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Assoc Prof Harry Mond
December 2, 2024
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Although the footprints of atrial and ventricular ectopy are similar, there are enough differences to justify ventricular ectopy having its own set of ECGs. Some of the ECGs have been covered previously and this may act as a refresher.Let us start with ventricular bigeminy:
Alternate complexes are ventricular ectopics (red highlight).Usually the coupling intervals are similar.When they are not, then ventricular ectopy may have a more sinister significance particularly if they are from the left ventricle (right bundle branch block). Interpolated ventricular bigeminy may create a kaleidoscope of findings.
Look before you read.
Ventricular bigeminy with retrograde conduction
Embedded in the ectopic T wave are retrograde P waves (red highlight). These are premature and not sinus P waves.Late ventricular ectopics are referred to as end-diastolic ventricular ectopics and if they occur in bigeminy, ventricular fusion is likely.
In this example, the ventricular ectopic (red highlight) coupling intervals gradually lengthen exposing sinus P waves (red arrows). Thus the ectopics lie in the PR intervals of the next sinus beat. The first ectopic (VE) is early enough to completely depolarize the ventricles, whereas the next two; V fusion1 and V fusion2 are well into the PR interval allowing some sinus generated ventricular depolarization and consequently fusion beats. Note that fusion beats involving the sinus node often have a pseudo-Wolff-Parkinson-White appearance.Ventricular trigeminy are sequences of two sinus cycles (red dots) followed by an ectopic (red highlight) and the sequence commences again.
There are embedded, concealed, non-conducted sinus P waves (yellow dots).The ventricular ectopics may be interpolated.
In this example, the sinus and the ventricular ectopic cycles remain constant in timing and all of the P waves are conducted. Ventricular quadrigeminy are sequences of three sinus cycles (red dots) followed by an ectopic (red highlight) and the sequence commences again.
There are embedded, concealed, non-conducted sinus P waves (yellow dots).Once again, the ventricular ectopics may be interpolated (red highlight) and all sinus P waves conducted.
Remember, it’s all in the timing.
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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.Â
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