ECG Basics Flashcards
(165 cards)
1
Q
What do the points of ecg correlate to P ? QRS? T?
A
P - Atrial depolaraiation
QRS - ventricular depolarisation
T - ventricular repolarisation
2
Q
Q R S are
A
Q first downward deflection
R first upward
S second downward
3
Q
If QRS has second upwards deflection it is called?
A
R prime (or RSR)
4
Q
What is this
A
QS wave - 1 large negative wave
5
Q
What waves are here
A
RS - no negative Q wave
6
Q
What waves in this complex
A
RSR (R-prime)
7
Q
Where are the P QRS and T waves
A
1 p wave hidden in QRS complex (arrow)
8
Q
What time interval is a small box? large box?
What about the amplitude?
A
Assuming paper speed is 25mm/second
1 large box (5mm) - 0.2s
1 small (1mm) - 0.04s
10mm = 1mV
9
Q
where is the PR interval? What does it measure
A
Start of P to start of Q
AV conduction time
(time of atrial depolarisation tkes to go through AV node to reach ventricles)
10
Q
Where is start and end of QT interval
A
Start of Q to end of T
11
Q
QT interval here?
A
Approx 0.44-0.48ms
12
Q
shows?
A
p mitrale
Also >0.12s -> LA enlargement
13
Q
What is this
A
1st degree AV block
14
Q
What is the general term for a short PR? 2 Main syndromes?
A
pre-excitation syndromes
Lown-Ganong-Levine LGL syndrome
- QRS immediately follows p wave
WPW
15
Q
what is this
A
Lown-Ganong-Levine LGL syndrome
- QRS immediately follows p wave
16
Q
A
WPW with delta wave
17
Q
A
R atrial hypertrophy (p wave is > 0.5mV)
18
Q
ECG dots where does v1-3 represent in the heart
A
RV
[V2-3 also basal septum]
19
Q
V2-V4 represent
A
anterior wall of lV
20
Q
v5/v6 represent
A
lateral wall of LV
21
Q
Where do you place v7-9. What do they represent?
A
V7 left posterior axillary line,
V8 left mid-scapular line,
V9 at the left paraspinal border
Posterior LV
22
Q
Whart is the R/S ratio? which leads is it <1 or >1?
A
<1 usually means corresponds to RV
>1 means usually corresponds to LV
=1 is in transition zone between RV/LV
RS ratio should increase as you go Right to Left
23
Q
What does the RS ratio here signify
A
Counterclockwise rotation
RS ratio is shifted right
24
Q
What is going on with RS ratio here
A
Clockwise rotation
RS ratio shifted to left
25
26
When can you not assess rotation using RS ratios
RBBB
Q wave infarction
WPW
27
Which ventricle is represented by this?
RV
(Probably v1/v2)
28
Which ventricle is represented by these leads under normal circumstances?
LV
29
What is this
M form or RSR pattern
30
LV leads have this?
M form - note sometimes just notching
LBBB
31
What does the M form or RSR signify
Delayed conduction - on side of heart where it is seen
32
2 main causes of RSR (M) patterns
Bundle branch blocks
Dilated / hypertrophic ventricles
33
Which BBB is this
LBBB - the M form is in v5/6
34
What is this?
WPW - can be mistaken for RBBB
- Dont fall for the M pattern in V1
35
What is an incomplete bundle branch block
QRS = 100-120ms
with RSR pattern
36
LBBB
37
RBBB
38
Incomplete RBBB - usually due to Volume overload RV
QRS is .1s with RSR v1
39
Usual cause of incomplete BBBs
Volume overload of R / L ventricle
40
RBBB
41
Which leads are the R waves usually biggest
V5 and v6
42
How to assess LVH on ECG . Calculate here?
Measure biggest R wave (usually v5/6)
Measure biggest S wave (usually v1/2)
and add them together
- If **>3.5mV** = positive sokolow index
Here is 2.2mV + 3.1mV = 5.3mV (positive)
43
How to indicate RVH on ECG
RSS criteria
1. R in v1 >0.5mV
2. R/S in v1 is >1
3. S in v5 is >0.5mV
If 1 correct - possible
If 2 correct - likely
If all 3 correct - very likely
44
Is there RVH here?
RSS
in V1. R is not >0.5mV
R/S ratio is not >1
S in v5 is not >0.5mV
= No RVH
45
Is there RVH here?
RSS
in V1. R is 0.6mV
R/S ratio in V1 is >1
S in v5 is >0.5mV (about 1mV)
= likely RVH
46
LVH - >3.5mV total
[note the negative T waves in v5/6 - indicates LVH with abnormal repolarisation]
47
LVH >3.5mV total
48
RVH and LVH
49
RVH + RV volume overload strain
50
LVH
LV volume overload (Incomplete LBBB) with strain (inverted T waves)
51
RVH
52
LVH + strain
53
LVH - no strain as positive t waves
54
What does the ST segment here tell you
Descending ST depression - likely ventricular hypertrophy with repolarisation problem
55
Usual causes
Sagging ST
1. Digoxin
2. hypokalaemia
3. CAD
56
usual causes
Horizontal ST depression
-CAD
57
What is the usual cause of upsloping ST depression
Usually exercise or increased sympathetic tone
58
Explain t waves here
Note A+B are Asymmetrical - Ventricular hypertrophy
C+D are symmetrical - Ischemia
[All could occur in intraventricular conduction delay]
59
LBBB
- Note you see the mirror image on the Right sided leads
ie STE in v1 and 2 in LBBB which is due to the ST segment changes in LV
60
LVH
Note descending asymmetric ST depression in v5/6
61
RVH with RV strain
LVH
62
WPW
[Can mimmic LVH or an MI]
63
Coronary T wave inversion (biphasic T wave)
64
2 things here
LVH with strain
CAD - biphasic Twaves
65
What happens to R and Q waves in MI
Q waves develop
R waves get smaller
66
What happens to QRS in mi? In this example of v1/v2?
Everything pulled down
Q wave gets deeper ie >1/3 of size
R wave gets smaller amplitude
[Pulled down]
67
What would happen to this complex in v5/v5 if there was infarction
Loss of R wave (as pulled down) and forms a QS complex
68
What would happen to this complex in v3/v4 if there was infarction?
Newly formed Q wave
69
What is the normal pattern of Q waves in V4-V6?
What would happen to this ECG if there was a infarct in the septal leads?
Normally the Q gets slightly bigger
In septal infarct it starts big and gets smaller
70
What would happen here to Q waves with a lateral MI
Qs would be large, but stable in size
Abnormal as there should never be Q waves in any lead with a deep S wave
71
Which leads usually have an initial small R wave
V1-3
72
This is a normal QRS in v1-2 what might it look like after MI
Q wave in v1-3 usually pathalogical
[V1-3 should start with an R wave]
73
What should happen to the amplitude of R wave in V1-6
Should be increasing as there is an increase in the muscular mass of LV
74
Whats the issue here
There are lateral Q waves
[normal on top]
75
Whats going on in B
Loss of R wave v2
Q waves v3-v4
Probably scar tissue from old septal infarct
76
Whats going on in C? What should you check when you see this?
Poor R wave progression v2/3
-> Proably old basal septal infarct (anterioseptal)
[Dont forget to check for RVH with this as may be the cause of a big R wave in v1]
77
When are q waves abnormal
>0.04s (1mm)
>1/4 of the R wave
78
RBBB
Anteriolateral infarction
79
Which of these have a pathological q wave? mi location?
v5-v8 - posteriolateral
80
Which leads have q waves? What else is seen?
LVH with strain
Anterioseptal MI
Note Q waves in v3-4
QS in v2
81
Which leads have q waves- MI location? what else is seen?
Anterolateral mi
Q waves v2-5
RBBB
82
Which leads have q waves - where is MI?
What else is found
V2-3 - anteroseptal
LVH with strain
1st degree AV Block
83
Where are the pathological q waves - location of mi?
What else is seen
V4-V6 Q waves - anterolateral MI
Complete RBBB
v1-v2 has normal R wave progression
84
Which leads have q waves? MI location?
q waves - v2 / v3 - anterioseptal
normal r in v1
85
Where is pathological q waves? mi location?
What else is seen?
Q waves v2-v5 - anteriolateral
RBBB
[Note small R rave normal in v1]
86
Which precordial leads have q waves? Why?
Septum is first part to depolarise from L->R which is away from leads v4-6
Also seen in I,II,aVF and aVL
87
Why do MIs produce q waves
When a depolarisation is towards a lead you get a positive deflection
- When away from lead -> negative deflection
Therefore, when myocardium is scarred (post-infarction) it becomes electrically silent and the electrical vector is away from it
[normal v5 vs v5 in lateral scar (in grey)]
88
Do all MIs produce q waves?
No
89
Where do the limb leads go?
R - R arm
Lellow - L arm
G L foot
Black R foot
90
Which direction do leads I,II and III face?
Think X guy
I - L arm
II - L leg
II - R leg
91
Which direction to the augmented leads read?
Think Y guy
aVL - left arm
aVR - right arm
aVF - foot
aVL = augmented Left
92
How do leads I-III and augmented leads reflect areas of heart
Think x / y guy for directions
Inferior - III, aVF and II
Lateral - aVL and I
93
Which leads mirror II, III and aVF?
V1,2,3
94
Which BBB is here
RBBB
95
Where is the MI
Anterolateral and inferior wall
96
Where is the MI?
Inferior
Q wave in II
QS in III and aVF
Note mirror image of leads v1-v3 (taller R and big positive T waves)
[borderline for LVH too]
97
What do you see
1st degree AV block
Inferior/lateral/posteiror MI
QS in v2,v3
Q wave v4,v5
STE inferior
98
Whats the main difference in ST segment changes vs q waves with regards to an MI
Q waves represent scar tissue so are usually permanent
99
STEMI vs NSTEMI vs unstable angina
Which has a troponin release?
NSTEMI / STEMI have trop release
note unstbale angina may have ECG changes
100
What is the usual path of ST segment changes in MI following STEMI if they recover
STEMI -> TWI -> ST isoelectric -> T wave normalisation
L side with Q waves, right without
101
Trop rise
NSTEMI in the territory of the left anterior descending artery (LAD). Leads V2, V3, and V4 are affecte
102
Chest pain of short duration (15 to 20 minutes) and
appears at rest or even during sleep with these ECG changes
Variant angina or Prinzmetal angina
103
How to differentiate STE in pericarditis vs STEMI
Pericarditis usually concave + ST segment originates from ascending part of the QRS
STEMI convex / flat
ST segment from descending part of QRS
104
When might you get a STE which lasts forever
Myocardial aneurysm EG post mi
105
Pericarditis - note STE in v2-v6
V2-4 - LAD
V5-6 - Cx
[Unlikely both are occluded at the same time]
Also Concave and STE comes from ascending part of QRS which is typical of pericarditis
106
These changes occur only when HR in 60s and resolve on increasing rate. No chest pain.
Vagotonia / High take off
-due to Early repolarisation
Usually has high T waves
107
How do you use j point to differentiate hyperkalemia and vagotonia as both have peaked t waves
J point elevated in vagotonia
108
What is going on here
Pericarditis
Note initial STE in v2-5 coming from ascending QRS and concave shape
In resolution STE coming down and has negative T waves
109
chest pain
anteriolateral NSTEMI
110
Acute anteriolateral STEMI
note loss of r waves in v2 and 3
111
inferiolateral STEMI
112
q wave STEMI
Note loss of r wave in v2-5 with QS complexes
113
inferior STEMI
note Q waves in anterolateral (probably old infarct - chronic)
1st degree av block
114
LVH with strain
note the R which looks smaller in V3 is actually proportionally getting bigger = normal
115
Which block? Ischaemia?
LBBB
- LBBB usualy has negative T waves but here there is raised
-> probably acute ischemia interiolateral STEMI
116
With Axis which lead is at 0 degrees? Where are the rest
Lead I
117
What is a normal cardiac axis? how can you tell this easily?
between –30° and +90° is called a “normal axis”
if I and II are both positive
118
If I is positive and II is negative - what is the axis?
The area between –30° and –90° is called “left axis deviation”
119
If I is negative and aVF is positive?
The area between +90° and +/–180° is called “right axis deviation”
120
both leads I and aVF are negative?
The area between –90° and +/–180° is called a “northwest axis”
121
If lead I is positive which lead do you use to work out if there is an axis deviation?
If it is negative?
Which leads are pos / neg for:
normal axis?
LAD?
RAD?
NWA?
Normal - I and II positive
LAD - I is positive and II is negative
RAD - I is negative and aVF is positive
NWA - leads I and aVF are negative
122
What is the breakdown of the bundles for ventricular depolarisation?
Bundle of his
-> Right bundle
->Left bundle -> Left posterior fascicle + left anterior fascicle
123
What is a bifasicular block? how does it appear on ECG?
RBBB + block of one of the L fascicles
RBBB + LAD = RBBB + LAFB
RBBB + RAD = RBBB + LPFB
124
How can you use axis deviation to help with suspicion of RVH?
If RSS criteria are positive (e.g., you have a patient with a tall R in V1 and a deep S in V5) + RAD
-> More likely there is RVH
125
LVH on ecg with RAD probably means?
Biventricular hypertrophy
126
What is p mitrale - where is it most pronounced?
LA hypertrophy
P wave has two peaks, and usually, the second peak is taller than the first one.
P-wave duration is greater than 0.1 seconds.
These changes are most pronounced in leads I and II.
127
Bar leads I and II where else is good to look for LAH?
V1 - look for a biphasic p wave
If the negative part is longer than 1 small box (or >0.04 s), then P mitrale is present
128
How do you assess RAH on ECG? which leads are best? What is is called?
Right atrial hypertrophy has peaked p waves in leads II, III, and aVF >0.25mV
- p-pulmonale
129
What do the p waves in v1 and II look like normally? in RAH? LAH?
130
What is a low voltage ECG? usual causes
none of the QRS complexes in the standard leads (i.e., leads I, II, and III) is higher than 0.5 mV
- peripheral edema, cardiac amyloid, pulmonary emphysema, large pericardial effusion, or severe myocardial damage
131
Which leads are positive or negative for all of the axis deviations
132
Which leads are best to look for atrial depolarization
v1 - as will be positive in RA depolarization followed by negative in LA Depolarisation
II - as points in the same direction -> biggest p wave to assess
133
What is the axis here
borderline LAD
134
Axis here?
Probably limb lead reversal with normal axis
note negative p in lead I / aVR and positive p in III
135
What block
I positive and II negative -> LAD
PR prolonged -> 1st degree AV block
QRS prolonged with RSR v1 -> RBBB
LAD + RBBB = bifasicular block + 1st AV block
This is termed incomplete trifasicular block
136
What is trifasicular block? implications
Right bundle branch block
Left axis deviation (Left anterior fascicular block)
Third degree heart block
-> PPM
137
Trifasicular block
Right bundle branch block
Left axis deviation (Left anterior fascicular block)
Third degree heart block
138
syncope
Trifasicular block
Right bundle branch block
Left axis deviation (Left anterior fascicular block)
Third degree heart block
-> PPM
139
Incomplete trifasicular block
[Bifascicular block + first degree AV block]
Right bundle branch block
Left axis deviation (= left anterior fascicular block)
First degree AV block
140
Axis? what else is seen?
p mitrale I, II -> LAH
LVH
RVH with strain
141
Axis? what else is seen?
I neg, II pos -> RAD
II, III -> p pulmonale -> RAH
R in v1 >0.5mV, s in v5 >0.5mV -> RVH
142
HyperK ECG
Tall T waves
-> widening of QRS if severe
143
Hypokalaemia ECG
T flattening
Sometimes ST depression
U wave ( second wave following T)
144
T waves in hyper vs hypo kalaemia
145
Classic mistake made when measuring QT interval in hypoK?
people measure QU interval rather than QT
146
Key hypoCa finding? HyperCa?
HypoCa - Prolonged QT
HyperCa - shortened QT
147
A simple way to say if QT is prolonged
Measure half way between RR inverval -> if end of QT in first half its normal
if in 2nd half abnormal
148
Is this QT prolonged?
no
149
is this QT prolonged?
YES
150
Which electrolyte is classic for short QT
HyperCa
151
How to calculate rate on ECG ? In this eg?
300 / large squares between RR interval
approx 300/5 = 60
[slightly more so approx 62-64]
152
Whats the rate here?
300/2.2
approx 136
153
How many big boxes between RR intervals for rate of 75?
4
154
Axis? electrolye? rotation? anything else?
RAD
HyperK
Clockwise rotation - transition zone in v5
RAH -
155
Axis? What is enlarged? rotation?
RAD
RAH
RVH - with strain [ the t-wave inversion going all the way to v5 is due to the extension of the RV there]
Clockwise - transition in v5
156
Axis? Enlargement? Block?
RAD
P mitrale -> LAH
RBBB -> bifasicular block (posterior fascicle)
157
Axis? electrolyte? elargement rotation?
normal axis
HypoK - STD with combination of T and U
LAH - p mitrale in I, II
Clockwise rotation
158
Axis? Enlargement? block?
RAD
RVH
RBBB
=bifasicular block (L posterior fasicle)
159
Axis? block? anything else?
RAD
RBBB
Deep S I, deep Q III, TWI III
S1QIIITIII
-> PE
160
Axis? Block? anything else?
LAD + RBBB -> bifasicular block (L anterior fasicle)
STEMI
161
Axis? What else?
LAD
PR short with delta in eg v2 = WPW
162
What are the criteria for sinus rhythm
P waves are positive in leads I and II
Every p is followed by a QRS
The time between p waves and QRS is constant
The distances between QRS are constant
163
Axis? block?
LAD
RBBB
1st degree AV block
= incomplete trifasicular block
164
Axis
Borderline rightward
RAH
RVH
165
