In the ECG of a patient with hyperkalaemia, which sequence of ECG changes is seen with progressively rising serum potassium?

• A Peaked T waves → prolonged PR → wide QRS → sine wave pattern → asystole ✓
• B U-wave prominence → T-wave flattening → prolonged QT → torsades de pointes
• C Delta waves → shortened PR → wide QRS
• D ST elevation → peaked T waves → J-point elevation → asystole

Explanation

Hyperkalaemia produces progressive ECG changes correlating with severity: at K+ ~5.5–6.5 mEq/L, tall peaked (tented) T-waves appear due to accelerated repolarisation; at K+ ~6.5–7.0 mEq/L, PR prolongation and P-wave flattening/disappearance occur as atrial conduction slows; at K+ ~7–8 mEq/L, QRS widens as conduction through the His-Purkinje system slows; at K+ >8–9 mEq/L, the wide QRS merges with T-wave producing a sine-wave pattern, preceding ventricular fibrillation or asystole. U-wave prominence is a hypokalaemia finding; delta waves suggest WPW.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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