Principles of the Electrophysiology Study

The electrophysiology study can be helpful in evaluating a broad spectrum of cardiac arrhythmias. This chapter introduces the principles used in performing the electrophysiology study, and discusses complications of electrophysiologic testing. The electrophysiology study is performed by inserting electrode catheters into blood vessels and positioning these catheters in strategic locations within the heart. Once in position, the catheters can be used to performthe two essential tasks of the electrophysiology study: recording the heart's electrical signals and pacing. The electrophysiology study can help to determine the effect of autonomic maneuvers on reentrant arrhythmias. The recording made of the cardiac electrical activity from an electrode catheter placed in the heart is called an intracardiac electrogram. The intracardiac electrogram is essentially an ECG recorded from within the heart. By recording and pacing from electrode catheters, one can evaluate the fundamental electrophysiologic properties of the heart—namely, automaticity, conduction velocity, and refractory periods.