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 165

Description

Baseline rhythm

Regular tachycardia at 140 bpm on the left of the recording. Thereafter, regular rhythm at 58 bpm.P-waves: visible during the tachycardia and negative in III and aVF, 160 ms from the R-wave.PR interval: normal in sinus rhythm, except for the first beat where it is short (100 ms). Transient second degree A-V block.QRS: normal except for the first complex after the tachycardia where it is broad.ST segment: depressed during the tachycardia.T-waves: normal.QT interval: normal.

Zones

Narrow QRS complex tachycardia with negative P' wave in III and aVF.

Diagnostic

WPW syndrome with orthodromic tachycardia cardioverting to sinus rhythm.

Comments

On close inspection of the tracing, we observe during the tachycardia, which is narrow complex, that the P’-waves are visible remote from the QRS (>100 ms) which is suggestive of a tachycardia utilizing an accessory pathway. The first complex in sinus rhythm is different from the next ones because it exhibits pre-excitation with a ∂-wave and short PR interval. This is therefore WPW syndrome with an accessory pathway that has a long refractory period. Indeed if this refractory period were shorter the pre-excitation would have been permanent in sinus rhythm. The morphology of the P’-wave in tachycardia allows the localization of the accessory pathway to the posterior region because this P’-wave is negative in III and aVF. Appearance of transient second-degree A-V block after cardioversion to sinus rhythm.

Keywords

Reading level

2 / 3

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