Strong Heart and Vascular Center
Electrophysiology (EP) Labs
What is Electrophysiology, or Heart Rhythm Disorders?
Normally, electricity flows from one heart cell to the next throughout the heart in a regular, measured pattern. This electrical system brings about heart muscle contractions. A problem anywhere along the electrical pathway causes an arrhythmia, or heart rhythm disturbance. By accurately diagnosing the precise cause of an arrhythmia, it is possible to select the best possible treatment.
Cardiac electrophysiology is the study of the heart’s electrical system. The term “electrophysiology study” or “EP study” applies to any procedure that requires the insertion of an electrode catheter into the heart. Electrode catheters are long, flexible wires that transmit electrical currents to and from the heart.
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Through invasive and non-invasive tests of your heart, your risk of arrhythmia is tested and treatment recommendations can be made. Some electrophysiology studies are performed in order to diagnose heart rhythm problems and conditions, while others are done to access the heart for treatment or correction of certain conditions.
The invasive test uses electrode catheters (long, flexible wires) that are inserted into veins and are guided into your heart to record electrical impulses. Abnormal sites in the heart that are causing the arrhythmia can be found and doctors can treat you accordingly. Learn more about what's involved in having an EP study.
Why Have an EP Study?
While electrocardiograms (EKGs) are important tests of the heart’s electrical system, they are brief tests that record only the events that occur while the tests are running. Arrhythmias, by their very nature, are unpredictable and intermittent, which makes it unlikely that an EKG will capture the underlying electrical pathway problem. Even tests that stretch over longer time lengths, such as Holter monitoring, may not capture an event.
EP studies most often are recommended for patients with symptoms indicative of heart rhythm disorders or for people who may be at risk for sudden cardiac death.
What Happens During an EP Study
During an EP study, a specially trained cardiac specialist, an electrophysiologist, will try to initiate arrhythmia events and collect data about the flow of electricity during actual events. As a result, EP studies can help locate the specific areas of the heart tissue that give rise to the abnormal electrical impulses that cause arrhythmias. This detailed electrical flow information provides valuable diagnostic and, therefore, treatment information.
The Value of an EP Study
An EP study provides information that is key to diagnosing and treating arrhythmias. Although it is more invasive than an EKG or an echocardiogram (ECHO), and involves provoking arrhythmias, the test produces data that makes it possible to:
- Diagnose the source of arrhythmia symptoms
- Evaluate the effectiveness of certain medications in controlling the arrhythmia
- Predict the risk of a future cardiac event, such as sudden cardiac death
- Assess the need for an implantable device (a pacemaker or ICD) or treatment procedure (catheter ablation)
How an EP Study Helps to Guide Treatment of Arrhythmias
- Insertion of a Pacemaker—If the EP study confirms
the presence of significant bradycardia, a permanent pacemaker
(or non-invasive heart rhythm monitoring device) can often be inserted immediately, during the same procedure. Learn more about pacemakers
- Ablation—If supraventricular tachycardia
(SVT), some forms of ventricular tachycardia (VT), and atrial fibrillation (AFib) are
found, radiofrequency
ablation can be the treatment of choice. The ablation
procedure is usually carried out during the same procedure, immediately
following the baseline EP study. Once the EP study has
confirmed the precise mechanism of the patient's tachycardia, a specialized
electrode catheter is inserted, and the heart's electrical
system is carefully mapped. Once the doctor identifies
the precise area of the heart most responsible for causing the
arrhythmia, radiofrequency energy is passed through the
tip of the catheter to cauterize the culprit area. For the
most
common forms of SVT, ablation is successful in eliminating
the arrhythmia in more than 95% of patients.
- Implantable Defibrillators—If rapid forms of VT and/or ventricular fibrillation (VF) are identified during the EP study, most commonly an implantable defibrillator is the treatment of choice. This device can now often be inserted in the EP laboratory, immediately following the EP study. In earlier years, the EP study was used to identify the "best" antiarrhythmic drug for patients with VT or VF, but today it is understood that no anti-arrhythmic drug is as effective as the implantable defibrillator in preventing sudden death from these arrhythmias. Learn more about implantable defibrillators