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 040

ECG 040


Basic rhythm

Regular sinus rhythm at 85 bpm.

P waves


PQ interval

Sometimes normal at 140 ms and sometimes prolonged at 240 ms.


Alternation of narrow and wide QRS complexes. Narrow QRS axis – 10°. Wide QRS axis + 120°. Predominant R wave in V1 in the wide QRS complexes. Micropotentials in the peripheral leads.

ST segment

Diffuse repolarisation changes following the wide QRS complexes.


Two QRS complexes morphologies.
Short PR interval. ∂ wave.
Prolonged PR interval.


2:1 conduction over a left lateral accessory pathway (WPW syndrome).


The morphology of the wide QRS complexes is not that of a conduction abnormality. It indicates either a ventricular origin (ventricular bigeminy) or preexcited complexes. As each wide QRS complex is preceded by a P wave, the latter hypothesis is correct. Intermittent preexcitation is explained by the duration of the refractory period of the accessory pathway, which is long in this case.




Reading level

2 / 3