QT Interval Flashcards
1
Q
What is the measurement of the QT interval?
A
Beginning of QRS to end of T wave
2
Q
How would you calculate QT intervals?
A
Bazett’s Formula: QTc = QT / sqrt(RR)
QTc = Should be 1/2 RR interval.
3
Q
What QT interval time is considered clinically significant.
A
> 500ms
4
Q
How is Torsades de Pointes triggered?
A
Triggered by “long-short” interval. Long QT then short QT.
Mechanism of afterdepolarization (triggered)
5
Q
What are the two etiology categories of LQTS?
A
Congenital and electrolyte disorders
6
Q
What electrolyte disorders cause LQTS?
A
Hypokalemia, hypomagnesemia, hypocalcemia (can cause hypo-k)
7
Q
What is Short QT Syndrome?
A
QT < 360ms associated with cardiac arrest and SCD.
