This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG, Subject name: Physiology
[{'content': 'Falsely prolonged QT interval may be a feature of which one of the following conditions? \nSelect and explain. \nA. Hypokalemia, B. Hyperkalemia, C. Hypocalcemia, D. Hypercalcemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hypokalemia (plasma K+ ~ 3.5 mEq/L) causes a widened concentration gradient for K+ (inside & outside). This results in altered repolarization of ventricles and there would be prominent U wave now, which will immediately follow the T wave. The actual QT interval remains normal (~ 0.4 sec); however, the U wave is erroneously considered a pa of the T wave, and a falsely prolonged QT interval of 0.6 sec is measured.', 'role': 'assistant'}]