How to Read ECG Electrocardiogram
The ecg electrocardiogram has twelve connected electrodes. Each 'lead' acts like one camera angle capturing the path the electricity takes across your chest. By looking at all the printouts of the ecg a trained observer can put them together his/her mind into a three dimensional view of heart activity. Each event in the production of a heart beat makes a characteristic shape or 'signature' on the ecg reading.
Above left is a photograph of a portable ECG machine. And right, you can see how it's connected. There are four 'limb' straps (1) placed around each of your wrists and each ankle. The bulbs (2) are then connected across your chest in predetermined order and a 'trace' of electrical activity drawn by the machine as below.
Certain patterns are read by health practitioners to help diagnose a variety of abnormalities such as abnormal blood chemistry, arrhythmia misfiring, and of course, heart attacks. ECG Q waves and inverted ECG T waves are two diagnostic wave forms seen in old heart attacks and new heart attacks respectively.
Doctors learn to 'read' ecg's by learning these basic patterns to look for, and then fine tune their interpretations through experience reading hundreds to thousands of ECGs. Typically a doctor reads an ecg the way you'd scan a magazine article looking for obvious things that jump off the page, then in more detail from the upper left corner down to the lower right corner.
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