Free Wall Accessory Pathway Research Articles

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.

Retrograde conduction properties after catheter radiofrequency ablation of atrioventricular accessory pathways

A total of 208 atrioventricular (AV) accessory pathways in 200 patients were abolished by catheter radiofrequency current ablation. The antegrade AV conduction was normal after the ablation. Approximately 66% of the patients experienced retrograde AV conduction dissociation, which is independent of the age, gender and antegrade conduction properties of accessory pathways (manifest or concealed). Retrograde conduction dissociation is more prevalent than decremental conduction in patients with left free (80% vs. 17%, P < 0.001) or right free (78.6% vs. 21.4%, P < 0.01) wall pathways. Eleven patients (5.5%) showed recurrence after an average of 213 days follow-up. The recurrence of right free wall pathways (21.4%) is much more common than that of left free wall (2.5%) and posteroseptal (4.8%) pathways. The recurrence in those with decremental conduction after the initial successful ablation is higher than that of patients with retrograde AV dissociation (8.8% vs. 3.8%, P < 0.01), and most of them required a second ablation session. Conclusion: most of the patients, especially those with free wall accessory pathways, will have retrograde conduction dissociation after the successful radiofrequency catheter ablation. Electrophysiological studies should be carefully performed on patients with decremental retrograde conduction after the ablation.

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.

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.

The 12-lead electrocardiogram in midseptal, anteroseptal, posteroseptal and right free wall accessory pathways

The 12-lead electrocardiograms of 50 patients with 1 anterogradely conducting accessory pathway were analyzed to obtain characteristics of electrocardiographic findings in the midseptal, anteroseptal, true posteroseptal and right free wall accessory pathway locations. Locations were confirmed by surgery (33 patients) or radiofrequency catheter ablation (17 patients). This study analyzed (1) QRS in the frontal plane, (2) delta wave axis in the frontal plane, (3) the angle between QRS and delta wave axes, (4) the rmR S ratio in lead III, (5) negativity of delta wave in inferior leads, and (6) the rmR S ratio in precordial leads. Results were (1) QRS axis in the frontal plane in the right free wall — range from +15 to −65 ° (−32 ± 19 °); true posteroseptal pathways — range from +30 to −60 ° (−38 ± 22 °); midseptal pathways range from +15 to +60 ° (+49 ± 11 °); anteroseptal pathways range from 0 to +75 ° (+46 ± 22 °); (2) delta wave axis in the right free wall −0 to −60 ° (−32 ± 22 °); true posteroseptal − 0 to −60 ° (−43 ° 18 °); midseptal −0 to +45 ° (+24 ± 15 °), and anteroseptal −0 to +60 ° (+45 ± 17 °); (3) QRS/delta wave axis angle in the right free wall − 7 ± 6 °, true posteroseptal −9 ± 7 °; midseptal − 22 ± 6 °, and anteroseptal accessory pathways − 3 ± 5 °; (p = 0.006); (4) the rmR S ratio lead III was <1 in true posteroseptal and right free wall, >1 in anteroseptal and equal to 1 in midseptal accessory pathways; (5) delta negativity in ≥2 inferior leads was observed in the right free wall −90%; in true posteroseptal −90%, in midseptal − 0%, and anteroseptal accessory pathways −0% (p < 0.0001); (6) the rmR S ratio >1 in lead V 2 was right free wall −20%, true posteroseptal −100%, midseptal — 12%, anteroseptal −0% (p < 0.0001). It is concluded that midseptal and anteroseptal accessory pathways can be differentiated from a right free wall and true posteroseptal location by the QRS axis and delta wave polarity in inferior leads. Midseptal pathways can be distinguished from anteroseptal pathways by the difference between the QRS and delta wave axes and the rmR S ratio in lead III. A QRS/delta wave axis angle of ≥20 ° and an rmR S ratio equal to 1 in lead III favor a midseptal accessory pathway location.

Surgical Treatment of the Wolff-Parkinson—White Syndrome in Children

From 1986 to 1989, seven children ranging in age from 5 months to 16 years underwent surgical treatment for the Wolff-Parkinson-White syndrome at the Shiga University of Medical Science. None of the patients had any other associated congenital heart disease. There was a right free wall accessory pathway in four patients and a left free wall accessory pathway in three. Surgical ablation of these accessory pathways was performed on eight occasions, using the endocardial approach three times and the epicardial approach five. All the children are alive and none has since had episodes of tachycardia. Only one patient had a recurrent delta wave, which was noted 18 months after the operation. Surgical ablation of the accessory pathway for the Wolff-Parkinson-White syndrome can be performed safely, even in infants and children; it is concluded that this useful procedure is capable of improving a patient's quality of life.

Evaluation of an abbreviated protocol for catheter ablation of left free wall accessory pathways

Evaluation of an abbreviated protocol for catheter ablation of left free wall accessory pathways

Patterns of radiofrequency catheter ablation of left free‐wall accessory pathways: Implications for accessory pathway anatomy

Despite the abundance of literature on the electrophysiology of accessory pathways, clinical data on their anatomic properties remain infrequent. The small and discrete nature of lesions generated by radiofrequency (RF) energy may allow better characterization of accessory pathway anatomy in the intact heart. RF catheter ablation was performed on 40 left free-wall accessory pathways in 39 consecutive patients with a unipolar endocardial approach. The patterns of accessory pathway ablation were identified. Spatial-electrophysiologic information provided by the ablation catheter at individual sites of RF application and corresponding data from the coronary sinus catheter were correlated with the effects of RF energy on accessory pathway conduction. Of 39 accessory pathways permanently (n = 37) or transiently (n = 2) ablated, 24 had "simple" ablation, with abolition of conduction by one individual RF application. In 15 of 24 pathways that could be crossed by the coronary sinus catheter, the concordance in anatomic and electrophysiologic information between the site of earliest retrograde atrial activation and the effective ablation position (ventricular approach) suggested a perpendicular fiber course. Fifteen pathways had "complex" ablations; of these, eight had spatial-electrophysiologic discordance between the atrial and ventricular insertions, suggesting an oblique fiber orientation. Seven pathways had modification or transient suppression of conduction, with or without subsequent abolition of conduction at identical or physically disparate (> 1 cm apart) sites; four pathways had sequential ablation of antegrade and retrograde conduction. These raised possibilities of broad fiber span and functional longitudinal dissociation of accessory pathway conduction. Accessory pathways with simple and complex ablations did not differ in clinical and electrophysiologic parameters. Complex ablations demanded more lengthy and difficult procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the retrograde and transseptal methods for ablation of left free wall accessory pathways

Objectives. The purpose of this study was to compare success rates, procedure and fluoroscopy times and complications for the transseptal and retrograde aortic approaches in a consecutive series of patients undergoing catheter ablation of left free wall accessory pathways.Background. Radiofrequency catheter ablation of left-sided accessory pathways can be performed either by a retrograde, transaortic approach or by means of a transseptal puncture,Methods. A total of 106 patients (mean age 33 years, range 4 to 79) underwent attempted catheter ablation of a single left-sided accessory pathway by either the retrograde or the transseptal approach, or both. In the first 65 patients, the retrograde aortic approach was the preferred initial method. In the most recent 51 patients, we first attempted the transseptal approach whenever a physician trained in the technique was available. Ultimately, 102 (96.2%) of 106 patients had successfull ablation.Results. Of 89 retrograde procedures, 85% resulted in elimination of accessory pathway conduction. Four retrograde procedures performed after failure of the transseptal approach were successful. Of the 13 patients with a failed retrograde procedure, 11 later underwent ablation using the transseptal approach. Twenty-six (85%) of 33 transseptal procedures were successful. All four patients with unsuccessful initial transseptal attempts were successfully treated with the retrograde method during the same session in the etectrophysiology laboratory. Ten of 11 transseptal procedures after unsuccessful retrograde procedures were successful. Crossover from the retrograde to the transseptal approach was performed during a separate session in 9 of these 11. There was no difference in total procedure time (220 ± 12.8 vs. 205 ± 12.5 min) (mean ± SEM) or fluoroscopy time (44.1 ± 4.4 vs. 44.7 ± 5.1 min) between the retrograde and transseptal methods. Ablation time was longer for the retrograde method (69.2 ± 10.5 vs. 43.4 ± 9.3 min) (p < 0.01). Of patients ≥ 65 or ≤ 16 years old, technical factors requiring crossover to the other technique or complications occurred in 7 (42%) of 17 patients undergoing the retrograde and 1 (11%) of 9 patients undergoing the transseptal approach (p < 0.01). The overall rate of complications was the same for both (6.7% for retrograde and 6.1% for transseptal). The most serious complication involved dissection of the left coronary artery with myocardial infarction during a retrograde procedure.Conclusions. The retrograde and transseptal approaches are complementary; if one method fails, the other should be attempted, yielding an overall success rate close to 100%. Because patients undergo heparinization immediately after the arterial system is entered during a retrograde procedure, failure of that approach requires crossover to the transseptal method during a separate session or reversal of heparin; if the transseptal method is tried first, crossover to the retrograde approach can be accomplished easily during the same session. To avoid complications related to access, the transseptal method should be the first used in children, the elderly and those with arterial disease or hypertrophic ventricles.

Radiofrequency ablation of a left-sided free-wall accessory pathway: a case study

Radiofrequency ablation of a left-sided free-wall accessory pathway: a case study

Catheter ablation of accessory atrioventricular pathways in young patients: Use of long vascular sheaths, the transseptal approach and a retrograde left posterior parallel approach

Objectives. This study retrospectively assesses the technical aspects of the catheter techniques used to ablate 83 accessory atrioventricular (AV) pathways during 88 procedures in 71 pediatric and adult patients (median age 14 years, range 1 month to 55 years). A number of catheter approaches and techniques evolved that may have improved success and shortened procedure times.Background. Radiofrequency catheter ablation of accessory AV pathways can be highly successful. However, the technical difficulty of many of the procedures is masked by the success rate.Methods. Left free wall, right free wall and septal accessory pathways were ablated with a variety of approaches.Results. Left free wall pathways were ablated successfully by using a standard retrograde approach through the aortic valve in only 10 (24%) of 43 cases. The remaining 33 (76%) required an approach that was either retrograde through the mitral valve (2 of 33), transseptal (21 of 33) or retrograde where the catheter was advanced behind the posterior mitral leaflet at the point of mitral-aortic continuity, so that the catheter course was parallelrather than perpendicularto the mitral anulus (10 of 33). Nineteen of 20 septal pathways were ablated successfully by using either the parallel approach (2 of 29), a transseptal approach (2 of 19), ablation within the coronary sinus or one of its veins (8 of 19) or ablation on the atrial side of the tricuspid valve (7 of 19). Fifteen of 20 right free wall pathways were ablated successfully with a variety of approaches on both the atrial and the ventricular side of the tricuspid valve. Long vascular sheaths were judged to contribute directly to success in 33 (43%) of 77 pathways. The overall success rate has been 93% (77 of 83 pathways), with 100% success for left free wall (43 of 43), 75% for right free wall (15 of 20) and 95% for septal pathways (19 of 20).Conclusions. Thus, successful ablation of accessory AV pathways in a mixed group of pediatric and adult patients appears to benefit from a wide range of vascular and catheter approaches.

Clinical characteristics and electrophysiologic properties of atrioventricular accessory pathways: Importance of the accessory pathway location

Objectives. This study was designed to assess the influence of accessory atrioventricular (AV) pathway location on the clinical and electrophysiologic characteristics of 384 consecutive symptomatic patients having a single accessory pathway.Methods. Four locations were studied: left free wall (n = 270), posteroseptai (n = 52), anteroseptal (n = 29) and right free wall (n = 33). Ten clinical variables and 12 electrophysiologic variables were analyzed, including the effective refractory period of the accessory pathway and the different clinically occurring and inducible arrhythmias.Results. Only two clinical findings were associated with accessory pathway location: 1) later age at onset of symptoms in the left free wall versus other accessory pathway locations (24 ± 12 vs. 20 ± 11 years, p = 0.02), and 2) later age at the time of electrophysiologic study in the left free wall accessory pathway location (36 ± 13 vs. 32 ± 11 years, p = 0.01).Six electrophysiologic variables showed a correlation with the accessory pathway location: 1) retrograde conduction only was found less frequently in right free wall (9%) and anteroseptal (10%) than in left free wall (26%) and posteroseptal (29%) accessory pathway locations (p = 0.05); 2) the retrograde effective refractory period of the accessory pathway was shorter in anteroseptal (253 ± 52 ms) and left free wall (270 ± 72 ms) as compared with right free wall (296 ± 101 ms) and posteroseptal (301 ± 76 ms) locations (p = 0.05); 3) retrograde decremental conduction over the accessory pathway was present in the posteroseptal (17%) and left free wall (3%) but absent in the other locations (p < 0.001); 4) anterograde decremental conduction was only seen in the right free wall location (12%) (p < 0.001); 5) orthodromic reentrant tachycardia was induced less frequently in the right free wall than in other locations (70% vs. 93%, p < 0.001); and 6) inducibility of atrial fibrillation was greater in anteroseptal (62%) than in right free wall (21%), left free wall (44%) and posteroseptal (36%) locations (p = 0.01).Conclusions. The location of the accessory AV pathway is associated with specific electrophysiologic characteristics.

Accuracy of various methods of localization of the orifice of the coronary sinus at electrophysiologic study

The coronary sinus (CS) orifice is an important reference point for determining electrode and, thereby, accessory pathway location at electrophysiologic study. The reliability of fluoroscopic landmarks used to identify the CS orifice is not known. This study compared the accuracy of several fluoroscopic landmarks for identifying the CS orifice with the location defined by radiopaque contrast injection of the CS. Forty patients were studied. Radiographic markers of the CS orifice that were examined included: (1) the point at which the CS catheter prolapsed during advancement, (2) the point of maximum convexity of the CS catheter when a superior vena caval approach was used, (3) the right side of the ventricular septum, and (4) the relation to the underlying vertebrae. The least-significant difference method of multiple comparisons was used for statistical analysis. The point at which the CS catheter prolapsed was the most accurate noncontrast method for determining the location of the CS orifice (p < 0.05), but was possible without the use of excessive force in only 48% of patients. The point of catheter prolapse was a median of 1 mm (range 0 to 11) from the true location of the os. Errors with other examined landmarks ranged up to 3 cm. Identification of the CS orifice is best performed by radiopaque contrast injection. The point of prolapse during catheter advancement in the CS is an accurate alternative when contrast injection is not feasible. Other noncontrast fluoroscopic landmarks are less reliable and are best avoided. If there is any doubt or if accurate location of the CS os is critical (particularly when distinguishing posterior septal from left free wall accessory pathways), direct radiopaque contrast injection should be used.

Stimulation of the summit of the right ventricular aspect of the ventricular septum during orthodromic atrioventricular reentrant tachycardia

Application of ventricular premature complexes (VPCs) from the right ventricular (RV) apex during orthodromic atrioventricular (AV) reentrant tachycardia has limitations both in the ability to shorten the succeeding atrial cycle length and in helping to identify accessory pathway location. Stimulation from the summit of the RV aspect of the septum during AV reentrant tachycardia was investigated as a new technique to improve the diagnostic utility of applying VPCs during AV reentrant tachycardia. VPCs were induced during AV reentrant tachycardia at 10 ms decrements in patients with left free wall (n = 15), posteroseptal (n = 5), and right free wall (n = 3) accessory pathways from the RV apex and then from the summit of the RV septum. When the His was refractory, shortening of the atrial cycle length was noted in 13% of patients with left free wall pathways, in 60% of patients with posteroseptal pathways, and in 100% of patients with right free wall pathways with VPCs from the RV apex, and in 47,100 and 100%, respectively, with VPCs from the summit of the septum. When all VPCs were considered, there was a significant shortening of the atrial cycle length in 67% of patients with left free wall pathways when stimulated from the RV apex, which increased to 93% with summit stimulation. An extrastimulus applied on or after the His effected a significant shortening of the atrial cycle length in no patients with left free wall pathways. The mean maximal shortening of the atrial cycle length when the His was refractory was 4 ± 11 and 9 ± 13 ms for left free wall pathways, 29 ± 30 and 40 ± 11 ms for posteroseptal pathways, and 35 ± 15 and 53 ± 35 ms for right free wall accessory pathway from the apex (p = 0.006) and summit (p = 0.0002), respectively. Stimulation of the summit of the RV septum improves the ability of VPCs to shorten the atrial cycle length during AV reentrant tachycardia.

Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation

The purpose of this study was to characterize the incidence and clinical features of accessory pathway recurrence after initially successful radiofrequency catheter ablation and to identify variables correlated with recurrence. Radiofrequency ablation was performed with a 7F deflectable tip catheter with a large (4 mm in length) distal electrode. Left-sided accessory patthways were approached through the left ventricle and right-sided pathways by way of the right atrium. Patients were included in the study if 1) they had an initially successful procedure, defined as the absence of accessory pathway conduction immediately after ablation, and 2) had undergone a 3-month follow-up electrophysiologic test or had documented recurrence of accessory pathway conduction.Accessory pathway conduction recurred after initially successful ablation in 16 (12%) of 130 patients. Almost half (7 of 16) of these recurrences were in the 1st 12 h after ablation, and the last occurred after 106 days. Return of delta waves on the electrocardiogram (ECG) or spontaneous paroxysmal supraventricular tachycardia was the initial indication of recurrence in 15 of the 16 patients. Two patients with manifest accessory pathways exhibited recurrence with exclusively concealed accessory pathway conduction.Accessory pathways ablated from the tricuspid anulus (right free wall or septal accessory pathways) had a much higher recurrence rate (24%) than did those on the mitral anulus (6%). Fourteen of 15 patients have had successful repeat accessory pathway ablation after the initial recurrence. After a mean follow-up period of 4 ± 3 months, there have been no repeat recurrences of any of these accessory pathways.It is concluded that accessory pathway recurrence is infrequent after successful radiofrequency catheter ablation. All but one episode of recurrence was diagnosed clinically, suggesting that routine follow-up electrophysiologic testing in asymptomatic patients is not warranted. Because manifest accessory pathways may recur with retrograde conduction only, patients with palpitation after ablation should have electrophysiologic testing even if no delta waves are seen on the ECG. The success rate of ablation after recurrence (93%) is comparable to that achieved at the initial session, suggesting that return of accessory pathway function should not be a contraindication to a repeat attempt.

Radiofrequency Current for Catheter Ablation of Accessory Atrioventricular Connections in Children and Adolescents. Emphasis on the Single-Catheter Technique

Catheter ablation of an accessory atrioventricular connection using 500-kHz radiofrequency current was attempted in 10 children and adolescents aged between 6 and 15 years (mean 10.5 years). Six children had the Wolff-Parkinson-White syndrome and four had tachyarrhythmias related to a retrograde-only conducting ("concealed") accessory connection. No child had associated structural heart disease. Symptoms ranged from disabling palpitations to episodes of syncope (three patients) and cardiac arrest (one patient). Ablation was attempted from the left ventricle in all children; in one child, ablation of a second, right-sided pathway was attempted via a right atrial approach. Ten of the 11 accessory connections were interrupted successfully. A single complication was encountered in a 10-year-old girl in whom the procedure had to be terminated because a thrombotic occlusion of the right internal iliac artery had evolved. A simplification of the ablation procedure associated with reduced procedure duration and radiation exposure time was achieved in three children with the Wolff-Parkinson-White syndrome and a left free-wall accessory pathway when a single catheter placed in the left ventricle was used for pathway localization as well as ablation. It is concluded that catheter ablation using radiofrequency current is effective and safe and may supersede surgery as the curative treatment for children with serious symptoms mediated by an accessory atrioventricular connection.

Success, safety, and late electrophysiological outcome of low-energy direct-current ablation in patients with the Wolff-Parkinson-White syndrome.

Percutaneous ablation of accessory pathways with the use of a defibrillator can be accomplished with high-energy direct-current (DC) shocks of 150-400 J, but complications include cardiac tamponade and sudden cardiac death, mostly resulting from significant electrical arcing and barotrauma. A new low-energy DC power source with a brief time-constant capacitive discharge delivers shocks of 2-40 J and eliminates or greatly reduces arcing. This report describes our initial experience with this device in 60 consecutive patients (mean age, 34 years; range, 9-67 years) with Wolff-Parkinson-White syndrome. Accessory pathways were located in the left free wall in 36 patients, in the right free wall in two, were posteroseptal in 18, and anteroseptal in four. Most patients (77%) had their initial diagnostic electrophysiological study and catheter ablation during the same session. Selective ablation of accessory pathways was successful in 55 patients (92%). The mean cumulative energy was 312 +/- 284 J and the mean creatine kinase MB peak (normal, 0-30 units) was 42 +/- 27 units. Patients with left free wall accessory pathways required less procedure time for ablation (2.7 +/- 0.8 versus 3.6 +/- 1.5 hours, p less than 0.0007) and less fluoroscopy time (46 +/- 24 versus 66 +/- 33 minutes, p less than 0.002). Complications were limited to transient pericarditis (three patients), one iliac artery dissection, and cardiac tamponade probably caused by catheter repositioning in the coronary sinus (one patient). An electrophysiological study was repeated in 50 of the 55 successful cases at a mean of 9 +/- 5 months. This study was normal in 48 of 50 (96%) patients. Low-energy DC ablation is safe and effective treatment for accessory pathways in children and adults. The long-term outcome is excellent as documented by electrophysiological restudy.

Single-catheter approach to radiofrequency current ablation of left-sided accessory pathways in patients with Wolff-Parkinson-White syndrome.

Catheter ablation with the use of radiofrequency current has been introduced as a therapeutic option for patients with tachyarrhythmias mediated by an accessory atrioventricular pathway. The technique conventionally implies the introduction of several catheters into the heart for assessment of electrophysiological parameters as well as for localization of the accessory pathway and may last for several hours. Thirty-four patients with Wolff-Parkinson-White syndrome and a delta wave pattern indicative of an overt (i.e., capable of consistent antegrade conduction) left-sided free-wall accessory pathway underwent attempts at radiofrequency current ablation of the pathway with the use of just one catheter. No patient had a previous electrophysiological study. The catheter was introduced into the left ventricle close to the mitral annulus and was used for pathway localization as well as for ablation. The approach was completely successful in 30 patients (88%). In the remaining four patients, ablation of the pathway was achieved by using the multiple-catheter approach. Overall procedure duration was 2.0 +/- 1.1 hours; radiation exposure time was 22.8 +/- 20.4 minutes (median, 17.3 minutes). There were no acute complications. The single-catheter approach to radiofrequency current ablation of overt left-sided free-wall accessory pathways is feasible, safe, and effective in the majority of patients. The approach requires considerable investigator experience but significantly reduces procedure duration and radiation exposure time.

Factors Associated with Recurrence of Accessory Pathway Conduction After Radiofrequency Catheter Ablation

Catheter ablation of 215 accessory pathways (APs) using radiofrequency current (RF) was attempted in 204 consecutive patients. Two hundred twelve of the 215 (99%) APs were successfully ablated. After a minimum of follow-up period of 1 month (mean 8.5 +/- 5.4 months), AP conduction had returned in 17 patients (8%). Recurrence of AP conduction was manifest by atrioventricular (AV) reentrant tachycardia in six patients, palpitations suggestive of AV reentrant tachycardia in five patients, ventricular preexcitation on electrocardiogram in five patients, and inducible AV reentrant tachycardia during a follow-up electrophysiological study in one asymptomatic patient. AP conduction returned as early as 12 hours and as late as 4.7 months, but was evident within 2 months of ablation in 15 of 17 (88%) patients. AP conduction recurred in 12%-14% of anteroseptal, right free-wall, and posteroseptal APs, but only 5% of left free-wall APs (P less than 0.01). Retrograde only conducting APs (concealed APs) had recurrence of AP conduction more frequently (16%) than APs that exhibited antegrade conduction (5.5%; P less than 0.01). Failure to record AP potentials from the ablation electrode, reflecting poor AP localization, was a strong predictor for recurrence of AP conduction. AP conduction returned in 19% of 48 APs when AP potentials were not recorded, compared to 5% of 164 APs where AP potentials were recorded from the ablation electrode (P less than 0.01). The time to block of AP conduction from the onset of RF current application was longer in APs with recurrence of conduction (4.9 +/- 6.1 sec vs 2.9 +/- 3.4 sec; P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Low Energy Direct Current Ablation in Patients with the Wolff-Parkinson-White Syndrome: Clinical Outcome According to Accessory Pathway Location

Forty-five patients with the Wolff-Parkinson-White syndrome underwent direct current (DC) ablation using a low energy power source (Cardiac Recorders). Anodal shocks of 10-40 joules were given to either a 6 French quadripolar catheter (Bard), a 7 French bipolar contoured catheter (Bard), or a 7 French deflectable catheter with a 4-mm distal electrode (Mansfield). The indifferent electrode consisted of a large patch that was positioned under the left scapula. There were 26 males and 19 females, with a mean age of 34 years (range 9-67). Accessory pathways were located in the left free wall in 30 patients (67%) and were posteroseptal in 15 patients (33%). The shortest ventriculoatrial interval during mapping (89 +/- 21 msec), the mean cumulative amount of energy per patient (322 +/- 283 joules), and the mean CK-MB rise (45 +/- 30 units, normal 0-30 units) were not significantly different between both groups. Ablation was successful in 29/30 patients (97%) with a left free-wall accessory pathway, and in 13/15 patients (87%) with a posteroseptal accessory pathway. All three patients with failure of ablation had multiple accessory pathways, and two of these patients had Ebstein's anomaly. Patients with left free-wall and posteroseptal accessory pathways, respectively, differed significantly in terms of: total session time (4.1 +/- 1 hours vs 5.3 +/- 1.3, p = 0.0001), total procedure time for ablation (2.6 +/- 0.8 hours vs 3.2 +/- 1.2, P = 0.02), and fluoroscopy time (46 +/- 24 min vs 64 +/- 29, P = 0.006). In 13 patients (29%) with a concealed accessory pathway, these variables were not significantly different from patients with overt preexcitation.(ABSTRACT TRUNCATED AT 250 WORDS)