RT Book, Section A1 Zimmerman, Franklin H. SR Print(0) ID 1200099885 T1 Heart Rate T2 ECG Core Curriculum YR 2023 FD 2023 PB McGraw Hill Education PP New York, NY SN 9780071785211 LK accesscardiology.mhmedical.com/content.aspx?aid=1200099885 RD 2024/04/25 AB It’s finally time to start making real measurements, so let’s begin by learning how to calculate the heart rate (HR). For every ECG, you should calculate both the ventricular rate and atrial rate. We can calculate the ventricular rate by measuring the time between the QRS complexes (R-R intervals), and the atrial rate by measuring the time between the P waves (P-P intervals). In normal sinus rhythm the atrial and ventricular rates are identical. In patients with cardiac arrhythmias, the atrial and ventricular rates may be very different, something we are going to learn in subsequent chapters. For the following discussion we will concentrate on the R waves to calculate the ventricular rate, but the same principles apply when using the P waves to calculate the atrial rate. There are a number of different methods that you can use, but I will present them in the order I find most practical.