What Is an Electrocardiogram (ECG or EKG)?

A machine records the electrical activity of your heart with a pen and graph paper. The doctor studies the shapes of these lines to check for any changes in the normal rhythm. It is used as a baseline to:

  • Evaluate the size of the heart
  • Evaluate the heart's valves and chambers
  • Detect abnormalities or presence of heart disease
  • Evaluate cardiac function after a heart attack

Types of Electrocardiograms

Resting ECG

The patient lies down for a few minutes while a record is made. In this type of ECG, disks are attached to the patient's arms and legs as well as the chest.

Stress Test (Exercise ECG)

The patient exercises either on a treadmill machine or bicycle while connected to the ECG machine. This test tells whether exercise causes arrhythmias or makes them worse or whether there is evidence of inadequate blood flow to the heart muscle (ischemia).

24-Hour ECG (Holter) Monitoring

The patient goes about his or her usual activities while wearing a small, portable tape recorder that connects to the disks on the patient's chest. Over time, this test shows changes in rhythm that may not be detected during a resting or exercise ECG.

Event Recorder (Transtelephonic Monitoring)

The patient wears the tape recorder and disks over a period of a few days to several weeks. Transtelephonic monitoring can reveal arrhythmias that occur only once every few days or weeks.

Like the Holter monitor, an event recording is used to record heart rhythm during daily activities. When you feel symptoms, you press a record button and the device records and stores the heart’s electrical activity. The information can be sent to the EP lab over the phone.

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