What are the ECG changes in Hyperkalemia?

Appeared in: AIIMS Rishikesh NO - 2019

Explanation

Hyperkalemia refers to an elevated serum potassium level, typically above 5.0-5.5 mEq/L.
Increased extracellular potassium alters myocardial cell membrane potential, affecting cardiac repolarization.
The earliest and most characteristic ECG manifestation of this change is the development of tall, peaked ('tented') T waves.
As potassium levels rise further, the PR interval prolongs, P waves flatten and disappear, and the QRS complex widens, which can progress to a sine wave pattern and cardiac arrest.

Option A: A prominent U wave is a hallmark sign of hypokalemia (low potassium), not hyperkalemia.
Option B: ST segment depression is not a primary or specific sign of hyperkalemia. While it can appear in severe cases, the T-wave and QRS changes are more characteristic.
Option D: A flat T wave is characteristic of hypokalemia (low potassium), which is the opposite of hyperkalemia.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG interpretation in electrolyte imbalances, specifically hyperkalemia as background academic context rather than a clinical decision trigger.
Nurses must be able to promptly recognize ECG changes of hyperkalemia, as it is a medical emergency that can lead to fatal arrhythmias.
Patients at high risk for hyperkalemia include those with renal failure, those taking potassium-sparing diuretics (like spironolactone), ACE inhibitors, or those with extensive tissue damage (e.g., burns, rhabdomyolysis).
Immediate reporting of peaked T waves or other signs of hyperkalemia to the physician is a critical nursing responsibility to ensure timely intervention.

How to Approach the Question

First, analyze the question, which asks for the specific ECG change associated with hyperkalemia.
Next, examine the provided image. Identify the key features on the ECG strip. Note the tall, pointed shape of the T waves.
Recall the classic ECG findings for major electrolyte imbalances. Associate tall, peaked T waves with hyperkalemia.
Evaluate the given options. 'Prominent U wave' and 'Flat T wave' are linked to hypokalemia. 'ST segment depression' is less specific. 'Tall T wave' directly matches the visual evidence and your knowledge.
Select the option that aligns with the classic, initial sign of hyperkalemia shown in the image.

Concept Tested & Keywords

Concept Tested: ECG interpretation in electrolyte imbalances, specifically hyperkalemia.
Stem keywords: ECG changes, Hyperkalemia
Lead-in keywords: What are
Clinical cues: The image shows an ECG with tall, peaked T waves, a classic sign of hyperkalemia.

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