Friday, October 2, 2015

Extreme Bradycardia after Diarrhea and Dehydration. Best ED treatment?

A patient presented with weakness.  He was found to be bradycardic, so this ECG was recorded:
There is atrial flutter with 3rd degree AV block and Left ventricular escape.  Why is it not slow AV conduction with RBBB?  The QRS occurs at different points on the flutter wave.  There is complete dissociation due to complete AV block.

More history

The patient has a history of congenital heart disease repaired as a child. He reports having had an extra pacemaker transiently but this was removed at a very young age. The patient describes a history of progressive bradycardia. In recent years, the patient states that his heart rate has generally been in the 30s. 

The patient states that he developed a gastrointestinal illness in recent days. This was associated with nausea and recurrent episodes of vomiting. He had decreased oral intake. The patient describes having taken potassium supplementation in recent days. Today, the patient became increasingly lightheaded. He took his pulse and felt that it was in the teens. He presented to the emergency department for further evaluation.

In the emergency department, the patient's heart rate was between 10 and 15.  EKG revealed atrial flutter with junctional rhythm. Laboratory studies revealed an elevated creatinine at 2.9 mg/dL and a K of 5.4 mEq/L. 

What is the best first ED treatment?  See below.

The patient has had bradycardia for years, but never this bad.  He clearly has chronic AV block, but why did it get so bad right at this moment?

Because his gastrointestinal illness led to renal insufficiency, which with K supplementation led to mild hyperkalemia of only 5.4 mEq/L, which was just high enough to tip him over the edge.

The best fast treatment is to treat hyperK with Calcium, insulin and glucose, and possibly bicarbonate.  One may add beta-2 agonists:

Terbutaline and Albuterol for Lowering of Plasma Postassium

The patient clearly needs a permanent pacemaker, but only needs an emergent ED pacemaker if treatment of hyperK does not work.

Emergency Transvenous Cardiac Pacing


  1. Why not just dilute the K with saline (or something else with none or low K concentration)? He propably needs fluids anyway and seems to be quite stable and surprisingly well adapted to the situation. Too slow? Will it mess with something else?

    -Just a Paramedic/RN guessing

    1. That is actually what was done and it did not work, though it might have. I would say this: why not give Ca, as it is totally harmless and very effective for hyperK.

    2. only prerenal failure? probably the pacemaker will rise the cardiac debit and will improve the renal function.

    3. Very likely, but initiated by prerenal, as he was doing fine until he started having fluid losses from gastroenteritis.


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