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Assoc Prof Harry Mond
February 23, 2026
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Previously, we covered some of the ECG patterns seen with atrial ectopy. Let us continue.An atrial couplet is defined as two consecutive atrial ectopics:
Both ectopics are premature and from a low atrial site.However, only one may be “obviously premature”:
Or neither:
An atrial couplet may not always be a couplet:
In this example, there may only be a single interpolated atrial ectopic, but the timing is against this. The R-R interval with the embedded ectopic should be the same or longer (due to partial refractoriness in the atrio-ventricular conducting system) than the sinus cycle length. It is significantly shorter and therefore most likely an atrial couplet.Atrial couplets may demonstrate Wenckebach atrio-ventricular block:
Non-conducted atrial ectopics (blue dots) may also occur:
But not all non-conducted atrial couplets are actually “couplets”:
The first non-conducted beat is part of a 2:1 atrio-ventricular block sequence (red dot) and the second is an atrial ectopic (blue dot), which not surprisingly is non-conducted.Three consecutive atrial ectopics an atrial triplet:
They too can present as a Wenckebach atrio-ventricular sequence:
Can non-conducted atrial triplets occur? Here is an example:
Although, there are three consecutive non-conducted atrial ectopics, the cycle length is very short and mimics the appearance of atrial flutter.More correctly, this is a short run of focal atrial tachycardia with Wenckebach block at the ectopic-myocardial junction.Here is a sequence of nine consecutive conducted atrial ectopics. We can’t call this supraventricular or atrial tachycardia, because the rate is <100 bpm.
My technicians call this an atrial run and it is a very common finding on Holter monitoring.Not surprisingly atrial runs (red highlight) can occur together with supraventricular tachycardia (yellow highlight).
Remember, it’s all in the timing.
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Harry Mond
October 29, 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.Â
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