88 year old female: Weakness – Discussion

This is the discussion for 88 year old female: Weakness. If you've not read the backstory, we suggest you check it out!

When we last left off, our patient was in an exam room with an irregularly irregular rhythm. The ED physician had asked you if the patient had a history of atrial fibrillation.

Let's review the rhythm strip and 12-Lead ECG.

All Over the Map - Rhythm Strip

We have a narrow complex, irregularly irregular rhythm at 70-110 bpm. There is no apparent atrial activity. This is presumably atrial fibrillation.

All Over the Map - 12-Lead

The 12-Lead ECG shows a narrow complex, irregulaly irregular rhythm with no acute changes to the ST-segments. What may be atrial activity is visible in multiple leads, however the baseline is variable. A diagnosis of atrial fibrillation cannot be ruled out, however, another atrial arrhythmia should be suspected.

When in doubt over atrial activity, the Lewis Lead can help you highlight it on the surface ECG (a tip of the hat to Kelly Grayson who first introduced me to this lead). All this requires is moving the RA and LA leads into position along the sterum like so:

Lewis Lead Placement

To acquire a Lewis Lead, place the RA electrode on the manubrium and the LA electrode approximately where V3R would go and then monitor Lead I.

Once they acquired a strip from the Lewis Lead they were certain of the eventual diagnosis:

All Over the Map - Lewis Lead - Marked Up

From the Lewis Lead strip we can easily appreciate at least 5 distinct P-wave morphologies! Therefore our patient is experiencing a multifocal atrial rhythm. For completeness, multifocal atrial rhythms with a normorcardic rate is referred to as Wandering Atrial Pacemaker, while a tachycardia rate is referred to as Multifocal Atrial Tachycardia. In either case, treatment is geared towards correcting the underlying problem rather than the rhythm.

So, what are some common causes of multifocal atrial arrhythmias?

Jason Roediger did our work for us in the comments and listed the major causes:

MAT is most commonly associated with chronic obstructive pulmonary disease (COPD) in addition to associated lung disorders:  far-advanced pneumonia, chronic bronchitis, emphysema, etc.  It can also be seen in digitalis intoxication as well as other diseased states.

Other causes include electrolyte disorders such as hypomagnesemia and hypokalemia or even theophylline usage can cause MAT.

In this case our patient was found to have a chest X-ray consistent with emphysema and cardiomegaly. Her labs were notable for a low chloride, bacteria in her urine, and an elevated white count. She was admitted for urosepsis and dehydration. On admission day two she was found to have a small bowel obstruction, however, after discussing treatment options with the patient and family she refused surgery and elected for comfort care only.

If our intrepid reader had not run the Lewis Leads in this case, the patient may have received antiarrhythmics and anticoagulation therapy for a new onset of atrial fibrillation. The key takeaway here is that not all irregularly irregular rhythms are atrial fibrillation!

1 Comment

  • Darren says:

    After reading the original discussion, I encountered a patient that had a weird looking atrial fib.  I decided to try the Lewis lead out to make sure it was a-fib.  It worked great!  The rhythm ended up being a-fib, but it was much easier to see with the Lewis leads.  Thanks again for this info.

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