Invasive cardiac electrophysiology has evolved rapidly from a research tool to an established clinical technique for the investigation and treatment of cardiac rhythm disorders [1,2]. This technique permits a detailed analysis of the mechanism underlying the cardiac arrhythmia, and precise location of the site of origin. Thus, electrophysiology (EP) studies can accomplish the following goals (table 1):
- Make a completely accurate diagnosis of an arrhythmia (supraventricular or ventricular tachyarrhythmias or a bradyarrhythmia)
- Establish the etiology for syncope (bradyarrhythmia or tachyarrhythmia) especially in patients with structural heart disease
- Evaluate prognosis
- Stratification for risk of sudden cardiac death
- Acquire data regarding indications for therapy (eg, permanent pacemaker or defibrillator implantation)
- Guide antiarrhythmic drug therapy
- Evaluate the feasibility or outcome of nonpharmacologic therapy (eg, transcatheter radiofrequency ablation, antiarrhythmic surgery, or implantable cardioverter/defibrillator therapy)
In 2000, an ACC/AHA task force on clinical competency published recommendations for technical and cognitive skills needed to perform electrophysiologic study and/or catheter ablation .
An overview of invasive cardiac electrophysiologic studies (EPS) will be presented here. Issues related to its use in the evaluation of specific arrhythmias are discussed separately. (See "Invasive cardiac electrophysiology studies: Bradyarrhythmias" and "Invasive cardiac electrophysiology studies: Tachyarrhythmias".)
Invasive EP studies are typically performed in a dedicated electrophysiology laboratory. Intravenous conscious sedation is used to ensure patient comfort. Standard ECG leads are applied to the patient, as well as "hands-off" defibrillation pads. In addition to the electrophysiologist, several other staff members are required. At least one nurse serves as a circulator. A second nurse, nurse anesthetist, or anesthesiologist administers the sedation. Either the electrophysiologist, another clinician, or a technician operates the stimulator. Arterial pressure may be monitored invasively or noninvasively, depending upon the complexity of the procedure. Oxygen saturation, as well as in some cases end-tidal CO2, is monitored.