Which statement about hypokalemia's effect on repolarization is true?

Which statement about hypokalemia's effect on repolarization is true?

• A. Prolongs repolarization
• B. Shortens repolarization
• C. Increases conduction velocity
• D. Decreases automaticity

Answer: (A)

Hypokalemia slows the outward potassium currents that drive repolarization, lengthening phase 3 of the cardiac action potential. With less K+ outside the cell, the repolarizing current (IKr/IKs/IK1) is reduced, so the cell takes longer to return to its resting potential. This prolongs the action potential duration and, on the ECG, lengthens the QT interval. That’s why the statement about repolarization being prolonged is the best answer. The other ideas aren’t the primary effect here: repolarization isn’t shortened, conduction velocity isn’t the main change, and automaticity isn’t the key consequence described by hypokalemia.

Hypokalemia slows the outward potassium currents that drive repolarization, lengthening phase 3 of the cardiac action potential. With less K+ outside the cell, the repolarizing current (IKr/IKs/IK1) is reduced, so the cell takes longer to return to its resting potential. This prolongs the action potential duration and, on the ECG, lengthens the QT interval. That’s why the statement about repolarization being prolonged is the best answer. The other ideas aren’t the primary effect here: repolarization isn’t shortened, conduction velocity isn’t the main change, and automaticity isn’t the key consequence described by hypokalemia.