This is more of how the physio of ions work with digoxin, but there is a little bit of how the EKG is affected.
Digoxin works on the sodium-potassium pump. The normal physiology as we may know is 3 Na+ go out to in exchange for 2K+ returned to the cell. It's MOA is by blocking the Na/K pump. So in this case, we have have increased sodium inside the cell and decreased potassium. So we have hypernatremia and hypokalemia. The only channels that are open all time are for potassium, so you will have potassium efflux, causing a more severe hypokalemia (this will be your T wave inversion). This will make the cell more negative and lead to a slurring of the QRS on the EKG (hockey sticking). This is the ST scooping I am guessing that the poster mentioned. When the pump is blocked at the very first moment, you will have momentary hyperkalemia (UWorld question)
Sodium is stuck inside the cell, making the cell more positive and more likely to depolarize. Causes in increase of seizures in the brain, arrhythmia in the heart, and diarrhea.
Normal physio dictates a sodium/calcium exchange as well, but sodium is trapped inside the cell. Calcium is stuck inside the cell, causing the atrium to depolarize, leading to atrial arryhthmias.
Normal physio also dictates that Chloride is in love with Sodium, and they are always together. So she will come inside, pulling water with her (normal physio), causing swelling throughout the body (ex: third spacing, peripheral edema, pleural effusions, ascites). In the eye, it causes swelling around the optic nerve leading to papilledema.
