Effects of enflurane on inducibility of ventricular tachycardia

Noninvasive programmed stimulation in the setting of ventricular tachycardia catheter ablation

In the setting of catheter ablation of ventricular tachycardia (VT), invasive programmed ventricular stimulation (PVS) is considered an important tool to assess the (residual) inducibility of ventricular arrhythmias and determine the acute success of the procedure. In patients with cardiovascular implantable electronic devices, noninvasive programmed stimulation via implantable cardioverter-defibrillator (ICD) leads can be an alternative to the invasive PVS with intracardiac catheters. The advantages of noninvasive programmed stimulation include preprocedure planning of the electrophysiology procedure to ensure optimal conditions for successful catheter ablation of VT. Following the procedure, noninvasive programmed stimulation has been shown to be used as a guide for repeat early ablation, to offer better programming of ICD, to offer prognostic value regarding the VT recurrence, and to guide antiarrhythmic drug therapy. The noninvasive nature of noninvasive programmed stimulation makes it an attractive alternative to PVS in patients with ICD who have not undergone catheter ablation of VT to obtain prognostic value regarding the occurrence of VT.

Clinical relevance and management of drug-related QT interval prolongation

Much attention recently has focused on drugs that prolong the QT interval, potentially leading to fatal cardiac dysrhythmias (e.g., torsade de pointes). We provide a detailed review of the published evidence that supports or does not support an association between drugs and their risk of QT prolongation. The mechanism of drug-induced QT prolongation is reviewed briefly, followed by an extensive evaluation of drugs associated with QT prolongation, torsade de pointes, or both. Drugs associated with QT prolongation are identified as having definite, probable, or proposed associations. The role of the clinician in the prevention and management of QT prolongation, drug-drug interactions that may occur with agents known to affect the QT interval, and the impact of this adverse effect on the regulatory process are addressed.

Cardiac electrophysiology and conduction pathway ablation

Invasive cardiac electrophysiological (EP) testing and transcatheter ablation are new methods available for the diagnosis and treatment of complex dysrhythmias. The purpose of this review is to familiarize anaesthetists with these procedures. The information presented combines a literature review with the authors' experience. This article reviews normal cardiac conduction, tachycardia pathogenesis, principles of cardiac EP study and techniques of conduction pathway ablation. The anaesthetic considerations, including the choice of anaesthetic agent, monitoring problems, drug interactions, special methods of dysrhythmia termination in the EP lab, and complications specific to these procedures, are detailed. Balanced general anaesthesia or monitored anaesthesia care (MAC) sedation with benzodiazepines, propofol and narcotics are acceptable. Several conclusions can be drawn: transcatheter ablation is an effective treatment for many reentry tachycardias; anaesthetic assistance for this procedure will increasingly be needed; anaesthesia can easily be provided without influencing accurate EP testing; overdrive pacing is the method of choice for terminating tachydysrhythmias in the EP lab.