“Jerry W. Jones, MD FACEP FAAEM is pleased to announce the move from LinkedIn to his ECG education website: https://medicusofhouston.com/ . Join him there for his popular twice weekly posts on ECG topics for beginners through advanced and announcements regarding his Masterclasses and book releases.” I want to thank all of you for your interest in my teaching and in electrocardiography. I hope to see you in one of my Masterclasses soon! And I hope to hear from you in my new location! Jerry W. Jones, MD FACEP FAAEM

The first 3 beats are sinus node beats, all have the same morphology of the P wave. This is followed by a PAC, which is conducted via the fast pathway in the AV node. The next PAC is conducted via the slow pathway, then the AV nodal reentry tachycardia (slow/fast) starts. The retrograde P waves are visible at the end of the QRS complex in the lower lead K3.

In order to differentiate supraventricular extrasystoles/tachycardias with aberrant conduction from ventricular extrasystoles/tachycardias, the search for P waves is often very important. Here are some examples of how the P waves can be positioned around the ventricular extrasystoles.

Here you can see a long rhythm strip from a Holter ECG, written at 25 mm/s. On the left, a sinus bradyarrhythmia can be seen first, followed by an atrial tachycardia. After a few beats this changes back into a sinus bradyarrhythmia. Then follows a short VT over 3 beats, after 1 sinus node beat then a ventricular couplet. Sinus bradyarrhythmia again at the end.