During an electrocardiograph, a nest of wires connected to pads on a patient’s chest and limbs sends signals to recording equipment. The recordings allow medical professionals to review heart activity for abnormalities that might indicate concern or evidence of a recent malfunction such as a heart attack. For those at risk of heart problems, electrocardiograms can serve as the “baseline,” to which doctors can compare future EKGs to determine changes in heart activity.

1. How EKGs Detect Heart Activity

Each lead of the EKG transmits an electrical signal from a different place on the heart, created as the atria and ventricles polarize and depolarize while the heart beats. These signals are transmitted through the skin. Medical professionals interpret heart activity through these signals, though they do not directly represent the beating heart. EKG signals and the relationships between them are used to quickly identify common heart malfunctions.

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