1. Electrolyte abnormalities and ECG
Elias Hanna, MD
LSU Cardiology

2. 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.

3. Hypokalemia: ST depression with prominent T Flat T with K~3
(actually U) and prolonged QT
when K<2.5-3
Flat T with K~3

4. -T progressively flattens
Hypokalemia:
-T progressively flattens
-U wave more and more prominent (looks like T)
-ST-segment more and more depressed
Large 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)

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

6. 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

7. 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.

8. Hypercalcemia: short QTc <390 ms
Hypercalcemia: short QTc <390 ms. No significant ST or T wave abnormality

9. Hypomagnesemia is not associated with characteristic or specific ECG findings
It 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.