34 Flashcards
How many small squares are in each large square in an ECG paper? What is the width and height of the large square
No. 5x5
Width and height:5mm x 5mm
What does the Y axis of each large square represent?
Voltage
(bc V looks like a Y without a stick)
How many milivolts is the Y axis of each large square?
0.5 mv
(so each small square it 0.1)
How many seconds is the x axis of each large square?
0.20
What does the X axis of each large square represent?
duration
How many seconds is the x axis of each small square?
0.04 s
(bc the large square is 0.20 and there are 5 small squares, so 0.20/5= 0.04)
How many milivolts is the Y axis of each small square?
**0.1 mv **
(bc the large square is 0.5, and we have 5 small squares, so 0.5/5= 0.1)
How do you measure the exact time interval of each heart beat?
You count the number of small boxes (or no. of big boxes x 5) between 2 R-R intervals, then you multiply it by 0.04.
How do you do an Exact calculation of Heart Rate from an ECG trace?
You calculate the R-R interval (the time of each heart beat)
then you divide 60 by it.
So if the R-R interval is 0.8, then the heart rate would be= 60/0.8 = 75 BPM
How do estimate the heart rate from ecg?
300/by number of big boxes in the R-R interval
How do you calculate the time of segments and intervals from the ecg?
1.Count the number of small boxes inside the interval
- Multiply No. of boxes x 0.04
What is the PQ/PR interval rate supposed to be?
0.12-0.2 seconds
What is the QRS complex time supposed to be?
< 0.10 seconds
What is the QT interval time supposed to be?
generally less than 0.4 s at rest
What does the mean electrical axis indicate?
Indicates:
– Orientation of heart –
Size of ventricular chambers
– Conduction block
What is the normal axis for the MEA?
From +90 till -30