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 025

ECG 025


Basic rhythm

Sinus rhythm, irregular; mean heart rate approx. 54 bpm.

P waves


PR interval

Variable, between 100 and 120 ms.


Duration variable between 110 and 130 ms; axis -30°. R/S ratio > 1 in all precordial leads.

ST segment


T waves

Flattened or negative in most leads.

QT interval



QRS morphology variation.
Short PR interval and ∂ wave.


Wolff-Parkinson-White syndrome.


In some leads (I,V5) some QRS complexes are characteristic of preexcitation (PR interval reduced by a delta wave). The orientation of the delta wave is typical of a left inferior accessory pathway. The variations of the PR interval, the morphology and amplitude of the QRS complexes depend on the respective parts of the nodo-Hisian pathway and accessory pathway in the ventricular excitation. It is the relationship between the conduction speeds through the A-V node and the accessory pathway that determines the significance of the preexcitation (concertina effect). This variation in the significance of the preexcitation depends on the heart rate, the neurovegetative tone, or even antiarrhythmic drug treatment.




Reading level

2 / 3