beth israel deaconess medical center a harvard medical school teaching hospital

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If you are experiencing a slow heart rate and dizziness, weakness or fainting spells, you will need to be evaluated by your doctor. Besides taking your pulse and blood pressure, he or she will also check for an alternating rhythm.

Diagnostic Tests

Tests to determine just what is causing your bradycardia will need to be performed. These tests include:

Electrocardiogram (ECG)

ECG/EKG WavesPainless, Noninvasive Test Using Electrodes

This is a painless, noninvasive test in which patches with electrodes are attached to your skin to measure electrical impulses produced by your heart. These impulses are recorded as waves displayed on a monitor or printed out on graph paper.

Shows Heart Rate and Rhythm

It shows how fast your heart is beating and its rhythm (steady or irregular). It also records the timing of the electrical signals as they pass through each part of the heart.

Holter Monitor

Records Heartbeats for 24 or 48 Hours

This is a portable device that records all of your heartbeats over an extended period, usually either 24 or 48 hours.

  • You wear small patches with electrodes on your chest that are connected by wires to a small, portable recorder.
  • The recorder can be clipped to a belt, kept in a pocket, or hung around your neck.
  • During the time you're wearing a Holter monitor, you do your usual daily activities.
  • You can press a button if you are experiencing symptoms, so your doctor will know what your heart rhythm was at the time of the symptoms.

Event Monitor

Records Electrical Activity When You Push A Button

This machine is similar to the Holter monitor, except that not all of your heartbeats are recorded.

  • You wear the device continuously, but it only records electrical activity when you push a button -- and you only push the button when you feel symptoms.
  • These devices may be worn for as long as one to two months.


Noninvasive Test

This test uses sound waves to create a moving picture of your heart. An echocardiogram:

  • Provides information about the size and shape of your heart and how well your heart chambers and valves are functioning.
  • Identifies areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.
  • Noninvasive and is performed by placing a probe on your chest wall. It is the same technique used in sonograms in pregnant women.

Blood Tests

These tests are used to detect:

  • Level of thyroid hormones
  • Balance of your body's electrolytes, minerals in your blood and body fluids that are essential for normal health and functioning of your body's cells and organs

Abnormal levels of these substances may cause heart rhythm disturbances.

Contact Information

Cardiovascular Medicine
Division of the CardioVascular Institute
Beth Israel Deaconess Medical Center
330 Brookline Avenue
Boston, MA 02215