Tag Archives: normal ECG

In the last few articles in this series, we have considered the methodological approach of working through an electrocardiogram (ECG), shared a few ‘hot tips’ and discovered the importance of actually looking at the ECG rather than relying on the digital interpretation! We have seen examples of how the digital interpretation can be very misleading at best, and totally inaccurate at worst. Hopefully by now, you know how to simply describe what you see, and from there build up the pieces of information to create a reasonable interpretation. So this issue, we are going to study an abnormal ECG and work through it. Here we are faced with a ty

Normal values Firstly, the most important things to know, are normal values. Providing the paper speed is standard at 25 mm/second, then each small square = 0.04 seconds. So the only other thing you need to know, in order to correctly identify ECG abnormalities, is your 4 times table! Simple. Looking at figure 1, you can see the following: 1 small square on an ECG trace (at 25 mm/s speed) = 0.04 s The P wave 0.08–0.11 seconds (2–3 small squares) PR interval 0.11–0.20 seconds (3–5 small squares) QRS complex 0.06–0.11 seconds (1.5–2.5 small squares) QT interval 0.36–0.44 (9–11 small squares). Figure 1. What’s what in an ECG