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 030

ECG 030


Basic rhythm

Sinus rhythm (for the narrow QRS complexes on the trace).

P waves

Normal before a narrow QRS complex, negative in aVL, positive in V1 before an enlarged QRS complex.

PR interval



Alternation of normal and enlarged QSR complexes, complete right bundle branch block type (rSR pattern in V1) and left bundle branch block type (first complex in the precordial leads).

ST segment

Isoelectric (for the narrow QRS complexes).

T waves

Normal in the sinus rhythm or inverted during the extrasystoles.

QT interval



P' wave.
LBBB aspect.
rSR' aspect.


Atrial bigeminy with conduction disturbances.


The atrial bigeminy occurs at a moment when either the right branch or the left branch of the bundle of His is in the refractory phase. The QRS complexes take on a bundle branch block pattern, either right or left. These atrial extrasystoles can cause paroxystic atrial fibrillation (focal AF). Their morphology shows that they originate in the left atrium.




Reading level

2 / 3