The Upside Down ECG - Cardiac Monitoring Service
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The Upside Down ECG

By Assoc Prof Harry Mond
January 30, 2020

Figures 1 and 2 are from a normal control. The tracing is normal in 1 and the leads reversed in 2 so that the arm leads are now on the feet and the leg leads are attached to the arms. Lead I looks at the legs and not the arms and its isoelectric appearance not surprising.

I see about two examples of this per month.

If you don’t, then you are not looking hard enough!

Normal control ECG with normal tracing

Normal control ECG with leads reversed

Figure 3 is a comparison of the lead positions with the classical features listed below.

Comparison of lead positions

The ECG should be repeated as important pathology may be missed. For example, the rhythm in figure 4 puzzled us and we eventually went with a supraventricular tachycardia, despite a consistent irregularity and possible p waves in V6. The isoelectric lead I made us ask for a repeat (figure 5). The P waves now emerge and the diagnosis is sinus tachycardia and atrial ectopics

supraventricular tachycardia

sinus tachycardia and atrial ectopics

Assoc Prof Harry Mond

About Assoc Prof Harry Mond

In 49+ years as a practicing cardiologist, Assoc Prof Harry Mond has published 260+ published manuscripts & books. A co-founder of Cardiac Monitoring Service, he remains Medical Director and oversees 500K+ heart studies each year.

Download his full profile here.

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