Unsuccessful AV Nodal Ablation in Atrial Fibrillation: An Alternative Method to Achieve Complete Heart Block

Abstract

We report the case of an elderly patient who presented with poorly tolerated episodes of atrial arrhythmia refractory to medical treatment. AV node ablation was identified as the only alternative expected to be efficacious for symptom relief. However, this usually simple intervention failed. The goal of creating a complete AV block was finally achieved through ablation of the anterior fascicle of the His bundle, which represented the only pathway for residual conduction in this patient.

To the Editor:

“…Beside the above‐mentioned mechanisms, tachycardia‐ (phase 3) and bradycardia‐ (phase 4) dependent conduction block may be responsible for intermittent preexcitation 3–5 . The latter (alone or in combination with the above‐mentioned mechanisms) could be responsible for the block that was observed in Figure 1B 1 . Some patients with accessory pathway have a narrow conduction window with a range of 20–160 ms which is responsible for intermittent preexcitation and conduction block 5 especially during atrial fibrillation (concealed conduction) as in this patient 4 …”

“…Sunthorn et al in a recent case report in the Journal have reported a case in which AV node ablation was impossible to perform, neither by right‐ nor by left‐sided access 1 . However, after a close look at the presented ECG (Fig.…”

“…Why did the patient show no conduction over AV node during the pause? The pause happened 3 h after admission 1 . The patient was chronically treated with oral digoxin and flecainamide for the atrial fibrillation and upon admission he also received intravenous doses of verapamil, amiodarone, and a β‐blocker to control the ventricular response rate 1 .…”

“…The pause happened 3 h after admission 1 . The patient was chronically treated with oral digoxin and flecainamide for the atrial fibrillation and upon admission he also received intravenous doses of verapamil, amiodarone, and a β‐blocker to control the ventricular response rate 1 . All these could temporarily hamper the conduction over the AV node (and the accessory pathway) especially in the presence of concealed conduction due to atrial fibrillation and/or flutter.…”