Normal characteristics Flashcards
1
Q
Duration of P wave:
A
<0.12 s (less than 3 small squares)
2
Q
Normal PR interval
A
0.12 - 0.20 Sec in adults
3
Q
Normal QRS duration
A
0.06 - 0.10 seconds
4
Q
What does the QT interval represent?
How is it measured?
A
TOTAL ventricular activity
Measured from the beginning of QRS to the end of the T wave.
Measure the interval between 2 consecutive R-R waves, divide by 2.
Result:
If QT is < 1/2 R-R then prob normal
If ~ 1/2 of R-R it’s borderline
If > than 1/2 then it’s prolonged
5
Q
Why is a prolonged QT interval concerning?
A
Indicates a lengthened relative refractory = increased vulnerability.
6
Q
Most accurate method of heart rate calculation:
A
Counting sm boxes between QRS’s, divided by 1500
