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Smooth Start in the EP LAB Control Room

Updated: Sep 27, 2022

EP Study Procedure: Set-Up for Success

In preparing for an EP study procedure, proper set-up of your electrogram display is one of the best ways to get the procedure off to a smooth start. Like the classic Porsche commercial, “As for me and my lab, we PREFER a smooth start,” what could be better? We all know that smooth starts in the control room can set the mood for the rest of the case. As well, a rocky start sets it up to be a long day.

You may notice most EP labs you walk into have their squiggly lines displayed in a distinctive pattern. This distinction can be found almost universally. Ever ask yourself why? Are we just not that creative? What's the point?

The reason that the EGMs and ECGs are aligned in a particular way is to appreciate the electrical activation of each and every heartbeat. You heard that correctly! EACH and EVERY heartbeat that is flying by at 100-400ms mind you! This normally occurs in a pattern of

high to low and right to left with or without diagnostic catheters and amazing technology.

Setting up the monitoring system correctly can assure that when one or more beats

DO NOT fall into this pattern, your eyes will notice these tricky Electrocardiograms (EGMs). Let’s dive into the catheter set-up and patterns associated with a basic EP study procedure.

Electrogram (noun)

elec·tro·gram | \ i-ˈlek-trə-ˌgram

What is an EGM?

An EGM is a graphical representation of cardiac electrical activity. The very activity that is studied and evaluated during EP procedures.

TWO types of electrograms are displayed during an EP study procedure: Body Surface Electrograms (ECGs/EKGs) and Intracardiac Electrograms (IEGMs)


Surface ECGs are equally valuable and are viewed on the display screen of the EP recording system during the procedure. All twelve leads are recorded. However, usually only three or four specific surface ECGs are displayed. The purpose of these specific leads is to reflect different aspects of the heart: lateral, Right vs Left, and High vs Low ECG activation patterns must be viewed. The most utilized ECGs on display in a typical EP study are as follows:

  • Lead I

    • Lead I reflects activity between the RIGHT and LEFT arm, displaying the lateral view of the heart

  • Lead II or aVF

    • Lead II or aVF displays information from HIGH TO LOW

  • Lead V1

    • Lead V1 displays RIGHT/SEPTAL activity of the heart

  • Lead V6

    • Lead V6 Displays LATERAL activity of the heart

For more on the conduction system, take Cardiac Arrhythmias: Don't Miss a Beat.




An even deeper dive into the heart’s electricity can make an EP Nerd out of just about anyone! We can evaluate these amazing patterns of electricity beat by beat.

During the EP study procedure, catheters are positioned at and recorded at very strategic conduction sites. Beginning at the High Right Atrium (HRA), through the AV Junction (His), Coronary Sinus (CS), and to the Right Ventricle (RV).

The number of IEGMs displayed are associated with the number of catheters placed in the heart, the type of EP study procedure performed, and physician preferences. The IEGMs are systematically aligned to follow normal concentric conduction of the heart, separated visually by colors according to catheter position. The recording system display of signals represents NORMAL CARDIAC ACTIVATION. Normal macro conduction is sequenced from HIGH to low (atrium to ventricle) and from RIGHT to LEFT, creating a linear and graphical snapshot of each beat.

High Right Atrium (HRA)

Discrete right atrial activity - Sino Atrial Node

His Bundle (HIS)

Discrete activity of the distal AV node, displaying atrial-His-ventricular deflections at the AV junction

Coronary Sinus (CS)

Discrete activity along the AV groove, displaying left atrial and left ventricular IEGMs.

Right Ventricle (RV)

Discrete right ventricular activity

When you have the data displayed in a logical sequence, identifying abnormal findings becomes so much easier, especially the more time you invest studying them. It may start as your eyes just catching something that didn’t look "quite right" to seeing it happen and recognizing the abnormality quickly. This type of engagement promotes an added benefit to the patient, the procedure, and your team. And as stated in a great bourbon commercial “Who doesn’t like a smooth finish?”

And as Sean Connery so eloquently stated, “Who doesn’t like a smooth finish?”

To learn more about the EP study procedure, join CHART Healthcare Academy’s Bootcamp!

EP Bootcamp for the AHP 3-day LIVE Virtual Event

October 5th - 7th, 2022

8:30a - 4:00p CDT

25.0 CEUs

Start with EP Building Blocks. Move to EP Nuts & Bolts. Finish strong as an Arrhythmia Guru!

About the ExPert.

Jennifer Busch, BSN, CEPS, IBHRE Ambassador is the

Sr. Manager of Professional Development - CV at

CHART Healthcare Academy.

Jen has been a nurse for over 15 years. She is a CHART Certified Coach, a gifted CHART Facilitator, enjoys complex VT ablations, and the great outdoors.

This is Jen's 2nd CHART Blog.

READ Jen's 1st Blog here: PVC Localization.

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