Norm of Electrophysiologic Study (EPS)
Negative for ability to induce dysrhythmias. Normal cardiac conduction system mapping. No reentrant pathways identified.
Usage of Electrophysiologic Study (EPS)
To document the anatomy and physiologic substrates of episodic dysrhythmias by reproducing them so that the mechanism can be identified. Helps diagnose cardiac conduction defects, circuit reentry, ectopic foci, syncope of unexplained cause, tachydysrhythmias, and ventricular preexcitation syndromes; evaluates the effectiveness of antidysrhythmic medications or ablation; helps determine proper choice of a pacemaker; maps the cardiac conduction system before ablation; determines the need for an implanted defibrillator to prevent sudden cardiac death; and records intracardiac electrocardiograms.
Description of Electrophysiologic Study (EPS)
Electrophysiologic study involves the introduction of an electrode catheter under fluoroscopy through a peripheral vein or artery and into the cardiac chambers or sinuses and the performance of programmed electrical stimulation of the heart. Clients who may require EPS include survivors of sudden cardiac death, those with syncope with other than cardiac causes ruled out, and clients with dysrhythmias. Clients who usually require repeat EPS are those who have undergone antidysrhythmic therapy or catheter ablation since the last study. EPS is usually performed in a special laboratory or operating room by a cardiologist, with a specially trained registered nurse and a technician in attendance, certified in ACLS (Advanced Cardiac Life Support).
Professional Considerations of Electrophysiologic Study (EPS)
Consent form IS required.
Arterial injury (rare), cardiac perforation or rupture, cerebrovascular accident, fatal dysrhythmias, death, hemorrhage (rare), infection, insertion-site hematoma, major venous thrombosis, myocardial infarction, pericardial effusion, pulmonary embolus.
Bleeding disorders, thrombocytopenia. Sedatives are contraindicated in clients with central nervous system depression.
- Antidysrhythmic drugs are usually discontinued for several days before the test, when tolerated, for initial EPS. For evaluation of effectiveness of antidysrhythmic therapy, drug levels should reach a steady state before EPS. This may take several days or even a few weeks for drugs such as amiodarone.
- The client should fast from food overnight and from fluids for 4 hours before the test.
- Establish intravenous access.
- If left ventricular stimulation that requires an arterial EPS route is planned, pre-heparinization may be prescribed.
- Have emergency cart and defibrillator or cardioverter readily available.
- A sedative may be prescribed.
- Obtain baseline vital signs. Monitor vital signs and level of consciousness continuously throughout the procedure. Observe respiratory status closely throughout the procedure, especially if a sedative is administered.
- Just before beginning the procedure, take a “time out” to verify the correct client, procedure, and site.
- The client is positioned on the procedure table, and the peripheral pulses distal to the insertion site are marked. The location and baseline quality of the pulses are documented.
- A baseline electrocardiogram is obtained. The leads are left in place for continuous cardiac monitoring.
- The insertion site is cleansed with povidone-iodine solution, allowed to dry, and draped.
- An introducer (sheath, Cordis) catheter is introduced, using the Seldinger technique, through a femoral, brachial, subclavian, or jugular vein. An arterial approach is used for stimulation of the left ventricle. A size 5F, 6F, or 7F electrode catheter is advanced under fluoroscopy to the heart.
- Intracardiac electrocardiograms are recorded.
- After proper catheter position is verified, the following or any combination may be performed, depending on the purpose of the study (an amnestic such as midazolam may be administered before induction of dysrhythmias):
- a. Mapping of the electrical system and pathways, with characterization of the electrical properties of the cardiac conduction system.
- b. Measurement of conduction times, refractory periods, and recovery times of different portions of the heart.
- c. Pacing of the atria may be performed, and extra stimuli may be added at specific intervals, to evaluate whether they can stimulate dysrhythmias.
- d. Attempts to induce dysrhythmias by delivery of a small electrical charge to specific locations of the chamber walls.
- e. Overdrive pacing.
- f. Antidysrhythmic drug effectiveness may be evaluated by administration of the drug to terminate stimulated dysrhythmias.
- Induced dysrhythmias that are poorly tolerated (that is, cause hypotension, loss of consciousness) may be terminated by overdrive pacing, cardioversion, or defibrillation.
- The catheter is removed, and pressure is applied to the site for 10 minutes, or at least until 10 minutes after bleeding stops. A pressure dressing is placed over the site.
- Assess and document the following every 15 minutes × 4, then every 30 minutes × 4, then hourly × 4, and then every 4 hours until 24 hours after the procedure:
- a. Vital signs.
- b. Insertion site for bleeding or hematoma.
- c. Color, motion, temperature, sensation, and the presence and quality of pulses in the extremity distal to the insertion site as compared to baseline value, and those for the opposite extremity. Notify the physician of any changes from baseline assessment.
- If deep sedation was used, follow institutional protocol for post sedation monitoring. Typical monitoring includes continuous ECG monitoring and pulse oximetry, with continual assessments (every 5–15 minutes) of airway, vital signs, and neurologic status until the client is lying quietly awake, is breathing independently, and responds appropriately to commands spoken in a normal tone.
- For bleeding at insertion site, apply firm pressure for 10 minutes. If bleeding continues after 10 minutes, continue holding pressure, and notify physician.
- A sandbag may be placed over the insertion site for several hours.
- Maintain continuous electrocardiographic monitoring and observe for dysrhythmias for at least 24 hours.
- Resume diet.
- If antidysrhythmic drugs were administered during EPS or begun after EPS, observe cardiac monitor pattern for their effect.
Client and Family Teaching
- Fast from food from midnight the night before the procedure. Fluids may be taken up to 4 hours before the test, but no caffeine is permitted.
- The procedure takes up to 8 hours.
- Because this procedure can be frightening, good explanations are necessary. Inform the client of the following information: you will have to lie as motionless as possible on your back, and feelings of flushing, anxiousness, dizziness, and palpitations are common during EPS. EPS will cause abnormal heart rhythms, and the doctors, nurses, and technicians are skilled at quickly treating these rhythms. The procedure may take 1–8 hours. After EPS, you must lie with the extremity distal to the insertion site motionless for several (usually 8) hours, and a sandbag may be in place over the site. Vital signs, the insertion site, and affected extremity circulation will be checked frequently after EPS.
Factors That Affect Results
- Antidysrhythmic drugs that are not completely cleared from the body before initial EPS may result in a falsely normal study.
- Subsequent treatment based on EPS findings may include antidysrhythmic drugs, ablation, implantation of an implantable cardioverter defibrillator (ICD), implantation of a rapid atrial pacemaker (overdrive pacing), combinations of the above, or other techniques.
- African-Americans have significantly lower rates of utilization of EPS and ICD procedures and higher subsequent death rates (Alexander et al, 2002).
- EPS can elicit latent atrial flutter or tachycardia in clients with refractory atrial fibrillation.
- See also His bundle electrophysiology.