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 199

ECG 199


Baseline rhythm

Pacing at 70 bpm.P-waves: sometimes visible before the QRS (second complex from the left), normal axis and duration.PR interval: normal when it can be measured.QRS: broad because it is preceded by a spike: When it follows a P-wave it is broad with a duration of 140 ms, rSR’ in V1. Normal axis.ST segment: isoelectric.T-waves: abnormal due to the pacing.QT interval: normal.


Spike in the T wave, without QRS complex
QRS complex preceded by a P wave, and spike not followed with a QRS complex..


VVI pacemaker dysfunction with sensing malfunction. Otherwise sinus rhythm and RBBB.


There is clearly a VVI pacemaker which captures the ventricles correctly as shown by the 1st, 3rd and 4th complexes. The polarity of pacing is unipolar given the amplitude of the spike. On the other hand, we see that the spikes are on the T-wave which signifies the pacemaker’s failure to sense the QRS. There is no capture failure because the spikes which are not followed by a QRS occur when the ventricle is still refractory after the normal QRS complex (except for RBBB).




Reading level

1 / 3