CET Electrolyte Imbalances & ECG Changes 3

Question 1

Which ECG finding is most specific for hypocalcemia compared to other QT-prolonging conditions?

Accepted Answer

Prolonged ST segment with a relatively normal T wave

Answer

Hypocalcemia uniquely prolongs the isoelectric ST segment rather than the T wave itself, so the QT appears long but T wave morphology remains relatively normal.

Question 2

What is the normal serum potassium reference range?

Accepted Answer

3.5-5.0 mEq/L

Answer

Normal serum potassium is 3.5-5.0 mEq/L; values below 3.5 (hypokalemia) and above 5.0 (hyperkalemia) both produce progressive ECG changes.

Question 3

A patient presents with Chvostek's sign, carpopedal spasm, and muscle cramps. Which ECG finding is most expected?

Accepted Answer

Prolonged QT interval

Answer

Chvostek's sign and carpopedal spasm indicate hypocalcemia, which prolongs the QT interval by extending the ST segment on ECG.

Question 4

T wave flattening, ST depression, and tall U waves that may fuse with T waves are most associated with which electrolyte imbalance?

Accepted Answer

Hypokalemia

Answer

Hypokalemia causes T wave flattening, ST depression, and prominent U waves that may fuse with T waves, falsely suggesting QT prolongation.

Question 5

Hypermagnesemia most commonly produces which ECG findings?

Accepted Answer

PR interval prolongation and QRS widening

Answer

Hypermagnesemia acts as a natural calcium channel blocker, slowing AV nodal and ventricular conduction, manifesting as PR prolongation and QRS widening.

(CET) Certified Electrocardiogram Technician Practice Test

(CET) Certified Electrocardiogram Technician Practice Test

CET Electrolyte Imbalances & ECG Changes 3