[2] EP studies are used to investigate the cause, location of origin, and best treatment for various abnormal heart rhythms, and are often followed by a catheter ablation during the same procedure.

If the reason for the EP study is for an arrhythmia, then antiarrhythmic drugs may be held to increase the likelihood of being able to induce the rhythm.

The electrophysiologist begins by moving the electrodes along the conduction pathways and along the inner walls of the heart, measuring the electrical activity along the way.

If the arrhythmia is reproduced by the drugs (inducible), the electrophysiologist will search out the source of the abnormal electrical activity.

If at any step during the EP study the electrophysiologist finds the source of the abnormal electrical activity, they may try to ablate the cells that are misfiring.

This is done using high-energy radio frequencies (similar to microwaves) to effectively heat up the abnormal cells, to form scar tissue.

If the femoral artery was used, the patient will probably be asked to lie flat for several hours (3 to 6) to prevent bleeding or the development of a hematoma.

It is also important to note that unless directed by a doctor, some patients should avoid taking blood thinners and foods that contain salicylates, such as cranberry-containing products until the clot has healed (1–2 weeks).

[6] There have been reports of patients feeling like they have hot fluid like blood or urine running down their leg for up to a month or two after the incision has healed.

More severe but relatively rare complications include: damage or trauma to a blood vessel, which could require repair; infection from the skin puncture or from the catheter itself; cardiac perforation, causing blood to leak into the sac around the heart and compromising the heart's pumping action, requiring removal using a needle under the breast bone (pericardiocentesis); hematoma at the site(s) of the puncture(s); induction of a dangerous cardiac rhythm requiring an external shock(s); a clot may be dislodged, which may travel to a distant organ and impede blood flow or cause a stroke; myocardial infarction; unanticipated reactions to the medications used during the procedure; damage to the conduction system, requiring a permanent pacemaker; death.