ECG Flashcards
What does the p-wave represent
Atrial depolarisation
What causes the p-wave
SA node
How many squares is 1 second
5
What does 5 big squares on the graph represent
1s
What does 1 big square represent
0.2 seconds (200ms)
What is 0.2s on the graph
1 big square or 5 small squares
What is 5 small squares
0.2 seconds
What is 0.04 s (40ms)
1 small square
What is 1 small square
0.04 s 40ms)
What are the typical settings on a voltage time graph
Speed
Voltage
Speed = 25 mm/sec
Voltage = 10 mm/mV
What voltage does one big square represent
0.5 mV
What voltage does 2 big squares represent
1 mV
Used a voltage time graph how do you calculate rate (bpm)
300/no. of large squares between cardiac cycle
OR
cycles in 10 seconds x 6
What is the equation of Ohm’s law
V = IR
Voltage = current x resistance
On an ECG lead what does a positive deflection show
Net current flow towards lead
On an ECG what does a baseline/isoelectric point show
No net current flow in direction of lead
On an ECG what does a negative deflection show
Nett current flow away from lead
What is the normal value of the PR interval
120-200 ms
3-5 small squares
What does a long PR interval show
1st degree heart block
Delayed AV conduction
What is the normal range for QRS complex
Less than 120ms
3 small squares
What is the QR interval a measure of
Time to ventricular repolarisation
What is the QR interval
Time from onset of QRS to end of T
What is the normal valve for QT interval for men
350-440 ms
What is the normal value of QT interval for women
350-460 ms
What does the PR segment represent
Av node holding charge
What does the QRS wave represent
Ventricular depolarisation
What does the T-wave represent
Ventricular repolarisation
How many leads does an ECG have
12
What is the division of the 12 leads
3 bipolar limb leads V1, V2, V3
3 Augmented unipolar limb leads avF, avR, avL
6 precordial (chest leads) V1-6
Which leads look at the heart in a frontal plane
bipolar and augmented
What leads look at the heart in a horizontal section
precordial
Where is lead I
RA to LA
Where is lead II
RA to LL
Where is lead III
LA to LL
What is Lead I looking at
Left/lateral heart
Where is lead II and III looking at
Inferior heart
How do you think leads are looking at the heart
From positive to negative
Where is electrode AVR looking
Right side of heart
Where is electrode AVF looking
Inferior side of heart
Where does electrode AVL looking
Left and lateral side
What is the placement of the 6 precordial/chest leads
V1 - 4th intercostal space R
V2 - 4th intercostal space L
V4 - 5th intercostal space L
V6 - 5th intercostal midaxillary line
What does V1/2 pick up
Intraventricular septum
What does V3/4 pick up
Anterior wall
What does V5/6 pick up
Left lateral wall
