Ablation
Once the arrhythmia mechanism was definitively established,
radiofrequency (RF) ablation of the putative slow pathway was performed.
An externally irrigated, contact force sensing catheter was positioned
via a deflectable sheath in the posterior interatrial septum. At sites
that showed low-amplitude, multiphasic atrial signals and large
ventricular signals, a total of 8 RF energy applications were delivered
using 30 watts of power with low flow rate of 2 ml; contact force was
kept between 8 and 15 grams; duration of application ranged between 10
and 20 seconds. Development of junctional rhythm without retrograde
conduction was noted, and would prompt termination of RF delivery.
Following the 5th RF application, repetitive fire
terminated, and normal sinus rhythm with 1:1 AV conduction was seen.
Repeat atrial and ventricular programmed stimulation (without and with
intravenous isoproterenol infusion) failed to reveal dual AVN physiology
or reinitiate the tachycardia. At outpatient follow up visit several
weeks later, he reported complete resolution of heart failure symptoms,
an ECG showed normal sinus rhythm.