ECGs Flashcards
How many limb leads are there?
three
Where does limb lead I look?
RA–> LA
Where does limb lead two look?
RA–> LL
Where does limb lead three look?
LA–>LL
What does the P wave show?
atrial depolarisation
What does the QRS complex show
ventricular depolarisation
What does the T wave show?
ventricular repolarisation
What does the PR interval show?
AV nodal delay
What does the ST segment show?
ventricular systole
What does the TP interval show?
diastole
What is a electrocardiograph?
The DEVICE used the record the potential differences between distant sites on the body surface
What is an electrocardiogram?
A recording of the potentail differences
What are the six ‘standard’ lateral looking leads?
VR, VL, VF
I, II, III
Where does VL, I and II look>
The left lateral surface of the heart
Where doe VF and III look?
The inferior surface
Where does VR look?
The atria
What leads look horizontally at the heart?
V1-V6
Where do leads V1 and V2 look?
Right ventricle
Where do leads V3 and V4 look?
Septum and the anterior wall of the left ventricle
Where do the leads V5-V6 look?
Anterior and lateral walls of the left ventricle
Which leads can determine the cardiac axis?
I, II, III
Where does the depolarisation usually spread?
From the 11 o, clock to 5 o’clock
What does a down ward deflection in lead I indicate?
Right axis deviation caused by right ventricular hypertrophy
What does a down ward deflection in he QRS of lead II and III indicate?
Left axis deviation
Left ventricular hypertrophy
What determines the magnitude of the electrical vector?
Size of the cardiac muscle
What determines the direction of the electrical vector?
Overall activity of the heart during the cardiac cycle
What is the normal length of the PR intervlal?
0.12- 0.2s
What is the normal length of the P wave?
0.08-0.1 seconds
What is the normal length of a QRS complex
< 0.1 s
What is the standard amplitude on and ECG?
10mm/1mV
What does one small box represent?
o.o4s
What does one large box represent?
0.2s
How do you calculate the heart rate on a regular ECG?
300/ number of large squares between QRS complexes
Which lead is the rhythm strip?
II
