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ABSTRACT Background Methods Results Conclusions Wolff‐Parkinson‐White (WPW) syndrome and fasciculoventricular pathway (FVP) present electrocardiographic manifestations characterized by delta waves, differentiating these two is challenging. Specifically, WPW type B with QRS width ≤120 ms, resembles typical FVP features. Because of the presence of repolarization abnormalities in WPW syndrome, our hypothesis centered on the potential utility of the QRS‐T angle for distinguishing WPW syndrome from FVP. To determine the discriminative value of the QRS‐T angle for delineating WPW syndrome from FVP.We included cases of WPW syndrome treated with catheter ablation and FVP diagnosed via adenosine triphosphate administration between 2007 and 2023. We excluded cases with WPW type A, QRS width >120 ms, intermittent WPW, congenital heart disease or myocardial damage, ablation history, tachycardia, palpitations within 3 months, and WPW syndrome featuring an accessory pathway on the left lateral wall. Eventually, we identified 40 and 54 patients from the WPW and FVP groups, respectively. The QRS‐T angle was compared between the WPW and FVP cohorts.The QRS‐T angle in the WPW group was significantly larger than in the FVP group (45.7 ± 46.3° vs. 17.8 ± 13.9°, p < 0.001). Receiver operating characteristic curve analysis with a sensitivity and specificity of 65.0% and 72.6%, respectively, demonstrated that the optimal cut‐off value for the QRS‐T angle was 22° for distinguishing WPW from FVP. Remarkably, all cases with a QRS‐T angle >65° were within the WPW group.The QRS‐T angle can offer promising utility in differentiating WPW syndrome from FVP. [ABSTRACT FROM AUTHOR]

We report a case of a 44‐year‐old male who underwent an electrophysiological study for symptomatic supraventricular tachycardia (SVT) with wide QRS complex. The SVT was diagnosed as an antidromic atrioventricular reentrant tachycardia (AVRT) via antegrade conduction of left‐sided accessory pathway (AP). However, the QRS morphology changed during the SVT, and then the SVT was terminated spontaneously. The mapping of AP was performed during sinus rhythm, and the radiofrequency application successfully eliminated the AP, which rendered tachycardias non‐inducible. This was a rare case of antidromic AVRT during which the QRS morphology changed. [ABSTRACT FROM AUTHOR]

A 51‐year‐old woman presented with recurring palpitations. Electrocardiography revealed narrow QRS tachycardia with short RP configuration. Computed tomography showed coronary sinus (CS) ostial atresia along with a small persistent left superior vena cava (PLSVC). Electrophysiological study identified the retrograde earliest atrial activation site (EAAS) at the CS ostium without decremental properties, and para‐Hisian pacing suggested retrograde atrioventricular nodal conduction. Using a 1.6‐Fr microelectrode catheter distally placed in the CS via the PLSVC, EAAS was confirmed within the left atrium, not the CS ostium. Transseptal approach revealed a left lateral accessory pathway, which was successfully eliminated. [ABSTRACT FROM AUTHOR]

We described the differential ventricular overdrive pacing during long RP' supraventricular tachycardia and discussed about its response leading to the dianosis. [ABSTRACT FROM AUTHOR]

Background: Open‐window mapping (OWM) is a novel automated mapping method for catheter ablation of an accessory pathway (AP), in which the local signal is annotated with window‐of‐interest parameters to analyze both atrial and ventricular signals. This study aimed to determine the utility of OWM in visualizing the location and width of APs in patients with Wolff‐Parkinson‐White syndrome. Methods: This two‐center study enrolled 30 patients (20 males; mean age: 56 years, interquartile range [IQR]: 22–69 years) who underwent high‐density OWM with the extended early‐meets‐late (EEML) algorithm using a 20‐electrode, 5‐spline catheter (PENTARAY, Biosense Webster). The lower threshold of the EEML was set to adjust the EEML gap to match the propagation mapping, and broad APs were defined as an EEML gap > 1 cm. Results: The median mapping points, mapping time, and lower threshold of the EEML were 2482 (IQR: 1755–4000) points, 23 (IQR: 15–30) min, and 23 (IQR: 18–25), respectively. All 30 APs (24 in the mitral annulus and 6 in the tricuspid annulus) were successfully eliminated. Of these APs, 21 (70%) were eliminated by the first radio frequency (RF) application. OWM revealed broad APs in 11 patients (37%), in four of whom (36%) the first RF application achieved a loss of AP conduction (vs. 90% of patients without broad APs; p =.004). Conclusion: OWM facilitates the visualization of the location and width of APs, which may be particularly useful for predicting whether multiple RF applications are required for broad APs. [ABSTRACT FROM AUTHOR]

Background: Wolff‐Parkinson‐White (WPW) concomitant with atrial tachyarrhythmia (ATA) has not been systemically characterized. Methods: Detailed electroanatomical mapping of the right atrium (RA) and/or left atrium (LA) was performed using three‐dimensional mapping and the accessory pathway (AP) was mapped. Results: WPW syndrome with ATA was diagnosed in 11 patients (median age 60 years). The characteristic of unidirectional anterograde conduction over the AP was displayed in nine patients, six of whom were intermittent. Sustained atrial tachycardia, that is, counterclockwise atrial flutter (AFL) with a median tachycardia cycle length (TCL) of 225 (220–275) ms, was mapped in eight patients; furthermore, "figure 8" right atrial reentry was mapped with TCL 250 ms in one patient with a surgical history of ventricular septal defect repair. The remaining two patients underwent mitral annulus‐dependent AT after paroxysmal atrial fibrillation (PAF) ablation and LA micro‐reentry AT, respectively. In four patients, the location of the APs was left posterior. Left‐lateral APs were identified in four patients. The locations of the APs in the remaining three patients were the right posterior and middle septum. All ATAs and APs were successfully ablated. After a median follow‐up of 37 (15–72) months, no anterograde conduction over the AP was recorded, new onset of PAF was recorded in three patients, and all of them underwent circumferential pulmonary vein isolation. Conclusions: WPW with concomitant ATA frequently had continuous anterograde conduction over the AP with a rapid ventricular rate. Most WPWs displayed the characteristic of unidirectional anterograde conduction. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 21-year-old man with an electrophysiological study for a long RP tachycardia. Topics include atrial-His (AH) and His-ventricular intervals being normal and programmed ventricular stimulation demonstrating a midline atrial activation with retrograde jump; and clinical tachycardia being induced during programmed atrial stimulation with an identical atrial activation sequence during ventricular stimulation.

The inability to ablate left accessory pathways (APs) from endocardial approaches may suggest an epicardial location. We report on a 43‐year‐old woman presenting with a wide QRS tachycardia with Right Bundle Branch Block (RBBB) morphology, right inferior axis, and the "pattern break" appearance in V2 resembled the outflow tract ventricular tachycardia. An electrophysiology study confirmed an antidromic atrioventricular reentrant tachycardia using an antegrade slow, decrementally conducting AP that was successfully ablated in the great cardiac vein‐anterior interventricular vein junction after failure of endocardial approach. [ABSTRACT FROM AUTHOR]

The article presents the case of a 70-year-old male who was presented for electrophysiologic testing of his supraventricular tachycardia to discuss the mechanism of a short stimulus-to-atrial interval during para-Hisian pacing. Topics include activation mapping during right ventricular pacing, the mechanism of ventriculoatrial (VA) conduction, and the para-Hisian pacing during sinus rhythm.

Background: The presence of anterograde conduction through an accessory pathway (AP) has been linked to sudden cardiac death. Unfortunately, pre‐excitation associated with classic pathways can be difficult to differentiate from benign APs such as nodofascicular fibers. Objective: Identifying characteristics on electrocardiogram (ECG) and exercise that differentiate classic and benign AP connections in suggested pre‐excitation patterns. Methods: Retrospective review of patients presenting between 1995 and 2017 with ventricular pre‐excitation on ECG, determined to have either typical left‐lateral AP during electrophysiology study (EPS), or benign, or no AP determined by either transesophageal electrophysiology study (TEP), or EPS. Results: A total of 96 patients were included, 14.2 years (4‐24), 45% female, 90% Caucasian. Of these, 60 (63%) had a classic APs identified on EPS and 58 (97%) underwent successful ablation. Conversely, 36 (37%) had benign pathways identified. ECG findings differed between the groups: PR‐interval 102 versus 120 ms (P < .0001), QRS‐duration 110 versus 102 ms (P < .0001), QRS‐axis 74 versus 59 degrees (P = .0005), and QRS onset to peak R/S in limb leads 64 versus 42 ms (P < .0001), and precordial leads 66 versus 46 ms (P < .0001). Change in QRS duration during exercise differed between the groups: 25 versus 2 ms (P < .0001) and ECG characteristics identified the presence of an AP with 97% sensitivity and 94% negative predictive value. Conclusion: Classic and benign APs exhibit different ECG characteristics, though clinical overlap does not allow for absolute differentiation. These data may help with risk stratification decision making though does not obviate the need for additional invasive testing. [ABSTRACT FROM AUTHOR]

The article presents the case of a 17-year-old man who was rushed to the emergency department due to symptomatic hemodynamically tolerated wide complex tachycardia (WCT). Topics include the occurrence of spontaneous premature atrial beat (PAB) from high right atrium (HRA) during tachycardia, and other topics like atriofascicular (AF) pathway and right bundle branch (RBB).

Abstract: Background: Radiofrequency catheter ablation (RFCA) in the septum close to the atrioventricular node or His bundle has an increased risk of irreversible complications. Cryothermal energy has the advantages of reversible cryomapping and increased catheter stability. The study aims to evaluate the efficacy and safety of cryoablation of the right anteroseptal or midseptal accessory pathways (APs) in pediatric patients. Method: A retrospective review was performed with 26 pediatric patients (16 males and 10 females; median age 6.0 years and average body weight 24.9 kg) with paroxysmal supraventricular tachycardia (PSVT) in our Pediatric Heart Center from 2014 to 2016. Half of them had manifest APs. All the children underwent cryoablation for the treatment of PSVT because of the right anteroseptal or midseptal APs (16 cases had right anteroseptal APs and 10 cases had right midseptal APs). Results: Acute cryoablation success was achieved in 23 cases (88%, 23/26). Atrioventricular block (AVB) occurred in eight cases (31%, 8/26) during the procedures and normal atrioventricular conduction recovered in seven cases except a case with I°AVB. During follow‐up, three cases recurred (13%, 3/23) and no permanent high degree AVB was found. Conclusion: Cryoablation of the right anteroseptal or midseptal APs in pediatric patients is both safe and effective. [ABSTRACT FROM AUTHOR]

Abstract: Background: Concealed left‐sided accessory pathways (CLAP) are a cause of supraventricular tachycardia (SVT) in the young. Most are mapped with right ventricular (RV) apical/outflow pacing. Rarely, alternative means of mapping are required. We review our experience from three pediatric electrophysiology (EP) centers with a rare form of “hidden” CLAP. Methods: All patients <21 years undergoing EP study from 2008 to 2014 with a “hidden” CLAP (defined as an accessory pathway [AP] for which RV pacing at cycle lengths [CL] stable for mapping did not demonstrate eccentric retrograde conduction) were included. Exclusion criteria: preexcitation. Demographic, procedural, and follow‐up data were collected. Results: A total of 23 patients met the criteria (median age, 14.3 years [range 7–21], weight, 51 kg [31–99]). 21 (96%) had SVT and one AFIB (4%). APs were adenosine sensitive in 7/20 patients (35%) and VA conduction was decremental in six (26%). CLAP conduction was demonstrable with orthodromic reentrant tachycardia in all patients, with RV extrastimulus testing in seven (30%) and with rapid RV pacing (

A 58-year-old man with a long R-P' narrow QRS tachycardia underwent an electrophysiological study. The tachycardia was diagnosed as a permanent form of junctional reciprocating tachycardia (PJRT), and the earliest atrial activation site during tachycardia was coronary sinus (CS) ostium. Radiofrequency ablation at the site was initially not successful because the tip impedance and temperature were unstable. After changing of the ablation catheter to that with contact force sensor, the accessory pathway was immediately ablated and the PJRT was no longer induced. A retrograde CS angiogram revealed a fusiform aneurysm, which was located at the earliest activation site during the tachycardia. [ABSTRACT FROM AUTHOR]

The article presents a case study of 42-year-old man with concealed accessory pathway who was referred for a catheter ablation of the atrioventricular reentrant tachycardia (AVRT). Topics discussed include left atrium (LA) myocardium and coronary sinus (CS) musculature that are connected with striated muscle fibers, tachycardia cycle length alternation at the time of AVRT, and ventricular pacing.

The article focuses on the differential diagnosis of a regular wide QRS complex tachycardia with left bundle branch block (LBBB) like morphology and 1:1 AV relationship. Topics discussed include ascertaining whether the tachycardia mechanism is antidromic tachycardia or supraventricular tachycardia with bystander accessory pathway, chart of twelve-lead electrocardiogram and intracardiac tracings, and fusion of ventricular activation between antegrade conduction.

Background Although a ventriculoatrial interval (VAI) of ≤70 ms is used to distinguish atrioventricular nodal reentrant tachycardia from orthodromic atrioventricular reciprocating tachycardia (AVRT), a VAI of ≤70 ms is sometimes observed in cases of AVRT. The study aimed to evaluate the short VAI that is seen in AVRT and to understand its underlying mechanism. Methods Electrophysiologic studies of 46 consecutive patients with AVRT involving an accessory pathway (AP) were examined retrospectively. Results AP was right sided in seven patients and left sided in 39. A VAI (interval from QRS onset to the earliest intracardiac atrial electrogram recorded by any mapping catheter during AVRT) ≤70 ms during AVRT (short VAI) was observed in eight patients: six with a left lateral AP and two with a left posteroseptal AP. During AVRT involving a left-sided AP, the QRS-V interval (from the earliest QRS onset to the local ventricular electrogram at a site which showed earliest atrial electrogram recorded from the coronary sinus catheter) was significantly shorter (37 ± 7 ms vs 54 ± 13 ms, P = 0.001) and supernormal conduction (QRS duration or the QRS-V interval shortening by ≥10 ms during AVRT) was more frequently seen (63% vs 6%, P = 0.02) in the short VAI group than in the normal VAI group. Furthermore, these parameters were shown to be determinants for short VAI. Conclusions A short VAI is sometimes observed during AVRT involving a left-sided AP. The short VAI may be caused by rapid propagation or supernormal conduction between the proximal Purkinje-muscle junction and basal left ventricular myocardium. [ABSTRACT FROM AUTHOR]

Background Cryoablation is increasingly utilized in children because of its safety profile. Recently, larger catheter tips have been more widely used to improve long-term success rates. The aim of this study was to assess the safety and efficacy of 8-mm-tip catheters for cryoablation of right-sided accessory pathways (APs) in children. Methods Electrophysiological procedures were performed using the EnSite™ system (St. Jude Medical Inc., St. Paul, MN, USA). Results Between July 2010 and July 2014, 54 patients (mean age: 13.1 ± 3.7 years) underwent cryoablation using an 8-mm-tip catheter. In 18 of 54 (33%) patients where an 8-mm-tip catheter was the first-choice catheter, the success rate was 18 of 18 (100%). There was a history of previous failed attempts or recurrence with radiofrequency ablation and/or 6-mm-tip cryoablation in 36 of 54 (67%) patients. The success rate in these patients was 24 of 36 (67%). No fluoroscopy was used in 34 of 54 procedures. The recurrence rate was six of 42 (14%) during a mean follow-up period of 32 ± 15 months. In one patient, transient atrioventricular block occurred. Conclusions Cryoablation with an 8-mm-tip catheter for right-sided APs in children who weigh over 40 kg appears to be safe and acutely effective in cases where conventional ablation methods fail and also as a first choice for ablation procedure. However, the recurrence rate still seems to be high. [ABSTRACT FROM AUTHOR]

Background Ventricular overdrive pacing (VOP) produces reset during the transition zone (TZ) of QRS fusion in orthodromic reentrant tachycardia (ORT) and after the TZ in atrioventricular nodal reentrant tachycardia (AVNRT), and this represents a simple diagnostic maneuver to differentiate the two tachycardia mechanisms. Objective The purpose of this study was to determine whether the number of beats with reset in the TZ predicts accessory pathway (AP) location in ORT. Methods We retrospectively reviewed 57 patients with ORT (21 left-sided AP, 20 septal AP, and 16 right-sided AP) and 20 patients with AVNRT (19 typical AVNRT and one atypical AVNRT) who underwent VOP from the right ventricular apex. We analyzed the number of beats with reset during or after the TZ, demonstrated by fixed ventricular stimulus-atrial (SA) interval during VOP. Results The overall mean tachycardia cycle length [CL] minus VOP CL was 22.6 ± 7.5 ms with no statistical difference between the groups (P = 0.480). The mean number of beats in the TZ with fixed SA interval was 2.5 ± 1.4 for the whole ORT group, 1.1 ± 0.4 for left-sided AP (range 1-2), 2.8 ± 0.9 for septal AP (range 1-5), and 4.0 ± 0.9 for right-sided AP (range 3-6) (P < 0.001). Using a cutoff >2 beats distinguished right- versus left-sided AP in all cases. Conclusion Assessing the number of beats in the TZ with fixed SA interval during VOP helps to determine AP location in ORT and adds valuable information to an established simple diagnostic pacing maneuver, especially when a two-catheter simplified approach is employed. [ABSTRACT FROM AUTHOR]

Abstract: A 16‐year‐old male presented with an orthodromic atrioventricular reentrant tachycardia over a concealed parahisian accessory pathway (AP). Cryoablation of the AP resulted in transient manifestation of a fully preexcited sinus rhythm of parahisian AP morphology. Potential causes for the paradoxical preexcitation include inadvertent atrioventricular nodal block, sourse‐sink mismatch, as well as the activation of a dormant AP capable of anterograde conduction. [ABSTRACT FROM AUTHOR]

The article discusses the case of a male patient with a history of radiofrequency (RF) ablation presented with recurrent episodes of paroxysmal palpitation. Topics include the recording of narrow QRS tachycardia with apparent concentric atrial activation, the differential diagnosis of a regular narrow QRS tachycardia with septal ventricular apex (VA ) interval and the VA dissociation within five seconds of RF energy initiation.

The article presents a case study of a 35-year-old female who was referred for evaluation of recurrent palpitation. Topics discussed include termination of left bundle branch block (LBBB) tachycardia with intravenous adenosine; results of surface electrocardiogram; and mentions that the patient underwent an electrophysiology study.

Background The stimulus-atrial (SA) interval minus ventriculoatrial (VA) interval (SA-VA) difference represents a simple diagnostic maneuver to distinguish between atrioventricular nodal reentrant tachycardia (AVNRT) and orthodromic reentrant tachycardia (ORT) during electrophysiology study. However, its usefulness has largely been studied in selected patient subgroups. The purpose of this study was to evaluate the performance of the SA-VA difference against commonly used diagnostic maneuvers in a large cohort of consecutive patients. Methods Consecutive patients with inducible supraventricular tachycardia and successful entrainment through pacing trains from right ventricular apex during an electrophysiological study were included. Atrial tachycardias were excluded. The following intervals were calculated for each patient: SA-VA difference, His potential, and atrial electrogram during entrainment minus His potential and atrial electrogram during tachycardia, and the corrected return cycle. Results A total of 456 patients fulfilled the inclusion criteria, of which electrophysiological study revealed 265 typical AVNRT, 38 atypical AVNRT, and 54 and 108 ORT through a septal and free-wall accessory pathway, respectively. An SA-VA difference >99 ms identified AVNRT in all patients with sensitivity, specificity, and positive and negative predictive values of 97.7%, 96.9%, 98.3%, and 95.7%, respectively. Conclusions This study confirms the high ability to distinguish AVNRT from ORT using the SA-VA difference, not only in selected patient subgroups, but as whole when a cut-off of >99 ms is used. [ABSTRACT FROM AUTHOR]

Background Fluoroscopic catheter ablation of cardiac arrhythmias in pediatric patients exposes the patients to the potential risk of radiation considering the sensitivity of this population and its longer life expectancy. We evaluated the feasibility, safety, and efficacy of accessory pathway (AP) ablation guided by CARTO3 electroanatomic mapping (EAM) system with both cryoenergy and radiofrequency (RF) energy in order to avoid x-ray exposure in pediatric patients. Methods We included 44 patients (mean age: 13.1 ± 3.3 years); nine of 44 presented concealed AP. An electrophysiological study with a three-dimensional EAM reconstruction was performed in every patient with a venous transfemoral direct right atrium approach or an arterial transfemoral retrograde approach to reach the mitral annulus. In two patients with left-sided AP, the ablation was performed via a patent foramen ovale. Results A total of 47 APs were present, left sided in 45% (21/47) of cases (15 lateral, one anterior, three posteroseptal, and two posterolateral) and right sided in 55% (26/47; one anterior, three anterolateral, one posterolateral, three lateral, five para-Hisian, 12 posteroseptal, and one anteroseptal). Ablation without the use of fluoroscopy was successfully performed in every patient (33 with RF and in 11 with cryoenergy). No complication occurred. At a mean follow-up of 16.0 ± 11.7 months, we observed seven recurrences, three of them successfully re-ablated without fluoroscopy. In one case cryoablation of a para-Hisian AP was ineffective in the long term. Conclusions Three-dimensional EAM allowed a safe and effective fluoroless AP ablation procedure in a pediatric population both with RF and cryoenergy. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 32-year-old woman who was subjected to electrophysiology for recurrences of palpitations and emergence of manifest preexcitation during electrocardiograpy (ECG). The patient was diagnosed with ventricular ectopy, tachyarrhythmias, and sinus bradycardia following 4-catheter electrophysiology examination. The article discusses the effectiveness of dual-chamber pacemaker for unusual cases of ventricular preexcitation and PRKAG2 gene mutation.

A case study is presented of a 32-year-old man with coincident proximal and distal retrograde left atrial activation. Topics discussed include use of ablation for blocking activation and ventriculoatrial dissociation; sequence of coronary sinus activation after ablation; and aborization at the atrial insertion site.

We report a case of a patient with right axillary ventricular. Similar congenital anomaly of the right atrium was reported as 'right appendage diverticulum or right atrial diverticulum.' However, this independent chamber has its own annulus, synchronizes with the right ventricular, and generates large ventricular potential. Under the guidance of the CARTO mapping system (Biosense Webster, Diamond Bar, CA, USA), a right atrioventricular accessory pathway associated with type B Wolff-Parkinson-White syndrome was ablated successfully. This pathway was close to the annulus of the axillary ventricular. The patient remained free of arrhythmia at 1-year follow-up. [ABSTRACT FROM AUTHOR]

Background This study describes the use of adenosine during ablation procedures to allow conduction through adenosine-dependent accessory pathways (APs), which are inactive at the time of the procedure. The technique allows for successful mapping and ablation of these pathways. Methods Retrospective review of all patients undergoing AP ablation from 1998 to 2008 to identify patients with absent or intermittent AP conduction during electrophysiology study. Adenosine boluses were used to activate the AP for the purpose of mapping in each case. Results Adenosine mapping was utilized in seven patients. One patient had a concealed AP at baseline and six patients had manifest preexcitation at baseline but lost AP conduction during the case. Alternative methods of enhancing AP conduction were attempted in five patients, but failed. Acute ablation results included: four patients with complete elimination of AP conduction, two patients with AP conduction only with adenosine, and one patient with return of baseline preexcitation. Patients with residual antegrade conduction had right superior (anterior) septal APs considered too close to the atrioventricular conduction system for safe ablation. At median follow-up of 2 years, all three patients with residual AP conduction had recurrence of supraventricular tachycardia; the remainder remained free of preexcitation and SVT. Conclusion Adenosine mapping is a useful technique for facilitating AP ablation when pathway conduction is absent or inconsistent, and may enhance conduction in mechanically inhibited or previously ablated APs. Recurrence of AP conduction only during adenosine administration is predictive of late recurrence. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 43 year old woman who presented to physicians with a history of recurrent paroxysmal episodes of palpitations without syncopal events. A discussion of the factors which could have led to her tachycardia and an abnormal electrocardiogram result related to a long HIV interval, is presented.

A 37-year-old man, known case of mitral valve replacement, was referred for ablation. Meticulous mapping showed the earliest signal in the distal coronary sinus (CS). Endocardial ablation via transseptal approach failed to permanently ablate the accessory pathway. Similarly, ablation within the CS was unsuccessful. Finally, the mapping catheter was introduced into the vein of Marshall (VoM) and a very early signal was obtained. In the first 3 seconds of the radiofrequency energy application within the VoM, delta wave disappeared. During 1-year follow-up, the patient had no recurrence of the palpitations and electrocardiogram showed no delta wave. (PACE 2013; 36:e132-e135) [ABSTRACT FROM AUTHOR]

Introduction In this case, electrophysiology and histology could be studied in the same heart. Clinical investigation, clinical electrophysiology, and postmortem serial histological sections of the septum were analyzed. Methods A patient with repeated seizures and a short PR interval with narrow QRS complex underwent electrophysiologic studies. Results The patient died while experiencing a very rapid supraventricular tachycardia and histologic examination showed a atrio-hisian bypass tract. Conclusion In our study, the lack of lengthening of the PR interval in spite of progressively premature atrial stimulation connected with the presence of atrio-hisian bypass tract. [ABSTRACT FROM AUTHOR]

Wolff-Parkinson-White (WPW) syndrome is a disorder characterized by presence of an accessory pathway that predisposes patients to tachyarrhythmias and sudden death. Radiofrequency ablation (RFA) is both effective and safe for patients with symptomatic tachyarrhythmias mediated by accessory atrioventricular pathways. During the procedure, fatal complications may occur but it is considered low in relation to the morbidity associated with the WPW syndrome. Coronary artery occlusion, as a complication of an RF catheter ablation, is quite rare. In this report, we present a 56-year-old male patient with a left main coronary artery (LMCA) occlusion during the ablation of left anterolateral wall accessory pathway. It should be kept in mind if the patient complains of new onset of severe chest pain, an immediate angiography should be performed. PACE 2012; 35:e43-e46) [ABSTRACT FROM AUTHOR]

Ablation of parahissian accessory pathways (APs) is a challenging procedure because of the high risk to provoke 'iatrogenic' atrioventricular (AV) nodal block. The feasibility and safety of cryoablation (CA) have been already demonstrated both in patients with AV nodal reentry tachycardia and in those with anteroseptal APs. However, dissociation between anterograde and retrograde conduction after CA has not yet been described. We report two cases of CA of parahissian AP associated with transient dissociation between anterograde and retrograde conduction. (PACE 2011; 34:e98-e101) [ABSTRACT FROM AUTHOR]

Background: We sought to assess the impact of routine use of a nonfluoroscopic navigation system in the procedural aspects of radiofrequency ablation of accessory pathways (APs) in pediatric and congenital heart disease (CHD) patients and the reduction of fluoroscopy in different pathway locations. Methods: This was a retrospective review of 192 patients, divided in two groups: group A (76 patients, fluoroscopic only ablation) and group B (116 patients, combined use of fluoroscopy and a nonfluoroscopic system (NavX™). Comparison of procedural aspects (procedure time, fluoroscopy time, success, complications, and recurrences) was performed. Results: The two groups were comparable in terms of age, AP location, and presence of CHD. The mean age was 11.34 ± 4.65 years in group A versus 10.91 ± 3.68 years in group B. The procedure duration was significantly shorter in group B than in group A (177.06 ± 62.18 vs 242.45 ± 99.07) (P < 0.001). There was a significant reduction in the fluoroscopy time in group B compared to group A (8.27 ± 8.23 vs 39.77 ± 32.65 minutes) (P < 0.001). The difference between the two groups was statistically significant in all categories of APs. The success rate was 97.4% in group A and 96.6% in group B. There were no complications directly related to the use of the nonfluoroscopic system. There was no difference in the recurrence rate. Conclusions: The use of a nonfluoroscopic system for catheter navigation resulted in significant reduction of total procedure and fluoroscopy time during catheter ablation of APs in pediatric and CHD patients, regardless of the location of the pathway, without a compromise in safety and efficacy. (PACE 2011; 34:1288-1296) [ABSTRACT FROM AUTHOR]

Individuals with ventricular preexcitation (VP) are known to have an increased risk of sudden death. This risk has been associated with conduction properties of the accessory pathway. Patients with VP underwent risk stratification through the use of exercise and transesophageal testing. All patients were initially screened with exercise testing and those with preexcitation throughout exercise went on to have transesophageal testing. Patients who demonstrated high-risk pathway characteristics by transesophageal testing or developed clinical indications for an electrophysiology (EP) study underwent ablation. This stepwise risk stratification technique was evaluated for the ability to avoid the need for intracardiac EP study. Patients stratified as low risk were contacted for follow-up. One hundred and twenty-nine exercise studies were performed in 127 patients. Thirty-five of 129 exercise studies demonstrated accessory pathway block during exercise. Twenty-seven of 35 underwent no additional testing. Sixty-six patients underwent transesophageal testing. Forty-nine of 66 patients demonstrated low-risk pathway characteristics and 40 of 49 underwent no further testing. In total, 68 of 129 (53%) patients avoided the need for intracardiac EP study and ablation. A noncardiac indication for the initial diagnostic electrocardiogram was associated with lower likelihood of intracardiac EP study. None of the patients stratified as low risk had additional invasive procedures or life-threatening arrhythmias upon follow-up. Successful risk stratification of pediatric patients with VP is possible through the use of exercise and transesophageal testing. In this patient population, half of the patients were able to avoid an intracardiac EP study. (PACE 2011; 34:555-562) [ABSTRACT FROM AUTHOR]

Cryoablation for arrhythmia substrates in pediatrics has been available since 2003. The purpose of this study was to evaluate the current approach of pediatric electrophysiologists to the use of cryoablation in the current era. We sent an Internet link to an online survey to all members of the Pediatric and Congenital Electrophysiology Society. Individuals and not institutions were surveyed. A total of 70 responses were received. Responding physicians were largely invasive pediatric electrophysiologists (94%) who practice at mid- to high-volume centers (>50 ablation procedures/year). Survey responders report that cryoablation was utilized for <50% of the ablation volume, and most utilize it for only 10%. With respect to specific arrhythmia substrates, 41% of responders use cryoablation as first-line therapy for atrioventricular nodal reentrant tachycardia. For accessory pathways, 94% report that cryoablation would only be utilized after mapping the accessory pathway to a 'high-risk location.' Other arrhythmia substrates considered for cryoablation would be accessory pathways mapped to high-risk areas, junctional ectopic tachycardia, a parahisian ectopic atrial tachycardia, or an atrial tachycardia near the phrenic nerve. For pediatric electrophysiologists who responded to the survey, radiofrequency energy remains the primary energy source for ablation. The current use of cryoablation technology is directed at arrhythmia substrates near the normal conduction system or other 'high-risk' areas. (PACE 2011; 34:304-308) [ABSTRACT FROM AUTHOR]

A 33-year-old woman presented with exercise-related palpitations after an apparently successful catheter-ablation of overt midseptal accessory pathway. Post procedure, the electrocardiogram at rest was normal, while the progressive appearance of delta-wave during treadmill stress testing was recorded. In addition, the occurrence of ventricular preexcitation was reproduced by controlled administration of dobutamine. Detailed understanding of the unusual pathway electrophysiology resulted in specific planning of the second procedure. In the basal state, pacing maneuvers did not demonstrate any evidence of pathway conduction. However, during infusion of dobutamine bidirectional conduction in the right anterior pathway was restored, enabling definitive cure by radiofrequency. (PACE 2010; 33:766–769) [ABSTRACT FROM AUTHOR]

The article presents a case study of a 42-year-old man with narrow complex tachycardia despite oral flecainide treatment. The authors assert that a diagnosis of atrial tachycardia (AT) is unlikely because the patient's increased heart rate was induced by ventricular stimulation. Retrograde activation sequence was present during spontaneous tachycardia and right ventricular pacing.

We report the case of a young man who presented with a rapid, narrow-complex atrial fibrillation. A few hours after being administered intravenous metoprolol and diltiazem for rate control, he developed intermittent ventricular preexcitation on the electrocardiogram (ECG) and experienced ventricular fibrillation, from which he was successfully defibrillated. A subsequent electrocardiogram in sinus rhythm demonstrated previously unknown Wolff-Parkinson-White pattern. A left lateral accessory pathway was successfully ablated. Wolff-Parkinson-White syndrome should be included in the differential diagnosis when a young patient presents with atrial fibrillation, even if the ventricular complexes on the ECG are not preexcited. [ABSTRACT FROM AUTHOR]

Background: Cryoablation is utilized for septal tachycardia substrates due its safety. Considering the recent studies which reveal coronary artery stenosis related to radiofrequency ablation (RFA) in children, cryoablation may offer advantages for nonseptal accessory pathways (APs) as well. The aim of this study was to investigate the efficacy and safety of cryoablation of APs in children. Methods: A total of 39 patients (median age = 9.3 years, range 4.8 to 17.2 years) underwent cryoablation of APs. A three-dimensional, surface electrode-based navigation system (EnSite NavX™, St.Jude Medical Inc., St. Paul, MN, USA) is used to decrease the fluoroscopy exposure. Results: A total of 45 APs were identified. Of these APs, 23 were septal (anteroseptal, midseptal, posteroseptal) and 22 were nonseptal. Acute success rate with cryoablation was 73%. RFA was used when cryoablation failed and overall acute success rate was 84%. To assess for the effect of institutional experience, the initial 23 APs were compared to the recent 22 APs and acute success rate revealed significant improvement (57% vs. 91%). Recurrence rate was 24% during a median follow-up of 282 days. Conclusion: Cryoablation of APs is safe and yields to high acute success rates in children. It can potentially be used as the first ablation option for all APs in children. However, recurrence rate is higher compared to the RFA and there is a need for prospective comparative studies. [ABSTRACT FROM AUTHOR]

Accessory pathways can be ablated with a high success rate. Occasionally, recurrences appear after successful procedures, sometimes shortly after the end of the procedure. We describe a successful ablation using remote magnetic navigation of a single catheter using stored vectors after recurrence of accessory pathway conduction while the patient was still in the electrophysiology laboratory. [ABSTRACT FROM AUTHOR]

CHENG, J., et al.: Protected Circumferential Conduction in the Posterior Atrioventricular Vestibule of the Left Atrium: Electrophysiologic and Anatomic Correlates . Background: The anatomic substrate for protected isthmus conduction in the right atrium has been well defined. Little is known of similar substrates in the left atrium (LA). Methods: Patients (pts) with reentrant tachycardia (AVRT) supported by a single left-sided accessory pathway were studied retrospectively (n = 64) and prospectively (n = 31). Intracardiac electrograms were recorded from the His bundle position and coronary sinus (CS). The LA was mapped with a steerable catheter using the transseptal approach. LA anatomy was examined grossly and histologically in six cadaver hearts after removal of endocardium. Results: A distal-to-proximal CS activation sequence during AVRT was seen in all patients with a left lateral accessory pathway before ablation. After one to three radiofrequency (RF) energy deliveries that did not interrupt accessory pathway conduction, the CS activation sequence was reversed in three patients in the retrospective group and bidirectional conduction block in the posterior atrioventricular vestibule of the LA (PAVV) was demonstrated in nine patients in the prospective group. Four of the six cadaver hearts showed a distinct circumferential inferoposterior myocardial bundle that coursed parallel to the CS in the PAVV. Conclusions: We described evidence of bidirectional intraatrial block in the PAVV after application of RF energy during accessory pathway ablation. Such conduction block may mimic the presence of a second accessory pathway. Our data suggest that circumferential conduction in the PAVV may be poorly coupled to the rest of the LA and may be involved in the macro-reentrant circuit around the mitral annulus. The circumferential inferoposterior myocardial bundle may serve as the underlying anatomic substrate (PACE 2005; 28:692–701) [ABSTRACT FROM AUTHOR]

STERNICK, E.B., et al.: Radiofrequency Catheter Ablation of an Accessory Pathway in a Patient with Wolff-Parkinson-White and Kartagener's Syndrome. We report a case of a manifest left free wall accessory pathway in a patient with Kartagener's syndrome and recurrent episodes of orthodromic atrioventricular reentrant tachycardia. To the best of our knowledge, it is the first report of Wolff-Parkinson-White syndrome associated with Kartagener's syndrome. Situs inversus and mirror image dextrocardia occurred with no additional detectable cardiac structural abnormalities. Diagnostic and therapeutic electrophysiological study was carried out via transaortic approach and a left-to-right reversal of monoplane fluoroscopic image. (PACE 2004; 27:401–404) [ABSTRACT FROM AUTHOR]

OH, S., et al.: Differential Diagnosis of Slow/Slow Atrioventricular Nodal Reentrant Tachycardia from Atrioventricular Reentrant Tachycardia Using Concealed Posteroseptal Accessory Pathway by 12-Lead Electrocardiography. Slow pathways are used as both antegrade and retrograde conduction pathway in slow/slow atrioventricular nodal reentrant tachycardia (SS-AVNRT), and patients with SS-AVNRT have tachycardia ECGs mimicking atrioventricular reentrant tachycardia using concealed posteroseptal accessory pathway (PS-AVRT). Therefore, SS-AVNRT can be misdiagnosed as PS-AVRT, and the differential diagnosis is clinically important. Standard 12-lead ECGs during tachycardia were analyzed in patients with SS-AVNRT (n = 10) and PS-AVRT (n = 10). All these patients were diagnosed by electrophysiological study and underwent successful catheter ablation. Differences of the RP' intervals (dRP') between V1 and the inferior leads were evaluated. SS-AVNRT had significantly longer RP' intervals measured in V1 (167 ± 25.2 vs 137 ± 26.8 ms, SS-AVNRT vs PS-AVRT, respectively, P = 0.02), longer dRP' between V1 and II (dRP'[V1-II], 37 ± 14 vs 17 ± 6.7 ms, P = 0.0007), longer dRP'[V1-III] (39 ± 14 vs 17 ± 9.9 ms, P = 0.0011), and longer dRP'[V1-aVF] (39 ± 13 vs 20 ± 9.5 ms, P = 0.0008). The following criteria were suggested for differential diagnosis of SS-AVNRT from PS-AVRT: dRP'[V1-II] >25 ms (sensitivity and specificity: 80% and 100%, respectively), dRP'[V1-III] >23 ms (90% and 90%), dRP'[V1-aVF] >30 ms (90% and 90%). Differences of the RP' intervals between V1 and the inferior leads in the tachycardia ECGs were useful for differential diagnosis of SS-AVNRT from PS-AVRT. (PACE 2003; 26:2296–2300) [ABSTRACT FROM AUTHOR]

KALARUS, Z., et al.: Electrophysiological Features of Orthodromic Atrioventricular Reentry Tachycardia in Patients with Wolff-Parkinson-White Syndrome and Atrial Fibrillation. --> The aim of this study was to compare the electrophysiological features of tachycardia between WPW patients with and without AF. The study population consisted of 114 patients with WPW syndrome and reciprocating tachycardia during electrophysiological study. Two groups were selected: group I with AF during the procedure(n = 42)and the control groupn = 72without AF (group II). Cycle length (V‐V interval), antero A‐V, retrograde V‐A conduction time during tachycardia and indexes V‐A/V‐V were analyzed. In addition, the relation between antero‐, retrograde conduction time, and V‐V was evaluated. Selection of the most predictive factor for AF presence was performed using regression analysis. Significant differences between the two groups were observed. These included a higher rate of tachycardia, shorter anterograde conduction time, A‐V/V‐V‐indexes, longer retrograde conduction time, and V‐A/V‐V‐indexes in group I compared with group II. Significant, positive correlations between anterograde conduction time and V‐V were present in both groups, but retrograde conduction correlated significantly with the V‐V‐interval only in group II and group I (r = 0.37 vs r =−0.01, respectively). Significant, negative correlations between A‐V and V‐A conduction time in all analyzed points has been found to exist in group I (r =−0.45 for the point of maximal preexcitation [PMP]), whereas there were no significant correlations between these parameters in group II (r = 0.04). The most powerful AF predictor has been identified as the V‐A/V‐V index. The presence of AF in WPW syndrome may be associated with discrete patient characteristics. Ventricular activation occurs earlier, and atrial later, in the tachycardia cycle in AF than in patients free of AF. The different ability of the accessory pathway for adaptation to tachycardia rate changes in group I causes prolonged retrograde conduction over the pathway while the tachycardia rate increases. (PACE 2003; 26[Pt. I]:1479–1488) [ABSTRACT FROM AUTHOR]

The aim of the present study was to localize the ventricular insertion site of concealed accessory pathway (APs) by using the ventricular pace mapping and examined if the analysis of the timing of retrograde atrial electrogram recorded at the ventricular side of the mitral annulus is useful in identifying the ventricular insertion site of the AP. In 39 patients with concealed left-sided APs, ventricular pacing was delivered along the mitral annulus at a cycle length of 500 ms while measuring the conduction interval from the pacing stimulus to the earliest retrograde atrial electrogram recorded in the coronary sinus (St-A). The ventricular insertion site of the AP was localized by identifying the shortest St-A. Also the interval between the onsets of QRS and atrial electrograms (QRS-A) and presence of continuous electrical activity (CEA) between the ventricular and atrial electrograms were evaluated at each mapping site during atrioventricular reciprocating tachycardia. Initial radiofrequency energy application to the site with the shortest St-A (46 ± 15 ms) eliminated the AP conduction in all patients, suggesting the accurate localization of the ventricular insertion site by ventricular pace mapping. The QRS-A and the percentage of the presence of CEA at the shortest St-A site were 79 ± 19 ms and 64%, respectively. However, the earliest retrograde atrial activation site did not coincide with the shortest St-A site in 19 of 39 patients, suggesting an oblique course of AP. Thus, in these 19 patients, there was a significant difference in St-A (47 ± 16 vs 59 ± 15 ms,P< 0.0001), QRS-A (83 ± 13 vs 72 ± 12 ms, P < 0.0001) and the presence of CEA (32 vs 74%, P < 0.01) between the shortest St-A site and the earliest retrograde atrial activation site, respectively. These indicate that the earliest retrograde atrial activation is not necessarily indicative of the ventricular insertion site of AP. However, ventricular pace mapping was considered to be useful for identifying and ablating the ventricular insertion site of AP, irrespective of the course of AP. [ABSTRACT FROM AUTHOR]

We describe a patient in whom two tachycardias with AV dissociation were inducible by ventricular extrastimulation. The first tachycardia was characterized by a narrow QRS preceded by a His deflection with an HV interval identical to that recorded in sinus rhythm (40 ms). Premature ventricular depolarization delivered when the His bundle was refractory advanced the next His deflection. These findings suggest the presence of a nodoventricular bypass tract involved in an orthodromic tachycardia. The second tachycardia was induced after propafenone infusion and exhibited a wide QRS complex with left bundle branch block morphology; each ventricular complex was consistently associated with a His deflection with a HV interval of -15ms. The second tachycardia may be considered to represent an antidromic tachycardia through the nodoventricular tract. However, a ventricular tachycardia cannot be excluded. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the anatomic relationship between the mitral annulus (MA) and the coronary sinus (CS). Fifty consecutive hearts of 31 men and 19 women, 63.5 ± 13.7 years of age, were examined at autopsy. MA was divided perpendicularly to the annular plane into an anteromedial block and a posterolateral block by sectioning from the CS ostium through the center of MA. The posterolateral block was subdivided radially into five equal sections at 36°, 72°, 108°, 144°, and 180°. The distance from the ventricular endocardium under MA to the nearest wall of CS (D) was measured in each cross-section. D measured 9.7 ± 2.3, 10.9 ± 3.3, 10.2 ± 3.6, 9.2 ± 3.4, and 8.2 ± 2.9 mm at 36°, 72°, 108°, 144°, and 180°, respectively. D at 72 was significantely longer than at 144° and 180° (P < 0.01). Likewise, D at 108° was significantly longer than at 144° and 180° (P < 0.05). The population was divided according to the morphology into five patterns. "Type C," the pattern that separated in the middle section and then reapproximated, was more common (66%) than any other pattern. D was confirmed to be longest at the level of the 72° section, corresponding to a left posterolateral free-wall location. The potential mapping in CS would be easily modified by this anatomic feature. When mapping activation from the CS, the electrophysiological data should be interpreted in light of these anatomic findings. [ABSTRACT FROM AUTHOR]

Radiofrequency catheter ablation is the procedure of choice for the nonpharmacological treatment of AV connections that are responsible for debilitating tachycardia. This article describes a patient with a manifest left posteroseptal accessory pathway and recurrent syncopes in whom a transient complete AV block occurred after transcatheter radiofrequency ablation of the left posteroseptal pathway. Three electrical abnormalities were present in this patient: AV infra-Hisian block, a left posteroseptal accessory pathway, and a AV nodal reentry tachycardia. This case report reminds you that one should be prepared for all fall backs during catheter ablation. [ABSTRACT FROM AUTHOR]

The purpose of this study ivas to determine the incidence and types of venous branches and anomalies in posteroseptal accessory pathways (APs) and whether these findings are indicative for successful ablation sites. Some posteroseptal APs may be located epicardially, or may be associated with venous anomalies or related to the middle cardiac vein. These APs account for many of the failures encountered during endocardial ablation. Direct coronary sinus (CS) angiography was performed in 43 consecutive patients with left posteroseptal APs (n = 23} and in 20 patients with A V nodal reentrant tachycardia prior to catheter ablation. In 14 (61%) of 23 APs, a venous branch or an anomaly of the CS was found in the posteroseptal region (6 with middle cardiac vein, 2 with other ventricular venous branches, and 6 had a diverticulum). Eleven (48%) of 23 APs were successfully abolished from within that demonstrated venous system, with a median of four radiofrequency impulses. In the remaining 12 (52%) patients, ablation was attempted from the endocardial site of the mitral annulus. Repeat angiography after energy delivery revealed no major complications in any patient. One (5%) patient with A V nodal reentrant tachycardia had evidence of a CS anomaly (P < 0.01). Various types of venous branches and anomalies are associated with the majority of patients with left posteroseptal APs. The APs are directly related to these complex findings, and AP conduction can easily be eliminated from within the venous branches. CS angiography is suggested prior to catheter ablation of left posteroseptal APs to facilitate the ablation procedure. [ABSTRACT FROM AUTHOR]