ECG Directory

Welcome to this interactive ECG course.

Although it is one of the oldest paraclinic exams, dating back to the late 19th century, the ECG is still of crucial clinical use. This examination often still poses problems of interpretation to the medical practitioner.

This course aims to help the student, the practicing physician and even the trained cardiologist to improve his knowledge in electrocardiography. It consists of 250 traces of varying complexity with a description of each one by experts. This allows the reader to compare his analysis with that of the experts. In addition, the areas of interest of the ECG can be activated to be clearly highlighted.

We hope that these plots will be useful to readers and will improve their knowledge.

The ECGs are available sorted by keywords and categories.

ECG 047

ECG 047


Basic rhythm

Regular tachycardia with a narrow QRS at 200 bpm

P waves

Negative at I, II, III, aVL and aVF with RP’ <P’R

PR interval

Variable, with alternation of normal and prolonged PR


Normal axis. Normal duration. Alternation of amplitude clearly visible at V3-V5.

QT interval



QRS complexes alternance.
Variation of RR interval.
Variation of P'R interval duration without variation of RP' interval duration.


Orthodromic tachycardia on left inferior accessory pathway.


The alternance of amplitude of the QRS complexes would support the diagnosis of bundle branch block orthodromic tachycardia. The RP’ interval is constant, indicating that there is only one accessory pathway used retrogradely. The PR interval varies with one long and one shorter interval. This phenomenon is due to the presence of a duality of A-V conduction routes. When the P’R is long the pulse uses the slow route and when it is short it is the rapid A-V route that is used. The polarity of the P wave allows the left bundle branch to be located.


Narrow QRS complex tachycardia


Reading level

3 / 3