Assoc Prof Harry Mond
February 23, 2026
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Asymptomatic 54-year old international commercial pilot.
Annual routine ECG – suggests previous septal infarct.
Normal coronary angiogram, but dense embolic stroke during procedure with permanent right hemiplegia.
What do you think?
Leads V1 and V2 are reversed and when placed in their correct position, the ECG is normal; V1 red highlight and V2 yellow highlight.
ECG lead malposition is not uncommon and frequently missed or incorrectly diagnosed with potential serious consequences. As the ECG cables age, the identification of the leads becomes more difficult to read, particularly under poor light. Before printing the recorded tracing, it is important to check the leads and the ECG.
Identification of lead malposition may be subtle.
This is another V1-V2 error, which was reported as normal.
This one took some working out, but there is a pattern to the way the leads are positioned. The ECG could have been reported as a previous lateral (Q V5, V6, red highlight) and posterior (R inV1, yellow highlight) myocardial infarction, particularly as there is also a previous inferior myocardial infarction (Q II, III, aVF, blue highlight).
Then there are those that are completely haphazard,
or completely reversed.
When corrected, the chest leads are normal.
Another malposition is lead placement on the right side in an otherwise normal patient.
Leads V1 and V2 are reversed(red highlight), and the remaining chest leads are small voltages on the right side of the chest away from the heart (yellow highlight).
This chest lead malposition (red highlight) can be coupled to reversed arm leads (yellow highlight) to create a very abnormal ECG.
Remember with reversed arm leads; lead I is flipped, leads aVR and aVL are reversed as are leads II and III.
The corrected ECG:
I call this “the full hand” and have seen it a number of times.
The arm leads are reversed (red highlight) as are the chest leads (yellow highlight).
This ECG was reported as dextrocardia. Remember, with dextrocardia the chest leads are not reversed, but are on the right side of the chest with reducing voltages from V3 to V6.
Dextrocardia: The arm leads are reversed (red highlight) and the chest leads are positioned on the wrong side with decreasing voltages (yellow highlight).
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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