Orthodromic Tachycardia Research Articles

Characteristics of Right-Sided Accessory Pathways Associated With Right Cardiac Veins.

The anatomy of myocardial fibers around the right cardiac veins (RCVs) and their roles in accessory pathways (APs) are rarely reported. Six RCV-APs were identified from 566 patients with right-sided APs. Mapping of retrograde atrial activation was performed using CARTO 3 system under orthodromic tachycardia or right ventricular pacing. Venography of RCVs was acquired at the earliest retrograde atrial activation. Patients enrolled had a median age of 30 (11-51) years, 5 of them were male. Venography of RCVs could be classified into 3 distinct patterns based on the identified ventricular branches, right marginal vein only (type I; n=3), both right marginal vein and anterior cardiac veins (type II; n=2), and anterior cardiac vein only (type III; n=1). Patients with type I venography had rS QRS pattern in lead V1, negative delta wave in lead III and negative or isoelectric delta wave in lead aVF. However, patients with type II and III venography had QS QRS patterns in lead V1 and variable patterns of delta wave in inferior leads. Earliest retrograde atrial activation was found at a median of 16.75 (14.60-20.00) mm away from the tricuspid annulus, all with A larger than V. At the earliest retrograde atrial activation, far-field ventricular electrogram was found 30 ms later than QRS onset in 1 patient under sinus rhythm. AP conduction was eliminated by mechanical pressure in 2 and by radiofrequency ablation in 4 at the ostium of the veins colocalizing with the earliest retrograde activation of the right atrium. No recurrence was observed during 36 (10-60) months follow-up. The RCV-AP is a rare form of right-sided APs characterized by atrial insertions distant from the annulus. ECG-speculated ventricular insertion sites conformed to the location of identified RCVs.

Abstract 13210: A Hidden Right Atrial Lipoma in a Patient With Recurrent Sustained Supraventricular Tachycardias

Introduction: Cardiac lipomas, known for their benign nature, compose 8 percent of primary cardiac tumors. Advanced imaging modalities allow improved diagnosis, yet little of their potential complications involving the heart's conduction system is known. Case: A 65-year-old male presented to the Emergency Department with palpitations. History was significant for recurrent sustained orthodromic atrioventricular reentrant tachycardia using a concealed left posterior accessory pathway from a prior EP study. He was treated with ablation twice in the past. The patient was hemodynamically stable on evaluation. ECG showed supraventricular tachycardia (SVT) involving orthodromic re-entry with a ventricular rate of 227 bpm. Computer tomography (CT) of the chest revealed a large, low-attenuated lesion with -102 Hounsfield unit (HU) attached to the right atrial roof, extending to both SVC and IVC. No sparing of foramen ovale was seen. Findings suggest right atrial lipoma. A transthoracic echocardiogram (TTE) visualized the same echo-dense structure without increased vascularity. The patient responded to intravenous Adenosine. We discussed the case with the Cardiothoracic surgery team. Outpatient cardiac MRI and elective surgery were planned. Discussion: The case presented clinically significant atrial arrhythmia in a patient with a massive right atrial lipoma. Although most cardiac lipomas remain asymptomatic, arrhythmias coinciding with the location of involved chambers have been reported. In addition, the recurrence of orthodromic tachycardia despite previous ablation suggests the potential benefit of surgical intervention.

Utility of open window mapping using high-density mapping approach in accessory pathways ablation

Abstract Introduction and purpose We sought to described a new protocol of open window mapping (OW) utilizing high-density mapping in accessory pathways (AP) in CARTO® 3 system. This protocol automatically map conventional electrophysiology criteria for AP location, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT)and annotation at unipolar signal (wavefront annotation). Methods This was a single center, prospective and observational trial of 21 consecutive patients who underwent an AP catheter ablation. Results We included 16 men and 5 women, with a mean age of 32.6±17.9 years. The characteristics of AP, including mapping and ablation were described in Table 1. Twelve AP were of left location and 9 in right location. Mapping was performed in anterograde conduction in 17 patients (80.9%), retrograde in 9 patients (42.9%) and orthodromic tachycardia in 7 patients (33.3%). Mean mapping points were 3205±2034, with 29.2 min±12.5 min of mapping. All 21 patients had a successful ablation after OW mapping and mean radiofrequency time until complete AP elimination was 2.76 s. We present an example of a Left lateral AP OW mapping in antegrade and retrograde conduction in Figure 1, which shows EEML mapping tool, targeting shorter interval EGM AV or VA and color adjust to determine earliest LAT in chamber of exit. Conclusions In our experience, automatically mapping of conventional electrophysiology criteria for AP diagnostic is feasible to localize AP insertion, suggesting an increasing in effectiveness of procedure, and reducing mapping time, ablation time and X-ray exposure time. More studies should be performed to corroborate these conclusions. Funding Acknowledgement Type of funding sources: None.

Accessory pathway properties are similar in symptomatic and asymptomatic preexcitation

PurposePatients with WPW syndrome have an increased mortality rate compared to the general population. Although asymptomatic preexcitation has previously been considered benign, recent studies have found that also asymptomatic patients have clinical and electrophysiological factors associated with increased risk of sudden cardiac death. This study compares the baseline electrophysiological characteristics of accessory pathways in symptomatic and asymptomatic patients with preexcitation. We hypothesized that a significant proportion of asymptomatic patients has inducible orthodromic tachycardia during programmed electrical stimulation.MethodsThis retrospective study includes 1853 patients with preexcitation who underwent invasive electrophysiological testing in two Swedish University Hospitals between 1991 and 2018. The mean age was 36 ± 17 years with a range of 3–89 years. Thirty-nine percent was women. A total of 269 patients (15%) were children younger than 18 years. Electrophysiological data included effective refractory period of the accessory pathway (APERP, in 1069 patients), tachycardia cycle length, inducibility and type of tachycardia, and AP localization.ResultsA total of 1703 (93%) patients reported symptoms suggesting tachyarrhythmias before the study and 128 (7%) were asymptomatic. The proportion of potentially dangerous pathways with short APERP (≤ 250 ms) were similar in symptomatic and asymptomatic patients (187/949, 20% vs. 25/108, 23%) (P = 0.40) as was the mean APERP (303 ± 68 ms vs. 307 ± 75) (P = 0.61). The proportion of patients who had inducible arrhythmia was larger in the symptomatic group (64% vs. 31%) (P < 0.001).ConclusionThe results of this study strengthen the present guideline recommendation (IIA) to consider invasive risk assessment in patients with asymptomatic preexcitation.

Feasibility of open window mapping approach in accessory pathways ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction and Objectives We described a new protocol of open window mapping (OW) in accessory pathways (AP) in CARTO® 3 system. This protocol automatically mapping conventional electrophysiology criteria of AP diagnostic, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT) and annotation at unipolar signal (wavefront annotation). Methods Single center, prospective and observational study of 17 consecutive patients underwent AP catheter ablation. Results Mapping was performed in anterograde conduction in 13 patients (76.5%), retrograde in 5 patients(29,4%) and orthodromic tachycardia in 2 patients (11,7%). Mean of numbers of points were 3092±2246, with 30min ± 13min of mapping. Ablation was effective in 17 patients( 100%) and RF time until complete AP elimination was 2.6s. Image 1 show representation of EEML tool, targeting shorter interval EGM AV or VA and color adjust to determine earliest LAT. Image 1 show representation of EEML tool, targeting shorter interval EGM AV or VA and color adjust to determine earliest LAT. Conclusions In our experience, automatically mapping of conventional electrophysiology criteria for AP diagnostic is able to localize AP insertion, suggesting an increasing in effectiveness of procedure, a reducing in mapping time, ablation time and X-ray exposure time.

Ventricular versus atrial side ablation for treatment of atrioventricular accessory pathways: a randomized controlled clinical trial.

The earliest atrial (A)/ventricular (V) activation potentials, or fused A/V potentials, are commonly used as ablation targets for atrioventricular (AV) accessory pathways (APs). However, these targets can be achieved in a relatively wide area of the heart around AV rings at both atrial and ventricular sides. The aim of this study is to analyze the height of intracardiac A and V waves and their correlation to find the most appropriate side for successful delivery of radiofrequency energy, atrial or ventricular edge. Ninety patients diagnosed with orthodromic AV re-entrant tachycardia (AVRT) or Wolff-Parkinson-White syndrome were enrolled. Local atrial/ventricular (A/V) amplitude potentials with the earliest activation or fused AV potentials were measured. Patients were randomly assigned into two groups with a 2:1 ratio. In group 1, ablation was done at the site where A was greater than V. In group 2, V was greater than A. Primary endpoint was success at first attempt, achieving antegrade AP conduction block, AV block during right ventricle pacing, or AVRT termination with no AP conduction. Fifty-one patients (56.7%) were male. Thirty patients had an ablation at an atrial site (A > V) and 60 at a ventricular site (V > A). Ablation was more successful at the ventricular site (87% vs 100%, P = 0.011). All 30 patients in the atrial arm and 71% of the ventricular group underwent ablation via the antegrade method. Success of catheter ablation of APs is higher where V > A (ventricular site of AP), indicating the priority of the ventricular edge of the mitral ring for a better outcome.

Miniseries 2-Septal and paraseptal accessory pathways-Part II: Para-Hisian accessory pathways-so-called anteroseptal pathways revisited.

Surgeons, when dividing bypass tracts adjacent to the His bundle, considered them to be 'anteroseptal'. The area was subsequently recognized to be superior and paraseptal, although this description is not entirely accurate anatomically, and conveys little about the potential risk during catheter interventions. We now describe the area as being para-Hisian, and it harbours two types of accessory pathways. The first variant crosses the membranous septum to insert into the muscular ventricular septum without exiting the heart, and hence being truly septal. The second variant inserts distally in the paraseptal components of the supraventricular crest, and consequently is crestal. The site of ventricular insertion determines the electrocardiographic expression of pre-excitation during sinus rhythm, with the two types producing distinct patterns. In both instances, the QRS and the delta wave are positive in leads I, II, and aVF. In crestal pathways, however, the QRS is ≥ 140 ms, and exhibits an rS configuration in V1-2. The delta wave in V1-2 precedes by 20-50 ms the apparent onset of the QRS in I, II, III, and aVF. In the true septal pathways, the QRS complex occupies ∼120 ms, presenting a QS, W-shaped, morphology in V1-2. The delta wave has a simultaneous onset in all leads. Our proposed terminology facilitates the understanding of the electrocardiographic manifestations of both types of para-Hisian pathways during pre-excitation and orthodromic tachycardia, and informs on the level of risk during catheter ablation.

Orthodromic Atrioventricular Tachycardia in Wolff-Parkinson-White Syndrome with Two Accessory Pathways Participation during the Same AVT

Case report of a 49-year-old patient with Wolff-Parkinson-White syndrome, very symptomatic, with apparent parahisian pathway who, during an electrophysiological study, presented orthodromic atrioventricular tachycardia, featuring two accessory pathways, retrogradely, the parahisian pathway and a hidden left posterolateral pathway, during the same tachycardia, alternating the retrograde pathway of tachycardia without interruption.

Comparison of Outcomes of Catheter Ablation in Asymptomatic Versus Symptomatic Preexcitation to Guidelines and Beyond

Management of asymptomatic subjects with preexcitation remains controversial. Our objective was to analyze the reasons an electrophysiological study (EPS) was performed in an asymptomatic population referred for the procedure, and compare the results of catheter ablation between asymptomatic and symptomatic patients. Patients ≥18years of age with preexcitation referred for an EPS and ablation were grouped as either symptomatic or asymptomatic. We analyzed in both subsets for (1) reasons for the procedure, (2) EPS results (anterograde effective refractory period of the accessory pathway, tachycardia/atrial fibrillation inducibility, anatomical localization), (3) success of the procedure, and (4) incidence of complications. We included 175 patients, 121 of which were symptomatic (39 ± 16 years) and 54 were asymptomatic (35 ± 14 years, p = NS not significant). The most frequent symptoms were palpitations (87%) and syncope (7%). EPS was performed in 44 of 54 asymptomatic patients mainly because of involvement in sports (60%) or high-risk employment (14%). Anterograde effective refractory period was significantly longer in asymptomatic patients (314 ± 55milliseconds) than in symptomatic patients (278 ± 46milliseconds; p <0.001). Orthodromic tachycardia inducibility was significantly higher in symptomatic than in asymptomatic patients (69% and 27%, respectively; p <0.001). A total of 170 accessory pathways (49% left free wall, 12% right free wall, 39% septal) were observed without significant differences in the anatomical location between groups. Catheter ablation was attempted in all patients, succeeding in 98% of symptomatic and 95% of asymptomatic patients, without major complications in either group. In conclusion, the reasons for invasive evaluation of asymptomatic patients with preexcitation may be outside the scope of current guidelines. Catheter ablation produces excellent results without major complications.

Case Report: Wide-to-Narrow QRS Tachycardia in a 3-Month-Old Infant

Introduction: It is rare to find that wide QRS tachycardia automatically changes to narrow QRS tachycardia, and it is more difficult to clarify the mechanism.Case Report: A 3-month-old infant with recurrent paroxysmal supraventricular tachycardia underwent transesophageal cardiac electrophysiological examination. The wide QRS tachycardia was induced by atrial RS2 stimulation, and it soon changed to narrow QRS tachycardia automatically. By the accurate measurement of esophageal lead, it was found that the electrocardiogram changes completely conform to Coumel law. The mechanism of wide and narrow QRS tachycardia was orthodromic atrioventricular reentrant tachycardia with or without ipsilateral functional bundle branch block, and the accessory pathway was defined as the left free wall-concealed accessory pathway.Conclusion: Transesophageal cardiac electrophysiological examination can reveal some special electrophysiological phenomena, and its non-invasive nature is especially suitable for infants.

Recurrence of palpitations following electrophysiological study and ablation in suspected but undocumented paroxysmal supraventricular tachycardias: follow-up results of the BELIEVE-SVT registry

Abstract Funding Acknowledgements Type of funding sources: None. Introduction ECG documentation of paroxysmal supraventricular tachycardias (PSVT) may be challenging due to their short duration and usually abrupt end. As ablation represents first-line treatment of this pathologies, it is not uncommon that physicians refer patients to electrophysiological study (EPS) when symptoms are suggestive of PSVT even though no ECG documentation has been obtained. Our objective was to evaluate the results of ablation performed in patients with induced arrhythmias in EPS but no previous ECG documentation. Methods Retrospective and observational multicenter registry of consecutive patients undergoing EPS, followed or not by ablation, referred because of undocumented clinical suspicion of PSVT. We collected clinical, EPS and clinical follow-up data, along with data regarding ablation, when performed. Descriptive statistical analysis was carried out using Stata. Results 427 patients of 12 centers were included. Mean age was 46.3 ± 16.1 and 297 (69.6%) were females. Sustained arrhythmias were induced in most patients (n = 255; 59.7%) and ablation was performed in 274 (64.2%). 10 complications (2.3% of procedures) were reported: 3 transient AV block, 2 PR interval prolongation, 2 puncture-related hematoma, 2 painful sites of puncture and 1 catheter entrapment in mitral chordae. During a mean follow-up of 3.1 ± 2.0 years, 111 patients experienced recurrence of palpitations, mostly (n = 77; 69.4%) without ECG documentation. Clinical recurrence was more frequent in subjects who had not been ablated (41.8% vs 17.2% in ablated patients; risk ratio 2.44 (CI 95% 1.77-3.36); p &amp;lt; 0.001). Table 1 shows types of clinical recurrences. Conclusions EPS in patients with high clinical suspicion of PSVT, followed by ablation when tachycardia is induced is effective in preventing future recurrences of palpitations. Early referral for EPS can, therefore, reduce visits to the emergency room, admissions and healthcare burden due to other low-yield, unnecessary tests. Type of recurrence ECG documentation 34(8.0%) ·Sinus rhythm 12(2.8%) ·Atrial tachycardia 6(1.4%) ·Typical atrioventricular nodal reentrant tachycardia 5(1.2%) ·Atrial fibrillation 5(1.2%) ·Premature ventricular beats 3(0.7%) ·Orthodromic atriventricular tachycardia 2(0.5%) Non documented recurrence 77(18.0%)

Ultra-high resolution mapping and ablation of accessory pathway conduction.

Detailed mapping studies of accessory pathway (AP) conduction have not been previously performed using ultra-high resolution mapping systems. We sought to evaluate the clinical utility of ultra-high resolution mapping systems and the novel "Lumipoint" algorithm in AP ablation. This study included 17 patients who underwent AP mapping using minielectrode basket catheters and Rhythmia systems. Ablation was performed with 4-mm irrigated-tip catheters. Antegrade and retrograde AP conduction was observed in 6 and 16 patients. Atrial activation map was obtained during orthodromic tachycardia and ventricular pacing in 13 (76.5%) and 14 (82.3%) patients, and the earliest activation area was identical. Ventricular activation maps were created during atrial pacing in 3 patients. All maps showed focal activation patterns on global activation histograms, and the valley on the histogram highlighted the earliest activation area. "Complex activation" features further highlighted limited areas with continuous electrical activity during the time period in the majority. APs were located at the mitral and tricuspid annuli in 15 and 2 patients, and all were successfully eliminated with 3.4 ± 0.6s applications. No patients had recurrences during a median follow-up of 15 [10.5-22.5] months. At successful ablation sites, the local atrial and ventricular electrogram amplitudes and ratio tended to be greater, and fusion or continuous electrical activity between the atrial and ventricular components was more frequently observed on the minielectrode than ablation catheter (17/17 vs. 12/17, p = 0.005). Ultra-high resolution activation mapping and a novel algorithm facilitated the AP localization. The local electrogram characteristics differed between the minielectrode and ablation catheters.

Electrophysiological manifestations of rare supra-ventricular tachycardias with concealed nodo-ventricular fibers.

To clarify the electrophysiological mechanism of supra-ventricular tachycardias (SVT) with concealed nodo-ventricular (NV) fibers. We studied the intra-cardiac electrograms during electrophysiological study (EPS) of three cases of SVT which concerned concealed NV fibers. Electrophysiological maneuvers including right ventricular apex entrainments, RS2 stimuli, adenosine triphosphate injection and so on were done for differential diagnosis before ablation. Among these patients, one had atrio-ventricular nodal reentrant tachycardia (AVNRT) with a bystander NV fiber; the other 2 had NV fiber mediated orthodromic reentrant tachycardias (NVRT). VA dissociation was observed during SVT in all 3 cases with an antegrade His bundle conduction sequence. Ventricular stimulation at His refractory period reset the H-H intervals and the V-V intervals sequentially, suggesting the existence of a retrogradely conductive accessory pathway. Adenosine injection could terminate these tachycardias. The cycle length of an NVRT prolonged during the status of functional right bundle branch block, suggesting that the fiber located on the right side. Multiple QRS fusion morphologies during ventricular entrainments or ventricular stimulation at His refractory period at a fixed position could be observed in these cases. Concealed NV fibers can either mediate orthodromic reentrant tachycardia or be a bystander of AVNRT. V-A dissociation usually occur during such SVTs. Dissociation of H and V due to entrainment of right ventricular apex is a newly discovered maneuver to differentiate AVNRT from NVRT.

SHORT RP TACHYCARDIA, SUCCESFULLY MANAGED WITH RADIO FREQUENCY ABLATION.

A 35-year female patient presented with recurrent palpitations. Her baseline ECG was normal but during the episode of palpitations, it revealed short RP tachycardia. Intracardiac ECG revealed orthodromic reentrant tachycardia due to concealed left lateral pathway (Figure 1). She was successfully treated by radio-frequency ablation through a trans-septal approach. Figure 2 shows RV pacing getting conducted over the left lateral pathway to atria which disappears after ablation of the pathway.

Wide complex tachycardia cycle length shorter than the narrow complex tachycardia. What is the mechanism?

15-Year-old man's cardiac event monitor showed an episode of wide complex tachycardia which transitioned into narrow complex tachycardia. The tachycardia cycle length was shorter during wide complex tachycardia compared with narrow complex tachycardia. He underwent electrophysiology study in which an orthodromic atrioventricular reentrant tachycardia (wide and narrow complex tachycardia) utilizing left posterolateral bypass tract was induced. We propose the mechanism for shorter tachycardia cycle length during wide complex tachycardia compared with narrow complex tachycardia.

P1010Electrophysiological characteristics of paroxysmal tachycardia in children with short PQ interval

Abstract Introduction It is well known that children with short PQ interval can have different types paroxysmal tachycardia (PT). Combination of short PQ interval with PT is called Lown-Ganong-Levine (LGL) syndrome. We have hypothesized that in children with short PQ interval electrophysiological types of PT do not correlate with shortening of PQ interval. Purpose The aim of the study was to assess the PT types based on results of the electrophysiological studies and radiofrequencycatheter ablation (RFA), and to estimate the AV conduction parameters and their dynamic changes before and after the procedure. Materials and methods of research: 55 children with supraventricular tachycardia (SVT) and short PQ interval were examined. The examination included:ECG, 24-hour Holter monitor, transesophageal pacing study (TEPS), intracardiac electrophysiological study (EPS). 22 children underwent RFA procedure. During the period of the study 55 children had 111 TEPS and 28 EPS studies. Results 21 (38,2%) children had orthodromic AV reentrant tachycardia with accessory pathway (AVRT), 27 (49,1%) had typical (slow-fast) AV nodal reentrant tachycardia (AVNRT), 2 (3,6%) had atypical AVNRT, 1 (1,8%) had combination of typical and atypical AVNRT, 1 (1,8%) had atrial ectopic tachycardia combined with atypical AVNRT, 4 (7,3%) had spontaneous atrial fibrillation or atrial flutter, 3 (5,4%) had combination with typical AVNRT and 1 child (1,8%) had AVRT. PQ interval measured 107,2 ms (83–120ms). 22 (40%) children underwent RFA-13 children with typical AVNRT, 9 with AVRT. In children with AVNRT tachycardia cycle length was 229–425 ms (309,8±67,6ms). Primary RFA was effective in 10 (76,9%) children. The AVNRT recurrence was found in 3 (13,6%) cases after 7,2±4,3 month from the time of procedure. After slow pathway ablation PQ interval length didn't change (107,1±9,1ms compared to 108,2±7,1ms; p=0,2). No change occurred with the maximal rate of 1:1 conduction through AV node (187,8±14,8 imp/min compared to187±12,5 imp/min; p=0,2). Effective refractory period of AV node (AVNERP) increased by a small amount (288,9±14ms, compared to 266±42,7ms; p=0,06). 9 (40,9%) children underwent RFA of the accessory pathway (AP). In all of the cases there were concealed AP with the left-sided localization. AVRT cycle length was 259–382 ms (304,2±41,2ms). After RFA of concealed AP maximal rate of 1:1 conduction through AV node increased by a small amount (220±26,4 imp/min compared to 191,2±23,6 imp/min) and AVNERP decreased (256,7±25,2ms compared to 268,6±38,9ms; p=0,09).After RFA of AP PQ interval length didn't change (110±5,9ms compared to 110±5ms; p=0,1). Conclusion In children with short PQ interval PT was associated with dual physiology of AV connection or with concealed AP. After the successful RFA in children with AVNRT and AVRT there was no PQ interval normalization, which remained short in all examinations. Thus, short PQ- interval is a co-existing phenomenon in children with AVNRT and AVRT.

Right free-wall accessory pathway with branched atrial insertions: Clinical, electrocardiographic, and electrophysiological characteristics

Right free-wall (RFW) accessory pathway (AP) with branched atrial insertions is a rare, underrecognized AP that may be associated with initial ablation failure. The purpose of this study was to investigate the clinical and electrophysiological characteristics of this AP. From January 2011 to March 2018, 10 patients identified with branched RFW-AP were enrolled in this study, and 30 consecutive patients with conventional RFW-APs served as control group. Right atrium (RA) was activation-mapped and 3-dimensionally reconstructed during AP-mediated orthodromic tachycardia or right ventricular pacing. Atrial insertions were defined as the earliest breakout sites, and their relationship with the tricuspid annulus (TA) were described and analyzed. An average of 3 separate atrial insertions on the atrial side were documented among these 10 cases (5 female and 5 male; mean age 38.0 ± 13.9 years). All atrial insertions were away from the TA. The nearest atrial insertions averaged 15.9 ± 3.4 mm away from the TA, and the farthest atrial insertions were 22.6 ± 5.7 mm away from the TA. Anterograde and retrograde AP conduction remained unaffected after ablation of the first earliest breakout site but were eliminated by ablating all insertions after an average of 2.5 (range 2-2.5) remaps, 3 sites of ablation (range 2.5-4.5), 21 (range 15.5-37.8) radiofrequency applications, and 659.5 (range 464.3-1144.3) seconds of radiofrequency ablation duration. After 12-month follow-up, no patients reported AP conduction recovery or recurrent tachycardia. RFW-AP with branched atrial insertions is an atypical AP variant and featured by >1 distinct atrial insertions on atrial side. Stepwise ablation rather than single focal ablation is required to eliminate all retrograde conduction.

An atriofascicular tract in a girl with Ebstein's anomaly and right bundle block

Described in this article is a clinical case of a 14-year girl with Ebstein's anomaly and a complex preexitation syndrome (two atrioventricular pathways and a true atriofascicular Mahaim's tract). The atriofascicular tract was involved in antidromic and orthodromic tachycardias. The Л-wave was absent initially, because the spontaneous right bundle block and the comparable AV conduction velocity imitated a normal sinus rhythm. All accessory pathways were eliminated successfully during catheter ablation.

Trans-subclavian Approach for Radiofrequency Ablation of Atrioventricular Accessory Pathway Associated with Coronary Sinus Diverticulum

A 20-year-old Chinese male presented with narrow-complex tachycardia related to type B pre-excitation pattern (Figure 1A and 1B). During the electrophysiological study, the earliest ventricular and atrial activation was adjacent to the coronary sinus (CS) electrode 9,0 during sinus rhythm and 7,8 during ventricular pacing (Figure 1D, 1E and 1G), respectively. An orthodromic atrioventricular reentry tachycardia could be induced reproducibly. Subsequently, a conventional 4 mm tip ablation catheter (Triguy, APT Medical, PRC) was introduced into the right ventricle via a long sheath (SR0, St. Jude Medical, USA). Repeated radiofrequency (RF) energy (50 W at 55 8C) delivery at the target site failed to eliminate the antegrade accessory pathway (AP) conduction due to rising impedance and poor power delivery. Considering the possibility of the AP located at the epicardium, coronary sinus angiography was implemented by Amplatz left 1 catheter. Two CS diverticula were identified near the ostium (Figure 1G, Online Video 1 and 2). A salineirrigated ablation catheter (Triguy, APT Medical, PRC) was reintroduced into the CS via the right femoral vein

SLOW/SLOW TYPE OF ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA IN FIRST DEGREE ATRIOVENTRICULAR BLOCK

The report describes the case of slow/slow type of atrioventricular nodal reentrant tachycardia in first degree atrioventricular block which simulate atrial ectopic or orthodromic tachycardia. Differential diagnosis technique is described and mechanisms of the phenomenon are illustrated.