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 046

ECG 046


Basic rhythm

Narrow complex tachycardia, regular at 150 bpm.

P waves

Negative in II, III, aVF, V5 and V6, detached from the QRS complex.

PR interval

RP' < P'R.


Axis, duration, and morphology normal.

ST segment


T waves


QT interval



Narrow QRS complexes tachycardia.
QRS complexes alternance.
P' wave distant from the QRS complex (200 ms).


Orthodromic tachycardia with an infero (postero)-septal accessory pathway.


The chronological relationships between the P waves and the QRS waves are the essential criteria for the differential diagnosis of narrow complex tachycardias. A clearly visible P wave occuring in the inferior and precordial leads rules out typical atrioventricular nodal re-entrant tachycardia, in which the P wave is concealed in the QRS complex. An RP' < P'R interval identifies orthodromic tachycardia, with an accessory pathway that a P wave, negative only in the inferior leads, indicates as being infero(postero)-septal.


Narrow QRS complex tachycardia


Reading level

2 / 3