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ClinE 470 > ECG + risk stratification > Flashcards

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

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2
Q

conduction through the Bundle of His and the Purkinje fibres is extremely …

A

rapid

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3
Q

The ventricles depolarise from …cardium to …cardium

A

endocardium epicardium

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4
Q

True or false, the heart depolarises from base to apex?

A

False - it depolarises from apex to base

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5
Q

Which heart cells show intrinsic audtorhythmicity?

A

SAN AVN Purkinje fibres

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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

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7
Q

What is the natural pacemaker of the heart? What rate does it beat at?

A

SAN 90-100bpm

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8
Q

A beat generated outside the normal pacemaker is an … beat

A

ectopic

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9
Q

The … pacemaker of the heart normally drives the heart and … other pacemakers

A

fastest suppresses

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10
Q

The AVN pacemaker beats at …-… bpm, and the Bundle of His “safety net” beats at …-…

A

40-60 15-30

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11
Q

Depolarisations of auto-rhythmic cells rapidly spread to adjacent cells through … …

A

gap junctions

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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

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13
Q

Intercalated discs in the amongst the heart cells allow…..

A

branching of the myocardium

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14
Q

4 structural features of cardiac cells

A

Intercalated discs Gap junctions Many mitochondria Large T tubules

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15
Q

Describe the process of cardiac contractile cell muscle excitation, contraction and relaxation (10)

A
  1. 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
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16
Q

ECGs … each individual membrane potential from contractile cells

A

summate

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17
Q

Atria contract just … p-wave is formed on the ECG recorder

A

after

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18
Q

PR segment represents…

A

conduction through AVN

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19
Q

T wave represents…

A

ventricular repolarisation

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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

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21
Q

Waveform on ECG gives indication of where cardiac axis vector is moving relative to …

A

electrode

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22
Q

Mean axis of polarity of heart exists as a …

A

vector

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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)

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24
Q

Name the 3 unipolar leads

A

aVR, aVL, aVF

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25
Q

aVR normally has a … deflection

A

downward

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26
Q

Name locations of chest leads

A

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

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27
Q

V1 and V2 represent … aspect of heart

A

septal

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28
Q

V3 and V4 represent … aspect of heart

A

anterior

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29
Q

V5 and V6 represent … aspect of heart

A

lateral

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30
Q

Inferior aspect of heart is represented by leads…

A

II, III, aVF

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31
Q

leads I and aVL represent … aspect of heart

A

lateral

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32
Q

Inferior heart is mostly perfused by the …

A

Right coronary artery

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33
Q

Anterior heart is mostly perfused by the …

A

Left anterior descending branch of left main stem

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34
Q

Lateral heart is mostly supplied by the …

A

circumflex branch of left main stem

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35
Q

Posterior wall infarcts are…

A

rare

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36
Q

How would you diagnose a posterior wall infarct?

A

Look at anterior leads as a mirror image - normally would show inferior infarct changes

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37
Q

Posterior heart blood supply

A

Right coronary artery

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38
Q

Normal PR interval length

A

12-20 ms (1-2 small squares)

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39
Q

Normal QRS length

A

8-12 ms (3 small squares)

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40
Q

Label left down then right

A

Atrial depolarisation

PR segment - conduction through AVN

Q wave

R wave

S wave

ST segment

T wave

END

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41
Q

Which chest lead is this?

A

V1

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42
Q

Which chest lead is this?

A

V2

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43
Q

Which chest lead is this?

A

V3

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44
Q

Which chest lead is this?

A

V4

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45
Q

Which chest lead is this?

A

V5

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46
Q

Which chest lead is this?

A

V6

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47
Q

What is the normal cardiac axis?

A

-30 to +90 degrees

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48
Q

What does this ECG show?

A

Right axis deviation:

Lead I inverted

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49
Q

What does this ECG show?

A

Pathologic left axis deviation:

lead II inverted, aVF inverted

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50
Q

What determines if left axis deviation is pathologic or non-pathologic?

A

Pathologic - lead II is negative

Non-pathologic - lead II is positive

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51
Q

8 causes left axis deviation

A

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

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52
Q

7 causes right axis deviation

A

Normal variant

RIght ventricular hypertrophy

Right bundle branch block

Left posterior hemiblock

Left ventricular ectopic rhythms

Some right ventricular ectopic rhythms

WPW syndrome

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53
Q

5 pieces of information shown on ECG

A

Heart rate

Conduction in the heart

Arrhythmias

Direction of cardiac vector

Damage to the heart muscle

(No mechanical information)

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54
Q

What does this ECG show?

A

Normal ECG

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55
Q

10 steps in analysing ECGs

A

Rate, Rhythm, Axis

P-wave, PR interval, QRS complex, ST segment, T-wave, U-wave, QT interval

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56
Q

5 large squares on ECG paper between R-R intervals is equal to…

A

60 bpm

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57
Q

2 causes of abnormal p-waves

A

Right and left atrial hypertrophy

Atrial premature beat

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58
Q

Normal p wave width is …-… small squares

A

1-2

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59
Q

PR-interval normal length is …-… s or …-… small squares

A

0.12-0.20

3-5

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60
Q

With what condition would you get short PR segment?

A

WPW syndrome

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61
Q

What condition would cause a long PR interval?

A

1st degree heart block

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62
Q

What causes broad QRS complexes?

A

A delay in the depolarisation of the ventricles because the conduction pathway is abnormal.

Eg. in bundle branch block

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63
Q

What is the diagnostic criteria for left ventricular hypertrophy?

A

V1 or V2 + V5 ir V6 ≥ 35mm (7 large squares)

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64
Q

It is abnormal to have Q waves in leads …, …, and …

All other leads have … Q waves which could be normal

A

V1, V2, V3

Small

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65
Q

Normal Q waves are less than …s

A

0.04

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66
Q

ST segment should normally be …

The beginning of the ST segment is called the …-…

A

Isoelectric

J-point

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67
Q

ST elevation or depression indicates what?

A

Myocardial infarction

Ischaemia

Angina

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68
Q

What do T waves represent in the cardiac cycle?

A

Ventricular repolarisation

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69
Q

Normal amplitude of T-waves

A

0.5-0.10mm

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70
Q

Normal depolarisation occurs from the … to the …

A

endocardium

epicardium

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71
Q

Normal repolarisation occurs from the … to the …

A

epicardium

endocardium

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72
Q

A positive (depolarisation) wave going towards a positive electrode (ECG lead) results in a … deflection

A

positive

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73
Q

A negative (repolarisation) wave going towards a positive electrode (ECG lead) results in a … deflection

A

negative

74
Q

U waves represent…

A

the final stages of ventricular repolarisation, repolarisation of purkinje network

(Often not seen)

75
Q

The QT interval represents what?

A

The time for depolarisation/repolarisation cycle

76
Q

QT interval varies inversely with …

A

HR

77
Q

Normal QT interval is…

A

0.35-0.45s

78
Q

QT interval should normally be … … … of the R-R interval

A

less than half

79
Q

What does this ECG show?

A

Sinus tachycardia

80
Q

Sinus tachycardia is defined as what?

A

HR > 100bpm

81
Q

What does this ECG show?

A

Sinus bradycardia (HR < 60bpm)

82
Q

What is the pacemaker of the heart?

A

SAN

83
Q

What does this ECG show?

A

Atrial flutter

84
Q

Atrial flutter is a … arrhythmia arising from the … …

A

Supraventricular

Right atrium

85
Q

In atrial flutter, electricity … around the RA at a rapid rate and drives the … at a fast rate, often at 100-200 bpm

A

circulates

ventricles

86
Q

What can cause atrial flutter?

A

Stretched atria due to valve disease, MI, or COPD

87
Q

Treatments for atrial flutter

A

Drugs to slow HR

Blood thinners

Cardioversion

Radiofrequency/cryo ablation

88
Q

Characteristic appearance of atrial flutter

A

Sawtoothed appearance

89
Q

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.

A

300

180-220

90
Q

What does this ECG show?

A

Atrial fibrillation

91
Q

In atrial fibrillation, there are no …

A

p-waves

92
Q

In atrial fibrillation, there are … … … setting the disordered contractions off

A

multiple ectopic foci

93
Q

In atrial fibrillation, there may be … or … undulations or no … activity at all

A

coarse

fine

atrial

94
Q

Describe the rhythm of atrial fibrillation

A

Irregularly irregular

95
Q

In atrial fibrillation QRS complexes are …

A

normal

96
Q

Premature ventricular contractions (PVCs) may be … or …

A

unifocal

multifocal

97
Q

What does this ECG show?

A

PVCs

98
Q

Multifocal PVCs have … sites of origin, which means their … are usually different

A

different

intervals

99
Q

PVCs can occur in … or …

A

couplets

triplets

100
Q

Usually a PVC is followed by a … … … caused by the ventricles being in their their … stage from the PVC

A

complete compensatory pause

refractory

101
Q

What does this ECG show?

A

Ventricular tachycardia

102
Q

3 features of ventricular tachycardia on ECG

A

No p waves

Wide QRS complexes

QRS complexes irregular and vary

103
Q

Causes of ventricular tachycardia

A

Irritable myocardium secondary to MI

PVCs causing R on T phenomenon

Coronary artery disease

Hypokalaemia

104
Q

What does this ECG show?

A

Ventricular fibrillation

105
Q

In ventricular fibrillation there is no … …., the cardiac output … and the patient can become …

A

organised rhythm

drops

unconscious

106
Q

In heart block there is a problem with the … …, so iit does not … correctly

A

AV node

conduct

107
Q

In heart block, the electrical signal can be … or … altogether

A

delayed

stopped

108
Q

What does this ECG show?

A

1st degree heart block

109
Q

First degree heart block is defined as having a … … longer than …ms

A

PR interval

200 (normal PR interval = 120-200)

110
Q

Causes of 1st degree heart block

A

Drugs - e.g. digoxin

Excess vagal tone

Ischaemia

Intrinsic disease at AV junction or bundle branch

111
Q

What does this ECG show?

A

Second degree heart block (Wenckebach’s)

112
Q

ECG features of second degree heart block

A

Lengthened PR interval with each contraction

Eventually one P-wave without a following QRS (Wenckebach’s phenomenon)

113
Q

What does this ECG show?

A

3rd degree (complete) heart block with ventricular escape rhythm

114
Q

What does this ECG show?

A

3rd degree heart block (complete) with junctional escape rhythm

115
Q

ECG features of 3rd degree (complete) heart block

A

No association between atrial (p waves) and ventricular (QRS) activity

Both P and QRS waves are regular

Wide QRS due to ventricular focus

116
Q

What does ST depression on ECG indicate?

A

Ischaemia

117
Q

What does the Na+/K+ pump usually do and what happens to it in ischaemia?

A

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
Q

How does ST depression occur physiologically?

A

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
Q

What causes upsloping ST-depression?

A

Normal exercise response

120
Q

What causes downsloping or horizontal ST-depression?

A

Downsloping could be due to digoxin or horizontal due to ischaemia

121
Q

Horizontal ST-depression must be >…mm below baseline in at least … leads

A

1

2

122
Q

Myocardial injury is generally associated with ST … typically indicating a … infarct

A

elevation

transmural

123
Q

2 possible ways ST elevation occurs with myocardial injury

A

Delayed depolarisation due to sodium channel changes stopping Na+ entering

Injured cells repolarise quickly thus T-wave abuts QRS

124
Q

How does myocardial infarction or ischaemia cause inferior T-wave inversion?

A

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
Q

What does an evolving or resolving infarct usually show on ECG?

A

Q waves and T wave inversion

126
Q

When do pathological q waves occur?

A

IN resolving or evolving infarct or indicate previos MI

127
Q

Q waves of >…mm indicate full thickness MI due to damage from infarction

A

>2mm

128
Q

What are the branches off aorta from left to right?

A

Brachiocephalic artery

Left common carotid artery

Left subclavian artery

129
Q

Label vessels starting bottom left and going clockwise

A

Right (acute) marginal artery

Right coronary artery

Left coronary artery

Circumflex artery

Left obtuse marginal artery

Left anterior descending artery

Diagonal arteries

130
Q

What structures does the right coronary artery supply? (5)

A

Right atrium

Right ventricle

Posterior wall of LV

SAN in 50% population

AVN in 90% population

131
Q

What structures does the left anterior descending artery supply? (3)

A

Anterior wall of LV

Apex of heart

Intraventricular septum

132
Q

What structures does the circumflex artery supply? (5)

A

LA

Lateral wall

Posterior wall of LV

SAN in 45% patients

AVN in 10% patients

133
Q

Name post-MI complications

A

DARTH VADER
Death

Arrhythmia

Rupture

Tamponade

Heart failure

Valve disease

Aneurysm of ventricle

Dressler’s syndrome

Embolism

Recurrence

134
Q

how can you determine the RATE of the ECG?

A

Locate QRS complex closest to the dark vertical line, and count either forward or backwards to the next QRS complex

135
Q

What would is mean if you pass the 2 lines before the next QRS?

A

HR would be < 150

136
Q

How much does each large box represent?

A

200msec

137
Q

How much does each small box represent?

A

40msec

138
Q

How do you determine whether the source of the rhytm is “sinus” or ectopic rhythem?

A

the relationship of the P-wave to the QRS complex

139
Q

How do you define if its a sinus?

A

P wave before each QRS, and if the P wave is in the same direction as the QRS

140
Q

how many ECG surface voltage leads are there?

A

2

141
Q

When the wave is travelling towards the +ve lead means?

A

theres an upward deflection

142
Q

If a wave travelling away from the positive lead, what does this mean?

A

downward deflection

143
Q

What happens if the waves are travelling at a 90 degree angle?

A

Create no deflection, also known as isoelectric lead

144
Q

The purpose of the axis sum of vectors produced by ECG leads is?

A

Produce a single electrical vector

145
Q

Having a +ve signal in Lead-I means

A

the signal is going right to left; producing a vector

146
Q

What are the 6 ECG leads called?

A

Leads I, II, II and augmented leated AVR, AVL and AVF

147
Q

Are leads I, II, III and AVR, AVL and AVF seen on 3 lead monitor and 12 lead monitor?

A

Yes

148
Q

in the ECG of three leads, where do they get placed?

A

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
Q

What occurs in a normal ECG?

A

Both I and AVF leads will be +ve as the signal travels from the SA node to the tip of the ventricles

150
Q

Based on the attached image can you identify which lead is picking up which bit of the heart?

A

V1-V2 –> R ventricle

V4-V6 —> L ventricle

V3 - approx over the intraventricular septum, (covers both ventricles)

V7-V8 —> L ventricle

151
Q
A
152
Q

What is hypertrophy in relation to the heart?

A

increase in size of myocytes in the myocardium creating thicker walls

153
Q

Can this be non-pathological?

A

Yes, can occur to those who frequently perform isometric exercise

154
Q

What happens with an increased afterload on the heart with an indiviudal with high BP

A

causes L sided afterload increase

155
Q

What can the L sided afterload (systemic hypertension or aortic stenosis) cause?

A

L ventricle to expand in reponse to giving L ventricular hypertrophy

156
Q

What will increased pressure on the R side of the heart in the pulmonary vessels cause?

A

increase in afterload (back-pressure) to the R ventricle, leading to increase in MM to compensate –> R ventricular hypertrophy

157
Q

As the P-wave becomes hypertrophic (dilated), what happens next? and which lead is this best seen in?

A

biphasic in bilateral artieral hypertrophy, resulting in Artieral Hypertrophy - seen in V1 (mostly over the R atrium)

158
Q

Within L ventricilar hypertrophy (LVH), what is seen in V1 and V5?

A

large S wave in V1

large R wave in V5

159
Q

what does the sum of the hieght of S and R wave have to be for LVH to be plasuable?

A

> 35mm

160
Q

What is a block defined as on a ECG?

A

interruption of normal flow of an electrical impluse traveling down from the SA node to the ventricles

161
Q

what is a SA node block?

A

failuse of the SA node to transmit an impluse

162
Q

What is an AV node block and how is it determined?

A

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
Q

What is the AV block?

A

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
Q

What is a block defined as?

A

complete block of singals from the atria to the ventricles - resulting in complete dissoaction between timing of P-waves and QRS complex

165
Q

In a “block” how will the P-waves and QRS act?

A

P-waves in a normal sinus rate

QRS will either be nodal rhythm (60bpm) or the ventricluar rhythm (30-40bpm)

166
Q

Examing the morphology of the QRS, what is the verdict if its narrow or wide?

A

narrow- orgin likely to be the nodal

wide - likely to be the ventricular

167
Q

What are Bundle Branch Blocks (BB)?

A

Blocks within the ventricle bundes, consisting of a L or R bundle branch block

168
Q

What is the key to recognise BB?

A

R-R wave - QRS complex firing seperatly but very close in time to each other

QRS must be wider than 0.12sec (3mm)

169
Q

On and ECG where is the block best seen and how do you determine which side its seen?

A

presents best in V1 and V2 = R BBB

V5-V6 = L BBB

170
Q

How is Ischemia defined?

A

BF to the myocardium is insufficent to maintain the metabolic demand of the myocytes

171
Q

How is Ischemia detected?

A

ST segment (elevation of depression)

172
Q

What is acute trasmural ischemia (across the heart wall from endocardium to epicardium)?

A

elevation of ST segment of ECG

  • visualised by ST segment > than the isoelectric baseline
173
Q
A
174
Q

Which leads allow you to find ischemia or infacted area of ventricular myocardium?

A

elevation inferior leads or lateral leads - both indicating ischemia/ infaracted myocardium

175
Q

How is J-point elevation identifed?

A

terminal portion of the QRS which then dips down towardsd the baseline before rising up t the ST segement

176
Q

What shows on the ECG after the ischemia has progressed to an infarct?

A

inverted T-wave

  • pronounced Q wave and loss of all or part of R wave may also be seen
177
Q

what is sub-endocardial ischemia?

A

decreased flow in the subendocardial regions - normal consequence when squeezing from the myocardimam, compressing blood supply to the endocardium during ventricular systole

178
Q

How is Sub-endocardial ischemia seen on a ECG?

A

ST segment depression

179
Q

How is the ST segmenet depression seen on the ECG?

A

tallest R waves, which are inferior leads (II, III and AVF and Leads V4-V6)

180
Q

What two catorgies is V-fibe recognised in on the ECG?

A

ranging from course ( large amplitude) to fine (close to asystole)

181
Q

What is the “cure” for V-Fib?

A

electrical cardioversion (defibillation)

182
Q
A

ClinE 470 (9 decks)

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