Electrolyte Imbalances & ECG Changes Flashcards
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Which ECG change is the hallmark finding of hyperkalemia?
Answer: Peaked (tall, narrow) T waves
Hyperkalemia causes tall, narrow, peaked T waves due to altered ventricular repolarization from elevated extracellular potassium.
Hypokalemia on a 12-lead ECG is most commonly identified by:
Answer: Prominent U waves with T wave flattening
Hypokalemia produces T wave flattening and prominent positive U waves (deflection after the T wave) most visible in leads V2-V3.
Hypercalcemia typically produces which ECG finding?
Answer: Shortened QT interval
Hypercalcemia shortens the ST segment and QT interval because elevated calcium accelerates ventricular repolarization.
Which electrolyte abnormality is most strongly associated with a prolonged QT interval and risk of torsades de pointes?
Answer: Hypocalcemia
Hypocalcemia prolongs the ST segment and QTc interval by extending the plateau phase of the action potential, increasing torsades de pointes risk.
In severe hyperkalemia, the ECG 'sine wave' pattern results from:
Answer: QRS widening merging with the T wave
As hyperkalemia worsens, progressive QRS widening causes the complex to merge with the T wave, creating a sinusoidal pattern that precedes cardiac arrest.
In which leads are U waves most prominently seen in hypokalemia?
Answer: V2 and V3
U waves in hypokalemia are best visualized in the mid-precordial leads V2 and V3, where they appear as a positive deflection after the T wave.
Hypomagnesemia on ECG most closely mimics which other electrolyte abnormality?
Answer: Hypokalemia
Hypomagnesemia causes T wave flattening and prominent U waves similar to hypokalemia, and the two deficiencies frequently coexist.