Radiofrequency catheter ablation of accessory atrioventricular connections in 250 patients. Abbreviated therapeutic approach to Wolff-Parkinson-White syndrome

Radiofrequency ablation of left-sided accessory pathways: transaortic versus transseptal approach

The aim of this study was to compare the efficacy of transaortic (n = 54) and transseptal (n = 28) techniques during radiofrequency (RF) ablation of left accessory pathways (n = 75) in both left posteroseptal and free-wall locations in 73 consecutive patients (mean age 32 +/- 15 years). The transseptal approach included transseptal puncture and use of a retained long sheath in the left atrium (n = 24) or direct insertion of the mapping/ablation catheter via a patent foramen ovale (n = 4). Transseptal RF ablation was used as the primary method in 23 patients or at a separate session after the transaortic RF ablation failed in 5 patients. Transaortic RF ablation was used as primary method in 50 patients and after failed transseptal ablation in 4 patients. Transaortic ablation was successful in 47 (87%) of 54 procedures, transseptal ablation in 24 (86%) of 28 procedures, with total RF ablation success in 70 (96%) of 73 patients. The transseptal puncture/long sheath method was successful in 23 (96%) of 24 patients. This latter technique resulted in more stable positioning and easier manipulation of the ablation catheter. Switching from transseptal puncture/long sheath to transaortic technique was needed in 1 of 24 patients, from transseptal/patent foramen ovale approach to the transaortic route in 3 of 4 patients, and from the transaortic to the transseptal approach at a separate session in 5 patients. The age of patients and number of RF lesions were similar in the two groups. Fluoroscopy time was lower for the transseptal group (81 +/- 57 vs 121 +/- 81 min; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of radiofrequency catheter ablation procedures in children, adolescents, and adults and the impact of accessory pathway location

Radiofrequency (RF) catheter ablation is an accepted treatment for supraventricular tachycardia. However, the determinants of success, difficulty, or risk of complication associated with ablation have not been defined. This study evaluated patient age and location of the accessory or extranodal pathway as determinants of these procedural variables. Patients were stratified by age, with those aged 2 to 12 years classified as children, those aged 13 to 19 years as adolescents, and those > or = 20 years as adults. Locations were defined as right, septal, or left free wall accessory pathways, or extranodal slow pathways associated with atrioventricular node reentrant tachycardia. A total of 443 RF ablation procedures performed in 413 patients were evaluated. All procedures were performed in the same laboratory by the same group of physicians. Success rates for ablation of supraventricular tachycardia did not differ among the 3 age groups, ranging from 93% to 95%. Procedural aspects, including total procedure time, fluoroscopy time, and number of applications of RF energy also did not differ by age group. However, analysis of outcome and procedural complexity with respect to pathway location demonstrated that ablation of right free wall and septal accessory pathways was significantly more difficult than left free wall or slow pathway (success rates of 85% and 88% vs 97% and 98%, respectively, p = 0.01 and 0.02), irrespective of age. Additionally, right free wall pathways required significantly greater procedure time (mean = 5.1 hours), fluoroscopy time (mean = 78 minutes), and RF applications (median = 16) than ablations performed at other sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiofrequency catheter ablation of concealed atrio-His bypass tract involved in paroxysmal supraventricular tachycardia

In a patient with paroxysmal supraventricular tachycardia and without any evidence for preexcitation syndrome or dual atrioventricular (AV) nodal pathways, the tachycardia reentry circuit consisted of the AV node as an antegrade limb of the circuit and a concealed atrio-His bypass tract located in the posterior septum as a retrograde limb. During the tachycardia, the atrial potentials in the septal region and coronary sinus were inscribed in the QRS complex, and the earliest atrial activation site was located in the posterior septum. Ventricular extrastimulation at critically short intervals reproducibly demonstrated a ventriculo-His-atrial activation sequence with the same earliest retrograde atrial activation site as that during the tachycardia. Radiofrequency energy (20 W) was applied to this earliest activation site during ventricular pacing, which resulted in complete ventriculoatrial block within 2 seconds after energy application. The antegrade AV conduction property was not affected and the tachycardia was no longer induced. The patient has been free from tachycardia attack for a follow-up period of 8 months. Therefore, radiofrequency catheter ablation for an atrio-His bypass tract is feasible without inducing any AV conduction disturbance.

An approach to therapy of supraventricular tachyarrhythmias: an algorithm versus individualized therapy

Approaches to the treatment of supraventricular arrhythmias, including atrial fibrillation, atrial flutter, atrial tachycardia, atrioventricular (AV) reentrant tachycardia, and AV nodal reentrant tachycardia, continue to evolve. Within the past two decades, many new and effective treatments have become available. These include several new antiarrhythmic agents, ablative therapies, pacing and surgical modalities, and cardioversion/defibrillation techniques. This paper provides an algorithm for the treatment of these supraventricular arrhythmias which includes therapy for the acute episode as well as the prevention of subsequent episodes of the tachyarrhythmia.

Radiofrequency catheter ablation of septal accessory atrioventricular pathways

OBJECTIVE

Septal accessory atrioventricular pathways are recognised as being more difficult to ablate than pathways in other locations. This paper describes an experience of 48 consecutive patients with septal accessory pathways who had catheter ablation with radiofrequency current.

PATIENTS AND METHODS

There were 28 male and 20 female patients, mean (SD) age 35 (17). 43 patients had a single accessory pathway and 5 patients had multiple accessory pathways. Pre-excitation was present in 37 patients, and 11 patients had concealed accessory pathways. 21 patients had had a previous electrophysiological study. Catheter ablation was undertaken with radiofrequency current delivered by a standard unipolar technique or by delivery of current across the septum (the bipolar technique).

RESULTS

The median total procedure time was 167 (83) minutes including a 30-40 minute observation period after the abolition of conduction by the accessory pathway. The median total fluoroscopic time was 56 (30) minutes. 42 (88%) out of 48 patients had successful ablation of the pathway during the first session. In the six patients in whom the procedure failed, five had a midseptal pathway and one had a right anteroseptal pathway. A second attempt at ablation was made in two patients and succeeded in both. In total, 49 accessory pathways were successfully ablated in 44 (92%) out of 48 patients. The bipolar technique was used in 11 patients and succeeded in 10 patients. Standard unipolar current delivery had previously failed in seven of the 11 patients. Complications developed in two patients with a mid septal pathway (one with complete atrioventricular block and the other with a small pericardial effusion).

CONCLUSION

Radiofrequency catheter ablation of septal accessory pathways is efficacious and safe. The procedure time can be shortened and success rate can be increased after improvement of the technique--that is, consideration of a bipolar approach for energy delivery in difficult cases.

Predictors of early and late recurrence of atrioventricular accessory pathway conduction after apparently successful radiofrequency catheter ablation

The correlation between electrophysiologic parameters and recurrence in 239 patients who underwent successful catheter ablation for an accessory pathway mediated tachycardia was analysed. Pathway conduction recurred in 15 patients (6.3%) after a mean follow-up of 7.3 months. Recurrence was most common in patients with right free wall pathways (17.1%). Accessory pathway conduction resumed in 18.9% of patients with decremental ventriculo-atrial (VA) conduction post-ablation compared with those patients without VA conduction (3.4%) (P < 0.001). Recurrence was common also in patients with repeated return of accessory pathway conduction during the ablation procedure (40% vs. 1.3%, P < 0.01). The patients in whom these observations are made should be monitored closely for recurrence of accessory pathway conduction post-ablation.

Memory T waves after radiofrequency catheter ablation of accessory atrioventricular connections in Wolff-Parkinson-White syndrome

Generalized, extensive electrical repolarization abnormalities, represented by negative or abnormally peaked T waves, are frequently observed after radiofrequency catheter ablation of overt accessory atrioventricular (AV) connections in Wolff-Parkinson-White (WPW) syndrome. Two mechanisms have been proposed to explain these changes: subendocardial injury, secondary to the application of radiofrequency lesions, and memory T waves. The purpose of this study is to evaluate the electrocardiographic (ECG) changes in patients with overt and concealed accessory AV connections after ablation. Fifty-one patients with accessory AV connections who underwent successful radiofrequency ablation were included in the study. Twenty-four patients with clear, manifest, and permanent preexcitation (group 1) were compared with 27 patients with concealed accessory AV connections (group 2). Electrocardiograms were obtained in all patients before ablation, shortly after ablation (within 4 hours), and late after ablation (6 weeks). The frontal and horizontal QRS-T angles in the ECGs, number of lesions, total Joules applied, total peak creatine kinase, and total peak creatine kinase-MB units were compared in both groups. Of the 24 patients with overt accessory AV connections, 23 (95.8%) demonstrated repolarization abnormalities in the ECG shortly after the procedure that reverted almost completely at 6 weeks. Of the 27 patients with concealed accessory AV connections, only 2 (7.4%) demonstrated repolarization abnormalities after the ablation (P < .0001). The persistence of an abnormal QRS-T angle immediately after ablation in patients with overt accessory AV connections is caused by an abnormality in the T wave axis, opposite to the direction of the normal QRS axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful and unsuccessful sites of radiofrequency catheter ablation of accessory atrioventricular connections

Local electrograms from 47 consecutive patients who underwent successful radiofrequency catheter ablation of 49 accessory atrioventricular (AV) connections were analyzed. One hundred twenty-two local electrograms were recorded at 27 successful and 95 unsuccessful sites immediately before radiofrequency catheter ablation of 27 manifest accessory AV connections during preexcited sinus rhythm or atrial pacing. Continuous electric activity was found in 96% of successful sites versus 71% of unsuccessful sites (p < 0.01). Possible accessory pathway (AP) potentials were present only in 15% of successful and 2% of unsuccessful sites, respectively (p < 0.05). All measured time intervals were significantly shorter for successful sites as compared to unsuccessful sites of ablation of manifest accessory AV connections. Unipolar electrograms from the tip of the ablation catheter of each successful and unsuccessful ablation site were available for the last 16 patients with manifest accessory AV connections. A PQS pattern of the unipolar electrogram was associated with a higher success rate, whereas a PrS pattern never resulted in successful ablation of an accessory AV connection. Multivariate logistic regression analysis of the local electrogram characteristics of rapidly conducting, concealed accessory AV connections revealed the interval between the onset of the local ventricular and atrial electrogram (VoAo interval) as the only independent variable associated with successful sites for radiofrequency catheter ablation. The only study patient with a slowly conducting, concealed accessory AV connection underwent successful ablation with the first lesion of radiofrequency energy at the site with the shortest VoAo interval. We conclude that (1) the shortest local AV intervals and local ventricular electrograms preceding the earliest onset of the delta wave in any surface lead are predictive of successful ablation of manifest accessory AV connections; (2) the shortest local VA intervals during orthodromic AV reentry tachycardia or right ventricular pacing are predictive of successful ablation of concealed accessory AV connections; and (3) unipolar recordings from the tip of the ablation catheter should be recorded routinely during mapping of manifest accessory AV connections to identify appropriate target sites for radiofrequency energy applications.

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.

Follow-up of radiofrequency catheter ablation in children: results in 100 consecutive patients

OBJECTIVES

The purpose of this study was to determine the outcome of a group of closely followed-up pediatric patients who had undergone radiofrequency ablation for cardiac arrhythmias.

BACKGROUND

Although radiofrequency ablation in children has been shown to be effective and safe in the short term, results of longer term follow-up of these children must be considered when determining the place of radiofrequency ablation in the management of pediatric arrhythmias.

METHODS

One hundred children aged 2 months to 17 years underwent a total of 119 radiofrequency ablation procedures for cure of tachycardia. Follow-up clinical data, electrocardiograms and 24-h Holter monitors were obtained and analyzed.

RESULTS

All patients were alive, and none were lost to follow-up after a mean follow-up of 21.5 months (range 6 to 50). Success at last follow-up included accessory pathways in 66 (89%) of 74 patients, atrioventricular (AV) node reentry in 15 (88%) of 17, intraatrial reentry in 2 (67%) of 3, atrial flutter in 3 (100%) of 3, atrial ectopic tachycardia in 2 (67%) of 3, junctional ectopic tachycardia in 1 (100%) of 1 and ventricular tachycardia in 2 (100%) of 2 (overall success, 90 [90%] of 100). All recurrences were observed within 6 months of ablation. Major and minor complications (7%) included chest burn (one patient), foot microembolus (two patients), hematoma without pulse loss (four patients), femoral arteriovenous fistula requiring repair (one patient) and transient Mobitz I AV block (one patient). Immediate success, recurrence and complication rates were similar in the > or = 12-year old versus the < 12-year old group. Echocardiograms, available in 109 (92%) of 119 patients, showed possible procedure-related abnormalities in 2 (mitral regurgitation in 1, tricuspid regurgitation in 1, both mild), with no aortic insufficiency after 30 left-sided ablations performed by the retrograde approach. Follow-up Holter monitors, available in 77 (77%) of 100 patients, showed possible procedure-related abnormalities in 5 (frequent atrial ectopic tachycardia in 2, atrial flutter in 1, accelerated ventricular rhythm in 2). There were no early or late deaths.

CONCLUSIONS

In children, the risks of radiofrequency ablation are low at follow-up evaluation. Longer-term follow-up of children undergoing radiofrequency ablation will be necessary to determine whether coronary abnormalities or serious new arrhythmias will develop.

Management of patients after catheter ablation of ventricular tachycardia

The management of patients after catheter ablation of ventricular tachycardia is not well defined. In this article we summarize recently published results and report our own experience. Factors influencing the clinical outcome of these patients and methods to identify patients with an increased risk of recurrence of ventricular tachycardia are discussed. Furthermore, a review is given on current concomitant therapeutic tools including antiarrhythmic drugs and the implantation of an automatic cardioverter defibrillator.

Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: clinical features, electrophysiologic characteristics and results of radiofrequency ablation

OBJECTIVES

This study was designed to evaluate the clinical features, electrophysiologic characteristics and results of radiofrequency ablation in elderly patients with accessory atrioventricular (AV) pathways or AV node reentrant tachycardia.

BACKGROUND

Radiofrequency ablation in elderly patients with paroxysmal supraventricular tachycardia has not been well described, and comparative study between elderly and younger patients is limited.

METHODS

Electrophysiologic studies and radiofrequency ablation were performed in 92 elderly patients (45 with an accessory pathway, 47 with AV node reentrant tachycardia).

RESULTS

The elderly patients had poorer electrophysiologic properties in accessory pathways and dual AV node pathways than those of younger patients. The success rate of radiofrequency ablation was similar in elderly and younger patients. However, elderly patients had more complications (14%) in left-sided accessory pathways.

CONCLUSIONS

Radiofrequency ablation in elderly patients with supraventricular tachycardia was effective. However, it must be performed cautiously in those patients with left-sided accessory pathways.

Ablation of left free-wall accessory pathways using radiofrequency energy at the atrial insertion site: transseptal versus transaortic approach

INTRODUCTION

Transcatheter ablation of the left free-wall atrioventricular accessory pathways (AP) by delivery of radiofrequency current at the ventricular insertion site has been shown to be effective. The efficacy of such a technique targeting the atrial insertion site of the AP was evaluated.

METHODS AND RESULTS

One hundred consecutive patients with left free-wall APs and symptomatic supraventricular tachyarrhythmias were included. APs were manifest in 55 patients and concealed in 45. There were 55 men and 45 women with a mean age of 35 years. A total of 107 left free-wall APs were identified in these patients. In these 100 patients, successful ablation was accomplished in all by using a transseptal (45 patients) or transaortic (54 patients) technique. In one patient, ablation was accomplished from within the coronary sinus. Seven patients required a repeat ablative procedure, which was performed successfully. During 107 ablative procedures, six were associated with nonfatal complications including pericardial effusion (hemopericardium) in two patients, mild mitral regurgitation in two patients, swelling of the left arm in one patient, and staphylococcal bacteremia in one patient. Eighty-two (82%) patients underwent a repeat electrophysiologic study 6 to 8 weeks after successful ablation and were found to have no functioning AP or inducible supraventricular tachycardia. During a mean follow-up of 20 +/- 8 months, none of the 100 patients had a recurrence of tachyarrhythmias.

CONCLUSION

These data indicate that the atrial insertion site of the AP can be successfully ablated in the majority of patients with left free-wall APs by using either a transseptal or transaortic approach. Furthermore, both techniques are associated with minimal morbidity and no mortality.

In vivo ventricular lesion growth in radiofrequency catheter ablation

While radiofrequency catheter ablation has proved highly effective in the treatment of various supraventricular tachyarrhythmias, results in the treatment of ventricular tachycardia invite improvement. Knowledge of lesion growth in vivo might improve understanding of this discrepancy. So far only information from in vitro and in vivo studies using a small 2 mm tip electrode is available. Growth of ventricular radiofrequency lesions created with a 4 mm ablation electrode was studied in 11 closed-chest dogs. Endocardial ablations were performed at 31 left and 15 right ventricular sites at a power setting of 25 Watts and 5, 10, 20, 30 or 60 seconds pulse duration. Macroscopic and histopathologic lesion examination were performed after one week survival. Mean lesion volume increased from 52 mm3 after 5 seconds pulse duration to a maximum 388 mm3 and approximately 7 mm depth after 30 seconds. Lesions were prolate spheroid in form, with a sparing of subendocardial myocardium and maximum lesion diameter at some millimeters depth. Results indicate that catheter positioning at no more than 7 mm from the target is required for successful ablation. Due to lesion geometry, subendocardial targets demand even more exact catheter positioning, while subepicardial substrates may not be ammenable to ablation if ventricular wall thickness exceeds 7 mm at the ablation site. Repeated pulses at adjacent sites may be required for ablation of extended arrhythmogenic areas. Volume at 5 seconds was only approximately 15% of mature lesions. Therefore, the use of a short 'test pulse' after careful mapping may be useful to pinpoint the most appropriate site for ablation in discrete pathways.

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.

Unipolar electrogram models for prediction of outcome in radiofrequency ablation of accessory pathways

Meticulous catheter positioning close to the accessory pathway is essential for successful radiofrequency ablation. The aim of this study was to identify local unipolar electrogram characteristics predictive of radiofrequency ablation outcome, enabling more accurate accessory pathway localization and catheter positioning. So far mainly bipolar electrogram parameters have been evaluated, stressing the importance of the presence of an accessory pathway potential. However, especially in the absence of this parameter, the unipolar recording mode can be expected to hold several advantages. Nine local unipolar electrogram characteristics were analyzed in preexcited sinus rhythm directly preceding radiofrequency pulses in 35 consecutive patients with a manifest accessory atrioventricular pathway. A total of 1,230 unipolar electrogram complexes were analyzed and recorded at 138 ablation sites. Ablation was successful in 30/35 patients (86%). Multivariate analysis provided two unipolar models for prediction of ablation outcome: in Model I, sites with a suspected accessory pathway potential, local AV interval < or = 30 msec and catheter stability had 76% probability of success, but no more than 1% in their absence. In contrast, using the bipolar recording mode, presence of a suspected accessory pathway potential was the only one of these parameters shown to differentiate between successful and unsuccessful sites, with a predicted chance of success of 48%. Model II, not requiring assessment of possible accessory pathway potentials, showed a 63% probability of success for the combination of initial positivity of the local ventricular signal < or = 0.1 mV, AV interval < or = 30 msec, and catheter stability, but no more than 7% in their absence. Moreover, gradual decrease of initial ventricular positivity and AV interval while approaching a subsequently successful site allows the use of these parameters as dynamic mapping tools. Local unipolar electrogram parameters may thus facilitate precise accessory pathway localization and catheter positioning while offering important information supplementary to the bipolar mode, and enable accurate prediction of ablation outcome at a given site also in the absence of accessory pathway potential recording.

Potential ablation of accessory atrioventricular pathways: injection of alcohol into the atrioventricular groove

Accessory atrioventricular (AV) pathways responsible for the Wolff-Parkinson-White syndrome have been treated successfully by surgical and radiofrequency catheter ablation techniques. In this study, we explored the feasibility of permanent chemical ablation of accessory pathways by direct injection of 100% ethanol into the canine AV groove. Right coronary artery blood flow and AV compartment pressure were measured in 5 adult mongrel dogs (part I) during injection of saline solution (10 to 15 mL) into the right AV groove. Atrioventricular groove compartment pressure increased from 1 +/- 1 to 31 +/- 12 mm Hg (p < 0.0001) and right coronary artery blood flow increased slightly from 117 +/- 17 to 138 +/- 44 mL/min (p = not significant). In 8 additional dogs (part II), 100% ethanol (10 mL) was injected into the left AV groove. After 6 weeks (n = 6) or 12 weeks (n = 2), histologic examination of the left AV groove demonstrated localized fibrous replacement of injured epicardial muscle, with only scant inflammatory infiltrate. Mild intimal fibrosis and intimal proliferation were present in the circumflex artery and its larger branches, but no significant luminal narrowing was evident. Angiograms at 12 weeks (n = 2) demonstrated no significant narrowing of the circumflex artery. In summary, injection of 100% ethanol into the AV groove is capable of locally ablating myocardial tissue, presumably including conductive tissues, while sparing the coronary arteries.

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

INTRODUCTION

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.

METHODS AND RESULTS

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.

CONCLUSION

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.

A randomized comparison of the right- and left-sided approaches to ablation of the atrioventricular junction

Radiofrequency ablation of the atrioventricular (AV) junction may be performed using either a right- or left-sided approach. This study prospectively compared the left-sided approach with persistent attempts from the right side in patients in whom initial radiofrequency applications on the right side were unsuccessful. Twenty-one of 54 patients did not have complete AV block induced after 3 right-sided radiofrequency applications. These 21 patients were randomly assigned to undergo either the left-sided approach (n = 10) or to undergo additional attempts from the right side (n = 11). The right-sided approach was performed by positioning the ablation catheter to record the largest possible atrial and His bundle electrograms. The left-sided approach was performed by positioning the ablation catheter along the left ventricular septum, where a His bundle potential was recorded. If either approach was not successful after an additional 17 radiofrequency applications, the alternative approach was then used. The AV junction was successfully ablated in all 10 patients randomized to the left-sided approach, but in only 6 of 11 patients randomized to persistent right-sided attempts (p < 0.05). The 5 patients in whom the AV junction was not successfully ablated using the right-sided approach underwent the left-sided approach and had a successful outcome after a mean of 1.2 +/- 0.4 radiofrequency applications. The left-sided approach required significantly fewer radiofrequency applications after randomization than the right-sided approach (3 +/- 3.4 vs 11 +/- 7.6, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Single physician approach to radiofrequency catheter ablation in patients with supraventricular tachycardia

The minimal requirements for safe and effective performance of catheter ablation using radiofrequency current are still unclear. To determine the feasibility and safety of single physician approach to catheter ablation of supraventricular tachycardia substrate using radiofrequency energy, the results of the ablation procedure in 52 consecutive patients were evaluated. The procedures were performed during 1 year by the same physician and nurse. Twenty-one patients had selective atrioventricular (AV) nodal pathway ablation and 31 patients had accessory AV pathway ablation. Forty-eight patients (89%) had the diagnostic and the ablative procedure during the same electrophysiological test. In the 21 patients with AV nodal reentrant tachycardia, all had successful selective ablation of the fast (13) or the slow (8) pathways. Eight patients had recurrence of the clinical tachycardia and had a successful reablation. No patient developed complete AV block or other significant complications. The mean fluoroscopy time during the procedure was 16.0 +/- 8.6 minutes. In the eight patients with Wolff-Parkinson-White syndrome, all concealed accessory pathways were successfully ablated with a mean fluoroscopy time of 30.0 +/- 27.9 minutes. Two patients had recurrence of the conduction through the accessory pathway and had a successful reablation. Eighteen of 19 patients with a single overt accessory pathway had successful ablation, with a fluoroscopy time of 22.7 +/- 20.6 minutes. Three patients had an early recurrence of the conduction through the accessory pathway, reablation was successful in two of them. Ten accessory pathways were ablated in four patients with multiple pathways during nine procedures. Only two patients developed minor peripheral vascular complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Recognition and catheter ablation of subepicardial accessory pathways

OBJECTIVES

The purpose of this study was to characterize left-sided accessory pathways that traverse the atrioventricular (AV) groove subepicardially and to describe results of radiofrequency catheter ablation within the coronary sinus in the patients studied.

BACKGROUND

Radiofrequency catheter ablation has proved to be a safe and effective method for treatment of accessory pathways; however, subepicardial accessory pathways may account for some of the failures encountered during endocardial ablation.

METHODS

The study group comprised 51 consecutive patients with a left-sided accessory pathway who were undergoing radio-frequency catheter ablation. Initially, the ablation catheter was introduced into a femoral artery and positioned on the ventricular aspect of the mitral annulus. If this endocardial approach was unsuccessful, the ablation catheter was introduced into the coronary sinus and energy applied at sites with shorter activation times than those recorded from the endocardium.

RESULTS

Five (10%) of 51 patients with a left-sided accessory pathway could not have accessory pathway conduction interrupted with a median of 18 endocardial radiofrequency energy applications. Accessory pathway potentials were less frequent during endocardial mapping in these 5 patients than in the 46 patients whose accessory pathway was successfully ablated from the endocardial surface. All five of these patients later had successful ablation using one or two applications of radiofrequency energy from within the coronary sinus. Effective target site electrograms in the coronary sinus were characterized by an accessory pathway potential that was larger than the corresponding atrial or ventricular electrogram. There were no complications or recurrences after ablation within the coronary sinus.

CONCLUSIONS

Some left-sided accessory pathways may be difficult to ablate from the endocardial surface because they traverse the AV groove subepicardially. The absence of an accessory pathway potential during endocardial mapping in combination with a relatively large accessory pathway potential within the coronary sinus may be a useful marker of a subepicardial pathway. In this select group of patients, radiofrequency catheter ablation from within the coronary sinus appears to enhance efficacy.

Radiofrequency catheter ablation for the management of cardiac tachyarrhythmias

Radiofrequency catheter ablation techniques allow for safe and highly effective curative therapy of a variety of cardiac dysrhythmias. The technique involves the delivery of a high-frequency, alternating electrical current through an intravascular catheter to sites of arrhythmogenic myocardium. This current induces resistive electrical heating of the tissue, resulting in discrete areas of myocardial destruction through coagulation and desiccation. Dysrhythmias most commonly treated with these techniques are atrioventricular nodal reentry and tachycardias related to accessory atrioventricular bypass tracts. For these dysrhythmias, success rates of 90% to 95% are achievable with a low (2% to 4%) risk of complications. Radiofrequency catheter ablation techniques also have been used to treat ventricular tachycardias, atrial flutter, ectopic atrial tachycardia, and sinus node reentry, albeit with lower success rates. These techniques are still evolving, alternate energy sources (such as microwave and laser) and improved catheter technology should enhance the technique's safety and efficacy for a wider range of dysrhythmias.

Inducibility of atrial fibrillation before and after radiofrequency catheter ablation of accessory atrioventricular connections

INTRODUCTION

The purpose of this study was to evaluate the inducibility of atrial fibrillation in patients with an accessory atrioventricular connection (AAVC) and to determine if the inducibility of atrial fibrillation is altered after successful radiofrequency catheter ablation of the AAVC.

METHODS AND RESULTS

Thirty-seven patients with an AAVC and 36 control patients were prospectively evaluated using a standardized atrial pacing protocol. The high right atrium was paced using a 25-beat drive train, 1.5-second intertrain pause, 10-mA pulse amplitude, and 2-msec pulse duration at cycle lengths of 250 to 100 msec, in 10-msec decrements. Pacing was performed twice at each cycle length. Thirty patients with an AAVC underwent repeat atrial overdrive pacing after successful radiofrequency ablation of the AAVC. Atrial fibrillation was induced in 26 (70%) patients with an AAVC and 22 (61%) controls (P = NS). Atrial flutter was induced in 11 (30%) patients with an AAVC and 13 (36%) controls (P = NS). The cumulative percentage of patients with atrial fibrillation/flutter induced at each pacing cycle length was the same in each group. There was no difference in the duration of atrial fibrillation/flutter between control patients and patients with an AAVC. Among the 30 patients who underwent repeat atrial overdrive pacing after radiofrequency ablation of an AAVC, there was no difference in the inducibility or duration of atrial fibrillation/atrial flutter after ablation compared to baseline.

CONCLUSION

These findings indicate that the vulnerability of the atrium to fibrillate in response to atrial pacing is independent of the presence of an AAVC.

Development of an aortic valve mass after radiofrequency catheter ablation

A 49-year-old woman underwent a successful radiofrequency catheter ablation of a left-sided accessory pathway using a retrograde approach across the aortic valve. Routine echocardiography performed 20 hours after the procedure revealed a new aortic valve mass. Five blood cultures were negative. An echocardiogram after 2 days of heparin therapy showed complete resolution of the mass. There was no clinical evidence of embolization. Echocardiography may need to be performed routinely after catheter ablations performed retrograde across the aortic valve so that this potentially devastating complication can be diagnosed and treated early in its course.

Radiofrequency ablation of accessory pathways associated with congenital heart disease including heterotaxy syndrome

Congenital heart disease complicates the management of most accessory pathway-mediated tachycardias and also increases the challenge of radiofrequency ablation. Since 1990, radiofrequency ablation of accessory atrioventricular (AV) pathways has been attempted in 10 patients (age range 3.5 months to 30 years) with congenital heart disease: Ebstein's anomaly (n = 5), heterotaxy with AV discordance (n = 3), tetralogy of Fallot (n = 1) and total anomalous pulmonary venous return (n = 1). Eight patients had manifest Wolff-Parkinson-White syndrome and 2 had concealed pathways. Five patients had multiple pathways including 4 of the 5 with Ebstein's anomaly. Of 16 pathways total, 15 were associated with the tricuspid valve including all pathways in the patients with Ebstein's anomaly and heterotaxy. The His bundle area was identified in all patients and involved an anterior AV node in 2 of 3 with heterotaxy. Ablation was performed on the atrial side of the AV ring in all cases. No instance of AV block was encountered. Complete success was achieved in 6 patients including the 3 with heterotaxy. In 2 patients, manifest preexcitation was eliminated and clinical symptoms were greatly modified. The procedure was transiently successful in 1 patient who later had surgical interruption of the accessory pathway during tetralogy of Fallot repair. Ablation was unsuccessful in 1 patient. Thus, the overall success was 80%.

Usefulness of serial follow-up electrophysiologic studies in predicting late outcome of radiofrequency ablation for accessory pathways and atrioventricular nodal reentrant tachycardia

A total of 408 patients received radiofrequency catheter ablation for paroxysmal supraventricular tachycardia, and 326 patients underwent serial follow-up electrophysiologic studies (early and late) after initially successful radiofrequency catheter ablation of accessory pathways (group 1, 186 patients with Wolff-Parkinson-White syndrome) and slow atrioventricular (AV) nodal pathways (group 2, 140 patients with AV nodal reentrant tachycardia). Among the patients in group 1, early (4 +/- 1 days) and late (129 +/- 14 days) studies found recurrent conduction through the accessory pathways in 12 and 16 patients, respectively. During a follow-up period of 21 +/- 7 months, recurrence of accessory pathway-mediated tachyarrhythmias was noted in six patients. Of these six patients, all had tachycardia inducible in the late study but not in the early study. Among the patients in group 2, four had recurrence of AV nodal reentrant tachycardia during a follow-up of 16 +/- 6 months. Of the four patients, one had tachycardia inducible in the early (4 +/- 1 days) study and three in the late (130 +/- 12 days) study. The results demonstrated that the early study was not as sensitive as the late follow-up electrophysiologic study in predicting late outcome of radiofrequency ablation, but both the early and late studies had a high total predictive accuracy (> 90%) in groups 1 and 2. Furthermore, only 4 of the 326 patients had initial evidence of recurrent tachycardia activated by programmed electrical stimuli during follow-up studies, suggesting that follow-up electrophysiologic studies in asymptomatic patients are not warranted.

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 successful 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 electrophysiology 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 > or = 65 or < 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.

Role of radiofrequency ablation in the management of supraventricular arrhythmias: experience in 760 consecutive patients

INTRODUCTION

Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular tachycardias. However, the efficacy, complications, risk of arrhythmia recurrence, and follow-up survival analysis have not been reported in a large series of consecutive patients with supraventricular arrhythmias with diverse electrophysiologic mechanisms. This report details the results of radiofrequency catheter ablation in 760 consecutive patients (386 males, 374 females) with a wide variety of supraventricular tachycardias treated at one center.

METHODS AND RESULTS

Arrhythmias were associated with the presence of an accessory pathway in 363 patients (384 accessory pathways), including four patients with Mahaim fibers and eight patients with the permanent form of junctional reciprocating tachycardia. The mechanism of the clinical arrhythmia was AV nodal reentrant tachycardia in 245 patients, and a primary atrial tachycardia in 20 patients (ectopic atrial tachycardia in 16 patients and sinus nodal reentry in 4 patients). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 13 patients. AV node ablation and permanent pacemaker implantation were performed in 119 patients with medically refractory atrial fibrillation or flutter. Radiofrequency catheter ablation was successful in 346 of 363 patients (95.3%, CI 93.1%-97.5%) with accessory pathways (367 of 384 pathways, 95.6%, CI 93.5%-97.6%) with a complication rate of 1.1% and a recurrence rate of 5.5%. Successful accessory pathway ablation was achieved for 179 of the first 192 pathways treated (93.2%, CI 89.7%-96.6%) and increased to 188 of 192 pathways (97.9%, CI 95.9%-99.9%) over the second half of the series. AV nodal reentry was successfully abolished in 244 of 245 patients (99.6%, CI 98.8%-100%) by selective ablation of the slow pathway in 234 patients and the fast pathway in 10 patients. The complication rate in this group was 2.0% with a recurrence rate of 6.5%. All 20 primary atrial tachycardias were successfully ablated with no complications and a recurrence rate of 15%. The reentrant circuit of atrial flutter was ablated successfully in 10 of 13 patients (77%) with recurrent atrial flutter in one additional patient. Complete AV block was achieved in 117 of 119 (98.3%, CI 96.0%-100%) patients with atrial fibrillation or flutter treated by AV nodal ablation with a complication rate of 0.8% and recurrence of AV conduction in 6%. The median duration of fluoroscopy exposure for the population was 23.4 minutes. The overall primary success rate for the entire population was 97.0% (737 of 760 patients, CI 95.8%-98.2%).

CONCLUSION

Thus, the results of this large series of patients demonstrates the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of supraventricular arrhythmias. It also appears that increasing experience with these procedures increases the rate of successful ablation and decreases the risk of complications.

Radiofrequency catheter ablation of accessory pathway during entrainment of the atrioventricular reciprocating tachycardia

Radiofrequency catheter ablation of the concealed atrioventricular (AV) accessory pathway was performed during entrainment of the AV reciprocating tachycardia. Right ventricular pacing at a rate 5 to 15 beats/min faster than the tachycardia rate was performed during the tachycardia, which resulted in transient entrainment. In 2 patients with a right-sided accessory pathway, constant fusion of the QRS complex was observed during entrainment, whereas in 2 with a left-sided pathway, no fusion beat was noted (concealed entrainment). Radiofrequency energy was applied to the accessory pathway while entraining the tachycardia. One to 4.5 seconds after initiation of energy delivery, ventriculoatrial conduction block occurred (i.e., the accessory pathway was ablated). This was associated with a change in the left ventricular activation sequence from orthodromic capture through the normal AV conduction system to antidromic capture through the right ventricle and with a change in the QRS morphology in patients with a right-sided accessory pathway. The left ventricular activation sequence and QRS morphology remained unchanged in patients with concealed entrainment. Radiofrequency energy was effectively delivered for 30 seconds with a stable ablation catheter position, and termination of rapid pacing resulted in sinus rhythm. Thus, radiofrequency ablation of the reentry circuit component during manifest entrainment fulfilled the third entrainment criterion defined previously. The results suggest that tachycardia entrainment can be used for continuous application of radiofrequency energy during tachycardia in selected patients, because it provides a constant ventricular rate during the procedure and thus maintains the catheter in a stable position.

Management of elderly patients with the Wolff-Parkinson-White syndrome: is less aggressive treatment justified?

To study the age-related differences in Wolff-Parkinson-White syndrome an elderly group of 20 patients aged 40-65 years was compared to a younger group of 26 patients aged 18-39 years with respect to clinical profile and electrophysiological characteristics. The two groups were comparable in terms of the mechanism of reentry tachycardia, accessory pathway location, the number of patients reporting syncopal episodes, and the incidence of inducible and/or documented atrial flutter/fibrillation while only elderly patients had also atrial tachycardias. The elderly group was characterized by a higher incidence of associated organic heart disease and a significantly higher percentage of resuscitation from circulatory arrest. Cardiocirculatory arrest due to arrhythmias was the event leading to transferral to our hospital in 30% of elderly patients compared with 7.7% in the younger group. Analogous results were obtained when stratified according to the age at manifestation of tachyarrhythmias (< 30, > or = 30 years), a history of cardiopulmonary resuscitation being the only significant difference between the two groups. There was no difference in any electrophysiologic parameter between the two age groups or with respect to the age at manifestation of arrhythmias. It is concluded that elderly patients with the Wolf-Parkinson-White syndrome should be managed as aggressively as their younger counterparts. In particular, manifestation of arrhythmias due to Wolff-Parkinson-White syndrome beyond age 30 should not be regarded as a more benign variation of the syndrome. Explanations for the more frequent history of resuscitation in the elderly include the presence of organic heart disease with impairment of left or right ventricular function and differences in the management of these patients.

Radiofrequency catheter ablation for paroxysmal supraventricular tachycardia: a report of 135 procedures

BACKGROUND

Paroxysmal Supraventricular Tachycardia (PSVT) is a common condition which until recently has been treated with anti-arrhythmic drugs or surgery. Radiofrequency (RF) catheter ablation is a new mode of treatment which provides a cure of this condition.

AIMS

To present our early experience of RF catheter ablation for PSVT.

METHODS

One hundred and thirty-five procedures were performed in 117 patients. The diagnostic study and therapeutic catheter ablation were performed as a combined electrophysiological procedure in 74 patients (63%). In 58 patients (50%), PSVT was due to Atrio-ventricular junctional (nodal) re-entrant tachycardia (AVJRT). Twenty-five of the 58 patients underwent a fast pathway ablation while 33 had ablation of their slow pathway. The mean number of radiofrequency pulses delivered was ten for a mean duration of 25 seconds. Radiofrequency ablation of accessory pathways was attempted in 58 patients; pathways were left-sided in 29 patients, postero-septal in 21, midseptal in five, Mahaim connection in two, antero-septal in one and right free wall in one patient. One patient with incessant automatic atrial tachycardia also underwent a successful RF ablation.

RESULTS

Using RF ablation cure of PSVT was achieved in 90% of patients. Cure of AVJRT was achieved in 95% (55/58) of patients using either fast or slow pathway ablation. Only one patient required permanent pacemaker implantation for Mobitz type I AV block following fast pathway ablation. The overall success rate for ablation of accessory pathways was 85%. There is an operator learning curve for this procedure suggested by the fact that the success rate for accessory pathway ablation at first attempt was 63% in the first 29 patients and 93% in the remaining 29. There was no significant morbidity or mortality during or after the procedure. In a mean follow-up of nine months in the patients with successful ablation only two patients with AVJRT had a recurrence of documented PSVT. Both these patients had successful repeat RF ablation. Catheter ablation using radiofrequency energy is an effective and safe therapeutic option for patients with symptomatic PSVT.

Investigation of palpitations

The uncomfortable awareness of a beating heart--palpitations--is a common complaint that can occur under normal or abnormal circumstances. For example, normal palpitations occur with exercise, emotions, and stress, or after taking substances that increase adrenergic tone or diminish vagal activity (coffee, nicotine, and adrenergic or anticholinergic drugs). Normal palpitations are recognised as such because individuals who experience them realise or are told that something happened to accelerate the normal rhythm of the heart. However, some people find sinus tachycardia troublesome enough to seek medical attention. In other situations palpitations are clearly abnormal. The heart beat which is felt for no apparent reason, may be fast, or strong and slow, or feel like a missed or extra beat. Although these abnormal palpitations usually point to a cardiac arrhythmia, this is not always the case. Moreover, many patients with arrhythmias do not have palpitations but manifestations such as syncope, shock, and chest pain (sudden death is also possible). We will discuss the approach to the patient who seeks medical attention because of a history of palpitations, with special emphasis on the history, physical examination, and 12-lead electrocardiogram (ECG) because they are simple and inexpensive diagnostic tools that are available to most physicians.

Radiofrequency ablation in multiple accessory pathways and the physiologic implications

The presence of multiple accessory pathways was noted in 24 of 210 consecutive patients (12 males and 12 females aged 15 to 77 years [mean +/- SD 43 +/- 16]) with the Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency ablation. Six had 3 and 18 had 2 accessory pathways. There were 25 manifest and 29 concealed accessory pathways. The location of the accessory pathways was in the left free wall in 22, the right free wall in 17, the left posterior portion of the ventricular septum in 8, the right posterior portion of the ventricular septum in 6, and the midseptum in 1. The success rate of accessory pathway ablation and the fluoroscopic time in these 24 patients with multiple accessory pathways were 89% and 78 +/- 66 minutes, respectively, whereas they were 98% (p < 0.01) and 36 +/- 37 minutes (p = 0.01) in the 186 patients with a single accessory pathway. The mean applications, the power level of the radiofrequency current and the application duration in these 24 patients were 21 +/- 22, 30 +/- 3 W, and 27 +/- 10 seconds, respectively. In the 186 patients with a single accessory pathway, they were 9 +/- 12 applications (p = 0.02), 30 +/- 4 W (p = NS) and 26 +/- 9 seconds (p = NS), respectively. Seventeen of the 24 patients had a follow-up electrophysiologic study 89 +/- 40 days after ablation, and 2 (12%) had resumption of a right and left accessory pathway conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed effects of radiofrequency energy on accessory atrioventricular connections

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

Relation between efficacy of radiofrequency catheter ablation and site of origin of idiopathic ventricular tachycardia

The results of radiofrequency catheter ablation of ventricular tachycardia (VT) in patients without structural heart disease are reported. Particular attention was focused on the relation between efficacy and the site of origin of the VT. Eighteen consecutive patients (5 women and 13 men; mean age 41 +/- 13 years) with idiopathic VT underwent catheter ablation using radiofrequency energy. Sites for radiofrequency energy delivery were selected on the basis of pace mapping. A follow-up electrophysiologic test was performed 1 to 3 months after the ablation procedure. Twenty VTs were induced. Radiofrequency catheter ablation was successful in eliminating all 10 VTs originating from the right ventricular outflow tract, and 5 of 10 from other sites in the left or right ventricle. There were no complications. The duration of ablation sessions was shorter, the frequency of identifying a site resulting in an identical pace map was higher, and the efficacy of catheter ablation was greater for VTs originating from the right ventricular outflow tract than for those from other locations. The results of this study demonstrate that radiofrequency catheter ablation of idiopathic VT is safe and effective. The efficacy of the procedure is dependent on the site of origin of the VT, with the efficacy being greater for VTs originating from the outflow tract of the right ventricle than for those from other locations.

Radiofrequency ablation of accessory atrioventricular pathways: predictive value of local electrogram characteristics for the identification of successful target sites

BACKGROUND

Radiofrequency catheter ablation of accessory arterioventricular pathways has been shown to be a highly effective treatment in patients with paroxysmal superventricular tachycardia. There is, however, considerable variability in the number of attempted ablation sites, contributing to lengthy operations in some cases. The purpose of this study was to investigate the predictive value of local electrogram characteristics for the identification of successful target sites.

METHODS AND RESULTS

Local bipolar electrograms from 60 patients recorded at 568 sites of attempted ablation were analysed. There were 511 sites at which ablation was guided by antegrade mapping, with 49 successful sites and 462 failed sites including 61 at which accessory pathway conduction was blocked temporarily. In multivariate analysis, the time of local ventricular activation relative to onset of the QRS complex (QRS-V interval) (p < 0.001) and the presence of a possible accessory pathway potential (p < 0.05) were found to be independent predictors of successful outcome, whereas the atrioventricular interval, atrioventricular amplitude ratio, stability of local electrogram, and presence of continuous electrical activity were not. A QRS-V interval of < or = +10 ms identified successful sites with a sensitivity of 98%, but the positive predictive accuracy was only 11%. Even a QRS-V interval of < or = 20 ms resulted in only a 24% probability of success with a sensitivity of just 18%. Combining the QRS-V interval with the presence of a possible accessory pathway potential greatly reduced the sensitivity at all cut off values, but failed to increase positive predictive accuracy above 25%. There were no significant differences in electrogram characteristics between the successful sites and the sites at which conduction of the accessory pathway was interrupted transiently. There were 57 sites (nine successful, 48 failed) at which ablation was guided by retrograde mapping, but none of the local electrogram characteristics analysed emerged as independent predictors of successful pathway ablation.

CONCLUSION

Local electrogram characteristics used to guide radiofrequency catheter ablation are all associated with a low positive predictive accuracy, which significantly contributes to duration of the operation. It is unlikely that this problem will be resolved solely by modification of the mapping techniques. It could require advances in catheter technology and power sources to enable larger tissue lesions to be delivered more reliably than is possible with the equipment in current use.

Safety, feasibility and cost of outpatient radiofrequency catheter ablation of accessory atrioventricular connections

OBJECTIVES

The purpose of this study was to evaluate prospectively the safety, feasibility and cost of performing radiofrequency catheter ablation of accessory atrioventricular (AV) connections on an outpatient basis in 137 cases.

BACKGROUND

The efficacy and low complication rate of radiofrequency ablation as performed in the hospital suggested that it might be feasible to perform it on an outpatient basis.

METHODS

In 100 cases (73%) performed between September 1, 1991 and April 20, 1992, patients met criteria for treatment as outpatients. Reasons for exclusion were age < 13 or > 70 years (4), anteroseptal location of the accessory AV connection (5 patients), obesity (> 30% of ideal body weight) (4 patients) or clinical indication for hospitalization (24 patients). Patients with only venous punctures had a recovery period of 3 h and those with arterial punctures had a recovery period of 6 h. There were 63 men and 32 women (5 patients underwent two ablation procedures > 1 month apart), with a mean age +/- SD of 36 +/- 13 years. The pathway was left-sided in 67 cases and right-sided or posteroseptal in 33.

RESULTS

The procedure was successful in 97 of 100 cases, with a mean procedure duration of 99 +/- 42 min. In 70 cases the patient was discharged the day of ablation, and in 30 cases the patient required a short (< or = 18-h) overnight stay because the procedure was completed too late in the day for recovery in the outpatient facility. The mean duration of observation was 4.8 +/- 1.5 h for outpatients and 15 +/- 1.4 h for patients who underwent overnight hospitalization. At follow-up study, two patients had a clinically significant complication; both had a femoral artery pseudoaneurysm detected > or = 1 week after the procedure and both required surgical repair. Thirty consecutive patients (22 outpatients and 8 hospitalized overnight) undergoing catheter ablation after January 1, 1992 were chosen for a cost analysis. The mean cost of the procedure was $10,183 +/- $1,082.

CONCLUSIONS

The majority of patients undergoing radiofrequency catheter ablation of an accessory AV connection can be treated safely on an outpatient basis.