**2.1 The setup of the electrophysiology study**

Equipment necessary for EPS includes an operation table, fluoroscopy unit, recorders, programmable stimulator, a multichannel lead switching box, an

oscilloscope, and emergency instruments. In addition, tools for vascular access and electrode catheters are also required [1]. A standard schematic set-up for typical EPS is shown in **Figure 1**.

#### **2.2 Signal recording, amplification, and filtering**

Electrical signals from humans obtained by surface or intracardiac electrodes are <10 mV in amplitude. These electrocardiograms must be amplified and filtered before digitalization, displaying, and storage for interpretation and analysis [2]. Amplification means the increase of the signal's amplitude. However, the signals are plagued with electrical noise, thus amplification results in increasing not only the original signals but the amplitude of noise also. For this reason, avoidance of extraneous signals is essential: all electrical tools used in EPS should be appropriately earthed and shielded. In addition, filtering is required to eliminate unnecessary components of the electrical signals. High-pass filters remove components below a given frequency, while low-pass filters eliminate high-frequency components of the electrical signal. Electrophysiological signals are often contaminated with power line noise (i.e., 60 Hz in North America and 50 Hz in Europe), thus notch filtering is often used to eliminate it [3].

Standard ECG devices run at 25 mm/s Increasing the paper output speed, subtle ECG findings hidden in the tracings become more evident. During an EPS, surface ECG leads and intracardiac electrocardiograms (IEGM) are generally displayed and interpreted at a sweep speed of 100 or 200 mm/s (**Figure 2**).

#### **2.3 Standard catheter positions**

For a standard EPS, a standard number of four catheters is necessary. Based on the operator's decision, EPS is also feasible using only three diagnostic catheters. Diagnostic catheters have two or multiple electrodes, and for each pair of consecutive electrodes, a distinct intracardiac electrogram gets recorded. Traditionally, catheter placement is carried out under fluoroscopy guidance. In the EP lab, three main

#### **Figure 1.**

*Standard schematic set-up for typical electrophysiology study. Abbreviation: RF—radiofrequency.*

*Electrophysiology Study: Interpretation of Intracardiac Electrocardiograms DOI: http://dx.doi.org/10.5772/intechopen.102079*

**Figure 2.**

*Same normal sinus beat at a paper speed of 25, 50, 100, and 200 mm/s.*

fluoroscopy projections are used: anteroposterior (AP), left anterior oblique (LAO), and right anterior oblique (RAO) views (**Figure 3**).
