Index
Ep Defined | Getting Started | Working in the EP Lab
Right Atrium | Right Ventricle | Left Atrium | Left Ventricule | Cardiac Conduction | Cardiac Cell Properties | Action Potential | Sympathetic or Not | Med Page
Electrograms Defined | Recording Modes | Electrode Spacing | Filters | EGM Interpretation | Arrhythmia Analysis
The Physical Lab | Tools of the Trade
Setting Up | Catheter Placement | Baseline Measurement | SNRT | Conduction Study | Arrhythmia Induction | Pacing Protocols | Ablation | Tilt Table | Secrets to Success
Bradycardia | Atrial Tach | Atrial Flutter | Atrial Fibrillation | AVNRT | AVRT | Ventricular Tachycardia
Surface ECG's | Intracardiac Questions | Med Challenge | Advanced

The EP Lab - EP Procedures

Let's do some EP...

          “The study of the electrical system of the heart is called cardiac electrophysiology, and the main concern of the field of electrophysiology is with the mechanisms and therapy of cardiac arrhythmias.” Richard Fogoros, M.D.

          This description of EP by Dr. Fogoros is a simple, straight forward explanation of cardiac electrophysiology. We perform diagnostic EP in order to determine if the patient has some type of abnormal rhythm, what type of rhythm it is and what therapy can be implemented to provide the best possible outcome while exposing the patient to the least amount of risk.

          This section looks at of the specific procedures performed in the EP lab. If you are looking for information regarding interpretation of electrograms, please review the section "Fundamentals of EP". If you are new to EP, both of these sections can provide you with valuable information that will help you become more familiar with this field of medicine. When you combine the physical aspects of the procedure with the ability to process the information collected during the diagnostic EP study, you will begin to understand what cardiac electrophysiology is all about. For now, we will focus on the procedural aspects of EP.

          The description provided by Dr. Fogoros gives us a general idea of the purpose of cardiac electrophysiology. Now we are faced with the question of how we determine the nature of a patient’s arrhythmia. This must be done before an appropriate therapy can be suggested, so we need to look at the tools used during a diagnostic EP study.

          We can collect information about cardiac rhythms by analyzing recordings made of the electrical signals that are the source of activity within the heart. There are two primary types of recordings used in EP, the surface electrocardiogram (ECG) and intracardiac electrograms (EGM’s). Most of what is done during the diagnostic EP process revolves around acquiring these electrograms. As some of the signals recorded during an EP study may be of a very low voltage level, it is important to know how to acquire these signals while picking up a minimal amount of noise.

          This area of the web page has been divided into sections that are specific to different stages of an EP procedure. The patient’s arrival into the lab and the pre-procedure preparations are covered in Setting Up. Once the patient is prepped and draped, the next important juncture is placing catheters to appropriate locations to collect enough information to determine the nature of the suspected arrhythmia. This information is covered in the Catheter Placement area.

          Once the catheters are in place, Baseline Measurements are recorded. It is important to know what measurements to take and what the normal values are for each interval recorded. Those who are good at identifying abnormal rhythms learned early on, the value of being able to determine what is normal.

          After the baseline measurements have been documented, evaluation of the electrical properties specific to individual anatomical regions is performed. The physician may choose to perform a Sinus Node Evaluation or a Conduction Study to evaluate the electrical properties of the sinus node and the AV node. Once this is completed, Arrhythmia Induction may be used to initiate an abnormal rhythm. Understanding the different tools used during this process is a key factor in succeeding in the lab.

          When an arrhythmia has been identified, the physician may chose to eradicate the tissue that is involved with originating or sustaining the documented rhythm. The Ablation process is one of the most common tools utilized in eliminating abnormal rhythms.

          There are some rhythm abnormalities that require a different approach than conventional invasive EP studies. The section about the head up Tilt Table Study discusses how nuero-cardiogenic syncope may be documented.

This section under development.
Indications and Goals of EP

Indications for Diagnostic EP
Survivor of Sudden Cardiac Death
Syncope, etiology unknown
Syncope with BBB or 2nd degree AV Block
Recurrent wide complex tachycardia
VT
Symptomatic narrow complex tachycardia

Goals of Diagnostic EP
To characterize physiologic and pathologic properties of the atria and ventricles, the AV conduction system, identify accessory pathways, and determine the sites and mechanisms of arrhythmias
To correlate patient symptoms with arrhythmias and evaluate risks for life threatening events and/or differentiate arrhythmias
To define arrhythmia induction and termination methods for EPS guided interventions.

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