Atrial Pacing During Radiofrequency Ablation of Junctional Ectopic Tachycardia

Abstract

ecause of its refractoriness to medical therapy and the high mortality rate, 1,2 junctional ectopic tachycardia (JET) has been treated by ablation of the atrioventricular (AV) junction using either direct 1 or radiofrequency (RF) current. 3,4 However, these therapies may result in the need for permanent cardiac pacing. Recently, selective ablation of the JET focus while preserving normal AV conduction was reported, [5][6][7][8][9] suggesting that the junctional focus is usually perinodal and that ablative lesions created over the anterior, mid or posterior septum, avoiding the His bundle, may be effective. However, in the present patient we believed that the automatic focus of the JET existed at a site ajacent to the His bundle. Case ReportThe patient was a 5-year-old boy with a tachyarrhythmia that had been present since birth and had been well controlled with propranolol and digoxin. For the 6 months prior to admission, he had recurrent episodes of tachycardia accompanied by signs of congestive heart failure, including vomiting, appetite loss, and cyanosis. Pharmacologic management with multiple antiarrhythmic drugs (excluding amiodarone) failed, and the patient was referred for catheter ablation. The 24-h Holter monitoring showed an incessant irregular narrow QRS tachycardia with a rate of 180 beats/min. Echocardiography showed a reduced left ventricular shortening fraction (22%).Two 5Fr quadripolar electrode catheters were introduced via the left femoral vein into the high right atrium and the right ventricle. A steerable 7Fr 20-pole catheter with a 2-mm interelectrode distance was placed across the tricuspid valve to record the AV junctional electrograms via a left femoral transvenous approach. A 6Fr 8-pole catheter was inserted from the right internal jugular vein into the coronary sinus. A baseline electrophysiologic study confirmed the diagnosis of JET based on the following observations: (1) during tachycardia, ventriculoatrial (VA) dissociation was present with a His potential always preceding the ventricular depolarization at an His-ventricular (HV) interval of 36 ms, (2) the earlier His potential recording was obtained by the more proximal electrode of the 20-pole catheter in the region expected to produce a His electrogram, (3) sinus beats that occasionally captured the ventricle caused a sudden shortening of the HH interval with subtle aberrancy in the QRS configuration, but the HV intervals were the same as those during tachycardia, (4) there was no evidence of retrograde atrial activation in the His bundle or the coronary sinus during tachycardia, (5) atrial overdrive pacing during tachycardia caused temporary suppression of the tachycardia, confirming normal AV nodal conduction, (6) with the termination of atrial overdrive pacing, the tachycardia immediately resumed with a warming-up of the HH interval and subtle changes in the QRS configuration (Fig 1), and (7) the tachycardia could not be terminated with either atrial or ventricular programmed pacing. A 7Fr ablation catheter (Medtronic CardioR...

Efficacy of a pure Ikr blockade with nifekalant in refractory neonatal congenital junctional ectopic tachycardia and careful attention to damaging the atrioventricular conduction during the radiofrequency catheter ablation in infancy

“…It is beneficial to preserve the AV conduction by performing atrial pacing during the energy application 17 or delivering the application from a low-dose energy 18 . In our case, monitoring the AV conduction by atrial pacing contributed to preventing CAVB.…”

Intrahisian Conduction Disease and Junctional Ectopic Tachycardia

“…JET is considered a rare arrhythmia presenting at the ECG with narrow ventricular complexes, AV dissociation, and QRS morphology resembling that of sinus beats 1–18 . Invasive electrophysiology has demonstrated that each ventricular electrogram is preceded by a “leading” His bundle deflection with an HV interval that has to be compatible with ante grade conduction (> 35 ms) 1–3,14,15 …”

“…As for the clinical presentation, JET appears more often incessant than paroxysmal and as a result it frequently causes hemodynamic impairment 1–20 . Most of the collected evidence relates JET electrophysiological mechanism to enhanced automaticity due to a focus located on the AV junction and this might also explain JET sensitivity to cathecolamines 1–20 . Class IC antiarrhythmic agents, amiodarone, and β‐blockers may be regarded as possible therapeutic options, although a decrease in ventricular rate rather than a complete resolution of the arrhythmia should be expected, since sinus rhythm restoration may not be accomplished in several cases 2,4–7,9,13 …”

“…Radiofrequency ablation represents a valid alternative to medical therapy, although in most cases it has to be followed by a pacemaker implantation, given the difficulties to abolish the JET focus without impairing AV conduction 1,10,15,16 …”

“…Junctional ectopic tachycardia (JET) is an uncommon arrhythmia mostly observed in pediatric patients, presenting as a congenital or postoperative form 1–13 . Its incessant nature is responsible for a poor prognosis even when JET is occasionally observed in adulthood 14–16 …”