Which of the following ECG findings is most characteristic of hyperkalemia?

Appeared in: GMCH Nursing Officer-2025

Explanation

Hyperkalemia, an elevated serum potassium level, directly affects cardiac muscle repolarization, altering the ECG.
The earliest and most characteristic ECG change is the appearance of tall, peaked, or 'tented' T waves, which are often narrow at the base.
As potassium levels rise further, conduction through the ventricles slows, leading to a widening of the QRS complex.
Eventually, P waves may flatten or disappear, and the PR interval can become prolonged.

Option A: U waves and flattened T waves are classic signs of hypokalemia (low potassium), the opposite condition of hyperkalemia.
Option C: ST-segment elevation and the presence of pathological Q waves are hallmark indicators of an acute myocardial infarction (heart attack), not an electrolyte imbalance.
Option D: Sinus tachycardia with premature atrial complexes (PACs) is a non-specific finding. While electrolyte imbalances can cause arrhythmias, this is not the defining feature of hyperkalemia.

Visual 1: ECG Strip Comparison - An infographic comparing four ECG strips: a normal sinus rhythm, one showing hyperkalemia (peaked T waves, wide QRS), one showing hypokalemia (flat T waves, U waves), and one showing myocardial infarction (ST elevation).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG Interpretation in Hyperkalemia as background academic context rather than a clinical decision trigger.
Recognizing hyperkalemia on an ECG is a critical nursing skill, as it is a medical emergency that can lead to fatal cardiac arrhythmias if not treated promptly.
Nurses must immediately report these ECG changes to the provider and prepare for emergency interventions, such as administering calcium gluconate to stabilize the heart, and insulin with dextrose to shift potassium into cells.
Patient education on a low-potassium diet is a key nursing role for patients with chronic kidney disease or other conditions predisposing them to hyperkalemia.

How to Approach the Question

First, identify the core concept of the question, which is linking a specific ECG finding to an electrolyte imbalance (hyperkalemia).
The keyword 'most characteristic' directs you to find the hallmark or classic sign, not just a possible one.
Mentally review the classic ECG patterns for major electrolyte disturbances: Hyperkalemia (peaked T, wide QRS), Hypokalemia (flat T, U wave), Hypercalcemia (short QT), and Hypocalcemia (long QT).
Evaluate each option against this knowledge base. Option A describes hypokalemia. Option C describes myocardial infarction. Option D is a non-specific arrhythmia.
Conclude that Option B perfectly matches the classic description for hyperkalemia.

Concept Tested & Keywords

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Practise the full GMCH Nursing Officer-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.