An ECG shows a QT interval of 384 ms and an RR interval of 0.64 s. What is the corrected QT by Bazett's formula?
Answer and explanation
Correct answer: A. 480 ms
- Step 1: Bazett: QTc = QT / sqrt(RR).
- Step 2: sqrt(0.64) = 0.8, so QTc = 384 / 0.8 = 480 ms.
Answer
480 ms.
Why not the others: Bazett divides by the square root of the RR interval; dividing by RR itself or multiplying gives other values.
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