Remote-controlled magnetic navigation and ablation of atrial flutter in a patient with an extracardiac total cavopulmonary connection

Abstract

Atrial tachycardias (AT) may occur in up to 50 % of patients following modifications of the Fontan operation [1]. The main challenge in patients with an extracardiac total cavopulmonary connection (TCPC) is the access to relevant structures such as the right atrium. Remote magnetic navigation (RMN) may offer the possibility to reach even complex anatomy without the risk of perforation or other complications [2]. A 28-year-old patient with double inlet left ventricle (LV), rudimentary right ventricle (RV), ventricular septal defect (VSD), pulmonary stenosis and ventriculo-arterial discordance had undergone a modified Fontan operation with connection of the pulmonary artery to the right atrium (RA) at the age of 5 years. Three years later, he began to suffer from recurrent ATs which necessitated antiarrhythmic drug (AAD) therapy with amiodarone as well as multiple cardioversions. In 2010, at the age of 25 years, the patient underwent a Fontan conversion operation [3] with a 20-mm extracardiac Goretex total cavopulmonary connection (TCPC). A DDD pacemaker with epicardial leads was implanted for sinus node dysfunction. Two years later, the patient began to suffer again from recurrent symptomatic tachycardia which was documented on the pacemaker Holter. He was taken to the electrophysiological lab for further evaluation and treatment. After venous and arterial puncture, an 8-polar steerable diagnostic catheter was introduced inside the conduit (XPT, C.R. Bard, Lowell, MA; USA). The right atrium could be sensed and captured via this access site. Mapping and ablation was performed with the use of the magnetic navigation system (Niobe II, Stereotaxis Inc, St Louis, MO) and a 3D mapping system (Carto3 RMT, Biosense Webster, Diamond Bar, CA, USA). A 7F irrigated-tip ablation catheter (Navistar RMT Thermocool, Biosense Webster) was introduced via a retrograde aortic approach into the RV. Using RMN, the LV was accessed via the VSD and finally the right and left atrium retrogradely passing the AV-valves (Fig. 1a). 3D-image integration with a previously performed CT scan (Fig. 1b) was used to facilitate the access. The atria were mapped in sinus rhythm (SR) and a scar area was delineated in the antero-lateral RA (Fig. 1c). Using programmed atrial stimulation, AT was induced with a cycle length (CL) of 480 ms and 1:1 AV conduction which corresponded to the pacemaker Holter recorded CL. Positive entrainment was confined to a limited zone of fractionated electrograms on the border region of the scar area, suggesting a localized re-entry mechanism. Irrigated radiofrequency (RF) energy with a maximum power of 38 W, a maximum temperature of 43 C and a flow rate of 30 ml/min was delivered in this zone and achieved termination to SR. For substrate modification, we then performed an ablation of all fragmented signals around the scar zone. After ablation, programmed stimulation and bursts failed to reinduce AT. The total procedure time was 200 min, with a total fluoroscopy time of 9 min and a fluoroscopy dose of 719 cGy/cm (with a total dose including the preinterventional CT scan of 735.1 cGy/cm). The patient has remained free from recurrent arrhythmia off AAD for the last 18 months. This was documented on the pacemaker Holter. S. Ammar (&) I. Deisenhofer T. Reents G. Hessling Deutsches Herzzentrum Munchen, Technische Universitat Munchen, Lazarettstrasse 36, 80636 Munich, Germany e-mail: ammar@dhm.mhn.de