potassium & ekg's
April 26, 2008 7:14 AM   Subscribe

[Bio-med-dorkfilter] Why does hyperkalemia cause peaked t-waves on an EKG?

On an EKG the t-wave represents the repolarization of the ventricles. It's my understanding that the first part of repolarization is potassium leaving the cell. This occurs by diffusion through potassium channels. Diffusion is the movement of particles from high concentration to low concentration. My thought was that if you increased the concentration of potassium outside the cell, then the potassium inside the cell would be slower to move because it naturally wants to go where there is less of it, not more. This would make the t-waves smaller, not heightened.

Where is the problem with my logic?
posted by brevator to Science & Nature (2 answers total) 1 user marked this as a favorite
Best answer: Your logic isn't wrong, but it neglects the fact that many of the ion channels in cardiac membranes are gated. Extracellular hyperkalemia activates some of the gated potassium channels (probably both directly and via adrenergic mechanisms), which speeds potassium efflux, even given the reduced potassium gradient. Hope that helps!
posted by LittleMissCranky at 7:52 AM on April 26, 2008 [1 favorite]

Response by poster: Thanks LMC!
posted by brevator at 9:25 AM on April 26, 2008

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