Conduction Properties and Ablation of Adenosine Sensitive Accessory Pathways in Children

Block in accessory pathway (AP) conduction with adenosine has been previously described. However, conduction characteristics of these APs has not been well defined to date. All patients with APs </ = 21 years old who underwent an EP study from 2014 to 2017 were included in our study. Patients with adenosine sensitive APs were identified (group 1). Demographic and AP conduction characteristics were compared between group 1 and the entire cohort of patients. Local atrioventricular (AV) or ventriculoatrial (VA) time, cycle length and need for isoproterenol were compared to a control group matched by age and AP location (group 2). Student's t test, Wilcoxon rank sum, χ² and Fisher's exact were used for analysis. Fourteen (7%) out of 207 patients had an adenosine sensitive AP. The median age of patients with adenosine sensitive APs was 11.8 (IQR 8.5-13.5) years vs. 14 (IQR 10.6-16.7) for the rest of the cohort (p = 0.04). Three of the 134 patients with preexcitation had adenosine sensitive APs (2%) vs. 11 of the 73 patients with concealed APs (15%) (p = 0.001). The median local AV/VA time at the site of successful ablation was longer in group 1 vs group 2 [78 ms, IQR 62-116 vs. 31 ms, IQR 30-38; p < 0.001]. Antegrade AP effective refractory period and total procedure time were longer in patients with adenosine sensitive APs (p = 0.03 & p = 0.04, respectively). Adenosine sensitive APs which occur in children are more often concealed. These APs have a longer conduction time at the site of successful ablation.

Change of Paradigm in the Management of Patients with Accessory Pathways over the Last Forty Years: Wolff-Parkinson-White Syndrome as an Electrophysiological Marvel at Risk of Extinction

Over the last decades, the approach to the Wolff-Parkinson-White syndrome, as well as its treatment, has substantially changed, leading to improvement in the prognosis and quality of life of these patients. From the first diagnostic electrophysiologic studies to the most recent evaluations, important data on pathophysiologic and clinical aspects have been gathered, and this learning journey is still not concluded. This body of knowledge is a fundamental part of any cardiologists' armamentarium despite the fact that this syndrome is rarely observed in adult patients.

Impact of Accessory Pathway Location on Electrophysiologic Characteristics and Ablation Success

BACKGROUND

To investigate the relationship between the location of accessory pathways, electrophysiologic characteristics, and ablation success in Wolfe-Parkinson-White (WPW) syndrome.

METHODS

Electrophysiologic study was performed in 178 patients for a pre-excitation syndrome. Accessory pathway location, anterograde or retrograde conduction, ablation success, and recurrence rate were evaluated.

RESULTS

Among 178 patients with WPW syndrome, the most frequent location of the accessory pathway was left lateral (39.3%) which had high ablation success rate (97%) and low recurrence rate (1%). A meaningful relationship exists between accessory pathway location and electrophysiologic characteristics. Ablation success rate was 89.7% and was statistically related to accessory pathway location. Recurrent occurred in 2.9% of our patients and was more frequent in right free wall and PJRT.

CONCLUSIONS

The location of accessory pathways has a great impact on conductivity, ablation success, and recurrence rate in WPW syndrome.

Localization Of Accessory Pathways In Wolff Parkinson White Syndrome Using R/S Ratios On Surface Ecgs

BACKGROUND

This study was conducted to establish the accuracy of R/S ratios in localizing accessory pathways in Wolff Parkinson White Syndrome on surface ECGs.

METHODS

This was a retrospective cross-sectional study from January 2002 till December 2016 conducted at National Institute of Cardiovascular diseases in Karachi, Pakistan. The sample included 157 patients with manifesting Wolff Parkinson White (WPW) Syndrome on a 12-lead surface ECG. As per the inclusion criteria, patients who had persistent or intermittent pre-excitation on surface ECG and had undergone electrophysiological study (EP) were included in the sample. Individuals with both successful and unsuccessful ablation procedures were included.

RESULTS

The sample consisted of 62.4% males (n=98) and 37.6% females (n=59) with mean age being 35.36±12.44. Accessory pathways (APs) were identified on the left side in majority of the patients with 54.1% (n=85) while right sided pathways were seen in 42.1% (n=66). Moreover, the most common accessory pathway amongst the males was Left Anterior (LA) and Left Lateral (LL) with a percentage of 48%, followed by Right Posteroseptal (RPS) at 20.4%. As opposed to this, the most common pathways amongst the females turned out to be RPS at 33.9% followed by LL and LA at 32.2%. Furthermore, the test using ratios were most effective in identifying left sided APs with sensitivity 74.1% and was least sensitive in identifying right sided pathways (sensitivity=40.7%). However, it was highly specific in locating right sided pathways with specificity of 94.6% as opposed to 83.3% in the left side. Furthermore, mid-septum regions had a sensitivity and specificity of 66.7% and 69.6% respectively.

CONCLUSIONS

This establishes the effectiveness of R/S ratios in determining the location of accessory pathway based on the surface ECG prior to the ablation procedure. Since the younger population is affected more commonly, prolonged exposure to ionizing radiation can cause long term complications therefore, by this means, the duration of exposure can be reduced.

Recording the Accessory His Bundle Potential from a Right Atriofascicular Accessory Pathway

The author discusses the case of a 42-year-old man with a long history of episodes of rapid palpitations. Recordings from the proximal end of a right atriofascicular accessory pathway at the lateral tricuspid annulus are discussed. There was successful catheter ablation of the right atriofascicular accessory pathway, without recurrence of tachycardia.

Correlation of accessory pathway location with gender and their manifest or concealed presentation

BACKGROUND

Atrioventricular reentrant tachycardias account for approximately one third of cases referred for electrophysiological study (EPS). The anatomical substrate responsible for the reentry is an accessory pathway (AP) able to conduct the electrical stimulus in an anterograde, retrograde or bidirectional manner.

OBJECTIVE

To evaluate the correlation of AP location with the male and female genders and AP clinical presentation, whether manifest or concealed.

METHODS

Retrospective observational study including 942 consecutive patients, all diagnosed with EPS-confirmed AP from January 1994 to December 2008. APs were classified into eight anatomical groups: left lateral (LL), left posterior (LP), left posteroseptal (LPS), right posteroseptal (RPS), right midseptal (RMS), right anteroseptal (RAS), right lateral (RL), and right posterior (RP).

RESULTS

Of the 942 patients, 52.6% were males. The mean age was 31.2±13.8years. As regards gender, APs were more prevalent among men. However, a statistically significant difference was observed only in the LPS (p=0.029) and RL (p=0.003) regions. In relation to the form of presentation of AP, the manifest form was more frequent than the concealed form in six of the eight regions studied, except for the LL and LPS regions.

CONCLUSION

AP predominated in males and the manifest form was more frequent than the concealed form in most of the regions studied.

[Endocardial Electrophysiological Study in an Asymptomatic Competitive Athlete With Ventricular Preexitation due to Conduction via Fasciculoventricular Accessory Pathway]

We present a clinical case of a rare form of the WPW phenomenon due to anterograde conduction over fasciculoventricular accessory pathway in 20-year-old competitive athlete. The patient had no history of palpitations or syncope. ECG revealed shortening of PQ interval (112 ms) and wide QRS complex due to conduction via accessory pathway. To address the question of participation in competitive activity and the need for ablation the patient underwent endocardial electrophysiological study in the course of which we verified conduction via fasciculoventricular accessory pathway. The result of the study was used in determination of strategy of further management.

Differential Responses of the Septal Ventricle and the Atrial Signals During Ongoing Entrainment: A Method to Differentiate Orthodromic Reciprocating Tachycardia Using Septal Accessory Pathways From Atypical Atrioventricular Nodal Reentry

BACKGROUND

Differential diagnosis between tachycardia mediated by septal accessory pathways (AP) and atypical atrioventricular nodal reentry can be challenging. We hypothesized that an immediate versus delayed pace-related advancement of the atrial electrogram, once the local septal parahisian ventricular electrogram (SVE) has been advanced, may help in this diagnosis.

METHODS AND RESULTS

We focused on differential timing between SVE and atrial signals at the initiation of continuous right ventricular apical pacing during tachycardia. SVE advancement preceding atrial reset was defined as SVE advanced by the paced wave fronts while atrial signal continued at the tachycardia cycle. We analyzed 51 atypical atrioventricular nodal reentry (45% posterior type) and 80 AP tachycardias (anteroseptal [10], parahisian [18], midseptal [12], and posteroseptal [40]). SVE advancement preceding atrial reset was observed in 98% of atrioventricular nodal reentries during 4±1.1 cycles; this phenomena was observed in 6 (8%) of the atrioventricular reentrant tachycardia mediated by septal AP (P<0.001; sensitivity 98%; specificity 93%; positive predictive value 90%; negative predictive value 99%) and lasted 1 single cycle (P<0.001). Right posteroseptal AP tachycardias were distinctly characterized by atrial reset preceding SVE advancement (with ventricular fusion; specificity 100%; positive predictive value 100%). In 11 cases, it was impossible to achieve sustain entrainment. In all of them, the differential responses at the entrainment attempt allowed for appropriate diagnosis.

CONCLUSIONS

The differential response of the SVE and the atrial electrogram at the initiation of continuous right ventricular apical pacing during tachycardia effectively distinguishes between atypical atrioventricular nodal reentry and atrioventricular reentrant tachycardia mediated by septal APs.

Radiofrequency catheter ablation at the non-coronary cusp for the treatment of para-hisian accessory pathways

AIMS

Radiofrequency catheter ablation (RFCA) is well established as a definitive therapy of accessory pathways (APs). Successful RFCA of anteroseptal APs at the non-coronary cusp (NCC) have been reported in several case reports. We aimed to evaluate the prevalence, safety, efficacy, and long-term outcome of RFCA at the NCC for the treatment of para-hisian APs.

METHODS AND RESULTS

Our study included 17 patients (58.8% female, mean age 46.9 ± 15.9 years) with para-hisian APs. We performed two different ablation approaches which targeted at either the right anterior septum (RAS) (n = 10) or the NCC (n = 7) as the initial target. We compared safety, efficacy, and long-term outcome between these two approaches. The para-hisian APs were successfully ablated in 15 patients and damaged in 1 patient, for the remaining patients, the ablation was abandoned for the suspicion of no atrioventricular conduction. Considering all ablation sites of the para-hisian APs, radiofrequency (RF) delivered at the NCC had a higher success rate (11/12 vs. 5/12, P < 0.05) and a lower complication rate (0/12 vs. 4/12, P < 0.05) compared with the RAS. During a mean follow-up period of 22.4 ± 15.0 months, all the patients were free of arrhythmias without any anti-arrhythmic drugs.

CONCLUSION

Para-hisian APs can be safely and effectively ablated at the NCC. Compared with the ablation at the RAS, RF delivered at the NCC has a higher immediate success, lower complication rate, and good long-term outcome.

Clinical and experimental evidence of supernormal excitability and conduction

True supernormality of excitability and conduction has been demonstrated in normal Purkinje fibers in in vitro studies. In the clinical setting, supernormality of conduction is manifested better than expected. This phenomenon is much more common than previously thought, particularly in the presence of certain clinical conditions. If a careful scanning of the cardiac cycle is performed on all patients with intermittent bundle branch block and second degree or advanced infranodal AV block, accessory pathways and mulfunctioning pacemakers, it is anticipated that a much larger amount of supernormal excitability and conduction will be unmasked.

Successful cryoablation of Mahaim tachycardia in a child with Ebstein's anomaly

Mahaim fibers with decremental atrioventricular (AV) node-like conduction properties comprise less than 3 % of accessory pathways. Radiofrequency ablation of right atriofascicular pathways guided by a distinct Mahaim potential detected at the anterolateral to posterolateral tricuspid annulus or in the right ventricular free wall is a safe and highly effective treatment method. The case report presents a 16-year-old boy with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. The electrophysiologic study and the entire ablation procedure were performed using a three-dimensional mapping system (EnSite Velocity; St. Jude Medical Inc., St. Paul, MN, USA). No fluoroscopy was used during the procedure. Electrophysiologic evaluation demonstrated typical atrioventricular nodal reentrant tachycardia and Mahaim tachycardia with a wide QRS and a left bundle branch block pattern. After Mahaim potential was located at the lateral tricuspid annulus, successful cryoablation was performed with an 8-mm-tip catheter followed by slow pathway ablation to eliminate typical atrioventricular nodal reentrant tachycardia. Cryoablation with an 8-mm-tip catheter can be an alternative treatment option for children with Mahaim tachycardia.

Prophylactic accessory-pathway ablation in asymptomatic patients with a Wolff-Parkinson-White electrocardiographic pattern

OBJECTIVES

The optimal approach is controversial in asymptomatic patients who are coincidentally found to have evidence of an accessory pathway (AP) on an ECG. The risk of sudden cardiac death (SCD) is low, and the risk of developing symptoms also appears to be low, although a wide range of incidences have been reported. In our trial, we tested the hypothesis that if prophylactic accessory-pathway ablation performed at the time of the initial electrophysiological testing would improve the long-term outcome in asymptomatic patients with a Wolff-Parkinson-White electrocardiographic pattern.

PATIENTS AND METHODS

Recruitment of patients began on February 1, 2004, and ended on February 5, 2009. All 110 asymptomatic patients were hospitalized and underwent electrophysiological testing the same day to assess the inducibility of atrioventricular reciprocating tachycardia. The anterograde effective refractory period of the accessory pathway was defined as the longest coupling interval at which anterograde block in the bypass tract was observed. For the statistical analysis, the statistical software SPSS version 15.0 for Windows (SPSS Inc., Chicago, IL, USA).

RESULTS

Of 110 asymptomatic patients with a Wolff-Parkinson-White electrocardiographic pattern, 80 patients were ablated. Ablation group consisted of these patients. Control group consisted of remaining 30 and were divided into two groups according to the anterograde effective refractory period of the accessory pathway. There was no significant difference between three groups in terms of arrhythmic events (p: 0.58).

CONCLUSIONS

Asymptomatic patients with the Wolff-Parkinson-White syndrome do not require prophylactic ablation, since they remain asymptomatic for many years.

Fusion during entrainment of orthodromic reciprocating tachycardia is enhanced for basal pacing sites but diminished when pacing near Purkinje system end points

BACKGROUND

In the electrophysiological laboratory, orthodromic atrioventricular reciprocating tachycardia (ORT) can be distinguished from atrial tachycardia and atrioventricular node reentry tachycardia by identifying orthodromic and antidromic wavefront fusion during ventricular overdrive pacing (VOP). Previous work has shown that basal VOP near the accessory pathway (AP) increases the likelihood of observing fusion; however, in a third of cases, fusion is not appreciable regardless of VOP location.

OBJECTIVE

To explore the hypothesis that pacing near His-Purkinje system (PS) end points reduces fusion quality, which may explain patients with nonresponsive ORT.

METHODS

In a novel computer model of ORT, simulations were performed with a variety of AP locations and pacing sites; results were analyzed to assess factors influencing fusion quality in pseudo-electrocardiogram signals.

RESULTS

Entrainment by basal VOP near the AP was more likely to produce fusion visible on simulated electrocardiograms compared to entrainment by apical VOP, but this advantage was dramatically diminished when the pacing site was also near PS end points. Prediction of fusion quality based on AP proximity alone was dramatically improved when corrected to penalize for PS proximity.

CONCLUSIONS

These results suggest that basal VOP near the AP and far from the PS is optimal; this could be tested in patients. A denser basal ramification of PS fibers is known to exist in a minority of human hearts; our findings indicate that this unusual PS configuration is a plausible explanation for ORT cases where fusion is never observed in spite of entrainment by basal VOP near the AP.

[Evaluation of the early effectiveness and late arrhythmia recurrences subjectively experienced by the patient after RF ablation of accessory pathway in Wolf-Parkinson-White syndrome depending on it's localization and the electrical parameters of ablation--own observation]

Nowadays, radiofrequency ablation (RF) is recommended treatment method of atrioventricular reentrant tachycardia associated with accessory pathway. This procedure is characterised by high early and late efficacy and low risk of complication. The aim of this study was to evaluate early effectiveness and late arrhythmia recurrences subjectively experienced by the patient after RF ablation of accessory pathway in Wolf-Parkinson-White Syndrome, depending on it's localization and the electrical parameters of ablation.

MATERIAL AND METHODS

Seventy two patient in age 13-79 (35 +/- 15,3) who had RF ablation of accessory pathway preformed were included in this study. Localization of the pathway, electrical parameters of ablation and early effectiveness of the procedure was assessed retrospectively. Group of patients who had successful ablation (n = 57) were asked about recurrence of heart palpitation after minimum 6 months from the procedure and further. Additionally, information about comorbidities and medication used by patients was collected.

RESULTS

Septal localization of accessory pathway was most frequent (59,7%) in study group (n = 72). Early effectiveness was achieved in 80% of patient. Electrical ablation parameters were similar in a group with successful (n = 57) and unsuccessful procedure (n = 15) with exception of numbers of RF application (14 vs 30). In a late observation, 59,09% of the patients did not experienced recurrence of heart palpitation.

CONCLUSIONS

In accessory pathway with difficult anatomy access, increased number of RF application do not increase procedure effectiveness. Subjective late effect of the ablation reported by the patient is lower than after electrophysiological study verification. Lack of correlation between pathway localization and early effectiveness of the ablation or late recurrence of heart palpitation reported by the patient.

[Wide spectrum of arrhythmias, with inductions and terminations of atrio-ventricular replica-nodal tachycardia by automaticity during successful radiofrequency ablation of long anterogradely slow conducting atrio-fasciculo-ventricular accessory pathway]

Mahaim syndrome is still a challenge. The specific characteristics of the pathway, the fact that it seldom occurs, and ambiguities about the pathophysiology and nomenclature make it, for electrophysiologists, still difficult to ablate. We present a case of a patient with anterogradely slow conducting accessory pathway, which has been effectively ablated although M potential was not observed nor was a mechanical conducting block of the accessory pathway. The accessory pathway showed a wide spectrum of electrophysiological characteristics of the "AV node physiology" including inductions and terminations of atrio-ventricular replica-nodal tachycardia by local automaticity, not only during electrophysiological study, but during successful application. The accessory pathway presented signs of two types of pseudo Mahaim fibers: atrio-fascicular and slow conducting atrio-ventricular connection.

[Wolff-Parkinson-White syndrome with a parahisian accessory pathway: the place of cryoablation]

The ablation of parahisian accessory pathways is a challenge because of the risk of atrioventricular block. In this observation, we describe the case of an eleven-year-old girl presenting a parahisian accessory pathway treated successfully by cryoablation. It is a pediatric case, in which, the accessory pathway and the nodo-hisian conduction pathway where superposed in anatomic and electrophysiological terms. Cryoablation should be the method of choice of ablation in pediatric patients.

An enhanced method for accessory pathway localization in case of Wolff-Parkinson-White syndrome

This paper presents an analysis of the Arruda accessory pathway localization method for patients suffering from Wolff-Parkinson-White syndrome, with modifications to increase the overall accuracy. The Arruda method was tested on a total of 79 cases, and 91.1% localization performance was reached. After a deeper analysis of each decision point of the Arruda localization method, we considered that the lead aVF was not as relevant as other leads (I, II, III, V1) used. The branch of the decision tree, which evaluates the left ventricle positions, was entirely replaced using different decision criteria based on the same biological parameters. The modified algorithm significantly improves the localization accuracy in the left ventricle, reaching 94.9%. An accurate localization performance of non-invasive methods is relevant because it can enlighten the necessary invasive interventions, and it also reduces the discomfort caused to the patient.

Electrophysiologic properties of para-Hisian atrial tachycardia

BACKGROUND

Focal atrial tachycardia (AT) originates from preferential sites, including the tricuspid and mitral annuli. AT arising from the atrioventricular annuli is initiated and terminated with programmed stimulation and is, in general, adenosine and verapamil sensitive. Para-Hisian AT arising from the apex of the triangle of Koch has been considered to be a distinct entity, characterized by unique electrophysiological properties.

OBJECTIVE

We sought to more fully delineate the electrophysiological and electrocardiographic properties of para-Hisian AT in a large series of patients.

METHODS

The study population consisted of 38 patients (63 ± 15 years; 23 female) with AT from the para-Hisian region. The ATs were focal and originated from the anteroseptal tricuspid annulus, in close proximity to the His bundle recording. Proximity to the His bundle was confirmed by electrogram recordings, fluoroscopy, and centrifugal activation during three-dimensional mapping.

RESULTS

The mean AT cycle length was 421 ± 69 ms. AT was associated with a distinct P-wave morphology that was significantly narrower than the P wave during sinus rhythm. Adenosine (5.0 ± 1.5 mg) terminated AT in 34/35 patients. Intravenous verapamil terminated AT in three of three patients. Catheter ablation was attempted in 30 patients and was successful in 26 (87%).

CONCLUSION

The para-Hisian region is a source of focal AT, with properties consistent with AT arising circumferentially along the tricuspid and mitral annuli, and should be considered a subset of this broader group of "annular" ATs. The electropharmacologic findings in para-Hisian AT are mechanistically consistent with cyclic AMP-mediated triggered activity.

Importance of accessory pathway location in the efficacy and safety of radiofrequency ablation

INTRODUCTION

Atrioventricular accessory pathways can be asymptomatic, or can cause reentrant tachycardia and, rarely, sudden cardiac death. In general, radiofrequency ablation is the curative treatment of choice. The aim of this study was to determine the importance of accessory pathway location in the efficacy and safety of radiofrequency ablation.

METHODS

We performed a cross-sectional study based on the clinical and electrophysiological data of 858 consecutive patients undergoing accessory pathway radiofrequency ablation in our hospital between November 1997 and December 2008.

RESULTS

Median age was 37.2 +/- 19.8 years (56.0% males); most patients were symptomatic (94.2%) and without structural heart disease (95.1%). The prevalence of concealed pathways was 28.0%. Slightly over half of the patients were on antiarrhythmic therapy. The anatomical distribution of the accessory pathways was as follows: left ventricular free wall (LVFW) (53.8%), posteroseptal (25.6%), right ventricular free wall (7.7%), anteroseptal (4.3%), midseptal (3.5%) and multiple (5.0%). The acute success rate was highest in LVFW accessory pathways (97.0%) and lowest in multiple accessory pathways (88.4%). Significant complications occurred in 0.5% of cases, midseptal and anteroseptal accessory pathways being most affected (3.3% and 2.7%, respectively). At one-year follow-up there were no deaths, and 4.4% of patients had recurrence of accessory pathway conduction, with no significant differences between anatomical locations.

CONCLUSIONS

The anatomical position of the accessory pathway affects the efficacy and safety of radiofrequency ablation.

Reversion of left ventricular systolic dysfunction and abnormal stress test: by catheter ablation, in a patient with Wolff-Parkinson-White syndrome from Para-Hisian Kent bundle

The diagnosis of Wolff-Parkinson-White syndrome is typically reserved for patients who experience ventricular pre-excitation and symptoms that are related to paroxysmal supraventricular tachycardia, such as chest pain, dyspnea, dizziness, palpitations, or syncope. Herein, we report the case of a 38-year-old woman who presented at our outpatient department because of exercise intolerance. Cardiac auscultation revealed a grade 2/6 pansystolic murmur over the left lower sternal border. Twelve-lead electrocardiography showed sinus rhythm at a rate of 76 beats/min, with a significant delta wave. Transthoracic echocardiography revealed abnormal left ventricular systolic function. The results of a thallium stress test were also abnormal. Coronary artery disease was suspected; however, coronary angiography yielded normal results. Electrophysiologic study revealed a para-Hisian Kent bundle and a dual atrioventricular nodal pathway. After radiofrequency catheter ablation was performed, the patient's left ventricular function improved and her symptoms disappeared. In Wolff-Parkinson-White syndrome, left ventricular systolic dyssynchrony can yield abnormal findings on echocardiography and thallium scanning--even in persons who have no cardiovascular risk factors. Physicians who are armed with this knowledge can avoid performing coronary angiography unnecessarily. Catheter ablation can reverse the dyssynchrony of the ventricle and improve the patient's symptoms.

Quadruple atrioventricular nodal pathways: involved in orthodromic atrioventricular reentrant tachycardia

Supraventricular tachycardia can be caused by multiple atrioventricular nodal pathways or atrioventricular accessory pathways. Herein, we report the case of a patient who was diagnosed with an orthodromic atrioventricular reentrant tachycardia that was caused by an unusual combination of quadruple atrioventricular nodal pathways and an atrioventricular accessory pathway. Radiofrequency catheter ablation of the accessory pathway successfully eliminated the arrhythmias and the patient's symptoms. Careful analysis of complete electrophysiologic studies can help in the diagnosis of such rare clinical presentations.