Recurrent Symptomatic Tachycardia Research Articles

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

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

Flecainide acetate treatment of paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation: Dose-response studies

The dose-response relations for efficacy and tolerance of the antiarrhythmic drug flecainide acetate were studied in 28 patients with paroxysmal supraventricular tachycardia (Group 1) and 45 patients with paroxysmal atrial fibrillation or flutter (Group 2). Recurrent symptomatic tachycardia was documented with use of transtelephonic electrocardiographic recording. Patients received flecainide in doses of 25, 50, 100 and 150 mg twice daily and placebo for 1 month treatment periods. Among 14 patients in Group 1 who qualified for efficacy analysis, 4 (29%) had no tachycardia while taking placebo. The number with no tachycardia increased with progressively larger flecainide doses; with the 150 mg twice daily dose, 12 (86%) of 14 patients had no tachycardia (p less than 0.01 for overall differences among all treatments). Among 28 patients in Group 2, 2 (7%) had no tachycardia while taking placebo. The number with no tachycardia also increased with progressively larger flecainide doses; with the 150 mg twice daily dose, 17 (61%) of 28 patients had no tachycardia (p less than 0.01 for overall differences among all treatments). Noncardiac adverse experiences were the leading cause of premature study discontinuation during flecainide treatment periods (five patients in Group 1 and six patients in Group 2).

Effective termination of reentrant supraventricular tachycardia by single dose oral combination therapy with pindolol and verapamil

We evaluated the efficacy of single oral dose combining 20 mg pindolol and 120 mg verapamil in termination of paroxysmal supraventricular tachycardia (SVT) in 12 patients with recurrent symptomatic tachycardia. All had electrically inducible SVT lasting longer than 30 minutes. Patients were administered placebo or crushed pindolol and verapamil on 2 consecutive days after tachycardia was electrically induced and allowed to sustain for 30 minutes. With placebo, SVT lasted 186 ± 18 minutes (mean ± SEM); five patients converted spontaneously within 121 to 180 minutes. With pindolol and verapamil, 9 of 12 patients (responders) converted to sinus rhythm within 8 to 74 minutes. The mean duration of SVT in the nine responders was 28 ± 8 minutes compared with 168 ± 20 minutes on placebo ( p < 0.001). Before termination, tachycardia rate on pindolol and verapamil slowed significantly from 182 ± 5 to 164 ± 7/min ( p < 0.05) compared with no significant change in the rate of SVT on placebo. The mean systolic blood pressure during tachycardia was 97 ± 5 mm Hg with placebo and 101 ± 7 mm Hg with pindolol and verapamil. Serum levels of pindolol and verapamil obtained in seven patients at time of spontaneous termination of tachycardia were 66 ± 13 and 56 ± 14 ng/ml, respectively. The side effects with pindolol and verapamil included lightheadedness in one patient and symptoms of rapid palpitations in three. A single oral dose of pindolol and verapamil is safe and effective in termination of acute paroxysmal SVT and may be the initial therapy of choice in selected patients.