Assoc Prof Harry Mond
December 2, 2024
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Over the last few weeks, I have presented a variety of Wenckebach sequences. Some may think I am obsessed with the subject and they are probably correct. However, there is so much that can be learnt by looking at the sequences.Broadly, they can be divided into atrioventricular (AV) and non-AV groups.We usually envisage AV Wenckebach with boring sinus rhythm and imagine the block at the AV node. It is, however, much more visually stimulating than that.Here is a short run of atrial tachycardia with 3:2 and 2:1 AV Wenckebach.
This represents upper rate physiology.If the rate is slower (<100 bpm) and nocturnal, then consider vagal hypertonia.
With very fast atrial rates such as atrial flutter, there is what I call a “regular irregularity”.
In this case, there are “regular” minor pauses with dropped beats (red highlight) making the overall rhythm “irregular”.Not all AV Wenckebach sequences are as a result of block at the AV node.Consider the bundle branches. Think of the ECG pattern, before you read further!Wenckebach AV sequences in the bundle branches was first described by the Royal Melbourne Hospital in 1976. It can be either the left or right bundle and is a sequence of increasing bundle branch block until complete and the sequence starts again. This is what the ECG looks like.
This is hard to recognise unless you amplify one or more leads.
I am unsure if this is physiologic or pathologic. My usual answer to that question is look at the rate: Fast then “aberration”. Slow then disease.I have seen it combined with AV nodal Wenckebach.
I suspect there is pathology here.
Remember it’s all in the timing.
Harry Mond
October 28, 2026
As its name implies, AVNRT is a reentrant junctional or supraventricular tachyarrhythmia which involves the fast and slow pathways within the AV node creating a self-perpetuating circus movement. It can be divided into typical (slow-fast) or atypical (fast-slow) as well as several rarer forms related to more than one slow or fast pathway with similar electrophysiological properties. On the ECG, they can be identified and differentiated by the positioning of the P wave in relation to the QRS complex, which in turn is related to the direction of the re-entrant AV nodal circuit. However, in about 60% of cases, the P wave is buried in the QRS/T and cannot be identified on the surface ECG.
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.
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