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 115

ECG 115


Basic rhythm

Sinus rhythm, regular at 50 bpm.

P waves

Normal, but every second wave is blocked.

PR interval



Normal duration, increased amplitude from V4 to V6, normal axis.

ST segment


T waves


QT interval

Prolonged (510 ms).


Blocked P wave.
Long QT interval.


Congenital long QT syndrome with functional 2:1 A-V block.


The long QT syndrome prolongs the refractory phase of the A-V conduction pathways, which explains why a portion of the P waves (which are clearly visible on the descending portion of the T wave) is blocked. In the time it takes for the next excitation to occur, the conduction pathways have completed the refractory phase and the atria-ventricles sequence returns to normal. The P waves are not completely regular, since the PP interval with a QRS complex is slightly shorter than the PP interval without a QRS complex. This is due to an ill-explained phenomenon called "ventriculophasic variation".


Prolongation of the QT interval


Reading level

3 / 3