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Novel approach of slow pathway ablation in common atrioventricular nodal reentrant tachycardia by peak frequency map

Abstract Background It is difficult to visualize slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) even with recent high-density mapping. This could be because the slow pathway potential is buried by the potential of atrial working cells during sinus rhythm and tachycardia. In other words, it is extremely difficult for conventional 3D mapping systems to annotate slow pathway potential even though the histological run of slow pathway is known .[1], [2] Purpose The purpose of this study is to visualize the atrial myocardial junction of rightward inferior extension by the peak frequency map of Ensite X in common AVNRT and to evaluate whether relative high frequency (HF) sites in low voltage area extending from Koch's triangle to tricuspid annulus (TA) is effective targets of slow pathway ablation and the characteristics of junctional rhythm (JR) after radiofrequency application. Methods This study is single-center prospective cohort study. In 37 consecutive common AVNRT patients, novel approach and conventional approach of slow pathway ablation were performed in 17 and 20 patients, respectively. The conventional approach is anatomical and electrophysiological approach. Peak frequency map was performed during sinus rhythm with HD-grid catheter in novel approach patients. A frequency scanning is performed to locate relative HF sites on the tricuspid annulus. Radiofrequencey application is 30 W, 30-60 sec, and the end point was no inducibility or until one echo under load of isoproterenol. Results The success rate was 100 % with two approaches. The relative HF sites in low voltage area were distributed at the TA side from 4 to 5 o'clock in all novel approach patients, mean peak frequency in success site was 419 ± 87 Hz. The distance to His bundle from success site was farther (24.8 ± 4.9 vs. 12.8 ± 4.4 mm, p<0.001), JR was slower (93 ± 14 vs. 118 ± 10 bpm, p=0.013), time to JR occurrence was shorter (3.0 ± 1.3 vs. 7.6 ± 4.6 sec, p=0.003), and elimination rate of jump up (78 % vs. 40 %, p=0.06) was higher in novel approach. Conclusions The relative HF sites in low voltage area at TA side from 4 to 5 o'clock by peak frequency map could be novel target of slow pathway ablation with high success rate and sufficient safety and efficiency.peak frequency map

Peak frequency annotation algorithm–guided slow pathway ablation in typical atrioventricular nodal reentrant tachycardia

BackgroundThe slow pathway potential is difficult to annotate because it is buried within the atrial potential. Omnipolar technology near field can automatically annotate the peak frequency potential associated with acquired intracardiac electrograms. ObjectivesThis study aimed to visualize the junction between the transitional cells and the slow pathway using a peak frequency map with omnipolar technology near field and evaluate whether the high-frequency site around the tricuspid annulus (TA) is an effective target for slow pathway ablation. MethodsThis prospective observational study enrolled 37 patients with typical atrioventricular nodal reentrant tachycardia. Patients underwent slow pathway ablation using a peak frequency map (n = 17) and the conventional approach based on anatomical and electrophysiological findings (n = 20). ResultsHigh-frequency sites were distributed at the TA side of the 4–5 o’clock position in all patients mapped using the peak frequency map of OTNF. The distance to the His bundle from the successful ablation site was farther (24.0 ± 4.8 mm vs 12.7 ± 4.0 mm; P < .0001), junctional rhythm was slower (88 ± 17 beats/min vs 115 ± 12 beats/min; P < .0001), the time to junctional rhythm after radiofrequency application was shorter (3.4 ± 1.4 seconds vs 8.2 ± 4.6 seconds; P < .0001), and the elimination rate of jump ups (71% vs 30%; P = .02) was higher in the peak frequency map–guided group. ConclusionThe high-frequency site of the TA at 4–5 o’clock in the peak frequency map could be a novel target of slow pathway ablation with high safety, efficiency, and efficacy.

AVNRT cryoablation in children

The recently published "electrophysiologically guided low-voltage bridge (LVB) strategy" is effective in the ablation of atrioventricular nodal re-entry tachycardia (AVNRT) in children. This study aimed to evaluate its efficacy and safety in children <26kgs. Fourteen children [64% males, median age 6.5 years (IQR 6-8 years), median weight 25.5kg (IQR 24-26kg)] with AVNRT were treated. In all patients, we detected a LVB associated to a typical slow pathway potential. The acute success rate was 100% with a mean of 5.5 cryoablation deliveries. All procedures were performed with near-zero fluoroscopic exposure (median time 0.15 min, IQR 0-0.7 min), in six patients fluoroscopy was 0 min. There were no complications or recurrences during the follow-up (median 20.91 months, IQR 11.7-26.7 months).

Atrioventricular Nodal Reentrant Tachycardia Ablation Using Mini-Electrode Recordings.

Catheter ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) is mainly performed using anatomical landmarks. We sought to see whether a new ablation catheter equipped with mini-electrodes may facilitate the mapping of slow pathway potentials for AVNRT ablation. We prospectively included patients referred for AVNRT in our center. Mapping and ablation were performed using an irrigated catheter equipped with 3 insulated mini-electrodes on the distal tip. Thirteen consecutive patients were included (85% female, median age 46 years). Slow pathway potentials could be identified in 77% of cases on mini-electrode bipolar tracings, versus 15% on conventional bipolar tracings (p = 0.0009). At the end of the procedure, double potentials on the ablation line were identified in all patients, only on mini-electrode bipolar tracings. Following ablation, an interval separating double potentials in sinus rhythm ≥15% of baseline tachycardia cycle length was associated with non-inducibility in all patients (p < 0.0001). No recurrence occurred during 1 year of follow-up. The use of mini-electrodes may help target slow pathway potentials during AVNRT ablation. Identification of sufficiently split double potentials on the ablation line might represent an electrophysiological endpoint in these patients.

Physiology of slow pathway conduction during sinus rhythm: evidence from high density mapping within the triangle of Koch.

To evaluate nature of AV nodal activation in patients with AVNRT using high density electro-anatomic mapping (HD-EAM). HD-EAM was created in 30 patients with AVNRT from the triangle of Koch (ToK) in sinus rhythm (SR). Isochronal late activation maps (ILAM) were created. EAMs were analyzed for slow pathway (SPW) and fast pathway (FPW) activation. A pivot point (PP) was defined where FPW and SPW collided and pivoted back to the AV node (AVN). Conduction was assessed with programmed extrastimulus (PES) in 9 patients until FPW refractory period (ERP). The change in PP distance from the HIS (ΔPP) was measured in SR and PES. The ΔPP was compared to ΔAH. The PP was ablated and SR re-mapped. The FPW activates the His and moves inferiorly toward the coronary sinus (CS). Activation also enters the ToK near the CS and collides with the FPW which then pivots around a functional line of block (LOB) within the ToK and moves superiorly along the septal tricuspid annulus. PP electrograms are fractionated, low amplitude, and consistent with SPW potentials (Haissaguerre et al. in Circulation 85:2162-2175, 1992). During PES the PP moved superiorly until FPW ERP when only SPW activation occurs. Normalized ΔAH and ΔPR vs ΔPP was highly correlated p < 0.0001. Ablation at the PP was successful and associated with loss of SPW fusion and pivot. We conclude HD-EAM/ILAM provide a novel method for localizing the SPW in SR. This study provides further understanding of dual AV nodal physiology and may aid in targeting the SPW for ablation of AVNRT.

P1005Origin, distribution and timing of the slow pathway potentials recorded inside the Kock's triangle in Avnrt patients through High-density Mapping

Abstract Background Atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) exhibits anatomic variability and spatially heterogeneous propagation inside the Kock's Triangle (KT). The mechanism of the reentrant circuit has not been elucidated yet. Purpose To evaluate signal characteristics and find out the origin, distribution, and timing of the slow pathway (SP) potentials recorded in the KT. Methods The 3-D KT geometry was created during both sinus rhythm (SR) and tachycardia (TR) from the basket mapping catheter IntellaMap Orion and the Rhythmia Mapping System (Boston Scientific). The KT was divided into 8 regions moving from an antero-septal to postero-septal areas and bounded by tricuspid annulus (TA) anteriorly and tendon of Todaro (TT) posteriorly. Each area was characterized in terms of distribution and timing of Jackman (JP) and Haissaguerre (HP) potentials and signal amplitude. Results 20 consecutive successful SP ablation cases of AVNRT were included (mean RA acquired points = 6000±1100, 275±63 inside the KT; mean KT area=29±3mm2; mean mapping time=12±5 minutes). During SR, the site of earliest atrial activation within the KT was anterior in 80% of patients whereas a midseptal activation occurred less frequently (20%). The mid-septal regions bounded by TA anteriorly and TT posteriorly showed higher prevalence of JP as compared to antero-/mid-septal regions across TT both in SR and TR (77.4% vs 4.8% during SR, p&lt;0.0001; 84.1% vs 0% during TR, p&lt;0.0001, respectively). HPs seemed to have variable distribution across KT (50% of these potentials recorded in antero- to mid-septal regions across TT for SR, 52.3% for TR). The median signal voltage was 0.44 [0.2–0.9] mV during SR and 0.5 [0.22–0.895] mV during TR. The mid-septal region was the area of lowest voltage compared to other regions (0.2 [0.1–0.7] mV vs 0.5 [0.4–1.5] mV for SR, p&lt;0.0001; 0.2 [0.15–0.6] mV vs 0.6 [0.4–1.5] mV for TR, p&lt;0.0001, respectively). Conclusion JPs seem to be associated with low signal-amplitude areas whereas HPs seem to have variable distribution across KT. Although not perfectly known, the typical low-high-type double potential of JP might be therefore explained by wavefront collision in the lowest area of the KT. Acknowledgement/Funding None

High-resolution mapping of the triangle of Koch: Spatial heterogeneity of fast pathway atrionodal connections

Dedicated mapping studies of the triangle of Koch to characterize retrograde fast pathway activation have not been previously performed using high-resolution, 3-dimensional, multielectrode mapping technology. To delineate the activation pattern and spatial distribution of the retrograde fast pathway within the triangle of Koch during typical atrioventricular nodal reentrant tachycardia (AVNRT) and right ventricular pacing in a consecutive series of patients using the Rhythmia mapping system (Boston Scientific, Natick, MA). A total of 18 patients with symptomatic typical AVNRT referred for ablation underwent ultra high-density mapping of atrial activation with minielectrode basket configuration during tachycardia. The earliest atrial activation was mapped using automated annotation, with manual overreading by 2 independent observers. The triangle of Koch was classified into 3 anatomic regions: anteroseptal (His), midseptal, and posteroseptal (coronary sinus roof). Thirteen patients underwent mapping of atrial activation during ventricular pacing. A median of 422 mapping points (interquartile range 258-896 points) was acquired within the triangle of Koch during tachycardia. The most common site of earliest atrial activation within the triangle of Koch was anterior in 67% of patients (n=12). Midseptal early atrial activation was seen in 17% (n=3), and posteroseptal activation was observed in 11% (n=2). One patient exhibited broad simultaneous activation of the entire triangle of Koch. Slow pathway potentials were not identified. With high-resolution multielectrode mapping, atrial activation during typical AVNRT exhibited anatomic variability and spatially heterogeneous activation within the triangle of Koch. These findings highlight the limitations of an anatomically based classification of atrioventricular nodal retrograde pathways.

Zero-fluoroscopy cryothermal ablation of atrioventricular nodal re-entry tachycardia guided by endovascular and endocardial catheter visualization using intracardiac echocardiography (Ice&ICE Trial).

Stochastic damage of the ionizing radiation to both patients and medical staff is a drawback of fluoroscopic guidance during catheter ablation of cardiac arrhythmias. Therefore, emerging zero-fluoroscopy catheter-guidance techniques are of great interest. We investigated, in a prospective pilot study, the feasibility and safety of the cryothermal (CA) slow-pathway ablation in patients with symptomatic atrioventricular-nodal-re-entry-tachycardia (AVNRT) using solely intracardiac echocardiography (ICE) for endovascular and endocardial catheter visualization. Twenty-five consecutive patients (mean age 55.6 ± 12.0 years, 17 female) with ECG-documentation or symptoms suggesting AVNRT underwent an electrophysiology study (EPS) in our laboratory utilizing ICE for catheter navigation. Supraventricular tachycardia was inducible in 23 (92%) patients; AVNRT was confirmed by appropriate stimulation maneuvers in 20 (80%) patients. All EPS in the AVNRT subgroup could be accomplished without need for fluoroscopy, relying solely on ICE-guidance. CA guided by anatomical location and slow-pathway potentials was successful in all patients, median cryo-mappings=6 (IQR:3-10), median cryo-ablations=2 (IQR:1-3). Fluoroscopy was used to facilitate the trans-septal puncture and localization of the ablation substrate in the remaining 3 patients (one focal atrial tachycardia and two atrioventricular-re-entry-tachycardias). Mean EPS duration in the AVNRT subgroup was 99.8 ± 39.6minutes, ICE guided catheter placement 11.9 ± 5.8minutes, time needed for diagnostic evaluation 27.1 ± 10.8minutes, and cryo-application duration 26.3 ± 30.8minutes. ICE-guided zero-fluoroscopy CA in AVNRT patients is feasible and safe. Real-time visualization of the true endovascular borders and cardiac structures allow for safe catheter navigation during the ICE-guided EPS and might be an alternative to visualization technologies using geometry reconstructions.

Atrioventricular nodal block with atrioventricular nodal reentrant tachycardia ablation.

The initial model of atrioventricular nodal tachycardia (AVNRT) as a small circuit of reentry within the AV node precluded a catheter-based cure for this arrhythmia without the occurrence of AV conduction block. Landmark observations that the atria were part of the circuit of AVNRT1 and that the arrhythmia could be reset with paced beats placed at sites anatomically distant from the compact AV node2 set the stage for the present expectation of curative ablation without AV block. Despite this understanding of the AVNRT mechanism and the large accrued operator experience during the past 3 decades when ablating this arrhythmia, AV block still occurs in ≈1% to 2.3% as a complication of ablation.3 See Article p 739 In this installment of teaching rounds, Chen et al4 share with us what we can learn from a series of patients with permanent or transient AV block noted during and soon after radiofrequency energy delivery. The authors provide an honest, transparent, and instructive view of their 5 cases. The fact that we are successful ≈99% of the time without complication suggests that the present methods for maintaining safety, including monitoring junctional rhythm during ablation and relating catheter position to the fluoroscopic anatomic approximation of the AV node location are mostly successful. The student of electrophysiology must, however, be aware of how these precautions can fail us. Even closely spaced bipolar electrodes placed over the compact AV node are not able to record electrograms from the node itself. Because we cannot map the structure we need to avoid, we must estimate anatomically its location and correlate this information with our standard fluoroscopic views. ### Utility The compact AV node is located within Koch’s triangle, approximately in its mid and central position. Using the His bundle as a surrogate for the superior vertex and …

Single center experience of fluoroless AVNRT ablation guided by electroanatomic reconstruction in children and adolescents

Purpose: Anatomical considerations and risks related to x-ray exposure make atrio-ventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety and efficacy of performing fluoroless slow pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents. Methods: Twenty-five consecutive patients (mean age 13.8±2.5 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow pathway potential and performed using a 4-mm tip catheter. Results: Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 96%. Acute success was achieved in 100% of the patients with a median of 2 cryo-applications. Fluoroless ablation was feasible in 23 patients, while in 2 subjects 50 and 45 seconds of x-ray were needed due to difficult vascular accesses. After a mean follow-up of 27.5 months AVNRT recurred in 6 patients. All the recurrences were successfully treated with a second procedure. In 4 patients a fluoroless cryoablation with a 6-mm tip catheter was successfully performed, while in the remaining 2 patients a single pulse of 60 s of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred. Conclusions: Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

Single Center Experience of Fluoroless AVNRT Ablation Guided by Electroanatomic Reconstruction in Children and Adolescents

Anatomical considerations and risks related to x-ray exposure make atrioventricular nodal reentrant tachycardia (AVNRT) ablation in pediatric patients a concerning procedure. We aimed to evaluate the feasibility, safety, and efficacy of performing fluoroless slow-pathway cryoablation guided by the electroanatomic (EA) mapping in children and adolescents. Twenty-one consecutive patients (mean age 13.5 ± 2.4 years) symptomatic for AVNRT were prospectively enrolled to right atrium EA mapping and electrophysiological study prior to cryoablation. Cryoablation was guided by slow-pathway potential and performed using a 4-mm-tip catheter. Sustained slow-fast AVNRT was inducible in all the patients with a dual AV nodal physiology in 95%. Acute success was achieved in 100% of the patients with a median of two cryo-applications. Fluoroless ablation was feasible in 19 patients, while in two subjects 50 seconds and 45 seconds of x-ray were needed due to difficult progression of the catheters along the venous system. After a mean follow-up of 25 months, AVNRT recurred in five patients. All the recurrences were successfully treated with a second procedure. In three patients, a fluoroless cryoablation with a 6-mm-tip catheter was successfully performed, while in the remaining two patients, a single pulse of 60 seconds of radiofrequency energy was applied under fluoroscopic monitoring. No complications occurred. Combination of EA mapping systems and cryoablation may allow to perform fluoroless slow-pathway ablation for AVNRT in children and adolescents in the majority of patients. Fluoroless slow-pathway cryoablation showed a high efficacy and safety comparable to conventional fluoroscopy guided procedures.

Non-reentrant atrioventricular nodal tachycardia

Dual ventricular response to a single supraventricular impulse through dual atrioventricular (AV) nodal pathways is an interesting and uncommon phenomenon. Rarely, some patients can exhibit sustained one-to-two conduction producing a non-reentrant AV nodal tachycardia during sinus rhythm [1–6]. We report the case of a patient whose arrhythmia was caused by this mechanism. A 44-years-old male patient who had frequent irregular palpitations was admitted to hospital. He was misdiagnosed with atrial fibrillation and referred to our institute for consideration of pulmonary vein isolation. He did not have any significant disease in his medical history. Echocardiography was normal. The electrocardiogram showed an irregular narrow QRS complex tachycardia. Careful evaluation of the electrocardiograms revealed the presence of two ventricular activations for each atrial beat (Fig. 1). On some occasions, the wide QRS complexes with right bundle branch block (RBBB) morphology not preceded by P waves simulating premature ventricular complexes (PVCs) were observed. Electrophysiological study revealed regular 1:2 AV relationship. Each ventricular signal was preceded by a His deflection with a constant HV interval (46 ms) (Fig. 2a). The AH1 interval between the atrial wave and the first His deflection was 159 ms. The AH2 interval between the atrial wave and the second His deflection was 528 ms. Both AH1 and AH2 intervals were slightly variable. When AH2 interval was shorter than 520 ms, second ventricular responses were conducted by RBBB morphology (Fig. 2a). Because of sustained double responses, we could not perform programmed atrial extra stimulation to identify a jump in AH interval. After detailed electrophysiological examination, radiofrequency (RF) energy was delivered (40 W, 55 C, 66 s) in the posterior aspect of Koch’s triangle, where the typical ‘‘slow pathway potentials’’ were observed. After first RF application, 1:2 response disappeared (Fig. 2b). During post-ablation tests, we did not observe dual AV nodal conduction properties, and we could not induce any arrhythmia. On the 6 month follow-up, the patient was asymptomatic. Non-reentrant AV nodal tachycardia (1:2 tachycardia) is a rare manifestation of dual AV nodal physiology. Persistent simultaneous conduction of P waves over a fast and a slow nodal pathways may lead irregular supraventricular tachycardia. The two major electrophysiological properties of simultaneous anterograde fast and slow conduction during sinus rhythm are: (1) Absence of retrograde ventriculoatrial conduction via fast and slow pathways and (2) Critical conduction delay in slow pathway to allow sequential conduction of impulse from both pathways [1, 2]. Delay has to be longer than the effective refractory period of infranodal conduction system. A recently published review reported just 49 cases between dates of 1950 and 2011 [3]. Nevertheless, the prevalence of AV nodal non-reentrant tachycardia is likely to be underestimated because of difficulties in differential diagnosis. Sustained cycle length alternans is the characteristic for this arrhythmia [4]. However, changes in autonomic tone affecting conduction properties may lead irregular cycle length alternans and rate-dependent aberrancy. For these reasons, it can be erroneously diagnosed as atrial fibrillation, atrial flutter or atrial tachycardia with Wenckebach periodicity [3, 5, 7, 8]. These arrhythmias, E. E. Ozcan G. Szeplaki B. Merkely L. Geller (&) Heart Center, Semmelweis University, Gaal Jozsef street 9, Budapest 1122, Hungary e-mail: laszlo.geller@gmail.com

A case of typical atrial flutter causing unexpected advanced atrioventricular block despite lateral cavotricuspid isthmus ablation

Here, we report a case of a 69-year-old patient with paroxysmal atrial fibrillation and inducible typical atrial flutter who required catheter ablation. After pulmonary vein isolation, cavotricuspid isthmus ablation was performed. During ablation at a lateral site of the cavotricuspid isthmus, a spiky potential appeared at the distal electrode of the ablation catheter, and subsequently, a 2:1 atrioventricular (AV) block occurred. Radiofrequency (RF) delivery at the same site caused a similar phenomenon, implying that the spiky potential may reflect a slow pathway potential as an anatomical variant of the rightward extension of the AV node.

The “Slow Pathway” Potential: Fact or Fiction?

The exact electroanatomic circuit responsible for atrioventricular nodal reentrant tachycardia (AVNRT) remains poorly understood. Initially, the pathological substrate was thought to be a small reentry circuit within the compact AV node (AVN).1 However, through a series of detailed histological studies,2 computer modeling,3 optical mapping,4 and uniquely insightful observations of tachycardia behavior, with the introduction of critically timed and placed premature atrial complexes,5–7 the determinative role played by the atrial inputs to the AVN has been established. Article see p 225 The primary objective of electric mapping for safe and effective ablation of AVNRT is to establish markers to identify the compact AVN (and avoid ablation) and the slow pathway input to the AVN (and target this site for ablation). Despite the promise of initial attempts to define an “AVN potential,”8 there is no present technique available to electrically define the site of the compact AVN. Whether or not there is a distinct potential that identifies the slow pathway is open to debate. This slow pathway potential, if present, could universally guide safe and effective AVNRT ablation, but if its presence and relevance are misunderstood, it may inadvertently give rise to ablation failure and complication. In this issue of Circulation: Arrhythmia and Electrophysiology , Pandozi et al9 report their observations on detailed sinus rhythm propagation maps into the critical regions surrounding the compact AVN and the atrial inputs to the AVN. In 32 patients (26 with AVNRT), the high-density maps of Koch's triangle in sinus rhythm in their analysis revealed no evidence of propagation block and widespread evidence of slow conduction throughout this region. Before we assess the impact of their detailed study attempting to elucidate the origin and nature of slow pathway potentials, we need to appreciate the impact of multiple …

RFCA of Tachycardias Associated with a cTGA

Introduction: Tachycardias associated with a congenital corrected transposition of the great artery (cTGA) are rare. Methods: To analyze the type and results of RFCA of tachycardias associated with non-operative cTGA. Results: Five patients were identified. Three patients had atrioventricular reciprocating tachycardia (AVRT) and two had atrioventricular nodal reentrant tachycardia (AVNRT). One AVNRT patient had situs inversus (IDD), and the others situs solitus. Two of the 3 AVRT patients had accessory pathways at the posterior septum (PS) of the anatomical tricuspid annulus (aTA) and the other at PS of the anatomical mitral annulus (aMA). Acute success was accomplished and there were no recurrences in any of the patients. One AVNRT patient had the slow/fast type, and the RFCA application was performed around the anterior. His bundle region in the 2nd session. The tachycardia was no longer observed after the 3rd session. The other patient which had a IDD, had slow/fast and slow/slow AVNRT. The RFCA application was delivered to PS of the aMA for the slow/fast AVNRT where a slow pathway potential was recorded to guide the RFCA application and acute success was achieved. However, when the application was delivered to the aTA for the slow/slow AVNRT in which the earliest atrial activation site was used to guide the application, recurrence immediately occurred. Conclusion: The RFCA results were good for AVRT, but they were not good for AVNRT.

Paroxysmal Supraventricular Tachycardia with Idiopathic Pulmonary Arterial Hypertension—A Case Report—

There were few reports regarding arrhythmias with idiopathic pulmonary arterial hypertension (IPAH). A 37-year-old woman was presented with a 6-year history of palpitations. She was diagnosed as IPAH at 25 years old and introduced continuous intravenous administration of PGI2 at 27 years old. Her electrocardiogram revealed paroxysmal supraventricular tachycardia (PSVT) and was referred for catheter ablation. The electrophysiological study revealed dual pathway in AV and VA conduction. PSVT was induced by programmed atrial stimuli with jump up phenomenon under a small amount of isoproterenol. The tachycardia cycle length was from 460 ms to 560 ms, but earliest atrial potential was recorded at His and intra-atrial propagation was similar in any cycle lengths. The single-extra ventricular stimuli did not reset the tachycardia, so we diagnosed as common type AV nodal reentrant tachycardia. Fractionated potential so called slow pathway potential were recorded in broad postero-septal area and junctional tachycardia was immediately obtained during the applications of radiofrequency current, but it was hard to eliminate the PSVT. After 12 deliveries of radiofrequency current, PSVT could not be induced by any programmed stimuli.

Radiofrequency Ablation in Noninducible Supraventricular Tachycardia

To evaluate the efficacy and safety of slow pathway radiofrequency ablation (RFA) in patients with clinically documented but noninducible paroxysmal supraventricular tachycardia (PSVT) and dual AV nodal physiology. We studied 8 out of 142 patients referred for PSVT RFA. They had documented but noninducible PSVT, corresponding to an AV nodal reentrant tachycardia (AVNRT) and dual AV nodal physiology (evidenced by AH jump ≥ 50 msec and one or more atrial echo beats) during the electrophysiological study. The presence of an accessory pathway was excluded. There were six women, mean age of 53±14 years. RFA was performed via anatomic approach (targeting the inferoposterior region of the triangle of Koch) and mapping of the slow pathway potential. A mean of 4 ± 2 pulses were delivered, at a mean power of 34 ± 8 W. The acute outcome was 100% successful, without any echo beats or AH jumps. No arrhythmia occurred during a mean follow-up period of 19 ±3 months. Slow pathway ablation might be beneficial in patients with documented but noninducible PSVT and dual AV nodal physiology.

Junctional Rhythm During Slow Pathway Radiofrequency Ablation in Patients with Atrioventricular Nodal Reentrant tachycardia: Beat-to-Beat Analysis and Its Prognostic Value in Relation to Electrophysiologic and Anatomic Parameters

Junctional rhythm usually is considered a sensitive but nonspecific marker of successful ablation of the slow pathway in AV nodal reentrant tachycardia. Nevertheless, this junctional rhythm has been little studied, and its relations to recognized predictors of successful radiofrequency (RF) application were never established in any study. Thirty-nine patients underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia. Ninety RF applications were delivered, and each ablation site was determined using three different fluoroscopic projections. Six anatomic zones were defined from low posterior septum to the site of distal His-bundle recording (P1, P2, M1, M2, A1, and A2). Characteristics of junctional rhythm during RF applications were analyzed. Atrial electrogram characteristics at the ablation sites also were studied. All patients had successful slow pathway ablation, without any complication. The ablation sites were located as follows: 41 at P1, 26 at P2, 20 at M1, and 3 in M2. Forty RF applications were successful: 14 of 41 attempts at P1, 7 of 26 at P2, 16 of 20 at M1, and 3 of 3 at M2. Mid-septal ablation site (M1 and M2) was associated with higher occurrence of junctional rhythm (P < 0.0001), earlier first junctional beat (P = 0.008), and earlier occurrence of the longest junctional burst (P = 0.03) compared with posterior ablation site (P1 and P2). The combination of a mid-septal ablation site and a first junctional beat occurring < or = 3 seconds after onset of RF application identified successful RF application with 100% accuracy. Using multivariate analysis, the ablation site, duration of atrial electrogram (including slow pathway potential when present), and occurrence of junctional rhythm were independent predictors of success. Successful slow pathway ablation depends on many factors. Junctional rhythm characteristics are related to the site of RF delivery and can be helpful in assessing successful slow pathway ablation.

Radiofrequency catheter ablation for AV nodal reentrant tachycardia associated with persistent left superior vena cava.

Slow AV nodal pathway ablation using RF is highly effective for patients with refractory AV nodal reentrant tachycardia (AVNRT). We report three catheter ablation cases using RF current in patients associated with persistent left superior vena cava (PLSVC). Three patients with drug refractory AVNRT of common variety were involved in this study. An electrode catheter introduced through the left subclavian vein inserted directly into the coronary sinus, a typical anatomical finding of PLSVC. The ablation procedure was initially performed at the posteroinferior region of Koch's triangle. A slow pathway potential could not be found from that area; nonsustained junctional tachycardia (NSJT) did not occur during the delivery of RF current; there was failure to eliminate slow AV nodal pathway conduction. The catheter then was moved into the bed of the proximal portion of the markedly enlarged coronary sinus. A slow AV nodal pathway potential was recorded through the ablation catheter, and the delivery of RF current caused NSJT in two patients. Complete elimination of slow AV nodal pathway conduction was accomplished in these two patients by this method. No adverse effects were provoked by this procedure. Catheter ablation of the slow AV nodal pathway guided by a slow pathway potential and the appearance of NSJT was feasible and safe in the area of the coronary sinus ostium in patients associated with PLSVC.

Prediction of Atrioventricular Block During Radiofrequency Ablation of the Slow Pathway of the Atrioventricular Node

Selective radiofrequency (RF) ablation of the slow pathway is an effective treatment for atrioventricular (AV) nodal reentry tachycardia. A previous report showed that rapid junctional tachycardia (JT) caused by RF associated with loss of ventriculoatrial (VA) conduction is related to increased risk for AV block. However, this can be difficult to detect during energy delivery, and more importantly, it cannot be measured before the onset of RF energy delivery. The aim of our study was to determine whether measurements made from electrograms could be used to predict the risk of AV block before RF energy is delivered. Fifty-eight patients underwent 63 selective slow pathway RF ablation procedures. In 46 (26.9%) of 172 JTs caused by RF, VA block was observed, and in 11 this was followed by AV block of various degrees. Electrograms before each application of RF were analyzed for the interval between the atrial signals in the His bundle catheter and in the distal mapping catheter [A(H)-A(Md)], the interval between the atrial signals in the His bundle catheter and in the proximal coronary sinus catheter [A(H)-A(CS)], the AV ratio, and the presence of a slow pathway potential or a fractionated atrial signal in the distal mapping catheter. Mean cycle length (CL) of JT was calculated if it consisted of at least 10 beats. These parameters were compared between patients with JT who developed VA block and subsequent AV block (group 1), patients with JT and VA block but without subsequent AV block (group 2), and patients with JT without VA block (group 3). The A(H)-A(Md) interval was significantly shorter in group 1 (17 +/- 8 ms) than in groups 2 (33 +/- 8 ms, P < .001) and 3 (32 +/- 10 ms, P < .001), whereas the A(H)-A(Md) intervals of groups 2 and 3 did not differ from each other. CL of JT, A(H)-A(CS) interval, AV ratio, presence of a slow pathway potential, or a fractionated atrial electrogram were not related to the occurrence of AV block. The A(H)-A(Md) interval provides an electrophysiological marker that can be used in addition to the radiological catheter position to assess the risk for AV block before onset of RF delivery. CL of JT and occurrence of VA block are not related to the risk of AV block.