ecg interpretation Flashcards
(15 cards)
-The electrocardiogram (ECG)is a representation of the — of the cardiac cycle
-Each event, such as atrial/ventricular contraction, has a distinctive – on an ECG
-The waveform of a normal heartbeat is called — since it arises from the –
-Abnormalities in the electrical activity of the heart can help to diagnose – and— diseases.
electrical events
waveform
sinus rhythm
sinoatrial node
cardiac and systemic
placing the ecg leads:
An ECG has – physical electrodes
Vectors are calculated from the – electrodes to generate the standard — lead ECG used in clinical practice
Chest leads: - physical electrodes
V1 — — intercostal space (ICS), – of the —
V2 — — ICS, just – of the –
V3 — midway between – and —
V4 — — ICS on the —
V5 — — , — line, same level as –
V6 — — , - — line, same level as — and —
-Limb leads: – physical electrodes
– electrodes for – limb leads
Right and left arm
Right and left leg
-Vectors are calculated from —leads the – — limb is a grounding lead
10
limb
12
6
4th
right of stream
4th
left of stream
v2 v4
5th ICS on midclaviualr line
anterior axial line
v4
mid-axially line
v4 v5
4
4
6
3
right lower
understanding ECG graph paper:
X-axis represents time:
Rate of tracing generally seen on ECG as — mm/sec = — boxes per second
Large box = – sec(–mm)
Small box = — sec(–mm)
Entire rhythm strip (lead II) is — seconds
Y-axis represents voltage:
Large box = – mV
Small box = – mV
25
5 large boxes
0.2 ( 5 mm)
0.04 (1mm)
10 seconds
0.5 mv
0.1 mv
check graph slide 7
1- p wave:
P wave represents —
Duration: < — ms or — squares
2- PR interval:
Represents the time taken for excitation to spread from the — node across the — and down to the — via the —
Normal PR interval is — ms i.e. — , – squares
3- QT interval:
-The time from the start of the — to the end of the —
Represents the time between — and —
-The QT intervalshortensat — heart rates
-The QT intervallengthensat — heart rates
QT interval is often corrected for — (QTc)
-A prolonged QT is associated with an increased risk of —
atrial depolarisation
<120 , 3 small
SA
atrium
ventricular muscle aka bundle of HIS
120-200
three to five small squares
q wave
t wave
ventricular depolarisation n repolarisation
fasrer
slower
heart rate
ventricular arrhythmias
4- ST segment:
TheST segmentis the — , —
section of the ECG between the – ofhe – wave (the – point) and the— of the – wave
The ST Segment represents the interval between — and —
Interpreted relative to the preceding TP segment
5- T wave:
- — of ventricles
- — deflection in — and —
flat , isoelectric
end
s
J point
beginning
t wave
ventricular depolarisation and repolarisation
repolarisation
-ve
V1 and aVR
The cardiac axis represents the overall — of —
Under normal circumstances the — is the most abundant cardiac muscle, therefore normal cardiac axis is directed – and slightly to the —
The – leads are used to determine the cardiac axis
Abnormal cardiac axis can indicate –
direction of cardiac depolarisation
left venticule
downward
left
limb
pathology
determining the axis:
The cardiac axis can be determined from leads —-
A lead is positive if its most prominent deflection is — the baseline
A lead is negative if its most prominent deflection is — the baseline
-LAD = left axis deviation
-RAD = right axis deviation
I , II , III
above
under
( pls check slide 14-23)
ECG- rate interpretation:
The rhythm strip (lead II) of an ECG represents cardiac aECGctivity over —
Therefore, the heart rate over 10 seconds is the number of QRS complexes ( – contractions) on the rhythm strip
The heart rate per minute can then be calculated by — the — complexes in — by —
In this example 11 QRS complexes in 10s = 66bpm
10 seconds
ventiuclar
multiplying
QRS
10 seconds
6
determining the rate from single cardiac cycle:
One large box on ECG = – seconds
Therefore, one minute will comprise — large boxes (60 seconds divided by 0.2 seconds)
To calculate the heart rate in one minute divide — by the number of — boxes in a single cardiac cycle
For ventricular rate the – wave is used
The small boxes can be utilized in the same way
One small box on ECG = — seconds
Therefore, one minute will comprise — small boxes (60 seconds divided by 0.04 seconds)
To calculate the heart rate in one minute divide — by the number of — boxes in a single cardiac cycle
( info: The normal heart rate is 60-100 beats / minute)
0.2
300
300
large
r wave
0.04
1500
1500
small
-Arrhythmia is anything other than normal —
-This may be an abnormal heart — and/or abnormal pathway — in the heart
-The normal conduction pathways in the heart are — . Damage to these pathways or conduction through abnormal pathways generally results in — conduction
-Cardiac rhythm is usually defined as – or — by examining the — between— complexes
sinus rhythm
rate or conduction
fast
slow
regular or irregular
spaces
QRS ( check slide 33)
Is there a P-wave before every QRS?
Normal sinus rhythm = always a P wave — every QRS complex. The electrical impulse is arising from the —
No discernible P waves = —
Sawtooth pattern of p-waves = —
-Normal QRS width is — ms
- QRS — ms is abnormal (broad)
Normal (narrow) complexes arise from normal conductance pathways (SA node to AV node)
Broad QRS complexes suggest the normal ventricular conductance pathways are impaired
before
arterial fibrillation
artrial flutter
70 - 120
>120
What is the PR interval?
A prolonged PR interval suggests — ( — conductance from SA node to AV node)
What is the QRS morphology?
A — (normal) QRS suggests a rhythm arising from the atria
A — QRS suggests a rhythm of ventricular origin
Is the QT interval normal?
A prolonged QT interval can cause —
AV heart block
prolonged
narrow
broad
ventricular arrhythmias
- atrial arrhythmia:
1- Sinus tachycardia/bradycardia – — , — complex QRS with — before all QRS complexes
2- Atrial fibrillation – — , — complex QRS with no discernible —
3- AV heart block – — , — QRS complex with prolonged — - ventricular arrythmias:
1- Ventricular tachycardia – – , — & – complex QRS with no discernible —
2- Ventricular fibrillation – – , — QRS complexes
regular , narrow
p wave
irregular , narrow
p wave
regular , narrow
prolonged PR
regular, fast , broad
p wave
chaotic , broad
ST segment abnormalities:
Causes of elevated ST segment:
—- , —
Causes of depressed ST segment
— , —- , — abnormalities
T- wave abnormalities:
1- Peaked:
— , —
2- Inverted
— , — , —
1- Acute transmural infarction,
Pericarditis
2- Non-ST elevation MI , ishcemias , electrolyte abnormalities
peaked: ‘Hyperacute’ Infarction ,
Elevated potassium
inverted : Myocardial infarction
Ischaemia
Pulmonary embolism
summary:
The ECG is an electrical representation of the —
Abnormal electrical activity in the heart can help to make the correct diagnosis
Interpretation of the ECG requires a — approach
Start with the – , followed by — (regular / irregular), look for – waves, followed by abnormalities of the other waves and intervals
cardiac cycle
systemic
rate
rhythm
p wave
