Prevention of atrial fibrillation by inter-atrial septum pacing guided by electrophysiological testing, in patients with delayed interatrial conduction.

AIMS: Interatrial septum (IAS) pacing seems efficient in synchronizing atrial depolarization in patients (pts) with delayed inter-atrial conduction, but its clinical role in preventing atrial tachyarrhythmias is still debated. This study was conducted in order to evaluate the clinical efficacy of IAS pacing guided by pace mapping of the IAS, as an alternative treatment modality in pts with drug refractory paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: We evaluated 29 pts (13 male, 16 female, 60 +/- 11 years), with drug refractory PAF, normal sinus node function and prolonged inter-atrial conduction time (P wave 142 +/- 10 ms). Multipolar catheters were inserted and the electrograms from the high right atrium (HRA) and proximal, middle and distal coronary sinus (CS) were recorded. The IAS was paced from multiple sites. The site of IAS where the timing between HRA and distal CS was <20 ms was considered the most suitable for synchronizing the atria. This site was found to be superior to the CS os. near the fossa ovalis in all pts. An active fixation atrial lead was positioned at this site and a standard lead was placed in the right ventricle. During IAS pacing, the P wave duration decreased significantly to 107 +/- 15 ms (P<0.001). At implant, the atrial sensing was 2.3 +/- 0.7 mV, the atrial pacing threshold was 0.95 +/- 0.15 V (0.5 ms) and the impedance was 760 +/- 80 Ohm. We evaluated the pts during four periods of 3 months duration each. The first period (control) was before pacemaker implantation, while the pts were under antiarrhythmic treatment. During the subsequent two periods, we evaluated the clinical efficacy of IAS pacing to prevent PAF recurrences, in AAT (75 bpm) and AAIR (75-140 bpm) mode, with random selection of the order and after discontinuation of antiarrhythmic treatment. During the fourth period, the same AAIR mode was assessed, but antiarrhythmic drugs were also administered. We compared the arrhythmia free interval among the four periods. The proportion of atrial paced beats in AAIR pacing mode plus antiarrhythmics was significantly higher compared with the drug-free period in AAIR mode (57 +/- 9% and 49 +/- 9% respectively, P=0017) and with AAT pacing mode (44 +/- 10%,(, P<0.001). In AAT mode, the arrhythmia free interval was 24.2 +/- 5.1 days, while it was 26.2 +/- 5.7 days in AAIR mode. These intervals did not differ significantly from the pre-implantation period (24.1 +/- 6.3 days). The arrhythmia free interval in AAIR pacing in combination with antiarrhythmic drug therapy was 38.7 +/- 8.1 days and this was significantly longer than the previous periods (P<0.05). CONCLUSION: Atrial septal pacing in combination with antiarrhythmic drug therapy reduced the incidence of PAF in pts with prolonged inter-atrial conduction times. Pace mapping of the IAS is an attractive technique to assess the shortest atrial activation time between HRA and distal CS. Whether placement of the atrial lead based on the shortest HRA--distal CS time is the best place in the IAS to prevent PAF still remains to be proven.

Implantable cardioverter defibrillator-an unusual case of inappropriate discharge during showering.

The evolution of diagnostic information provided in implantable cardioverter defibrillators (ICDs) has paralleled the advances in the therapeutic options incorporated in these systems. Contemporary devices are capable of providing recordings of electrical events surrounding all delivered and aborted device therapy. This report presents un unusual case of inappropriate discharge of an ICD, resulting from electromagnetic interference. A transvenous ICD system (Sentry Hot Can 4310 HC, Telectronics Denver, CO), was implanted in a patient with ischemic heart disease due to episodes of ventricular tachycardia refractory to antiarrhythmic treatment. One month post-implant the patient reported two consecutive shocks from the device while showering. The non-physiological cycle length (100 ms) recorded in conjunction to the scenario of the event, raised the suspicion of electromagnetic interference through electrical current leakage in the bathroom, an hypothesis that was subsequently proved. This case report underscores that electromagnetic interference can become hazardous in common daily activities of patients with an ICD.

Ventricular performance and quality of life in patients who underwent radiofrequency AV junction ablation and permanent pacemaker implantation due to medically refractory atrial tachyarrhythmias.

UNLABELLED: In patients with drug refractory atrial tachyarrhythmias and previous failed attempts of ablation of the arrhythmia substrate, radiofrequency (RF) modulation or ablation of the atrioventricular (AV) junction is an alternative procedure. AIM: Of this study was to assess the efficacy and long term results of RF AV junction ablation in conjunction with permanent pacemaker implantation, in the management of patients with drug resistant atrial tachyarrhythmias. METHODS: Between 4/92 and 1/97, 46 patients (30 male, 16 female, 67 +/- 12 years) underwent RF AV junction ablation because of paroxysmal atrial fibrillation (24 patients), chronic atrial fibrillation (13 patients), atrial flutter (5 patients) and atrial tachycardia (4 patients). The underlying heart disease was dilated cardiomyopathy (16), ischemic heart disease (9), hypertensive heart disease (6), hypertrophic cardiomyopathy (3), atrial septal defect (2) and non structural heart disease (10). The duration of symptoms was 6.4 +/- 3.5 years at a maximal heart rate 169 +/- 24 bpm. The hospital admissions in the last 12 months were 8.2 +/- 3 per patient. The failed antiarrhythmic drugs were 3.5 +/- 2.1. The functional NYHA class was 2.7 +/- 0.6. Patients with atrial flutter and atrial tachycardia had previous failed attempts of RF ablation of the arrhythmia substrate. Thirty patients had a compromised left ventricular systolic function with LVEF below 50% (mean 34 +/- 9%). AV junction ablation was achieved in all patients after 4 +/- 2.5 RF applications. Post ablation, the selected pacing mode was DDD-R for the 33 patients with paroxysmal atrial tachyarrhythmias and VVI-R for the 13 pts with chronic atrial fibrillation. The dual chamber pacemakers implanted had the option of automatic mode switch. RESULTS: During the follow-up period of 28 +/- 13 months (6-47), AV conduction recovered in 1 patient. Antiarrhythmic treatment was necessary in only 7 patients. Post ablation the new functional NYHA class was 1.4 +/- 0.8 (p < 0.001). Post ablation hospital admissions, including ordinary pacemaker follow-up visits, were 4 +/- 1 per patient per year (p < 0.001). Six months after the procedure the LVEF of the study population was increased from 42 +/- 16% to 50 +/- 14% (p = NS). In the 30 patients with heart failure the LVEF was significantly increased to 46 +/- 8% (p < 0.05). Symptomatic relief or significant improvement was observed in all patients as showed by the answers given in a customized questionnaire before and after the procedure. CONCLUSIONS: In patients with drug refractory atrial tachyarrhythmias, RF AV junction ablation and permanent pacemaker implantation is an alternative therapy with excellent long term results in terms of arrhythmia control, ventricular performance and quality of life.