Electrophysiology(EP) Study

When an arrhythmia is seen or strongly suspected from symptoms reported, an EP study may be recommended to clarify the problem. The EP study is a procedure during which electrical recordings are gathered both from the inside of the heart and from the body surface. ECG electrodes are placed on the body surface and are recorded throughout the study. Wires called electrode catheters mounted small metal bands are guided into the heart from veins in the leg and/or the neck using X-ray. The catheters are positioned at various locations in the heart so that electrical signals can be recorded from each of the locations simultaneously. The catheters can also serve as pacemakers that allow the physician to stimulate the heart and start the arrhythmia. The study therefore allows the physician to observe what part of the heart is involved in the production of the arrhythmia and, in some cases, to map the location and attempt to destroy it so that the arrhythmia cannot recur. The external (ECG) signals allow the physician to match the arrhythmia with arrhythmias which have already been observed in the other recordings (ECG or other monitors) made by the patient.

The EP study is performed in a specially equipped laboratory which is very similar to a typical heart catheterization laboratory. Since X-ray equipment is used, women are not allowed in the laboratory while they are pregnant. The studies vary in length but usually last approximately 2 hours. The catheters are sometimes inserted into an artery in the leg as well if access to the left atrium or ventricle is required. Local anesthesia and IV tranquilizers and sedatives are used to make the study as comfortable as possible for the patient. At the end of the study, bed rest of 4-8 hours duration is necessary while the catheter insertion sites seal. Recovery time from the EP study is minimal. Strenuous activity is prohibited for 4 days after the study, but routine activities of daily living can resume the day after the study.

Like any invasive procedure, there are some risks associated with EP studies. The main risks are bleeding at the site of catheter insertion or damage to the blood vessel or vessels entered during the study. Infection can also occur at the sites of catheter insertion, although the procedure is performed using strict sterile technique. If veins in the neck or chest are used for access, it is possible, although rare, to puncture the lung and cause an air leak into the space in which the lung resides. If the leak is persistent, air may need to be drained from the space by insertion of a tube through the chest wall. The catheters are stiff wires which can actually perforate the thin walls of the right ventricle and cause bleeding into the pericardial space around the heart. Most of the time these perforations seal themselves and no therapy of any kind is necessary. Rarely, however, the blood must be drained from the pericardial space with a needle or with surgery. Death has been reported during EP studies, but the incidence is less than one one-hundredth of one percent.