Assoc Prof Harry Mond
February 23, 2026
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39-year old one single-handed, one-eyed, musketeer with congenital dislocation of the hips.
Holter monitor.
Report says: Atrial and multifocal ventricular ectopics
What do you think?
The rhythm is sinus (red arrows) with atrial bigeminy (blue arrows).
The atrial ectopics are conducted with ventricular aberration.
To summarize:
• Aberrant conduction results from intermittent uneven physiologic refractoriness in the ventricular conducting system from an early supraventricular beat.
• There is QRS widening usually with a right bundle branch block configuration, consequent to a delay or block in that bundle or a more peripheral branch.
Let us review the action potentials in the bundle branches.
With frequent atrial ectopy, search for normal and aberrant conduction.
With a coupling interval of 640 ms, the atrial ectopic is conducted normally (red highlight). A slightly shorter coupling interval and there is aberrant ventricular conduction with a right bundle branch block (yellow highlight).
Although aberrancy is usually conducted with a right bundle branch block, a left bundle branch block can also occur even within the same tracing.
Atrial fibrillation with a rapid ventricular response. There is right bundle branch block aberration (RBBB, red highlight) after a “long-short” period and left bundle branch block aberration (LBBB, yellow highlight) also after a “long-short” period.
Our case:
Each of the atrial ectopics in the bigeminal run has a different conduction.
Normal (red highlight), right bundle branch block (yellow highlight) and left bundle branch block (blue highlight).
Easy!
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.
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?
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