How to Read EKG Rhythms

An electrocardiogram, or EKG, is a machine that measures a heartbeat. It produces a paper called an EKG strip, which displays the heart's electrical activity. Your doctor uses that information to analyze how healthy your heart is.

Instructions

• 1

  Look along the horizontal axis of the EKG strip. Each small-sized square is one millimeter long and indicates 0.04 seconds. Each of the larger squares is five millimeters long and represents 0.2 seconds.

• 2

  Use the vertical axis to measure voltage. On the strip, 10 millimeters are the same as 1mV (milliVolt) in voltage.

• 3

  Notice the sharp spikes of the line. These are the QRS complexes, the spikes that represent ventricular depolarization. When looking at each spike, Q is the bottom left, or the dip just before the sharp spike. R is the top of the spike, and S is the dip at the bottom right side.

• 4

  Calculate the heart rate of someone with a regular rhythm by taking the number 300 and dividing it by the number of large squares that fall between the QRS complexes or spikes. If there are three large squares between the QRS complexes, the heart rate is 300/3 or 100.

• 5

  Use a different formula to determine heart rate of someone with an irregular rhythm. Take into account the number of R waves in a six-second portion of the EKG strip. R waves are the top of each QRS complex. Multiple that number by 10. If there are eight R waves in a six-second piece of strip, the heart rate is 80 because 8x10=80.