Back to Harry's Corner
Assoc Prof Harry Mond
February 23, 2026
To receive a free PDF copy of The Fundamentals of Electrocardiograph Interpretation by Harry Mond, subscribe to his email blog by entering your email address below. Â
Purchase a hard cover or paperback copy of The Fundamentals of Electrocardiograph Interpretation by Harry Mond on Amazon.
Continuing ventricular ectopy, let us start with ventricular couplets.
Two consecutive ventricular ectopics (red highlight).The cycle length between the ectopics may not always be short (red highlight):
Couplets are not always identical but may appear to come from the same focus with different conduction or aberration (red highlight).
The differences with the first example may be related to the underlying bundle branch block.Ventricular interpolation can occur with couplets. For timing purposes, the sinus cycle should be long with the ectopics having a short coupling period (red highlight).
The first ectopic is within the PR interval and the embedded concealed P wave (stippled red arrow) conducts to the ventricle with a very long PR interval.And then there are multifocal ventricular couplets:
Note the position of the embedded concealed sinus P wave (red stippled arrow).Not all multifocal couplets are couplets! Again it is in the timing.
The embedded sinus P wave in the T wave can be seen and conducts to the ventricle with aberration. Thus this is a late interpolated ventricular ectopic rather than a couplet.To summarize:
On the left is an obvious multifocal ventricular couplet with two embedded concealed sinus P waves (red highlight).On the right is an apparent multifocal ventricular couplet, but only one embedded concealed sinus P wave which may have conducted to the ventricle with aberration (red highlight).On occasion ventricular couplets can occur in groups:
This is reversed trigeminy. My technicians have given it a name; unipolar bigemilets, because it is an amalgam of bigeminy and couplets.Obviously, there must be trigemilets.
A triplet is three consecutive ventricular ectopics (red highlight).
Some authorities refer to this as ventricular tachycardia if >100 bpm or a ventricular run if <100 bpm. A ventricular triplet may be multifocal:
A salvo is a run of 3 to 5 ventricular ectopics:
Multifocal salvos look and may be sinister.When the rhythm is slow it is called an idioventricular rhythm (red highlight):
Fusion beats are very common (yellow highlight).Cycle lengths may differ during a salvo:
I will discuss this ECG in more detail in a future presentation.
Remember, it’s all in the timing.
‍
Harry Mond
October 16, 2026
Retrograde conduction is defined as conduction from an ectopic site to the atrium via the AV node or accessory pathway and referred to as VA conduction. II results in a P wave configuration which differs from an anterograde P wave, and in most ECG leads is inverted. The site from where the impulse originates can be the AV node, Bundle of His, distal conducting system or the body of the ventricles including ventricular pacing. On the ECG, the QRS complex usually precedes the inverted retrograde P wave but on occasion may follow it.
October 1, 2026
In 1970, I commenced work as a “novice” cardiologist at The Royal Melbourne Hospital. Training at that time was learning how to recognise the diastolic murmur of mitral stenosis and making sure the ECG and chest x-rays were the correct way up. As this was prior to coronary artery surgery, stenting and echocardiography, the ECG was a highly respected tool for the diagnosis of many conditions. I was fortunate to befriend a number of the gurus of ECG interpretation who taught me to look into the soul of an ECG. Today, even though the ECG is the first investigation performed by a cardiologist, the art of ECG interpretation has been lost because we depend on the new tools for cardiac diagnosis.Â
September 18, 2026
Dr Thura Thant asked for an opinion on this confusing ECG. By using arrows and highlight, the ECG bared its soul and gave me an answer. ‍See if you can work it out? What do you think?
CardioScan Services Pty Ltd. All rights reserved
