Objectives. The purpose of the present study was to assess the feasibility of and electrophysiologic criteria for successful radio-frequency catheter ablation of left-sided accessory pathways during atrial fibrillation in patients with Wolff-Parkinson-White syndrome.Background. The onset of recurrent or sustained atrial fibrillation can complicate or significantly prolong accessory pathway catheter ablation procedures.Methods. We studied 19 consecutive patients (mean age [±SD] 44 ± 16 years) with Wolff-Parkinson-White syndrome who had ongoing atrial fibrillation with rapid anterograde conduction over the accessory pathway (mean ventricular rate [±SD] 173 ± 26 beats/min, range 130 to 220) at the beginning of the localization procedure during radiofrequency catheter ablation. Localization and ablation of the accessory pathway were performed with a 7F deflectable catheter (4-mm tip) that was placed underneath the mitral valve annulus. The electrophysiologic criteria from unipolar and bipolar local electrograms were compared for successful (n = 18) and unseccessful (n = 39) sites.Results. The accessory pathways were localized in the left posteroseptal (n = 6), posterior (n = 1), posterolateral (n = 7) and lateral (n = 5) regions and successfully ablated during atrial fibrillation in 18 (95%) of 19 patients with a mean of 3 ± 2 radiofrequency pulses (range 1 to 8, median 2). Presence of an accessory pathway potential (94% vs. 44%), early activation time of the ventricular electrogram (−3.2 ± 9.2 vs.−15.3 ± 12.6 ms) and recording of atrial activation (88% vs. 61%) from the ablation catheter were helpful in identifying successful sites (p < 0.001, p < 0.001 and p < 0.05, respectively, compared with unsuccessful sites). In addition, the ventricular activation time in relation to the intrinsic deflection of the unipolar electrogram was significantly earlier at successful than unsuccessful sites (18.1 ± 4.8 vs. 24.4 ± 6.6 ms, p < 0.01). A QS complex on the unipolar electrogram was observed at 96% of successful sites and at 94% of unsuccessful sites (p = 0.74). Multivariate logistic regression analysis revealed that the presence of an accessory pathway potential (p < 0.002) and early ventricular activation time in relation to the onset of the QRS complex (p < 0.001) were independent predictors of ablation success.Conclusions. Localization and radiofrequency catheter ablation of left-sided accessory pathways is possible in patients with sustained atrial fibrillation and rapid anterograde conduction over the accessory pathway during the ablation procedure. The electrophysiologic criteria described here can be used to reliably identify successful sites for radiofrequency ablation.

Effect of accessory pathway location on the efficiency of heating during radiofrequency catheter ablation

During radiofrequency catheter ablation of accessory pathways there is a poor correlation between applied power and temperature at target sites for catheter ablation. This study was designed to examine the relation between power and temperature during radiofrequency catheter ablation in patients with accessory pathways and to identify the factors that affect the efficiency of heating, defined as the ratio of applied power and temperature. Twenty-nine patients underwent radiofrequency catheter ablation of an accessory pathway. Among 257 energy applications, 108 were applied for ablation of a right-sided accessory pathway, 105 for a left-sided accessory pathway, and 44 for a posteroseptal accessory pathway. During each application of radiofrequency energy, temperature was continually monitored by use of an ablation catheter with a thermistor embedded in the tip of the distal electrode. During some applications of energy, fluctuations in temperature were observed. The average power, impedance, temperature, and efficiency of heating for all applications of radiofrequency energy was 37 ± 11 W, 100 ± 9 ohms, 53 ± 9° C, and 1.7 ± 0.8° C W (range 0.9° to 6.6° C W ), respectively. The efficiency of heating varied by location ( p < 0.0001), with the greatest efficiency of heating for posteroseptal energy applications (2.3 ± 1.2° C W , which were significantly greater than for left-sided (1.8 ± 0.8° C W ; p < 0.01) or right-sided (1.2 ± 0.4° C W ; p < 0.0001) applications. Phasic fluctuation in temperature was observed during 127 (49%) energy applications, and the efficiency of heating was 1.5 ± 0.7° C W . For the 130 applications with a stable temperature curve, the efficiency was 1.8 ± 0.9° C W ( p < 0.02). The mean impedance during energy applications correlated weakly with efficiency ( r = 0.2, p = 0.0012). In conclusion, the efficiency of heating varies according to the location of the application of radiofrequency energy. Inadequate contact, as manifested by fluctuating temperature during ablation, results in less efficient heating.

Radiofrequency catheter ablation of accessory atrioventricular pathway in Wolff-Parkinson-White syndrome.

Eighty patients with manifest or concealed Wolff-Parkinson-White (WPW) syndrome underwent catheter ablation of 86 accessory pathways (AP) using radiofrequency current. There are 65 AP located on the left side and 21 on the right side of the heart. The atrioventricular reciprocating tachycardia was previously documented in 77 patients and atrial fibrillation with a rapid ventricular response in 21 patients. Ablation was attempted via a catheter positioned at the atrial aspect of the tricuspid annulus in patients with a right-sided AP and via a catheter positioned in the left ventricle directly below the mitral annulus in patients with a left-sided AP. AP conduction was permanently abolished in 82 of the 86 pathways (95%). The number of radiofrequency current applications for these 82 successfully ablated AP was 7.6 +/- 0.9. Of the 65 left-sided and 21 right-sided AP, 62 (95%) and 20 AP (95%) were successfully ablated, respectively. The current application to the right-sided AP was 16.7 +/- 2.2, which was greater than that to the left-sided one (4.7 +/- 0.6, p < 0.001). No serious complication was observed in any case. Catheter ablation of AP using radiofrequency current is an effective and safe therapeutic modality for patients with symptomatic WPW syndrome.

Embolic complications after radiofrequency catheter ablation

Although radiofrequency catheter ablation of accessory pathways is very efficacious and the procedure is well tolerated with a relatively low risk of serious complications, some concern is warranted for ablations in the left heart. The risk of systemic embolism may be quite significant despite heparinization during the procedure and therapy with 325 mg acetylsalicylic acid orally for 3 months. The issue of anticoagulation during ablation and the method and duration of therapy after ablation requires further scrutiny.

Anatomic, electrical, and mechanical factors affecting bipolar endocardial electrograms. Impact on catheter ablation of manifest left free-wall accessory pathways.

The use of bipolar endocardial electrogram characteristics to guide radiofrequency (RF) current catheter ablation of accessory pathways (APs) has been advocated by several investigators. However, the influences of a varying anatomy of the AP and the atrioventricular groove, of different ablative approaches, and of RF current pulses preceding the final pulse have not been adequately addressed. Local bipolar endocardial electrograms were retrospectively analyzed in a uniform cohort of 62 consecutive patients with a single manifest AP located on the left free wall; in all patients, the AP had been ablated by a uniform approach with a single catheter advanced retrogradely toward the mitral annulus. Electrogram parameters assessed were the presence or absence of a presumed AP potential, the atrial-to-ventricular (A/V) amplitude ratio, the A-V interval, and the onset of delta wave to local ventricular activation (delta-V) interval. The AP location was classified on fluoroscopy as anterior, lateral, or posterior. Catheter stability was verified by comparing pre- and post-RF amplitudes of local atrial potentials. The ablation site was ventricular in 52 patients (group A) and atrial in 10 (group B). In group A, 26 APs (50%) required a single RF current pulse for ablation. These APs showed no anatomic predilection and no statistically significant differences in electrogram parameters from 24 APs that were ablated only after a median of three pulses had failed, suggestive of a wider ventricular insertion of the latter APs. A lower A/V ratio and a higher incidence of transient AP block found in the remaining 2 group A patients, who had anteriorly located APs requiring > 10 failed pulses, suggested an adverse anatomy of the A-V groove in that region. A stepwise multivariate logistic regression analysis revealed that the simultaneous presence of (1) a presumed AP potential, (2) an A/V ratio > or = 0.10, (3) an A-V interval < or = 40 milliseconds, and (4) a delta-V interval < or = 0 milliseconds was associated with a specificity of 94% and a positive predictive accuracy of 87% for an RF pulse to be successfully applied to the ventricular insertion to the AP. Compared with APs of group A, APs of group B were distinguished by unsuccessful ventricular pulses associated with a delta-V interval > 10 milliseconds in the presence of an A/V ratio > 0.33 (specificity of 97% and positive predictive accuracy of 82%), which is suggestive of a more epicardial ventricular insertion of these APs. The effect of anatomic variations of the AP and the A-V groove is reflected in the bipolar endocardial electrogram and needs to be considered in the approach to AP ablation. The stepwise inclusion of the four electrogram criteria introduced in this study may improve the efficacy of RF catheter ablation of a manifest left free-wall AP at its ventricular insertion. Whenever mapping cannot improve on a delta-V interval > 10 milliseconds despite apparently close contact with the mitral annulus ("good" A/V ratio), attempts at ablation are likely to be successful at the atrial aspect of the mitral annulus.

Safety of radiofrequency catheter ablation of accessory atrioventricular pathways

The acute anatomic and valvular consequences of radiofrequency catheter ablation of accessory pathways were evaluated in 62 patients by means of serial echocardiographic examinations. Semiquantitative assessment of valvular incompetence and classification into one of four grades according to the width and the extension of the jet from the valvular orifice were carried out. Segmental wall motion abnormalities were evaluated semiquantitatively with four grades of severity (normal, hypokinesia, akinesia, or dyskinesia). New echocardiographic abnormalities were observed in five patients. One thrombus on the ventricular aspect of the mitral valve, three hemodynamically insignificant pericardial effusions, and one increase in severity of tricuspid incompetence were found 1 day after radiofrequency catheter ablation. We conclude that echocardiographic changes after radiofrequency ablation of accessory pathways are rare and of minor significance. These findings confirm the safety of the procedure.

Radiofrequency Catheter Ablation of Accessory Pathways:

Catheter ablation techniques are now advocated as the first line of therapy for arrhythmias caused by accessory pathways (APs). The most common energy source is radiofrequency current, but technical characteristics vary. Several parameters can be used to determine the optimal target site: AP potential, AV time, atrial or ventricular insertion site, or unipolar morphology. Specific considerations are needed depending on AP location. Despite the different approaches described, there is no significant difference in the reported success rate, which is over 90%. However, the number of radiofrequency applications needed to achieve ablation appears to differ significantly, with median values from 3 to 8 reported. A combination of criteria related to both timing and direction of the activation wavefront or use of subthreshold stimulation could improve the accuracy of mapping. In patients with "resistant" APs, different changes in ablation technique must be considered during the procedure to achieve elimination of AP conduction. The incidence of complications in multicenter reports is close to 4%, with a recurrence rate of 8%. The long-term safety of catheter ablation requires further study.

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.

Limitations of adenosine in assessing the efficacy of radiofrequency catheter ablation of accessory pathways

Adenosine has been shown to reliably confirm the success of accessory pathway catheter ablation by producing transient atrioventricular (AV) block during atrial and ventricular pacing. This is due to the insensitivity of accessory pathway conduction to adenosine (with the rare exception of accessory pathways with decremental conduction properties). However, 4 of 204 consecutive patients who underwent successful accessory pathway ablation (as shown by adenosine-induced transient AV block) had recurrent AV reciprocating tachycardia involving a second, previously nonmanifest accessory pathway. In each case, the second accessory pathway was localized to a site disparate from the original pathway. No pathway showed decremental anterograde or retrograde conduction properties. In 2 patients, adenosine initially did not show the presence of the second concealed accessory pathway, because the refractory period of the accessory pathway was longer than the pacing cycle length used to assess ventriculoatrial conduction. Only when the refractory period of this second accessory pathway was shortened by infusion of isoproterenol did adenosine reveal the presence of the pathway during follow-up electrophysiologic study. In another patient, a non-decremental accessory pathway was shown to be sensitive to adenosine. In the remaining patient, the second accessory pathway may have been transiently injured during the initial study, thereby simulating adenosine sensitivity. Therefore, it is concluded that (1) adenosine is a highly, but not completely, effective method for immediately assessing the efficacy of accessory pathway catheter ablation; (2) concomitant infusion of isoproterenol during adenosine administration is necessary to recognize the presence of accessory pathways with prolonged refractory periods; and (3) assessment of the presence of accessory pathway conduction with adenosine after ablation should preferably be performed at the longest possible, paced cycle length.

Catheter ablation of accessory pathways in children

The efficacy and safety of catheter ablation of accessory pathways (AP) was studied in 79 children (age, 4-16 years), using DC shocks (n = 25) or radiofrequency energy (n = 54). All patients had documented arrhythmias including ventricular fibrillation in four. Organic heart disease was present in four patients. AP locations were left lateral (n = 36), posteroseptal (n = 36), right lateral (n = 8), Mahaim fibres (n = 2) and right anteroseptal (n = 6). Seven patients had multiple AP. One patient had a preexcitation which appeared secondary to an atrio-infundibular connection (Fontan procedure). The ablation site of concealed or overt AP was identified by retrograde or anterograde conduction mapping, respectively. A mean of 2.6 +/- 1 cathodal shocks (80-160 J) was delivered to 25 patients over 29 sessions, resulting in initial AP ablation in all. Fulguration was uncomplicated in all except in one patient (4%) who developed a secondary complete AV block post-ablation. During a follow-up period of 30-69 months, intermittent preexcitation recurred in two asymptomatic patients, but no significant tachycardia was inducible at late electrophysiological study, including under isoproterenol infusion. Radiofrequency energy was applied to 54 patients during 62 sessions, using 20-40 watts for 30-60 s. AP ablation was initially achieved in all patients using a median of three impulses, without significant immediate side-effects. Two patients (4%) developed a short episode of blurred vision possibly due to a microembolism. After discharge, the follow-up period was 10 +/- 5 months (range 1 to 24). All patients but one (98%) were asymptomatic without any drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple accessory pathways in the permanent form of junctional reciprocating tachycardia

The permanent form of junctional reciprocating tachycardia (PJRT) has been successfully eliminated by ablation of the accessory pathway responsible for the tachycardia. The coexistence of multiple accessory pathways responsible for different, long RP-interval tachycardias was not documented previously. Five patients with PJRT underwent radiofrequency catheter ablation of accessory pathways. Three of 5 patients had 2 accessory pathways each: 1 had 2 left free wall accessory pathways, another had a right posterior free wall and right posteroseptal pathway, whereas the third had 2 right posteroseptal pathways approximately 1 cm apart. The remaining 2 patients each had 1 right posteroseptal accessory pathway. Seven of 8 pathways were successfully ablated with a median of 3 radiofrequency pulses. No patient developed complications. Peak serum creatine kinase ranged from 131 to 311 IU/liter, with peak MB fraction 7 to 17 IU/liter, or 5 to 11%. Follow-up electrophysiologic study, 29 to 70 days after ablation, revealed no inducible tachycardia and no evidence of accessory pathway conduction, except for the 1 pathway not ablated. All patients remained asymptomatic 17 to 29 months after ablation. Thus, patients with PJRT can have several accessory pathways that can be safely and effectively eliminated with radiofrequency catheter ablation.

Radiofrequency Catheter Ablation of Atrioventricular Accessory Pathways : Factors Influencing the Outcome of Catheter Ablation of Accessory Pathways

Radiofrequency Catheter Ablation of Atrioventricular Accessory Pathways : Factors Influencing the Outcome of Catheter Ablation of Accessory Pathways

Site of accessory pathway block after radiofrequency catheter ablation in patients with the Wolff-Parkinson-White syndrome.

Recent studies have demonstrated that the most common site of accessory pathway conduction block following the introduction of a premature atrial stimulus during atrial pacing is between the accessory pathway potential and the ventricular electrogram, consistent with block at the ventricular insertion of the accessory pathway. However, no prior study has evaluated the site of conduction block during radiofrequency catheter ablation procedures. Therefore, the objective of this study was to determine the site of conduction block after catheter ablation of accessory pathways by analyzing and comparing the local electrograms recorded before and after radiofrequency energy delivery at successful ablation sites. The electrograms evaluated in this study were obtained from 85 consecutive patients who underwent successful radiofrequency catheter ablation of a manifest accessory pathway. The 50 left free-wall accessory pathways were ablated using a ventricular approach and the 35 right free-wall or posteroseptal accessory pathways were ablated using an atrial approach. The characteristics of local electrograms recorded immediately before and immediately after successful ablation of the accessory pathway were determined in each patient. The site of accessory pathway block was determined by comparing the amplitude, timing, and morphology of the local electrograms at successful sites of radiofrequency catheter ablation before and after delivery of radiofrequency energy. A putative accessory pathway potential was present at the successful target site in 74 of the 85 patients (87%). Conduction block occurred between the atrial electrogram and the accessory pathway potential in 66 patients (78%) and between the accessory pathway potential and the ventricular electrogram in eight patients (9%). The site of block could not be determined in 11 patients (13%) in whom an accessory pathway potential was absent. Conduction block occurred most frequently between the atrial electrogram and the accessory pathway potential regardless of accessory pathway location. No electrogram parameter or accessory pathway characteristic was predictive of the site of conduction block. The results of this study demonstrate that conduction block occurs most frequently between the local atrial electrogram and the accessory pathway potential during radiofrequency catheter ablation of accessory pathways. This is true regardless of whether the accessory pathway is ablated from the atrial or ventricular aspect of the mitral or tricuspid annulus.