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 056

ECG 056


Basic rhythm

2 types of tachycardia. The wide QRS complex tachycardia (first 3 complexes) followed by narrow QRS complex tachycardia (last 4 complexes). Both are regular at 187 bpm.

P waves

Not visible when the QRS complexes are wide. Visible at the end of the narrow QRS complex (terminal r wave).

PR interval

Not definable.


Normal axis (for the narrow QRS complexes) +20° (for the wide QRS complexes); rS (QS) pattern in the right precordial leads (for the wide QRS complexes). Pseudo r wave present in V1, corresponding to a P wave.

ST segment, T waves

Diffuse non-specific changes.

QT interval



Wide QRS complexes tachycardia (LBBB) followed by a narrow QRS complexes tachycardia.


Typical atrioventricular nodal re-entrant tachycardia with intermittent left bundle branch block type conduction disturbance.


On the second part of the trace, there is narrow QRS complex tachycardia, with a P wave visible at the end of the narrow QRS complex (pseudo r wave). This is a case of typical atrioventricular nodal re-entrant tachycardia which, in the first part of the trace, shows as a left bundle branch block type conduction disturbance.

If there was orthodromic reciprocating tachycardia on a left accessory pathway, the left bundle branch block would have caused the rate of the tachycardia to decrease (block with a slowing effect). Since the ventricular heart rate is perfectly regular in all parts of the trace, we can exclude this hypothesis.


Wide QRS complex tachycardia


Reading level

3 / 3