Does Hyperkalemia Cause Bradycardia or Tachycardia?

[rileowski]

I can't seem to find a straight answer on this. My book says one thing and my professor will say another. My understanding is hyperkalemia causes the electrical activity in the heart to increase, therefore causing tachycardia. But if the hyperkalemia is severe enough, it can cause bradycardia and possible cardiac arrest. Is this correct or am I missing something? Thanks!

[Here.I.Stand, BSN, RN]

Excess serum K+ impedes electric activiy, so you'll see brady-arrhythmias/BBBs etc. if K+ is high enough. Now most healthy people will excrete some of that; someone with renal failure however, is unable. That's why you see those dangerously high levels >6-7 in pts with renal failure -- and unless level is reduced (with medical shift like insulin&D50, or with dialysis), the pt is at risk for cardiac arrest