Electrolyte abnormalities and ECGElias Hanna, MDLSU Cardiology

Hyperkalemia:T wave in hyperkalemia is typically tall and narrow, but does not have to be tall(may be just narrow and peaked pulling ST segment).

Tall T means > 2 big boxes in the precordial leads or >1 small box in limb leads, or T wave taller than QRS.

Hypokalemia:Flat T with K~3ST depression with prominent T(actually U) and prolonged QT when K

Hypokalemia: -T progressively flattens -U wave more and more prominent (looks like T) -ST-segment more and more depressedLarge U wave simulates and hides T wave with severe hypokalemia, the ST-T pattern may mimick: ST-segment depression with a flat or upright wide T wave (actually U) and a prolonged QT interval (actually QTU)

On the other hand, the pattern of T inversion is not seen with hypokalemia:

ECG changes of digoxin effect (digoxin therapy) simulate the changes seen with hypokalemia (U wave and ST depression), except that with digoxin therapy QT is not prolonged

Hypocalcemia:

Long QT that is due to a long ST segment, which is different from long QT due to congenital long QT syndrome, drugs, or hypokalemia. T wave is not wide, there is no T wave abnormality.

Hypercalcemia: short QTc

Hypomagnesemia is not associated with characteristic or specific ECG findingsIt is associated with a non-specific prolongation of QT and/or QRS intervals, and is often associated with hypokalemia and hypocalcemia. Therefore, changes related to the latter 2 abnormalities may be seen.

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