Which ECG changes are associated with hypokalemia?

Which ECG changes are associated with hypokalemia?

• A. Peaked T waves and shortened QT interval.
• B. ST elevations in multiple leads.
• C. Widened QRS only.
• D. Flat T waves or ST depression with U waves, and QT prolongation.

Answer: (D)

Low potassium slows ventricular repolarization, so the ECG shows changes reflecting delayed and altered electrical recovery. The classic pattern includes flat or inverted T waves, ST segment depression, and the appearance of prominent U waves after the T wave, along with a longer QT interval. These findings together point to hypokalemia because reduced potassium shifts the heart’s repolarization dynamics, making T waves less prominent, allowing U waves to stand out, and prolonging the overall time of ventricular repolarization. In contrast, peaked T waves with a shortened QT interval are associated with hyperkalemia, not hypokalemia. ST elevations in multiple leads suggest conditions like acute myocardial infarction or pericarditis, not electrolyte disturbance. A widened QRS complex alone is not the characteristic hallmark of hypokalemia and is more typically linked to other issues such as hyperkalemia or conduction abnormalities.

Low potassium slows ventricular repolarization, so the ECG shows changes reflecting delayed and altered electrical recovery. The classic pattern includes flat or inverted T waves, ST segment depression, and the appearance of prominent U waves after the T wave, along with a longer QT interval. These findings together point to hypokalemia because reduced potassium shifts the heart’s repolarization dynamics, making T waves less prominent, allowing U waves to stand out, and prolonging the overall time of ventricular repolarization.

In contrast, peaked T waves with a shortened QT interval are associated with hyperkalemia, not hypokalemia. ST elevations in multiple leads suggest conditions like acute myocardial infarction or pericarditis, not electrolyte disturbance. A widened QRS complex alone is not the characteristic hallmark of hypokalemia and is more typically linked to other issues such as hyperkalemia or conduction abnormalities.