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 127

ECG 127


Basic rhythm

Regular at 86 bpm.

P waves

Not visible except in II, replaced by small stimulation spikes (I). PR interval: prolonged spike-QRS interval (260 ms).


RSR pattern in V1, wide S wave in V6. Axis: -50°.

ST segment

Oblique and descending in V1 and V2.

T waves

Negative in V1.

QT interval



Spike followed by P wave.
Rigth bundle branch block (RBBB).
Left axis deviation.


Pacemaker stimulating the atria. First degree A-V block. Complete RBBB, left anterior hemiblock.


The P waves are preceded by a spike, as the atria are paced. The axis and morphology of the P wave allow the pacing to the located to the right atrium. The PR interval (in this case the spike-R interval) is prolonged, a sign of a first degree A-V block. The QRS complexes are wide with a pattern typical of complete RBBB (rSR pattern in V1); the left axis deviation is due to a left anterior hemiblock. The pacemaker is working in AAI mode to compensate for bradycardia. A dual chamber (DDD) pacemaker was implanted due to a block which was probably trifascicular (first degree A-V block + right bundle branch block + left anterior hemiblock) which would be likely to lead to a complete A-V block. In V4 there is interference in the trace, but the QRS complexes can still be recognised.




Reading level

2 / 3