CET Electrolyte Imbalances & ECG Changes

Question 1

Which ECG change is the hallmark finding of hyperkalemia?

Accepted Answer

Peaked (tall, narrow) T waves

Answer

Hyperkalemia causes tall, narrow, peaked T waves due to altered ventricular repolarization from elevated extracellular potassium.

Question 2

Hypokalemia on a 12-lead ECG is most commonly identified by:

Accepted Answer

Prominent U waves with T wave flattening

Answer

Hypokalemia produces T wave flattening and prominent positive U waves (deflection after the T wave) most visible in leads V2-V3.

Question 3

Hypercalcemia typically produces which ECG finding?

Accepted Answer

Shortened QT interval

Answer

Hypercalcemia shortens the ST segment and QT interval because elevated calcium accelerates ventricular repolarization.

Question 4

Which electrolyte abnormality is most strongly associated with a prolonged QT interval and risk of torsades de pointes?

Accepted Answer

Hypocalcemia

Answer

Hypocalcemia prolongs the ST segment and QTc interval by extending the plateau phase of the action potential, increasing torsades de pointes risk.

Question 5

In severe hyperkalemia, the ECG 'sine wave' pattern results from:

Accepted Answer

QRS widening merging with the T wave

Answer

As hyperkalemia worsens, progressive QRS widening causes the complex to merge with the T wave, creating a sinusoidal pattern that precedes cardiac arrest.

(CET) Certified Electrocardiogram Technician Practice Test

(CET) Certified Electrocardiogram Technician Practice Test

CET Electrolyte Imbalances & ECG Changes