Most clinicians will go their entire career without knowingly seeing a patient with dextrocardia but when you do, it can completely throw your ECG interpretation off track.
Dextrocardia is a rare congenital condition where the heart sits on the right side of the chest instead of the left.
The cardiac chambers and electrical axis are effectively mirrored, and unless you recognise it, the ECG will look utterly abnormal at first glance.
Before we talk about correction, here’s why dextrocardia creates so much confusion.
How Dextrocardia Affects the ECG
1. Lead I Looks “Upside Down”
One of the most consistent findings is global negativity in Lead I, inverted P wave, inverted QRS, and inverted T wave. This isn’t ischaemia. It’s simply the electrical activity heading in the opposite direction to what Lead I expects to see.
2. Precordial Leads Show Poor R-Wave Progression
V1–V6 are positioned to read electrical activity across a left-sided heart.
If the heart is actually on the right, these chest leads end up sitting over the “wrong” side, producing:
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very small R waves
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dominant S waves
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a flat, poor, or absent R-wave progression
It can look worryingly like anterior pathology if you don’t know what you’re looking at.
3. Axis Deviation That Doesn’t Add Up
The limb leads often create a picture of extreme right-axis deviation, but in a way that doesn’t match the clinical context.
It’s not an electrolyte problem or ventricular strain, it’s the heart’s reversed position.
The Key: The Patient Isn’t Unwell, Your Lead Placement Is
A mirrored heart gives you a mirrored ECG.
Once you correct your lead positions, the ECG suddenly becomes interpretable again.
How to Record a Correct ECG in Dextrocardia
You don’t need to move everything, just the chest leads.
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Leave V1 and V2 where they normally go.
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Move V3–V6 onto the right side of the chest, mirroring their usual left-sided positions.
These become: V3R, V4R, V5R, and V6R.
With proper right-sided placement, you’ll regain:
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normal-looking R-wave progression
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expected precordial morphology
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a trace that makes anatomical sense for a right-sided heart
This simple adjustment prevents misdiagnosis and avoids unnecessary delays in assessment or treatment.
Why This Matters in Pre-Hospital Care
Missing dextrocardia can lead you down the wrong path, suspected STEMI, conduction defects, chamber abnormalities, when the heart is just positioned differently.
A correct lead set gives you a true clinical picture.
And in the back of an ambulance, accuracy matters.
Make Lead Placement Mistakes a Thing of the Past
If you want a quick, pocket-sized reminder of:
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standard 12-lead placement
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posterior leads
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right-sided leads (V3R–V6R)
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when and why to use each configuration
…that’s exactly what our ECG Lead Placement Card was built for.
Designed for pre-hospital clinicians, built for real-world use, and printed to survive your uniform pocket — it’s the fastest way to double-check placement in the moment.
Upgrade your ECG accuracy here → [ECG Lead Placement Card]