As a medical professional with expertise in cardiology, I can explain how to determine the heart rate from an electrocardiogram (ECG or EKG). The ECG is a graphical representation of the electrical activity of the heart, which can be used to diagnose various heart conditions and to calculate the heart rate. Here's a step-by-step guide on how to determine the heart rate from an ECG: 1. Identify the QRS Complex: The QRS complex on an ECG represents the depolarization of the ventricles, which is a crucial part of the heart's rhythm. Each QRS complex corresponds to one heartbeat. 2. Measure the Time Between QRS Complexes: Use a caliper or a ruler to measure the distance between two successive QRS complexes. The ECG paper is standardized, with 25 millimeters (mm) equal to 0.2 seconds (s) in time. 3. Calculate the Heart Rate: If you have measured the distance between two QRS complexes, you can calculate the heart rate by taking the number of large squares (each is 0.2 seconds apart) between the complexes and dividing 300 by that number. For example, if there are three large squares between two QRS complexes, the heart rate is 300 / 3 = 100 beats per minute (bpm). 4. Consider the Rhythm: If the rhythm is regular, the heart rate can be calculated by simply counting the number of QRS complexes in 15 seconds and then doubling it to get the beats per minute. If the rhythm is irregular, you may need to count the number of QRS complexes in a full minute to get an accurate heart rate. 5. Use a Heart Rate Calculator: Some ECG machines come with a built-in heart rate calculator that automatically computes the heart rate based on the QRS complex intervals. It's important to note that the ECG must be properly calibrated and that the patient should be in a resting state to get an accurate measurement. Additionally, certain medications or medical conditions can affect the heart rate, so it's always best to interpret ECGs in the context of the patient's overall health and medical history. read more >>

to go by RR or PP interval. If it is 1 big box (0.2 secs) then the rate is 60/0.2 = 300 bpm. ... Count the number of RR intervals between two Tick marks (6 seconds) in the rhythm strip and multiply by 10 to get the bpm. This method is more effective when the rhythm is irregular.read more >>