A 12-lead ECG records a 10 second rhythm strip. On this strip, the heart’s activity is translated into line tracings. The dips and spikes in an EKG cycle are called waves that represent different phases of the heart’s activity. To read an EKG, it’s important to understand the components of the wave.

The goal of reading an EKG rhythm strip is to determine the rate and rhythm of the patient. This is great for identifying baseline cardiac rhythm as well as any arrhythmias or ectopy that may occur (like a premature beat). A 12-lead EKG also looks at the rate and rhythm, but additionally gives nearly a complete 360° view of the heart.

When interpreting an EKG, it’s important to go through five steps: assess if the rhythm is regular or irregular, observe its rate, inspect P waves for any abnormalities, and measure their PR interval. Analyze the QRS complex in terms of morphology as well as look out for other clues.