CET Electrolyte Imbalances & ECG Changes 2

Question 1

What is the FIRST ECG change seen as serum potassium rises in progressive hyperkalemia?

Accepted Answer

Peaked T waves

Answer

Peaked T waves are the earliest manifestation of hyperkalemia, appearing before any conduction abnormalities such as PR prolongation or QRS widening.

Question 2

A patient with end-stage renal disease presents with absent P waves and a widened QRS. The most likely cause is:

Accepted Answer

Severe hyperkalemia

Answer

Absent P waves and widened QRS in a renal failure patient indicate severe hyperkalemia impairing both atrial depolarization and ventricular conduction.

Question 3

The QTc interval is most reliably prolonged in which electrolyte condition?

Accepted Answer

Hypocalcemia

Answer

Hypocalcemia specifically prolongs the ST segment (isoelectric portion), extending the QTc and increasing risk of torsades de pointes.

Question 4

Which electrolyte imbalance is the first-line treatment target when a patient develops torsades de pointes?

Accepted Answer

Hypomagnesemia correction

Answer

IV magnesium sulfate is the first-line treatment for torsades de pointes; hypomagnesemia facilitates the QT prolongation that initiates this arrhythmia.

Question 5

How does hyperkalemia progressively affect the PR interval on ECG?

Accepted Answer

Prolongs it beyond 200 ms

Answer

Hyperkalemia slows AV nodal conduction, causing PR interval prolongation that can progress to complete AV block if potassium continues to rise.

(CET) Certified Electrocardiogram Technician Practice Test

(CET) Certified Electrocardiogram Technician Practice Test

CET Electrolyte Imbalances & ECG Changes 2