An electrocardiogram (EKG or ECG) is perhaps the single most useful and often-used test in the field of cardiology, said Dr. Humberto Vidaillet, a Marshfield Clinic cardiologist.

What does an EKG show?

“It shows an incredible amount of information,” Vidaillet said. “It can reveal heart rate, rhythm, size of the heart chambers, conduction properties of the heart, presence of old and acute heart attacks, and many more potential abnormalities.”

An EKG also can identify how well a pacemaker is working.

An EKG works by measuring electrical activity of the heart from the surface of the chest. The first EKG in history was recorded in 1887.

Vidaillet said one advantage of an EKG is it allows doctors to compare a patient’s tracings over time, which can help determine changes. Comparing EKGs for the same patient from two different times may give cardiologists an idea of what and when a change occurred in the heart.

A painless test

EKG tests are not dangerous or painful, and once a patient is ready, the actual test lasts a few minutes. Vidaillet said computer algorithms have been developed for fast preliminary interpretations of EKGs, but having an experienced reader review the tracings is still necessary for an accurate assessment.

For patients whose heart health needs to be closely monitored, Vidaillet said he might order EKGs in consecutive appointments or, on rare occasions, even multiple EKGs in one day.

“Heart rhythm can change in a matter of a second,” he said. “Despite how useful an EKG can be, there’s still no substitute for getting a patient’s medical history, a thorough physical examination and understanding each patient’s preference for care.”

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