ECG 1 Flashcards
(13 cards)
component of ECG:
1- waves : — , —
2- — complex
3- —- , — intervals
4- — segment
p and t wave
QRS
QT interval
PR interval
ST segment
( pls check the pic ffs)
the 12 leads of ECG:
* Lead I
– — to —
* Lead II
– — to —
* Lead III
– — to —
* Lead AvF
– — to —
* Lead AvL
– — to —
* Lead AvR
– —- to —
right arm
left arm
right arm
left leg
left arm
left leg
lead I
left leg
lead II
left arm
lead III
right arm
( check the photo too )
the cardiac axis:
* The cardiac axis represents the general — of — with the heart
* On the whole, this starts in the – , — of the heart ( — node) and
spreads to the — , – and the — of the heart
* A person’s cardiac axis determines whether the deflection in a particular lead is — or — , — or —
direction
depolarisation
top right
SA nide
bottom left
apex
large or small
positive or -ve
check slide 7,8,9,10,12
summary:
* The ECG is an — representation of the cardiac cycle
* Each lead gives a different view of the heart
– size of deflections reflect how — leads fit cardiac axis
– the presence of — indicates where it is in the heart
* Interpretation of the ECG requires a — and — approach
electrical
closet
pathology
systematic and logical
10 rules for normal ECG :
- PR interval should be 3-5 small
squares - Width of QRS should be <3 small
squares - QRS complex should be a mainly
upwards deflection in leads I & II - QRS and T wave should have the same
general direction in limb leads - Waves should be downward
deflections in AvR - R wave should increase in size from
V1-V4 - ST segment should be isoelectic
(except in V1 and V2 where it may be
raised) - P wave should be upward deflection in
I, II & V2-6 - There should be no (or only a small) Q
wave in I, II & V2-6 - T wave must be an upward deflection
in I, II & V2-6
the p wave:
* The first event in the cardiac cycle is the — of the —
* Depolarisation spreads through the — and to the —
* This depolarisation generates the– on the ECG
* The P wave is a reflection of — activity
– but is not specifically the sino atrial node
the PR interval:
* Depolarisation spreads through the — towards the —
* Conduction through the AV node is —
– thus allows ventricular —
* Slowed conduction produces the —
– this should be >— and <—
– — to — small squares
depolarisation
sino atrial
right and left atria
p wave
SA node
AV
ventricles
slowed
filling
PR interval
0.12 s
0.2 s
three to five
the QRS complex:
* Conduction spreads from the — node, down the— and through the — and up through the —
* The nature of this spread produces different QRS complexes in each
of the leads
* The QRS complex does not need to have all three components
– Q waves for example are only seen in certain leads
av node
bundle of HIS
purkinjie fibres
epicardium
- The Q wave
– a — wave preceding an —
– caused by — of the —
– seen in – pointing leads (I, II, AvL, V5, V6) - The R wave
– an —
– (whether preceded by a Q wave or not) - The S wave
– a — , — the — line
– (whether preceded by a Q wave or not)
-ve
R wave
depolarisation
ventricular septum
left
upward deflection
deflection
below the isoelectric line
PLS check photos slide 10 so important
T wave:
* Depolarisation flows from the — to the –
* Repolarisation flows in the opposite direction
– — to —
– (the action potential is — in the epicardial cells)
* As it moves in the opposite direction, the T wave is in the — deflection as the QRS complex
endocardium
epicardium
epicardium
endocardium
shorter
same
check slide 13
reporting an ecg:
- As with a lot of things you want a procedure to do this properly
- Rhythm
- Conduction intervals
- Cardiac axis
- A description of the QRS complexes
- A description of the ST segment and T wave
ecg and abnormalities:
* Increased voltage from to ( check photo)
– —
* Axis deviation
– left axis deviation
– left ventricle hypertrophy
– more muscle mass, pulls depolarisation to the —
– deflections in lead I get — , while AvF gets —
– right axis deviation
– right ventricle hypertrophy
– more muscle mass, pulls depolarisation to the —
– deflections in AvF get — , while lead I gets —
* Delayed conduction
– — PR interval, QRS or QT
* ST depression ( —- NSTEMI)
– only seen in leads pointing towards —
* ST elevation (—- STEMI)
– only seen in leads pointing towards —
– — , — thickness of the myocardium
hypertrophy
left
bigger
smaller
right
bigger
smaller
elongated
ishcemia
damage
infraction
damage
acute infarction
full
conduction intervals:
* The ECG is based on the — and should reflect the – of those events
* Conduction through the AV node is — and produces a – of —- seconds
– — small squares
– shorter suggest depolarisation originates near the —
– longer suggests a – and —
* Depolarisation of the ventricles is – and spreads — to the left and right
* This means the QRS should be – and consist of a — peak
– less than – small squares
cardiac cycle
timings
slowed
PR interval
0.12-0.2 s
AV node
delay and heart block
rapid
equally
narrow
single peak
3
heart block:
* Decreased or total block of — conduction
– due to — /— / —of –
* 1st Degree is the — in conduction
– characterised by an — of — interval (> — or — large box)
* 2nd Degree is the —
– so that now some QRS complexes are— (PQRS > P > PQRS > P…)
* 3rd Degree is the —
– ventricles contract (automaticity /”ventricular escape”) but — (~40 bpm)
– SA node still firing but no relationship between P and QRS
AV conduction
ischemia/compression/inflammation of AV node
delay
increase of PR
>0.2 sec or one large
increased delays
dropped
complete plock
slower
( check diagrams from 11 to 13)
