How to calculate hr on ekg
Introduction:
An electrocardiogram (EKG or ECG) is a diagnostic tool that measures and records the electrical activity of the heart. One important aspect of interpreting an EKG is calculating the heart rate. This article provides a step-by-step guide on how to calculate heart rate using an EKG.
Step 1: Identify the QRS Complexes
The first step in calculating heart rate from an EKG is to identify the QRS complex, which are part of the cardiac cycle representing ventricular depolarization. These complexes appear as a small downward deflection (Q), followed by a taller upward deflection (R), and finally, a small downward deflection (S). On an EKG, these QRS complexes are paramount in determining heart rate.
Step 2: Choose a Method to Calculate Heart Rate
There are two common methods for calculating heart rate using an EKG – the 300 rule and 1500 rule. The 300 rule is suitable for regular rhythms, whereas the 1500 rule works best for irregular rhythms.
a) The 300 Rule:
After identifying the QRS complexes, locate two consecutive R waves and count the number of big boxes between them. Big boxes are 0.20 second wide. Then simply divide 300 by this number to get the heart rate per minute.
For example, if there are three big boxes between two R waves:
Heart Rate = 300 / 3 = 100 beats per minute
b) The 1500 Rule:
For irregular rhythms, find several consecutive R-R intervals on the EKG strip and calculate their average length in small boxes (each small box is equivalent to 0.04 seconds). Then, divide that average by 1500 to get the heart rate per minute.
For example, if you find an average of 25 small boxes between R-R intervals:
Heart Rate = 1500 / 25 = 60 beats per minute
Step 3: Evaluate Your Results
Using the methods mentioned above, calculate the heart rate and compare it to the expected range. A normal adult resting heart rate is typically between 60 and 100 beats per minute. However, it can vary depending on factors like age, fitness level, stress, medications, and medical conditions.
Conclusion:
Accurately calculating heart rate from an EKG is an essential skill for medical professionals and can provide valuable information about a patient’s cardiac health. By following these steps and practicing on various EKGs, you can become proficient in determining heart rates and interpreting EKGs more efficiently.