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Assoc Prof Harry Mond
December 2, 2024
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I awoke feisty this morning and decided to be controversial.How would you interpret this ECG?
The rhythm is atrial fibrillation with ventricular bigeminy. Or is it?Firstly, let us look at ventricular bigeminy:
The footprints are:
Trigeminy is similar:
Now, let us return to our original ECG.
So what else could this be?Consider ventricular parasystole. Ventricular parasystole:
ECG features:
Our ECG conforms to these features (no fusion beats).To be absolutely sure, we need longer strips and hence the controversy.Here is an example with fusion beats:However, the coupling intervals are fixed. Hence longer tracings are required to confirm the diagnosis.
Here is another confusing tracing:
Interpolated ventricular quadrigeminyIs ventricular parasystole really rare? It is rarely looked for and strips are not long enough.Is there a pseudo-ventricular parasystole?Consider very slow asynchronous ventricular pacing (VOO) and sinus rhythm. What about atrial parasystole?It is said to occur, and I believe I have seen it.One of the arrhythmias of digitalis toxicity and hence not seen today.
It’s all in the timing.
Harry Mond
November 5, 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 26, 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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