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 013

ECG 013


Basic rhythm

Regular narrow complex tachycardia at 200 bpm.

P waves

Negative in I, aVL, positive in III and V1.

PR interval

RP' < P'R.


Alternance (of amplitude) clearly visible in II, III, aVF; vertical axis, normal morphology.

ST segment, T waves

Non-specific changes in the terminal phase.

QT interval



Narrow QRS complexes tachycardia.
P' waves negatives in I and aVL, positives in III and V1. RP'< P'R.


Orthodromic tachycardia with a left lateral accessory pathway.


In the differential diagnosis of narrow complex tachycardias, the chronological relationship between the QRS complex and the P wave (here RP'< P'R) is the key to the diagnosis. Alternance of the QRS complexes is another non-specific indication which is sometimes present in other tachycardias, in particular atrial tachycardias. The axis of the P' wave, pointing in a right-anterior direction, indicates that the accessory pathway is localised in a left lateral position. In the case of sinus rhythm in WPW syndrome, the QRS complex is deformed by a delta wave. If the delta wave is absent it is not a case of WPW syndrome. The accessory pathway only conducts in a retrograde direction ("concealed" accessory pathway).


Narrow QRS complex tachycardia


Reading level

2 / 3