ECG + risk stratification Flashcards
1
Q
The action potential starts at the … node and is … at the … node before entering the … … …
A
SA Delayed AV Bundle of His
2
Q
conduction through the Bundle of His and the Purkinje fibres is extremely …
A
rapid
3
Q
The ventricles depolarise from …cardium to …cardium
A
endocardium epicardium
4
Q
True or false, the heart depolarises from base to apex?
A
False - it depolarises from apex to base
5
Q
Which heart cells show intrinsic audtorhythmicity?
A
SAN AVN Purkinje fibres
6
Q
Describe 2 features of auto-rhythmic cells in the heart
A
They pass their excitation and hence their contraction to each other
Intercalated discs connect adjacent cardiac muscle cells
7
Q
What is the natural pacemaker of the heart? What rate does it beat at?
A
SAN 90-100bpm
8
Q
A beat generated outside the normal pacemaker is an … beat
A
ectopic
9
Q
The … pacemaker of the heart normally drives the heart and … other pacemakers
A
fastest suppresses
10
Q
The AVN pacemaker beats at …-… bpm, and the Bundle of His “safety net” beats at …-…
A
40-60 15-30
11
Q
Depolarisations of auto-rhythmic cells rapidly spread to adjacent cells through … …
A
gap junctions
12
Q
Why do myocardial contractile cells have a different looking action potential to myocardial auto-rhythmic cells?
A
Due to the presence of calcium channels
13
Q
Intercalated discs in the amongst the heart cells allow…..
A
branching of the myocardium
14
Q
4 structural features of cardiac cells
A
Intercalated discs Gap junctions Many mitochondria Large T tubules
15
Q
Describe the process of cardiac contractile cell muscle excitation, contraction and relaxation (10)
A
- AP enters from adjacent cell 2. VGCCs open, Ca2+ enters cell 3. Ca2+ induces Ca2+ release from ryanodine receptor channels 4. Local release causes Ca2+ spike 5. Summed Ca2+ sparks create a Ca2+ signal 6. Ca2+ binds to troponin to initiate contraction 7. Relaxation occurs when Ca2+ unbinds troponin 8. Ca2+ is pumped back into SR for storage 9. Ca2+ is exchanged with Na+ 10. Na+ gradient is maintained by Na+/K+ ATPase
16
Q
ECGs … each individual membrane potential from contractile cells
A
summate
17
Q
Atria contract just … p-wave is formed on the ECG recorder
A
after
18
Q
PR segment represents…
A
conduction through AVN
19
Q
T wave represents…
A
ventricular repolarisation
20
Q
If wave of contraction moves toward positive electrode what deflection do you see on ECG? And what do you see if wave is moving away?
A
Towards - upward Away - downward
21
Q
Waveform on ECG gives indication of where cardiac axis vector is moving relative to …
A
electrode
22
Q
Mean axis of polarity of heart exists as a …
A
vector
23
Q
3-lead ECG leads and colour: Red - Yellow - green - Black -
A
Red - right arm Yellow - left arm Green - left leg Black - right leg (earth lead)
24
Q
Name the 3 unipolar leads
A
aVR, aVL, aVF
25
aVR normally has a ... deflection
downward
26
Name locations of chest leads
V1 - 4th ICS, right sternum V2 - 4th ICS, left sternum V3 - between V2 and V4 V4 - 5th ICS MCL V5 - 5th ICS anterior axillary line V6 - 5th ICS mid axillary line
27
V1 and V2 represent ... aspect of heart
septal
28
V3 and V4 represent ... aspect of heart
anterior
29
V5 and V6 represent ... aspect of heart
lateral
30
Inferior aspect of heart is represented by leads...
II, III, aVF
31
leads I and aVL represent ... aspect of heart
lateral
32
Inferior heart is mostly perfused by the ...
Right coronary artery
33
Anterior heart is mostly perfused by the ...
Left anterior descending branch of left main stem
34
Lateral heart is mostly supplied by the ...
circumflex branch of left main stem
35
Posterior wall infarcts are...
rare
36
How would you diagnose a posterior wall infarct?
Look at anterior leads as a mirror image - normally would show inferior infarct changes
37
Posterior heart blood supply
Right coronary artery
38
Normal PR interval length
12-20 ms (1-2 small squares)
39
Normal QRS length
8-12 ms (3 small squares)
40
Label left down then right
Atrial depolarisation
PR segment - conduction through AVN
Q wave
R wave
S wave
ST segment
T wave
END
41
Which chest lead is this?
V1
42
Which chest lead is this?
V2
43
Which chest lead is this?
V3
44
Which chest lead is this?
V4
45
Which chest lead is this?
V5
46
Which chest lead is this?
V6
47
What is the normal cardiac axis?
-30 to +90 degrees
48
What does this ECG show?
Right axis deviation:
Lead I inverted
49
What does this ECG show?
Pathologic left axis deviation:
lead II inverted, aVF inverted
50
What determines if left axis deviation is pathologic or non-pathologic?
Pathologic - lead II is negative
Non-pathologic - lead II is positive
51
8 causes left axis deviation
May be normal in elderly and v.obese
Due to high diaphragm in pregnancy or abdominal tumours
Left anterior hemiblock
Left bundle branch block
WPW syndrome
Congenital lesions
RIght ventricular pacer or ectopic rhythms
Emphysema
52
7 causes right axis deviation
Normal variant
RIght ventricular hypertrophy
Right bundle branch block
Left posterior hemiblock
Left ventricular ectopic rhythms
Some right ventricular ectopic rhythms
WPW syndrome
53
5 pieces of information shown on ECG
Heart rate
Conduction in the heart
Arrhythmias
Direction of cardiac vector
Damage to the heart muscle
(No mechanical information)
54
What does this ECG show?
Normal ECG
55
10 steps in analysing ECGs
Rate, Rhythm, Axis
P-wave, PR interval, QRS complex, ST segment, T-wave, U-wave, QT interval
56
5 large squares on ECG paper between R-R intervals is equal to...
60 bpm
57
2 causes of abnormal p-waves
Right and left atrial hypertrophy
Atrial premature beat
58
Normal p wave width is ...-... small squares
1-2
59
PR-interval normal length is ...-... s or ...-... small squares
0.12-0.20
3-5
60
With what condition would you get short PR segment?
WPW syndrome
61
What condition would cause a long PR interval?
1st degree heart block
62
What causes broad QRS complexes?
A delay in the depolarisation of the ventricles because the conduction pathway is abnormal.
Eg. in bundle branch block
63
What is the diagnostic criteria for left ventricular hypertrophy?
V1 or V2 + V5 ir V6 ≥ 35mm (7 large squares)
64
It is abnormal to have Q waves in leads ..., ..., and ...
All other leads have ... Q waves which could be normal
V1, V2, V3
Small
65
Normal Q waves are less than ...s
0.04
66
ST segment should normally be ...
The beginning of the ST segment is called the ...-...
Isoelectric
J-point
67
ST elevation or depression indicates what?
Myocardial infarction
Ischaemia
Angina
68
What do T waves represent in the cardiac cycle?
Ventricular repolarisation
69
Normal amplitude of T-waves
0.5-0.10mm
70
Normal depolarisation occurs from the ... to the ...
endocardium
epicardium
71
Normal repolarisation occurs from the ... to the ...
epicardium
endocardium
72
A positive (depolarisation) wave going towards a positive electrode (ECG lead) results in a ... deflection
positive
73
A negative (repolarisation) wave going towards a positive electrode (ECG lead) results in a ... deflection
negative
74
U waves represent...
the final stages of ventricular repolarisation, repolarisation of purkinje network
(Often not seen)
75
The QT interval represents what?
The time for depolarisation/repolarisation cycle
76
QT interval varies inversely with ...
HR
77
Normal QT interval is...
0.35-0.45s
78
QT interval should normally be ... ... ... of the R-R interval
less than half
79
What does this ECG show?
Sinus tachycardia
80
Sinus tachycardia is defined as what?
HR \> 100bpm
81
What does this ECG show?
Sinus bradycardia (HR \< 60bpm)
82
What is the pacemaker of the heart?
SAN
83
What does this ECG show?
Atrial flutter
84
Atrial flutter is a ... arrhythmia arising from the ... ...
Supraventricular
Right atrium
85
In atrial flutter, electricity ... around the RA at a rapid rate and drives the ... at a fast rate, often at 100-200 bpm
circulates
ventricles
86
What can cause atrial flutter?
Stretched atria due to valve disease, MI, or COPD
87
Treatments for atrial flutter
Drugs to slow HR
Blood thinners
Cardioversion
Radiofrequency/cryo ablation
88
Characteristic appearance of atrial flutter
Sawtoothed appearance
89
In atrial flutter, the atrial rate is usually about ... bpm, the AVN won't accept impulses faster than ...-...bpm thus ratios pf 2:1 - 4:1 (P:QRS) are seen.
300
180-220
90
What does this ECG show?
Atrial fibrillation
91
In atrial fibrillation, there are no ...
p-waves
92
In atrial fibrillation, there are ... ... ... setting the disordered contractions off
multiple ectopic foci
93
In atrial fibrillation, there may be ... or ... undulations or no ... activity at all
coarse
fine
atrial
94
Describe the rhythm of atrial fibrillation
Irregularly irregular
95
In atrial fibrillation QRS complexes are ...
normal
96
Premature ventricular contractions (PVCs) may be ... or ...
unifocal
multifocal
97
What does this ECG show?
PVCs
98
Multifocal PVCs have ... sites of origin, which means their ... are usually different
different
intervals
99
PVCs can occur in ... or ...
couplets
triplets
100
Usually a PVC is followed by a ... ... ... caused by the ventricles being in their their ... stage from the PVC
complete compensatory pause
refractory
101
What does this ECG show?
Ventricular tachycardia
102
3 features of ventricular tachycardia on ECG
No p waves
Wide QRS complexes
QRS complexes irregular and vary
103
Causes of ventricular tachycardia
Irritable myocardium secondary to MI
PVCs causing R on T phenomenon
Coronary artery disease
Hypokalaemia
104
What does this ECG show?
Ventricular fibrillation
105
In ventricular fibrillation there is no ... ...., the cardiac output ... and the patient can become ...
organised rhythm
drops
unconscious
106
In heart block there is a problem with the ... ..., so iit does not ... correctly
AV node
conduct
107
In heart block, the electrical signal can be ... or ... altogether
delayed
stopped
108
What does this ECG show?
1st degree heart block
109
First degree heart block is defined as having a ... ... longer than ...ms
PR interval
200 (normal PR interval = 120-200)
110
Causes of 1st degree heart block
Drugs - e.g. digoxin
Excess vagal tone
Ischaemia
Intrinsic disease at AV junction or bundle branch
111
What does this ECG show?
Second degree heart block (Wenckebach's)
112
ECG features of second degree heart block
Lengthened PR interval with each contraction
Eventually one P-wave without a following QRS (Wenckebach's phenomenon)
113
What does this ECG show?
3rd degree (complete) heart block with ventricular escape rhythm
114
What does this ECG show?
3rd degree heart block (complete) with junctional escape rhythm
115
ECG features of 3rd degree (complete) heart block
No association between atrial (p waves) and ventricular (QRS) activity
Both P and QRS waves are regular
Wide QRS due to ventricular focus
116
What does ST depression on ECG indicate?
Ischaemia
117
What does the Na+/K+ pump usually do and what happens to it in ischaemia?
Cells need ATP to repolarise via the K+/Na+ ATPase pump keeping high conc of K+ in cell and low outside (vice versa for Na+) maintaining conc gradient down which K+ can move
Ischaemia reduces pump activity increasing K+ ions outside of the cell reducing gradient, K+ stay in cell with Ca and Na ions causing depolarisation - cells stay more positive for longer before they repolarise
118
How does ST depression occur physiologically?
Due to equal balance of K+ ions inside and outside cell so depolarisation does not occur at the same level, the cell is more positive due to lack of K+ efflux.
a pocket of positively charged cells shifts baseline voltage of ECG upwards before QRS and s-wave ends at normal isoelectric line when ventricle is completely depolarised --\> this causes ST segment to appear to be depressed relative to baseline
So ST depression due to resetting of isoelectric line due to pocket of positively charged cells
119
What causes upsloping ST-depression?
Normal exercise response
120
What causes downsloping or horizontal ST-depression?
Downsloping could be due to digoxin or horizontal due to ischaemia
121
Horizontal ST-depression must be \>...mm below baseline in at least ... leads
1
2
122
Myocardial injury is generally associated with ST ... typically indicating a ... infarct
elevation
transmural
123
2 possible ways ST elevation occurs with myocardial injury
Delayed depolarisation due to sodium channel changes stopping Na+ entering
Injured cells repolarise quickly thus T-wave abuts QRS
124
How does myocardial infarction or ischaemia cause inferior T-wave inversion?
Causes a reversal of the sequence of repolarisation - i.e. endocardial to epicardial as opposed to normal epicardial to endocardial
Thus a negatove wave travelling toward a positive electrode results in a negative ECG deflection
125
What does an evolving or resolving infarct usually show on ECG?
Q waves and T wave inversion
126
When do pathological q waves occur?
IN resolving or evolving infarct or indicate previos MI
127
Q waves of \>...mm indicate full thickness MI due to damage from infarction
\>2mm
128
What are the branches off aorta from left to right?
Brachiocephalic artery
Left common carotid artery
Left subclavian artery
129
Label vessels starting bottom left and going clockwise
Right (acute) marginal artery
Right coronary artery
Left coronary artery
Circumflex artery
Left obtuse marginal artery
Left anterior descending artery
Diagonal arteries
130
What structures does the right coronary artery supply? (5)
Right atrium
Right ventricle
Posterior wall of LV
SAN in 50% population
AVN in 90% population
131
What structures does the left anterior descending artery supply? (3)
Anterior wall of LV
Apex of heart
Intraventricular septum
132
What structures does the circumflex artery supply? (5)
LA
Lateral wall
Posterior wall of LV
SAN in 45% patients
AVN in 10% patients
133
Name post-MI complications
DARTH VADER
Death
Arrhythmia
Rupture
Tamponade
Heart failure
Valve disease
Aneurysm of ventricle
Dressler's syndrome
Embolism
Recurrence
134
how can you determine the RATE of the ECG?
Locate QRS complex closest to the dark vertical line, and count either forward or backwards to the next QRS complex
135
What would is mean if you pass the 2 lines before the next QRS?
HR would be \< 150
136
How much does each large box represent?
200msec
137
How much does each small box represent?
40msec
138
How do you determine whether the source of the rhytm is "sinus" or ectopic rhythem?
the relationship of the P-wave to the QRS complex
139
How do you define if its a sinus?
P wave before each QRS, and if the P wave is in the same direction as the QRS
140
how many ECG surface voltage leads are there?
2
141
When the wave is travelling towards the +ve lead means?
theres an upward deflection
142
If a wave travelling away from the positive lead, what does this mean?
downward deflection
143
What happens if the waves are travelling at a 90 degree angle?
Create no deflection, also known as isoelectric lead
144
The purpose of the axis sum of vectors produced by ECG leads is?
Produce a single electrical vector
145
Having a +ve signal in Lead-I means
the signal is going right to left; producing a vector
146
What are the 6 ECG leads called?
Leads I, II, II and augmented leated AVR, AVL and AVF
147
Are leads I, II, III and AVR, AVL and AVF seen on 3 lead monitor and 12 lead monitor?
Yes
148
in the ECG of three leads, where do they get placed?
L and R shoulder, and L side of abdomen/ Iliac crest (sometimes a black cable is put on the R side of the abdomen)
149
What occurs in a normal ECG?
Both I and AVF leads will be +ve as the signal travels from the SA node to the tip of the ventricles
150
Based on the attached image can you identify which lead is picking up which bit of the heart?
V1-V2 --\> R ventricle
V4-V6 ---\> L ventricle
V3 - approx over the intraventricular septum, (covers both ventricles)
V7-V8 ---\> L ventricle
151
152
What is hypertrophy in relation to the heart?
increase in size of myocytes in the myocardium creating thicker walls
153
Can this be non-pathological?
Yes, can occur to those who frequently perform isometric exercise
154
What happens with an increased afterload on the heart with an indiviudal with high BP
causes L sided afterload increase
155
What can the L sided afterload (systemic hypertension or aortic stenosis) cause?
L ventricle to expand in reponse to giving L ventricular hypertrophy
156
What will increased pressure on the R side of the heart in the pulmonary vessels cause?
increase in afterload (back-pressure) to the R ventricle, leading to increase in MM to compensate --\> R ventricular hypertrophy
157
As the P-wave becomes hypertrophic (dilated), what happens next? and which lead is this best seen in?
biphasic in bilateral artieral hypertrophy, resulting in Artieral Hypertrophy - seen in V1 (mostly over the R atrium)
158
Within L ventricilar hypertrophy (LVH), what is seen in V1 and V5?
large S wave in V1
large R wave in V5
159
what does the sum of the hieght of S and R wave have to be for LVH to be plasuable?
\> 35mm
160
What is a block defined as on a ECG?
interruption of normal flow of an electrical impluse traveling down from the SA node to the ventricles
161
what is a SA node block?
failuse of the SA node to transmit an impluse
162
What is an AV node block and how is it determined?
block delaying the electrical impluse as it travels between the atria and the ventricle in the AV node
- determined by PR interval greater than 0.2 seconds (200m Large box)
163
What is the AV block?
when there are more than 1 P-wave preceding each QRS complex with a ratio of 2:1 of P-waves to each QRS
164
What is a block defined as?
complete block of singals from the atria to the ventricles - resulting in complete dissoaction between timing of P-waves and QRS complex
165
In a "block" how will the P-waves and QRS act?
P-waves in a normal sinus rate
QRS will either be nodal rhythm (60bpm) or the ventricluar rhythm (30-40bpm)
166
Examing the morphology of the QRS, what is the verdict if its narrow or wide?
narrow- orgin likely to be the nodal
wide - likely to be the ventricular
167
What are Bundle Branch Blocks (BB)?
Blocks within the ventricle bundes, consisting of a L or R bundle branch block
168
What is the key to recognise BB?
R-R wave - QRS complex firing seperatly but very close in time to each other
QRS must be wider than 0.12sec (3mm)
169
On and ECG where is the block best seen and how do you determine which side its seen?
presents best in V1 and V2 = R BBB
V5-V6 = L BBB
170
How is Ischemia defined?
BF to the myocardium is insufficent to maintain the metabolic demand of the myocytes
171
How is Ischemia detected?
ST segment (elevation of depression)
172
What is acute trasmural ischemia (across the heart wall from endocardium to epicardium)?
elevation of ST segment of ECG
- visualised by ST segment \> than the isoelectric baseline
173
174
Which leads allow you to find ischemia or infacted area of ventricular myocardium?
elevation inferior leads or lateral leads - both indicating ischemia/ infaracted myocardium
175
How is J-point elevation identifed?
terminal portion of the QRS which then dips down towardsd the baseline before rising up t the ST segement
176
What shows on the ECG after the ischemia has progressed to an infarct?
inverted T-wave
- pronounced Q wave and loss of all or part of R wave may also be seen
177
what is sub-endocardial ischemia?
decreased flow in the subendocardial regions - normal consequence when squeezing from the myocardimam, compressing blood supply to the endocardium during ventricular systole
178
How is Sub-endocardial ischemia seen on a ECG?
ST segment depression
179
How is the ST segmenet depression seen on the ECG?
tallest R waves, which are inferior leads (II, III and AVF and Leads V4-V6)
180
What two catorgies is V-fibe recognised in on the ECG?
ranging from course ( large amplitude) to fine (close to asystole)
181
What is the "cure" for V-Fib?
electrical cardioversion (defibillation)
182
