QT Flashcards

1
Q

what is the QT interval?

A

depolarisation and repolarisation of the ventricles

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2
Q

how to measure qt interval

A

start of QRS to end of t wave

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3
Q

how to calculate correct QT interval? QTc

A

QTc = QT / square root of RR

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4
Q

what causes a prolonged QT interval?

A
acure myocardial ischaemia
myocarditis
bradycardia
head injury
hypothermia
U&E imbalance (low K+, Ca2+ or Mg)
congenital
drugs (Quninidine, antihistamines, macrolides, amiodarone, pehnothizines)
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5
Q

normal QT and QTc

A

normal QT is less than half the preceeding RR interval

prolonged >440 men > 460 women

<350ms is short

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6
Q

what does a long QT mean

A

heart takes longer to recharge between beats (repolarise)

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