The electrophysiology study (EPS) is an invasive procedure that plays a major role in the diagnosis and management of serious dysrhythmias and is used (1) to distinguish atrial from ventricu-lar tachycardias when the determination cannot be made from the 12-lead ECG, (2) to evaluate how readily a life-threatening dysrhythmia (eg, ventricular tachycardia, ventricular fibrillation).
The initial study can take up to 4 hours. The patient receives moderate sedation. Catheters with recording and electrical stim-ulating (pacing) capabilities are inserted into the heart through the femoral and right subclavian veins to record electrical activ-ity in the right and left atrium, bundle of His, and right ventri-cle. Fluoroscopy guides the positioning of these catheters. Baseline intracardiac recordings are obtained; programmed elec-trical stimulations of the atrium or ventricle are then adminis-tered in an attempt to induce the patient’s dysrhythmia. If the dysrhythmia is induced, various antiarrhythmic medications are administered intravenously. The study is repeated after each med-ication to evaluate which medication or combination of medica-tions is most effective in controlling the dysrhythmia.
After the study, the patient receives an equivalent oral anti-arrhythmic agent, and subsequent studies may be necessary to evaluate the effectiveness of that medication. Results of the study may indicate the need for other therapeutic interventions, such as a pacemaker or implantable cardioverter defibrillator.
During EPS, lethal dysrhythmias may be induced; therefore, the procedure must be performed in a controlled environment with resuscitation equipment (eg, defibrillator) readily available. Possible complications include bleeding and hematoma from the catheter insertion sites, pneumothorax (air in the pleural cavity that may collapse portions of the lung), deep vein thrombosis, stroke, and sudden death.
Patients receive nothing to eat or drink for 8 hours before the pro-cedure. Antiarrhythmic medications are withheld for at least 24 hours before the initial study, and the patient’s cardiac rate and rhythm are carefully monitored for dysrhythmias. Other medications may be taken with sips of water.
Thorough preparation before EPS will help to minimize pa-tient anxiety. Ensure that the patient understands the reason for the study and is able to describe the common sensations and ex-periences expected during and after the study. Often the EPS lab-oratory has relaxation interventions available for patients, such as headsets with music. Also, the patient needs to be aware that the nurses in the EPS laboratory will be monitoring carefully for signs of discomfort and will offer intravenous medications to reduce discomfort or anxiety. Patients should be reminded to request these medications if necessary. Postprocedure interventions in-clude careful monitoring for complications. The nurse takes vital signs, reviews tracings of continuous ECG monitoring, assesses the apical pulse, auscultates for pericardial friction rub (which in-dicates bleeding into the pericardial sac), and inspects the catheter insertion sites for bleeding or hematoma formation.
In addition, the nurse assists the patient to maintain bed rest with the affected extremity kept straight and the head of the bed elevated to 30 degrees for 4 to 6 hours. The frequency of assess-ments and the duration of bed rest may vary based on institu-tional policy and physician preference.