# Hyperkalemia and hightened T waves.



## Anjel (Dec 27, 2011)

So, I just had a pt with hyperkalemia. 

On the transfer sheet it said she had hightened T waves. 

Also pulse was 112. 

I am assuming all of those things are related, since I know potassium causes repolarization in the heart. 

Can anyone explain exactly how it is all related??? 

Pleaasse.


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## silver (Dec 27, 2011)

Anjel1030 said:


> So, I just had a pt with hyperkalemia.
> 
> On the transfer sheet it said she had hightened T waves.
> 
> ...



You have to remember that the ekg records the macro level of depolarization and repolarization of the atrium and ventricles. The T wave is the repolarization of the ventricles. I hope that clarifies it.


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## silver (Dec 27, 2011)

silver said:


> You have to remember that the ekg records the macro level of depolarization and repolarization of the atrium and ventricles. The T wave is the repolarization of the ventricles. I hope that clarifies it.



I realized you probably wanted a more thorough answer. I know I am not an expert, but just trying to explain.

Increased extracellular potassium levels increase the conductance of potassium through the membrane which results in the potassium ions flowing easier. Hogdkins and Huxley related the conductance and ion current, where if the potentials stay relatively constant (driving force) the current will increase as the conductance increases. This in turn results in peaked T waves as the potassium ions want to flow back and quicker. Additionally the increased extracellular potassium depolarizes the resting membrane potential and inactivates the sodium channels, which widens the QRS.


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## Anjel (Dec 27, 2011)

Ummm so the potassium kinda super charges the repolarization process?? 

I am still kinda confused.


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## Hate (Dec 29, 2011)

Anjel1030 said:


> Ummm so the potassium kinda super charges the repolarization process??
> 
> I am still kinda confused.



depolorization process. 

typically hypoxia causes an extacellular increase in K+. This happens because the potassium is able to exit the cell through KATP Channels, which are inhibited by ATP in homeostatic conditions.

Ventricular repolarization causes the "t wave", when voltage gated K+ channels are open, and increases K+ conductance. This causes the cell to be "postively charged" with respect to the extracellular. The rapid efflux of K+ causes repolarization of the resting membrane potential.

When there is an excess of extracellular K+, the cell becomes more negative than the outside of the cell/less positive. This causes a depolarization instead of repolarization. i.e membrane potential moves in the positive direction, and t waves peak


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## Trevor (Dec 30, 2011)

okay.....

Phase 3 of the Cardiac Action Potential corresponds with the T wave on the ECG. 

Normally, in Phase 3, "the K+ channels open and K+ flows rapidly out of the cell, Carrying positive charges to the outside and returns the Action Potential to its resting state."

_Jacobson, C. 2007. Cardiovascular Nursing Practice. A Comprehensive Resource and Study Guide for Clinical Nurses. Burien, WA. Cardiovascular Nursing Education Associates. _

So if K+ is increased the net change would be greater therefore causing a larger (your "heightened"), or "peaked" T Waves... 

Hyperkalemia can also effect phase 0 and 1 of the Action Potential, since these 2 phases deal with Na+. If increased, K+ will slow the depolarization of the cell, leading to widened QRS length, and evenutally (just prior to cardiac death) a "Sine Wave" (VERY BAD!)....


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