Paradoxical responses to pacing maneuvers differentiating atrioventricular node reentrant tachycardia and junctional tachycardia.

A 40-year-old female presented at our hospital because of heart palpitations. During an electrophysiological study, atrioventricular (AV) conduction showed dual AV nodal physiology. Three types of supraventricular tachycardia (SVT) were induced. The initiation of SVT was reproducibility dependent on a critical A-H interval prolongation. An early premature atrial contraction during SVT repeatedly advanced the immediate His potential with termination of the tachycardia, indicating AV node reentrant tachycardia (AVNRT). However, after atrial overdrive pacing during SVT without termination of the tachycardia, the first return electrogram resulted in an AHHA response, consistent with junctional tachycardia. The mechanism of paradoxical responses to pacing maneuvers differentiating AVNRT and junctional tachycardia was discussed.

Differentiating junctional tachycardia and atrioventricular node re-entry tachycardia based on response to atrial extrastimulus pacing.

OBJECTIVES: The purpose of this study was to differentiate non-re-entrant junctional tachycardia (JT) and typical atrioventricular node re-entry tachycardia (AVNRT). BACKGROUND: JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. METHODS: We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. RESULTS: In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. CONCLUSIONS: The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.

Remote magnetic catheter mapping and ablation of permanent junctional reciprocating tachycardia in a seven-year-old child.

BACKGROUND: Mapping and catheter ablation of permanent junctional reciprocating tachycardia (PJRT) in children can be challenging. Remote magnetic navigation may improve precise mapping and catheter stability during ablation, as well as reduce fluoroscopy time, especially in conjunction with a non-fluoroscopic mapping system. OBJECTIVE: We report a case of PJRT ablation in a 7-year-old child using remote magnetic navigation. METHODS AND RESULTS: Mapping of the right atrium (RA) and the coronary sinus (CS) and catheter ablation were performed using remote magnetic navigation in conjunction with a non-fluoroscopic mapping system (NavX). We observed excellent catheter steering abilities and constant wall contact during ablation, allowing a short and safe procedure. CONCLUSIONS: Remote magnetic navigation may be used for mapping and ablation of PJRT in children.

Transcatheter cryothermal ablation of junctional ectopic tachycardia in the normal heart.

BACKGROUND: Junctional ectopic tachycardia in the normal heart is rare and often is resistant to pharmacologic management. Transcatheter ablation using radiofrequency energy places the AV node at risk. OBJECTIVES: The purpose of this study was to report our experience with transcatheter cryothermal ablation using three-dimensional mapping in six patients with junctional ectopic tachycardia. METHODS: A review of clinical and electrophysiologic data was performed on all patients with structurally normal hearts who underwent cryothermal ablation for treatment of junctional ectopic tachycardia at two institutions. RESULTS: Six patients (age 7.7-36.5 years) underwent attempted transcatheter cryothermal ablation using three-dimensional mapping. Only one patient had achieved arrhythmia suppression on medical management. Cryothermal mapping (-30 degrees C) localized the junctional focus while normal conduction was monitored. The junctional focus was high in the triangle of Koch in four patients and was low in one patient. The sixth patient had only one run of junctional ectopic tachycardia during the procedure and therefore received an empiric cryoablation (-70 degrees C) lesion. Subsequent cryoablation lesions were delivered at and around the junctional focus. In one patient, cryomapping eliminated the junctional focus but resulted in transient complete AV block; therefore, cryoablation was not performed. All patients who received the cryoablation lesions had elimination of their junctional ectopic tachycardia at 6-week follow-up. The patient who did not receive a cryoablation lesion remained in a slower junctional rhythm at follow-up. CONCLUSION: Cryoablation of junctional ectopic tachycardia is safe and effective. Nonetheless, proximity to the His-Purkinje system may preclude success. Empiric cryoablation can be effective; cryotherapy may not yield immediate success, but a delayed salutary effect can follow.

Permanent form of junctional reciprocating tachycardia in adults: peculiar features and results of radiofrequency catheter ablation.

AIM: PJRT occurs predominantly in infants and children and is limited to small series in adults. The aim of this study was to describe the clinical presentation, electrophysiological characteristics, feasibility and safety of radiofrequency ablation, and the long-term prognosis in a large group of adult patients with the permanent form of junctional reciprocating tachycardia (PJRT). METHODS AND RESULTS: Forty-nine adult patients (22 male and 27 female; mean age 43+/-16) with a diagnosis of PJRT confirmed at electrophysiological study were included. Eight patients (16%) presented with tachycardia-induced cardiomyopathy (TIC). Ventricular rate was 146+/-30 bpm. The arrhythmia was permanent or incessant in 23/49 cases (47%) and paroxysmal in 26/49 (53%). A significant correlation was found between symptom duration and tachycardia rate (r(2)=0.12, P=0.01). The accessory pathway (AP) was located in the right posteroseptal region in 37 cases (76%) and in atypical sites in 12 cases (24%). Patients with the incessant or permanent form of PJRT had longer duration of symptoms, more frequently TIC and a slower tachycardia rate. Radiofrequency catheter ablation was initially successful in 46 cases (94%) without any serious complication. Long-term success rate was 100% (49/49 patients) in the absence of any antiarrhythmic drug treatment (mean follow-up 49+/-38 months). Regression of TIC was observed in all cases (8/8). CONCLUSION: PJRT in adults is often paroxysmal (53%), and the retrograde slowly conducting, decremental AP is not infrequently in a non-posteroseptal location. Radiofrequency catheter ablation is highly effective and should be considered as the treatment of first choice in adult patients with PJRT.

Cryoenergy catheter ablation: a new technique for treatment of permanent junctional reciprocating tachycardia in children.

INTRODUCTION: Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of reciprocating tachycardia, almost incessant from childhood and usually refractory to drug therapy. Radiofrequency catheter ablation currently is the first-line therapy for PJRT, but its application in the septal region may be associated with complications. In contrast, cryoenergy has several advantages, such as the ability to test the effects of ablation while the lesion is still forming, thus reducing the number of ineffective, useless, and potentially harmful lesions. The aim of this study was to investigate the potential clinical utility of percutaneous cryoenergy catheter ablation for treatment of pediatric patients with PJRT. METHODS AND RESULTS: Four patients (age 14 +/- 5 years; mean +/- SD) with a clinical diagnosis of PJRT underwent catheter cryoablation. The ablation was successfully accomplished in 4 (100%) of 4 patients. The mean +/- SD number of cryoapplications was 1.8 +/- 0.8, and from 1 to 6 cryomappings were performed for each permanent cryolesion. The successful site was in the mid-septal region (2 patients), at the coronary sinus orifice (1 patient), and in the middle cardiac vein (1 patient). No complications with cryoablation were reported, nor was there prolongation of the AH interval during cryomapping or cryoablation. No pain was reported by patients during the cryoenergy catheter ablation procedure. PJRT recurrence occurred in 1 patient who underwent a second successful cryoablation procedure. CONCLUSION: The outcomes of cryoenergy catheter ablation in these 4 patients treated for PJRT suggest that cryoablation is a safe, effective, and pain-free technique for treating pediatric patients with PJRT.