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Saint Thomas Heart


The Electricity of the Heart

Electrophysiology is the study of the electrical activity in the heart. An arrhythmia is an abnormality with the rate or rhythm of the heartbeat. These abnormal heart rhythms may start in the atria (the upper chambers of the heart) or the ventricles (the bottom chambers of the heart which provide the main pumping pumping of blood through the body). During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

Saint Thomas Heart electrophysiologists are extensively trained in treating a wide range of heart rhythm conditions including:

For more information on arrhythmia, click here

Diagnostic Testing

Saint Thomas Heart electrophysiologists rely on a patient's medical history and the results of a variety of procedures to diagnose heart rhythm abnormalities. Some of these tests may include:

  • Electrocardiogram (ECG/EKG) - recording of your heart's electrical activity for several seconds.
  • Holter monitor - recording of your heart's electrical activity during 24 or 48 hour period of time.
  • Event recorder - longer term recording of your heart rhythm, usually worn for up to a month.
  • Implantable loop recorder insertion – monitoring up to 3 years. An implantable loop recorder (ILR) is a small device which is implanted under the skin on the chest. This device records the heart’s rate and rhythm continuously. These recordings are transmitted on a regular basis to a monitoring center and are reviewed by your doctor. ILRs are most often used in patients with suspected, but intermittent abnormal rhythms.
  • Echocardiogram - ultrasound that provides pictures of the heart's valves, chambers, and pumping function.
  • Exercise test (stress test or treadmill stress test) - helps to determine abnormal heart rhythms during exercise.
  • Tilt table test - a procedure performed to evaluate causes of lightheadedness or fainting. A table starts in a horizontal position and then is tilted upwards at different angles while heart rate and blood pressure are monitored.
  • Advanced cardiac CT scanner - Advanced CT technology that uses intravenous dye to obtain high-resolution, three dimensional (3D) pictures of the moving heart and great vessels.
  • Cardiac MRI - Magnetic resonance imaging of heart to evaluate the heart's structure and function. No radiation is involved in this test.
  • Diagnostic invasive electrophysiology studies.
  • Three dimensional mapping systems to assist ablation of complex arrhythmias.


With advanced resources, including leading edge technology in the hands of experienced clinicians, Saint Thomas Heart offers our patients many options to help manage arrhythmias. Available treatments include:

  • Antiarrhythmic medications
  • Implantable cardioverter defibrillators (ICDs)
    • An ICD is an electronic device, usually implanted in the patient’s chest, that designed to recognize and correct certain types of abnormal heart rhythms (arrhythmias). ICDs constantly monitor the heart’s rate and rhythm. They function as pacemakers for abnormally slow heart rates, and for dangerously fast rhythms, they deliver precisely calibrated and timed electrical therapies which may include rapid pacing or shocks. ICDs are 99% effective in stopping ventricular fibrillation - the major cause of sudden cardiac death.
  • Pacemaker insertion
    • A pacemaker is a system that monitors and regulates the patient’s heart rate and rhythm. If the pacemaker “senses” that the rate is too slow, it transmits electrical impulses to the heart muscle and “paces” the heart. Pacemakers may be programmed to pace the heart continuously at a set rate, or it may be programmed to increase the patient’s heart rate as it “senses” an increase in the patient’s activity.
  • Catheter ablation for SVT, atrial fibrillation and ventricular tachycardia using the technologies of radiofrequency ablation and cryoablation
    • During this non-surgical procedure, a catheter (thin, flexible tube) is guided via x-ray through the blood vessels into a specific area of the heart. A special machine directs energy through the catheter to small areas of the heart muscle that cause the abnormal heart rhythm. This energy "disconnects" the pathway of the abnormal rhythm by destroying very small areas of tissue that give rise to abnormal electrical signals. It can also be used to disconnect the electrical pathway between the upper chambers (atria) and the lower chambers (ventricles) of the heart.
  • Cardiac resynchronization therapy (CRT) –
    • This special pacemaker was designed for patients in heart failure, whose heart strength is weakened and whose lower chambers (ventricles) are not contracting together in “synchrony”. This device resynchronizes the contractions by pacing both ventricles at the same time in an effort to improve the efficiency and increase the strength of the heart.
  • Electrical cardioversion –
    • This is a procedure performed in the hospital, with the patient under sedation, in which an electrical shock is used to convert an abnormal rhythm back to a normal rhythm.
  • Left Atrial Appendage Closure (LAAC) to prevent strokes due to atrial fibrillation
  • Pacemaker and ICD lead extraction using a laser system