What is the mechanism of hyperkalemia affecting ECG ( peaked T waved, widened QRS and flattened P wave)?

Question

What is the mechanism of hyperkalemia affecting ECG ( peaked T waved, widened QRS and flattened P wave)?

Answer 1

The discharge of the electrical impulse through the heart depends upon the movement of calcium and potassium into and out of cells, respectively.  The movement of these ions depends upon voltage-gated ion channels (and there are different types of these that respond to different cations, like Na+ and K+), which open when the membrane potential of the cell becomes positive enough (reaches a threshold value) to allow them to do so.  

This sounds complicated, but basically all that means is that the special cells of the electrical conduction system of the heart depend upon a certain balance of cations (positive ions) inside and outside of the cell--that is what drives their action.

If there is too much potassium (K+) outside the cell, as there is in hyperkalemia, that upsets the balance and the normal activity of depolarization and repolarization cannot occur.  That activity is what the EKG traces.  Too much potassium outside the cell can increase the activity of the potassium channels, speeding repolarization (the peaked T waves), and inactivate the sodium channels, preventing the proper conduction of the electrical activity through the heart (flattened P waves and widened QRS complex).

Tl;dr?  You need a higher concentration of K+ inside the cell than outside the cell or else the cells of the electrical system can't fire or reset normally.  When they can't fire or reset normally, those are the things you see on EKG.  ;-)