Electrophysiology (EP) Tests

UW Health Heart, Vascular and Thoracic Care doctors perform electrophysiology tests (EP tests) to determine how the heart is affected by an arrhythmia.
What are electrophysiology (EP) tests?
Due to the unpredictability of arrhythmias, it can be difficult for doctors to prescribe medications or surgery without actually seeing how the arrhythmia starts or behaves once it has started.
In order to determine how the heart is affected by an arrhythmia, doctors may try to replicate a brief episode of the arrhythmia. This can be done with electrical stimulation of the heart during an electrophysiology (EP) test.
EP studies are often recommended to diagnose arrhythmias, or to determine the exact cause of and plan treatment for a previously-identified arrhythmia.
During an EP test, doctors can monitor the heart's electrical function or stimulate the heart with electrical impulses in order to produce and observe the effects of an arrhythmia and map the site it comes from. The map of damaged areas can be used by doctors during a corrective procedure, such as ablation.
EP tests are also used to investigate further when it appears a person may need a Pacemaker or an Implantable Cardioverter Defibrillator, or ICD. Basically, the EP study is performed by doing two things:
  • Recording electrical signals: Electrode catheters sense electrical activity in various areas of the heart and measure how fast electrical impulses travel.
  • Pacing the heart: Electrode catheters can also be used to deliver tiny electrical impulses to pace the heart. By doing so, doctors try to induce certain abnormal heart rhythms so they can be observed under controlled conditions.

The results of an EP test complement the information a doctor gains through knowledge of a person's medical history, a physical exam and non-invasive tests such as chest x-rays, echocardiograms, electrocardiograms or heart monitors.


Preparing for an EP Study


Electrophysiology ProgramIf you are scheduled for an electrophysiology (EP) study at University of Wisconsin Hospital and Clinics, you should not eat or drink anything for eight to 12 hours before the test. You may be asked to hold certain medications such as blood thinners or anti-arrhythmic medications for several days prior to the procedure.


Local anesthetic is used to numb the area where the catheters are to be inserted, so most people feel only a slight pressure or a sensation of mild tugging. Other than a sedative, people having an EP study may not receive any other drugs because some anesthetics can alter how the heart functions.


An EP test can take anywhere from one hour up to five or six hours. Because of the unpredictable length of the test, it is often recommended that people scheduled for an EP test use the bathroom immediately before the test begins.


The Electrophysiology (EP) Study Procedure


Results and Treatment


When your EP study is complete, the sheath and catheters are withdrawn and pressure is applied to the insertion point to control bleeding. The patient is usually asked to remain lying down for four to six hours. Patients are asked to refrain from heavy lifting for approximately five days. With some restrictions, most people can resume normal activity within eight hours of the procedure.


The results of an EP study can be used to prescribe or adjust anti-arrhythmic medication. When an EP test confirms the presence of a slow or erratic heart rhythm, pacemaker implantation may be indicated.


An Implantable Cardioverter Defibrillator (ICD) - a device that constantly monitors the heart rate and electrically stimulates or shocks the heart when the device detects ventricular tachycardia or fibrillation - may be required for people with ventricular arrhythmias. Surgery may also follow EP testing.


For isolated or benign arrhythmias that do not present a serious danger to normal heart function, no further treatment may be necessary.