47: Atrial Electrogram

Published on 06/03/2015 by admin

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Last modified 06/03/2015

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Atrial Electrogram

Teresa Preuss and Debra Lynn-McHale Wiegand

An atrial electrogram is obtained to determine the presence of atrial activity in a dysrhythmia or to identify the relationship between atrial and ventricular depolarizations.

PREREQUISITE NURSING KNOWLEDGE

• Understanding of the anatomy and physiology of the cardiovascular system, principles of cardiac conduction, and basic dysrhythmia interpretation is necessary.

• Principles of general electrical safety apply with use of temporary invasive pacing. Gloves should always be worn when handling pacing electrodes to prevent microshock because even small amounts of electrical current can cause serious dysrhythmias if transmitted to the heart.

• Advanced cardiac life support knowledge and skills are needed.

• Atrial electrograms (AEGs) offer a more definitive means for assessing and interpreting rhythm abnormalities.⁴

• The American Heart Association Practice Standards for Electrocardiographic Monitoring in Hospital Settings recommend recording an AEG whenever tachycardia of unknown origin develops in a patient after cardiac surgery.2,4

• Indications for AEG are as follows:

When atrial activity is not clearly detected on electrocardiographic (ECG) monitoring

For determination of the relationship between atrial and ventricular activity

For differentiation of wide-complex rhythms (i.e., ventricular tachycardia and supraventricular tachycardia with aberrant ventricular conduction)

For differentiation of narrow-complex supraventricular tachycardias (i.e., sinus tachycardia, atrial tachycardia, paroxysmal supraventricular tachycardia, atrial flutter, atrial fibrillation with relatively regular RR intervals, or junctional tachycardia)

• AEGs can be performed with multichannel telemetry or a bedside ECG monitor that allows for simultaneous display of the AEG along with the surface ECG. A 12-lead ECG machine also can be used to obtain an AEG.

• AEG is a method of recording electrical activity that originates from the atria with use of temporary atrial epicardial wires placed during cardiac surgery. Standard ECG monitoring records electrical events from the heart with electrodes located on the surface of the patient’s body, which is a considerable distance from the myocardium. One limitation of ECG monitoring may be its inability to detect P waves effectively.

• AEGs detect electrical events directly from the atria, which provides a greatly enhanced tracing of atrial activity. This enhanced tracing allows for comparison of atrial events with ventricular events and determination of the relationship between the two.

• Accurate identification of the epicardial atrial pacing wire or wires is important.

• The two types of AEGs that can be obtained from epicardial pacing wires are unipolar and bipolar.

A unipolar electrogram measures electrical activity between one atrial epicardial wire and a surface ECG electrode. The unipolar AEG detects atrial and ventricular activity.

A bipolar electrogram detects electrical activity between the two atrial epicardial wires. The bipolar AEG predominantly detects atrial activity because both electrodes are attached to the atria.

EQUIPMENT

• Nonsterile gloves

• Temporary atrial epicardial pacing wires placed during cardiac surgery

• Multichannel ECG monitor and recorder or 12-lead ECG machine (ensure that biomedical safety standards are met and machine is safe for use with epicardial wires)

• Sterile dressings and materials needed for site care

Additional equipment as needed:

• ECG electrodes

PATIENT AND FAMILY EDUCATION

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