ECGs Flashcards
how many wires are there to give a 12 lead ECG
where are they
10
3 limb leads (RA, LA, LL)
1 earthed wire
6 chest wires - V1-V6
what wires contribute to lead I
RA-LA
I = 1 L
what wires contribute to lead II
RA-LL
II = 2 L
what wires contribute to lead III
LA-LL
III = 3 L
where is the earthed wire
right leg
what wire does aVR come from
RA
what wire does aVL come from
LA
what wire does aVF come from
LL
F = foot
where is V1 on the chest
R sternal edge 4th intercostal space
where is V2 on the chest
L sternal edge 4th intercostal space
where is V3 on the chest
between V2 and V4
where is V4 on the chest
5th intercostal space, midclavicular line (apex beat)
where is V5 on the chest
anterior axillary line, same level as V4
where is V6 on the chest
mid axillary line, same level as V4 and V5
sinus arrythmia aetiology
sinus bc P wave followed by QRS
normal person with caffeine overdose/drugs etc
common in children
which lead is at the bottom of the ECG for you to read (figure out rate etc)
lead II
how long is one big square on ECG
0.2 seconds
how many small squares are in a big square on ECG
5
how long is one little square on ECG
0.04 seconds (0.2/5)
how to figure our rate if regular rhythm
300/number of large squares between QRSs
how to figure out rate if irregular rhythm
number of QRS in 30 boxes x10
what area of the heart does lead I represent
lateral
what area of the heart does lead II represent
inferior
bc connected to foot (LL) = inferior
what area of the heart does lead III represent
inferior
bc connected to foot (LL) = inferior
what area of the heart does lead aVL represent
lateral
bc most to left
what area of the heart does lead aVF represent
inferior
bc F = foot = inferior
what area of the heart does lead V5 represent
lateral
bc most to left
what area of the heart does lead V6 represent
lateral
bc most to left
normally, which lead is inverted
aVR
what does P represent
atrial depolarisation
what does QRS represent
ventricular depolarisation (and atrial repolarisation)
what does T represent
ventricular repolarisation
what does PR interval represent
AV node delay
normal length of P wave
<0.12secs (3 small boxes)
normal length of QRS
0.04-0.12secs (1-3 small boxes)
normal length of PR interval
0.12-0.2secs (3-5 small boxes)
steps to reading ECG (14)
patient details date and time of ECG calibration of ECG paper axis - normal? activity present? rhythm regular/irregular rate P waves present PR interval QRS after each P wave QRS duration delta waves ST elevation T waves - tall?
tall T waves
hyperkalaemia
ST elevation
STEMI
wide QRS
ventricular problem
eg ventricular tachycardia
absent P waves
atrial problem
eg atrial flutter, atrial fibrillation
sawtooth baseline
atrial flutter
treatment of ventricular tachycardia
defib them
P waves regular
QRS regular
P waves not followed by QRS (no correlation between the 2)
third degree heart block
inferior MI lead changes
II, III, aVF
anterior MI lead changes
V1-V6
which artery is occluded in inferior MI
right coronary artery
anterolateral MI lead changes
I, aVL, V1-V6
which artery is occluded in anterior MI
left anterior descending
posterior MI lead changes
V1-V3
ST depression!
lateral MI lead changes
V5-V6, I, aVL
high lateral MI changes
I, aVL
not V5-V6 bc theyre lower
treatment of STEMI
primary PCI ASAP (<90mins)
thrombolysis >90mins
prolonged PR
AV block
a type of heart block - need to figure which one
which leads do you look at for axis deviation
I and aVF
what is the axis deviation if;
I QRS positive
aVF QRS positive
no axis deviation
what is the axis deviation if;
I QRS negative
aVF QRS positive
right axis deviation
what is the axis deviation if;
I QRS positive
aVF QRS negative
left axis deviation
more common than right
which artery is occluded in lateral MI
circumflex
hr of sinus rhythm
60-100
hr of sinus bradycardia
<60
hr of sinus tachycardia
> 100
ECG of sinus node block
missed P wave and QRS (together)
how does supraventricular tachycardia differ from ventricular tachycardia
narrow QRS complex in supraventricular tachycardia
broad QRS complex in ventricular tachycardia
loss of P waves
chaotic rhythm
QRS complexes present
atrial fibrillation
prolonged PR interval
first degree heart block
increasing PR interval until a QRS is dropped
second degree heart block type 1
normal P waves but dropped QRS complex
second degree heart block type 2
hr >100
broad QRS
ventricular tachycardia
chaotic rhythm with no QRS = no heart rate detectable
ventricular fibrillation
