Interaction Between Autonomic Tone and the Negative Chronotropic Effect of Adenosine in Humans

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72287/1/j.1540-8159.1999.tb00412.x.pd

Rise in Chronic Defibrillation Energy Requirements Necessitating Implantable Defibrillator Lead System Revision

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72617/1/j.1540-8159.1997.tb03890.x.pd

Recurrent cardiac events in patients with idiopathic ventricular fibrillation, excluding patients with the Brugada syndrome

BACKGROUND: The recurrence of cardiac events in patients with idiopathic ventricular fibrillation (VF) excluding patients with the Brugada syndrome is unclear since this entity remains present in previous studies. METHODS: Since 1992, 18 patients (72% male) with idiopathic VF out of 455 ICD implants were treated with an implantable cardioverter defibrillator (ICD). The mean age at first ICD implantation was 42 ± 14 years. Brugada syndrome, as well as other primary electrical diseases (e.g. long QT), were systematically excluded in all patients by the absence of the typical electrocardiogram (ST elevation in the right precordial leads) at rest and/or after pharmacological tests (ajmaline, flecainide, or procainamide). Recurrence of cardiac events was prospectively assessed. RESULTS: During a mean follow-up period of 41 ± 27 months, VF recurrence with appropriate shock occurred in 7 patients (39%) covering a total of 27 shocks. The median time to first appropriate shock was 12 ± 9 months. There were no deaths. In the electrophysiological study, 39% of patients were inducible, but inducibility failed to predict subsequent arrhythmic events. Forty-four percent of patients suffered 21 inappropriate shocks, which were caused by sinus tachycardia, atrial arrhythmias or lead malfunction. CONCLUSION: Idiopathic ventricular fibrillation patients have a high recurrence rate of potentially fatal ventricular arrhythmias, excluding patients with the Brugada syndrome or other known causes. ICD prevents sudden cardiac death but inappropriate shocks remained a major issue in this young and active population