Electrolyte Imbalances & ECG Changes Flashcards
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Read the first 7 Electrolyte Imbalances & ECG Changes flashcards as text
Which ECG finding is most specific for hypocalcemia compared to other QT-prolonging conditions?
Answer: Prolonged ST segment with a relatively normal T wave
Hypocalcemia uniquely prolongs the isoelectric ST segment rather than the T wave itself, so the QT appears long but T wave morphology remains relatively normal.
What is the normal serum potassium reference range?
Answer: 3.5-5.0 mEq/L
Normal serum potassium is 3.5-5.0 mEq/L; values below 3.5 (hypokalemia) and above 5.0 (hyperkalemia) both produce progressive ECG changes.
A patient presents with Chvostek's sign, carpopedal spasm, and muscle cramps. Which ECG finding is most expected?
Answer: Prolonged QT interval
Chvostek's sign and carpopedal spasm indicate hypocalcemia, which prolongs the QT interval by extending the ST segment on ECG.
T wave flattening, ST depression, and tall U waves that may fuse with T waves are most associated with which electrolyte imbalance?
Answer: Hypokalemia
Hypokalemia causes T wave flattening, ST depression, and prominent U waves that may fuse with T waves, falsely suggesting QT prolongation.
Hypermagnesemia most commonly produces which ECG findings?
Answer: PR interval prolongation and QRS widening
Hypermagnesemia acts as a natural calcium channel blocker, slowing AV nodal and ventricular conduction, manifesting as PR prolongation and QRS widening.
Which electrolyte condition is associated with a SHORT QT interval and increased risk of ventricular fibrillation?
Answer: Hypercalcemia
Hypercalcemia shortens the QT interval by accelerating repolarization; severely shortened QTc values increase susceptibility to ventricular fibrillation and sudden cardiac death.
When monitoring a hemodialysis patient, the ECG technician should be most alert for which sequence of electrolyte-related changes?
Answer: Peaked T waves progressing to widened QRS and sine wave pattern
Dialysis patients are at high risk for hyperkalemia; the classic ECG progression is peaked T waves then PR prolongation then P wave loss then QRS widening then sine wave then ventricular fibrillation.