Posteroseptal Pathway Research Articles

Accessory pathway localization by QRS polarity in children with Wolff-Parkinson-White syndrome.

Location of the accessory pathway (AP) in Wolff-Parkinson-White (WPW) syndrome can be determined accurately by the QRS polarity on resting ECG. These ECG characteristics may be different in children, and no algorithm has yet been tested. A total of 153 resting ECGs of symptomatic children with WPW syndrome were retrospectively analyzed. The anatomic AP location had been established fluoroscopically at eight possible sites during radiofrequency catheter ablation. Two independent observers predicted AP location on blinded ECGs with a QRS polarity algorithm for adults using leads II, III, aVL, V1, and V2. Subsequently, the QRS polarity for all individual ECG leads was evaluated and a new algorithm for children was devised. With the adult algorithm, the observers correctly predicted only 55% to 58% of AP locations. The septal and right-sided pathways often were inseparable, and mid-septal and parahisian pathways were missed. In the new children's algorithm, left lateral, left posteroseptal, and posteroseptal pathways shared a positive or intermediate QRS polarity on V1, with the left lateral pathway separated by a positive QRS polarity on lead III. Negative QRS polarity on lead V1 and positive QRS polarity on lead V3 were shared by right posteroseptal, mid-septal, parahisian, and anteroseptal pathways, with the latter two having a positive QRS polarity on lead aVF. Right lateral pathways had negative QRS polarity on lead V1 and negative or intermediate QRS polarity on lead V3. Overall accuracy for these five regions was 90%. AP characterization by QRS polarity in children with WPW syndrome is more diverse than in adults and requires other ECG leads to establish five AP regions.

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Ablación con catéter de vías accesorias en lactantes y niños de peso inferior a 10 kg

Low weight is considered an independent risk factor for the appearance of complications in radiofrequency catheter ablation of accessory pathways in children. The purpose of this study was to evaluate the results and long term follow-up of radiofrequency catheter ablation in eight infants and small children of accessory pathways of less than 10 kg in weight. There were 3 boys and 5 girls with a mean age of 6.3 +/- 5 months (range, 2.5 to 17) and an average weight of 6.2 +/- 1.9 kg (range, 3.5 to 9). The eight patients underwent a single successful ablation procedure. Five left free wall pathways were ablated by transseptal approach, two right posteroseptal pathways were ablated from the inferior vena cava and a left posteroseptal was approached from the inferior vena cava into the coronary sinus. A deflectable 5F bipolar electrode catheter with a 3 mm tip was used in the first five patients and a deflectable 5F tetrapolar catheter with a 4 mm tip and temperature monitoring using closed loop control in the 3 remaining patients. An abrupt increment in impedance due to the development of a coagulum was observed in 2 procedures. One patient developed an acute ischemic complication during ablation of a left lateral accessory pathway by transseptal approach. This patient had mild pericardial effusion after the procedure. Moderate pericardial effusion was also noted in another patient after radiofrequency ablation that resolved itself spontaneously. In the remainder of the procedures there were not complications. After a mean follow-up of 32.3 +/- 22.1 months (median 42) all patients are asymptomatic without antiarrhythmic treatment. a) radiofrequency catheter ablation can be performed successfully in infants and small children weighing less than 10 kg, and b) echocardiography must be performed inmediately after the procedure in infants to investigate pericardial effusion.

Potential added value of three-dimensional reconstruction and display of single photon emission computed tomographic gated blood pool images

Background. Single photon emission computed tomographic (SPECT) acquisition provides potential advantages for blood pool imaging. However, the method has been little applied. Methods. An improved method of three-dimensional (3-D) reconstruction and display of SPECT equilibrium blood pool scintigrams and related phase data was developed. Dynamic slices and volume-rendered dynamic 3-D images were displayed. Images were viewed from each of 34 solid angles referenced to a sphere surrounding the reconstruction field. Each image pixel was “painted” with intensity-coded regional amplitude and color-coded for its phase angle. The method was applied to evaluate the cardiac anatomy, regional contraction, and related conduction sequence at rest in 17 patients. Twelve had normal left ventricular function including 7 patients with minimal septal preexcitation. Five patients had abnormal left ventricular function, including 2 with left bundle branch block. Results. Slices contained all of the functional information, but necessary data integration was time-consuming and evaluation of chamber size and anatomy was difficult. Three-dimensional projection images condensed and integrated the data, presenting new vantage points on anatomy, contraction, and conduction not otherwise available in the clinically limited angulations of planar images. This provided excellent visual separation of cardiac chambers with full and increased visualization of right and left ventricular wall motion in all segments compared with the conventional projections acquired clinically ( p < 0. 05). Atria and great vessels were well separated with evident size and function. Phase-angle progression paralleled the electrocardiogram, permitting bypass pathway localization and the direct noninvasive localization of posteroseptal pathways. Conclusions. The 3-D method permits greater access to and utilization of SPECT blood pool image data. It suggests specific advantages for clinical use.

Radiofrequency catheter ablation of accessory pathways in infants.

OBJECTIVE: To evaluate the indications, results and complications of radiofrequency catheter ablation in small infants with supraventricular tachycardia due to an accessory atrioventricular pathway. METHODS: Five infants less than 9...

Effect of electrophysiologic properties and location of manifest accessory pathways on local electrogram intervals at effective radiofrequency ablation sites

The purpose of this study was to determine if the electrophysiologic properties and the anatomic location of manifest accessory pathways affect the local electrogram intervals recorded at sites of successful radiofrequency ablation. Accessory pathways in 149 consecutive patients were categorized according to their anatomic location on the basis of the site of successful ablation. Three anatomic groups comprised 90 left free wall, 28 right free wall, and 31 posteroseptal pathways. The accessory pathways were also categorized according to their electrophysiologic properties on the basis of a hierarchical classification of the accessory pathway block cycle length. Four electrophysiologic groups (A, B, C, and D) comprised 54, 51, 28, and 16 accessory pathways, with mean accessory pathway block cycle lengths of 254 ± 9, 288 ± 10, 347 ± 19, and 458 ± 56 msec, respectively. The local atrial to ventricular (A-V) and atrial to accessory (A-K) pathway electrogram intervals recorded in sinus rhythm at the successful ablation site were significantly affected by the electrophysiologic group and were longest in group D compared with groups A, B, and C (A-V interval F (3,145) = 13.6, p < 0.001; A-K interval F (3,88) = 12.6, p < 0.001). The local A-V interval was also affected by the anatomic group and was longer in posteroseptal compared with free wall accessory pathways (F (2,146) = 15.0, p < 0.001). In contrast, the timing of the local ventricular activation to the delta wave onset (δ-V) was not significantly affected by the electrophysiologic group or the anatomic location of the accessory pathway. Thus the local A-V interval at the successful ablation site may vary because it is affected by the electrophysiologic properties and location of the accessory pathway, whereas the δ-V interval remains unaffected. These effects should be taken into account when selecting ablation sites in patients with manifest accessory pathways.

Interne Defibrillation zur Kardioversion bei Vorhofflimmern zur Radiofrequenzablation einer akzessorischen Bahn bei WPW-Syndrom

Although radiofrequency catheter ablation of accessory pathways during atrial fibrillation is possible (1), localisation of bypass tracts and delivery of radiofrequency current may be easier and safer in sinus rhythm. We report on a patient who developed atrial fibrillation with a fast ventricular response during mapping of a right posteroseptal atrioventricular pathway; after internal atrial defibrillation a successful radiofrequency ablation of the accessory pathway could be performed.Having venous sheaths already in place during electrophysiological studies, internal atrial cardioversion is a fast and uncomplicated procedure which may be the treatment of choice in case induced atrial fibrillation does not resolve spontaneously.

A New Electrocardiographic Algorithm Using Retrograde P Waves for Differentiating Atrioventricular Node Reentrant Tachycardia From Atrioventricular Reciprocating Tachycardia Mediated by Concealed Accessory Pathway

Objectives. The purpose of this study was to use an electrocardiographic (ECG) algorithm, derived from the results of radiofrequency ablation, to discriminate atrioventricular node reentrant tachycardia (AVNRT) from atrioventricular reciprocating tachycardia (AVRT) and to localize a concealed accessory pathway, prospectively.Background. Information about ECG criteria for differentiating AVNRT from AVRT is limited and has not been confirmed by surgical or catheter ablation.Methods. Four hundred six ECGs (obtained from 406 different patients) that demonstrated narrow QRS complex (<0.12 s) supraventricular tachycardia with an RP′ interval less than the P′R interval or pseudo r′ wave in lead V1or pseudo S wave in inferior leads, or both, were examined, and the results were confirmed by radiofrequency catheter ablation. The initial 226 ECGs were analyzed to develop a stepwise algorithm, and the subsequent 180 ECGs were prospectively evaluated by the new algorithm.Results. The presence of a pseudo r′ wave in lead V1or a pseudo S wave in leads II, III, aVF indicated anterior-type AVNRT with an accuracy of 100%. With the difference of RP′ intervals in leads V1and III >20 ms, posterior-type AVNRT could be differentiated from AVRT utilizing a posteroseptal pathway with a sensitivity of 71% (95% confidence interval [CI] 55% to 89%), a specificity of 87% (95% CI 67% to 97%) and a positive predictive value of 75% (95% CI 56% to 91%). According to the polarity of retrograde P waves in leads V1, II, III, aVF and I during AVRT, the concealed accessory pathway could be localized to one of the nine regions on the atrioventricular annuli with an accuracy of 75% (for a right midseptal pathway) to 93.8% (for a left posterior pathway). Overall, the new algorithm had an accuracy of 97.8% in discriminating AVNRT from AVRT and 88.1% in localizing a concealed accessory pathway, prospectively. Prediction was incorrect in only 15 patients (9.1%).Conclusions. The new ECG algorithm derived from the analysis of retrograde P waves during tachycardia could provide a criterion for differential diagnosis between AVNRT and AVRT and for predicting the location of concealed accessory pathways.(J Am Coll Cardiol 1997;29:394–402)

Reversibilidad de la miocardiopatía inducida por taquicardia supraventricular incesante en niños tras ablación con radiofrecuencia

The so called tachycardia-induced cardiomyopathy may develop as a complication of persistent abnormal high rates. It is especially common in patients who have either a permanent form of junctional reciprocating tachycardia or an ectopic atrial tachycardia. Radiofrequency catheter ablation has become established as an effective and safe treatment to eliminate both arrhythmias. Four children aged from 3 months to 8 years, who had incessant tachyarrhythmias and left ventricular dysfunction (shortening fraction of mean +/- SD, 21.7 +/- 1.2%) underwent radiofrequency catheter ablation. The youngest patient had permanent junctional reciprocating tachycardia caused by a left posteroseptal pathway. She was presented with severe heart failure that did not improve with digoxin and amiodarone. The other patients had palpitations and exercise intolerance. Two of them had an ectopic atrial tachycardia caused by a single atrial focus localized in the left atrial appendage apex and the orifice of the right atrial appendage respectively. The other patient had the permanent form of junctional reciprocating tachycardia caused by a right posteroseptal pathway. All four patients underwent one successful ablation. The average procedure mean time was 3.7 hours with an fluoroscopy time of 44 minutes. There were no complications. Subsequently shortening fraction improved progressively. After a mean follow-up of 21.7 months all patients are asymptomatic without medical treatment. Radiofrequency catheter ablation is the therapy of choice in children with either the permanent form of junctional reciprocating tachycardia or ectopic atrial tachycardia refractory to medical treatment. The tachycardia-induced cardiomyopathy is reversible after the elimination of the arrhythmia. The presence of tachycardia-induced cardiomyopathy is an indication for radiofrequency ablation even in small infants.

Radiofrequency catheter ablation of posteroseptal atrioventricular accessory pathways--location-specific electrographic characteristics of successful ablation sites.

The electrographic features of successful sites of radiofrequency catheter ablation were analyzed in 33 cases of posteroseptal accessory pathways and compared with those from 155 cases of free wall accessory pathways. The atrioventricular intervals in the posteroseptal cases were significantly longer than in the free wall cases (posteroseptal vs left and right free wall; 38 vs 33 and 26 msec, respectively; p < 0.05), and the incidences of continuous electrograms (42 vs 63 and 79%; p < 0.01) and PQS-pattern unipolar electrograms (50 vs 76 and 78%; p < 0.05) were significantly lower in the posteroseptal cases. The V-delta intervals in the posteroseptal cases were significantly longer than in the left free wall cases (17 vs 13 msec; p < 0.05), but shorter than in the right free wall cases (17 vs 23 msec; p < 0.05). No statistically significant difference in the incidence of Kent potentials among the 3 groups was observed. In radiofrequency ablation of posteroseptal pathways, the length of the atrioventricular interval and the incidences of continuous electrograms and PQS-pattern unipolar electrograms may be unsatisfactory even at the appropriate target site, but the V-delta interval and Kent potential are good indicators of suitable target sites.

Electrophysiologic characteristics, electropharmacologic responses and radiofrequency ablation in patients with decremental accessory pathway

Objectives. This study sought to characterize the functional properties of decremental accessory atrioventricular (AV) pathways and to investigate their pharmacologic responses.Background. Although decremental AV pathways associated with incessant reciprocating tachycardia have been studied extensively, information about the electrophysiologic characteristics and pharmacologic responses of anterograde and retrograde decremental AV pathways is limited.Methods. Of 759 consecutive patients with accessory pathway-mediated tachyarrhythmia, 74 with decremental AV pathways were investigated (mean age 43 ± 18 years). After baseline electrophysiologic study, the serial drugs adenosine, verapamil and procainamide were tested during atrial and ventricular pacing. Finally, radiofrequency catheter ablation was performed.Results. Five patients had anterograde decremental conduction over the accessory pathway but had no retrograde conduction. Of the 64 patients with retrograde decremental conduction over the accessory pathway, anterograde conduction over the pathway was absent in 41 (64%), intermittent in 5 (8%) and nondecremental in 18 (28%). In the remaining five patients, anterograde and retrograde decremental conduction over the same pathway was found. The anterograde and retrograde conduction properties and extent of decrement did not differ between anterograde and retrograde decremental pathways. Posteroseptal pathways had the highest incidences of anterograde and retrograde decremental conduction. Intravenous adenosine, procainamide and verapamil caused conduction delay or block, or both, in 10 of 10, 10 of 10 and 4 of 10 of the anterograde and 20 of 20, 20 of 20 and 8 of 20 of the retrograde decremental pathways, respectively. All patients had successful ablation of the decremental pathways without complications. During the follow-up period of 31 ± 19 months, only one patient experienced recurrence.Conclusions. Decremental accessory pathways usually had functionally distinct conduction characteristics in the anterograde and retrograde directions. Their pharmacologic responses suggested the heterogeneous mechanisms of decremental conduction.

Efficiency of heating during radiofrequency catheter ablation of accessory atrioventricular pathways

Adequate heating with myocardial thermal injury is necessary for successful ablation. This study was designed to examine the relationship between power, temperature, and efficiency of heating during radiofrequency catheter ablation of accessory pathways in 76 patients. During each application of radiofrequency energy, temperature was continually monitored by use of an ablation catheter with a thermistor embedded in the tip of the distal electrode. The efficiency of heating varied by location, with the greatest efficiency of heating for posteroseptal energy applications (2.7 ± 2.3 °C/W), which were significantly greater than for left-sided (2.1 ± 1.9 °C/W, P < 0.01) or right-sided (1.0 ± 1.1 °C/W, P < 0.01) applications. For patients with left free wall and posteroseptal pathways, the temperature, radiofrequency power, time to peak temperature and efficiency of heating were similar between the successful and unsuccessful pulses. However, the mean temperature (53.5 ± 4.5 vs. 45.1 ± 5.1 °C, P < 0.01) and radiofrequency power (49.6 ± 5.2 vs. 40.3 ± 10.2 watt, P < 0.05) differed significantly between the successful and unsuccessful ablation pulses in patients with right free wall pathways. To achieve greater efficiency of heating and higher temperature, it is reasonable to use higher power outputs (40–50 W) in radiofrequency ablation of right free wall pathways, whereas less power outputs (30–40 W) are likely to produce adequate heating of posteroseptal and left free wall pathways, and minimize the risk of impedance rise and coagulum formation.

Catheter ablation of permanent junctional reciprocating tachycardia with radiofrequency current

This study evaluated accessory pathway location, its relation to retrograde P wave polarity on the surface electrocardiogram and radiofrequency ablation efficacy and safety in a large group of patients with permanent junctional reciprocating tachycardia. Permanent junctional reciprocating tachycardia is an uncommon form of reciprocating tachycardia, almost incessant from infancy and usually refractory to drug therapy. It is characterized by RP > PR interval and usually by negative P waves in leads II, III, aVF and V4 to V6. Retrograde conduction occurs through an accessory pathway with slow and decremental properties. Although this accessory pathway has been classically located in the posteroseptal zone, other locations have been recently reported. The study included 32 patients (20 men, 12 women, mean [+/- SD] age 29 +/- 15 years) with a diagnosis of permanent junctional reciprocating tachycardia confirmed at electrophysiologic study. Seven patients had depressed left ventricular function. Radiofrequency energy was applied at the site of the earliest retrograde atrial activation during tachycardia. There were 33 accessory pathways. The site of the earliest retrograde atrial activation was posteroseptal in 25 patients (76%), midseptal in 4 (12%), right posterior in 1 (3%), right lateral in 1 (3%), left posterior in 1 (3%) and left lateral in 1 (3%). Thirty pathways were ablated with a right approach; in 11 patients with posteroseptal pathway the ablation was performed through the coronary sinus. Three pathways were ablated with a left approach. Positive retrograde P wave in lead I suggested that ablation could be performed from the right side; if negative, it did not exclude ablation from this approach. All the accessory pathways were successfully ablated, with a median of 3 and a mean of 5.6 +/- 5 radiofrequency applications of 70 +/- 26 s in duration. In two patients with the accessory pathway in the midseptal zone, a transient second- and third-degree atrioventricular block, respectively, was observed after ablation. At a mean follow-up of 18 +/- 12 months, 31 patients (97%) are asymptomatic without antiarrhythmic therapy (95% confidence interval [CI] 84% to 99%). Recurrences were observed in four patients (13%) (95% CI 4% to 29%), three of whom had the accessory pathway ablated successfully at a second session. All patients with depressed left ventricular function showed a marked improvement after successful ablation. In our experience, most of the patients with permanent junctional reciprocating tachycardia had posteroseptal pathways; all these pathways were ablated from the right side. P wave configuration may be helpful in suggesting the approach to the site of ablation. Catheter ablation using radiofrequency energy is an effective therapy for permanent junctional reciprocating tachycardia.

Temperature monitoring during radiofrequency catheter ablation procedures using closed loop control. Atakr Multicenter Investigators Group.

The purpose of this study was to evaluate electrode temperatures obtained using a radiofrequency ablation system that incorporates closed loop feedback control to achieve preset target electrode temperatures and to determine if closed loop temperature control results in a lower incidence of developing a coagulum. Two hundred seventy patients underwent catheter ablation of atrioventricular nodal reentrant tachycardia, an accessory pathway, and/or the atrioventricular junction using an ablation system incorporating closed loop feedback control. Forty-five patients underwent catheter ablation in the power control mode in which power output was fixed, and 225 patients underwent catheter ablation in the temperature control mode. A coagulum occurred during 0.8% of radiofrequency applications in the temperature control mode versus 2.2% in the power control mode (P < .01). Electrode temperatures were within 10 degrees C of the targeted temperature during 35% of applications in the temperature control mode. Ability to achieve the targeted electrode temperature was related to the target, with radiofrequency energy applications at the atrioventricular junction resulting in the highest temperatures (70 +/- 12 degrees C) and those for ablation of the atrioventricular node the lowest (59 +/- 11 degrees C, P < .001), using a maximum of 50 W of power for both. Electrode temperatures were higher during ablation of left free wall and posteroseptal pathways than during ablation of right free wall and septal pathways. The mean and minimum temperatures associated with success were 64 +/- 12 degrees C and 44 degrees C, respectively. Overall, the electrode temperatures at successful and unsuccessful ablation sites did not differ (P > .05). Temperature monitoring with closed loop control of power output facilitates radiofrequency catheter ablation procedures by minimizing the probability of developing a coagulum while ensuring maximum lesion formation.

Atrial and accessory pathway activation direction in patients with orthodromic supraventricular tachycardia: Insights from vector mapping

Objectives. The purpose of this study was to utilize vector mapping to investigate atrial and accessory pathway activation direction during orthodromic supraventricular tachycardia.Background. Although advances have been made in the electrophysiologic evaluation and management of accessory pathways, our understanding of accessory pathway anatomy and physiology remains incomplete. Vector mapping has been validated as a method of studying local myocardial activation.Methods. In 28 patients with a left-sided or posteroseptal accessory atrioventricular (AV) pathway referred for ablation, atrial and accessory AV pathway activation direction was determined during ventricular pacing or orthodromic supraventricular tachycardia, or both, by summing three orthogonally oriented bipolar electrograms recorded from the coronary sinus to create three-dimensional vector loops. Atrial and accessory AV pathway activation direction was determined in all patients from the maximal amplitude vectors of the vector loops. Because of beat to beat variability in the directions of the vector loops, data from 8 of 28 patients could not be analyzed.Results. At 81 of 83 sites, atrial activation direction along the long axis of the coronary sinus corresponded with the direction suggested by activation time mapping. Activation direction along the anteroposterior and inferosuperior axes was variable, potentially due to variations in the level of the atrial insertion of the accessory AV pathway and in the depth or angling of pathway fibers in the AV fat pad. In eight patients, at least one recording was obtained at the site of an accessory AV pathway potential. Accessory AV pathway activation proceeded superiorly and to the right in seven of eight patients; in one patient with a posteroseptal pathway, accessory AV pathway activation proceeded superiorly and to the left.Conclusions. 1) Vector mapping is a useful technique for localizing accessory AV pathways; 2) left-sided accessory AV pathways angle from left to right as they traverse the AV groove; and 3) variable activation directions of the atrial myocardium adjacent to the coronary sinus suggest that accessory AV pathway insertion into the atrium differs from patient to patient.

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.

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.

New algorithm for the localization of accessory atrioventricular connections using a baseline electrocardiogram

Objectives. In this study, we propose a new algorithm for accessory atrioventricalar pathway localization using a 12-lead electrocardiogram (ECG).Background. Radiofrequency catheter ablation produces a very discrete lesion, and ECG localization based en surgical dissection is obsolete.Methods. Stepwise discrimination analysis was used to assess the relation of 18 pro-excited ECG (QRS duration >100 ms) variables to the site of successful ablation in 93 patients. The most discriminating variables were combined to form rules for each location. The ECGs were retested by these rules to determine predictive accuracy.Results. If the precordlal QRS transition was at or before lead V1, the pathway had been ablated on the left side. If it was after lead V2, the pathway had been ablated on the right side. If the QRS transition was between leads V1and V2or at lead V2, then if the R wave amplitude in lead I was greater the S wave by ≥1.0 mV, it was right-sided; otherwise, It was left-sided (p < 0.0001, sensitivity 100%, specificity 97%). Right-sided pathways. If the QRS transition was between leads V2and V3, the pathway was right septal; if after lead V4, it was right lateral. If it was between leads V3and V4, then if the delta wave amplitude in lead II was ≥1.0 mV, it was right septal; otherwise, it was right lateral (p < 0.0001, sensitivity 97% specificity 95%). In right lateral locations, if the delta wave frontal axis was ≥0 °, or if it was <0 ° but the R wave amplitude in lead III was ≥0 mV, it was anterolateral; otherwise, it was pesterolateral (p < 0.0001, sensitivity 100%, specificity 87.3%). Anteroseptal pathways had two or more positive delta waves in leads II, III and aVF (p < 0.0001, sensitivity 100%, specificity 100%). Postereseptal pathways (two or more negative inferior lead delta waves) were less well discriminated from right midseptal pathways (inferior wave sum ≤1≥−1) (p < 0.0001, sensitivity 76.5%, specificity 71%).Leftsided pathway. Two or more positive delta waves in the inferior leads or the presence of an S wave amplitude in lead aVL greater than the R wave, or both, discriminated left anterolateral pathways from posterior pathways (p < 0.001, sensitivity and specificity 100%). If the R wave in lead I was greater than the S wave by ≥0.8 mV, and the sum of inferior delta wave polarities was negative, the location was posteroseptal; otherwise, It was posterolateral (p < 0.05, sensitivity 71.4%, specificity 100%).Conclusions. Using the algorithm derived, a right-sided accessory pathway can be reliably distinguished from one that is left-sided, right free wall from right septal, right anterolateral from posterolateral and anteroseptal from other right septal pathways. Left anterolateral pathways can be distinguished from left posterior pathways and left posterolateral pathways from left posteroseptal pathways.

Radiofrequency catheter ablation of accessory atrioventricular pathways in children and young adults.

To assess the efficacy of radiofrequency ablation for reentrant tachyarrhythmias in children and young adults. A tertiary cardiac referral centre. Over a 16 month period 22 patients aged less than 20 years (median age 16.5 years) underwent 26 radiofrequency ablation procedures for atrioventricular reentry tachycardia through an accessory pathway. The results of radiofrequency ablation were compared with those in a group of 16 patients (median age 14 years) who had had surgical ablation for atrioventricular reentry tachycardia over a preceding six year period. Ablation of an accessory atrioventricular pathway was accomplished for 18 (76%) of 25 pathways in 16 (73%) of 22 patients. There were no procedure-related complications. Surgery was eventually curative in 15/16 patients (94%). However, three patients required a second open heart surgical procedure because tachyarrhythmia recurred. There were no surgical deaths. Failures for radiofrequency ablation were related to accessory pathway location, and were greater for right free wall and posteroseptal pathways (success rate of 50% and 57% respectively). Recurrence after surgery was also associated with pathways in these locations. Transcatheter radiofrequency current ablation was safe and achieved a cure with less patient morbidity and improved cost efficiency. It is an attractive alternative to long-term drug therapy or surgery in older children and adolescents. A higher success rate may be expected with increased experience.