How does an EKG work?

by | May 13, 2009 10:00 AM ET

You Asked:

How does an EKG work? --- Kia, Boise, Idaho

Marshall Answered:

And EKG is also called an Electrocardiogram or an ECG. It is a way of measuring the electrical impulses that the heart generates as it is beating. If you look at How your heart works , you can see that there is a network of nerve pathways on the surface of the heart. Signals spread out from the sinoatrial node in a pattern that causes the heart muscle to contract properly during each beat.

Using a few electrical pickups and a fairly simple amplifier circuit, it is possible to detect the heart's electrical impulses on the skin. You can see how simple the circuits are here and here. The impulses can then be displayed on a screen for a doctor to interpret.

Many different heart abnormalities can be detected by looking at an EKG, especially following a heart attack. This library of EKG strips shows you how different problems can show up on an EKG.

For more info see:

- How to do CPR

- How a heart defibrillator works

- How stents work

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