ECG Underwriting Puzzler

Presented by: William Rooney, M.D.

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Week 13 in the “Case of the Week” seriesQUESTION????What is the major abnormality on this ECG?

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OK, fine. There are several abnormalities. So, how about rhythm abnormalities?

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Week 13 in the “Case of the Week” seriesCLUE:

Look for the p waves

P waves are hard to find huh.

Analysis

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How about the regularity of the rhythm?

Irregularly irregular….what could cause that

appearance?

Week 13 in the “Case of the Week” seriesYou are right if you said

Atrial Fibrillation

Notice that they have no identifiable repetitive pattern

Reviewing the Disorder

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The intervals are all different

Measure the R-R interval

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1 2 3

Don’t get confused if you observe electrical activity in some leads suggestive of p

waves but no distinct p waves are found such as is

seen in V6. Baseline artifact is common and can

be confusing.

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Animation of the disorder

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Here is a diagram of the normal conduction system of the heart

This is animation trying to depict a normal SA node generated beat in

the atrium

This animation tries to depict atrial fibrillation competing with the normal SA node in the atrium

The AV node is stimulated repeatedly from different focus. It

irregularly allows an impulse through causing an irregularly,

irregular heart rate

Atrial fibrillation occurs when there are multiple irritable automaticity foci in the atria

Ectopic foci

Ectopic foci can develop anywhere in the atrium and can compete

with the normal SA node

When multiple ectopic foci are present it can get chaotic

SA NODE

AV NODE

Features

Features of atrial fibrillation• No discrete P waves• F waves (fibrillatory) are present sometimes• No repetitive pattern to the RR interval• Ventricular rate typically between 90-170 beats/min when untreated.• QRS complexes are typically narrow (although they can be wider if other

conditions are associated with it --such as bundle branch block)

ECG features of this disorder

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Week13 in the “Case of the Week” series

CAUTION:Other conditions which have irregularly irregular R-R

intervals include:Multifocal atrial tachycardia

Multifocal atrial premature beatsAtrial tachycardia or atrial flutter with varying AV block

Final Thoughts - ECG Solved

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This concludes this edition of the ECG puzzler. Contact me if you have questions!

Other abnormalities on this ECG:(Just to be complete)

Q waves in leads III and aVF suggestive of but not diagnostic of an inferior wall MI

Extensive “minor” T wave changes with low/flat T waves noted in the inferior and lateral leads as well as

leads V4-6. Leftward axis

For further reading:Please see page 110 in Dale Dubin’s 6th edition

of Rapid Interpretation of EKG’s