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 126

ECG 126


Basic rhythm

Alternating regular and irregular tachycardia with QRS complexes which are sometimes wide and sometimes narrow, at 200 bpm.

P waves

Negative in II, III and aVF.

PR interval

RP' is shorter than P'R, before a blocked P wave RP' is prolonged.


Normal morphology and duration for the narrow QRS complexes; the wide complexes are typical of right bundle branch block.

ST segment, T waves

Widespread permanent changes in repolarisation.

QT interval



Narrow QRS complexes tachycardia.
Blocked P wave.
Aberrant conduction type RBBB.
Negative P' waves.


Right atrial tachycardia with intermittent conduction disturbances. A-V conduction with Wenckebach's phenomenon.


For most of the trace, a P wave is detached from the QRS complexes, with the RP interval longer than the PR interval. The basic rhythm corresponds to narrow QRS complex atrial tachycardia, the focus of which is in the lower part of the right atrium (negative P' wave in II, III and aVF). Intermittently (mainly in V1) the RP' interval is lengthened up to a blocked P' wave, which corresponds to a Wenckebach type A-V block. The widened QRS complexes are typical of a right bundle branch block. They correspond to an aberrant ventricular conduction, which arises after an long RR interval (Ashman phenomenon).


Wide QRS complex tachycardia


Reading level

3 / 3