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 026

ECG 026


Basic rhythm

Sinus, 75 bpm

P waves


PR interval



Sometimes narrow (100 ms) with a normal axis, sometimes widened (120 ms) with left-axial hyperdeviation

ST segment

Isoelectric with narrow QRS complex

T waves

Flattened in the lower leads

QT interval



Ventricular premature contraction.


Monomorphous ventricular extrasystole


Broad complexes not preceded by a P wave are ventricular extrasystoles. They are sometimes interpolated (in the peripheral leads), sometimes shifting (2nd extrasystole from precordial leads). The coupling interval varies widely and an extrasystole that falls on the T wave of the preceding complex (R-on-T phenomenon) is capable of causing so-called “idiopathic” ventricular fibrillation, in the absence of any underlying cardiac disease. This is what has happened in the case of this patient who has been fitted with an internal defibrillator.

The extrasystoles are only slightly widened and their overall morphology shows that they occur near intraventricular conduction routes (His-Purkinje system). The P wave following the last extrasystole is blocked; the A-V conduction routes are in refractory phase due to the extrasystole whose coupling interval is particularly long.




Reading level

1 / 3