ECG of the Week: ECG of the Week - 27th May 2013

This rhythm strip is from a mid forties male who presented following an episode of syncope.
He complains of nausea and dizziness on arrival to the ED.
Whilst being assessed he has an episode of unresponsiveness, the rhythm strip below was taken during this period.

Click to enlarge
Paper speed 25mm/s

Rate:

Variable 40 - 65 bpm

Rhythm:

Sinus rhythm

Axis:

Indeterminate
Single lead tracing only - Lead II

Intervals:

PR - Normal (180-200ms)
QRS - Normal (100ms)
QT - 400ms

Segments:

Possible minor ST elevation <1mm

Additional:

'Spikes' noted in 3rd, 4th and 10th rows

No PPM in situ therefore artefactual in origin

Sinus pauses

2 x ~2 second pauses - 9th row down
~3.65 second pause - 10th row down

Interpretation:

Symptomatic sinus bradyarrhythmia

Differential diagnosis:

Drugs
Ischaemia
Increase vagal tone
Sinus Node Dysfunction

Vince DiGiulio has given an extensive interpretation of this ECG which I've pasted below from the comments section.

Eesh, that's what I call a Marked Sinus Brady.

H&P is going to be crucial here. I've only seen a few similar cases, but it's always dicey trying to sort out the etiology in the ED.

The most benign cause is the most obvious, and that's going to be a massive vagal response secondary to N/V leading to syncope. The pitfall there is sorting out and addressing the cause of the N/V and making sure you don't get distracted by the rhythm.

Then I'd be running down my D.I.E. (drugs-ischemia-electrolytes) differential for reversible causes.http://www.medialapproach.com/die-from-bradycardia/
This doesn't appear to be a "diagnostic quality" rhythm strip so I'll defer to a 12-lead for the initial ischemia and electrolyte workup while the Hx should address D.

The final two "big players" on my radar for these cases are also the hardest to sort out. The cardiologist will claim this patient needs a pacemaker for his sick-sinus syndrome and the neurologist will try to start them on an anti-epileptic for their seizures with "ictal arrhythmia." I've tried to dive into the lit on this subject before and it turns into a bit of a chicken-and-egg situation, especially if the patient shakes during their unresponsive episode. Did the patient have a seizure which precipitated bradycardia (or even asystole) or did the arrhythmia cause them to DFO? As best I can tell I've seen both, but SSS is probably much more common than ictal bradycardia/asystole. H&P and witnessing the "spell" will be the real way to sort it out, but even then I suspect you're really only giving a best guess to the Dx in the ED.

What happened ?

The patient went on to have another episode of protracted pause ~5 seconds.
Following this he was commenced on an isoprenaline infusion and transferred to CCU.
He had no electrolyte abnormality and was not taking any culprit medication.
A PPM was inserted with the final diagnosis being sinus node dysfunction.

VAQ Corner

This rhythm strip is from a mid forties male who presented following an episode of syncope.
He complains of nausea and dizziness on arrival to the ED.
Whilst being assessed he has an episode of unresponsiveness, the rhythm strip below was taken during this period.

a) Describe & interpret his ECG (50%)
b) Outline your management (50%)

References / Further Reading

Life in the Fast Lane