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Cardiovascular > ECG > Flashcards

ECG Flashcards

1
Q

What does the P wave on an ECG represent?

A

Atrial depolarisation. Duration is less than 0.12s.

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2
Q

What does the QRS complex on an ECG represent?

A

Ventricular depolarisation. Duration is 0.08-0.1s.

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3
Q

What does the T wave on an ECG represent?

A

Ventricular repolarisation.

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4
Q

What might an elevated ST segment be associated with?

A

MI

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5
Q

ECG: where would you place lead 1?

A

Right arm (-ve) to left arm (+ve).

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6
Q

ECG: where would you place lead 2?

A

Right arm (-ve) to left leg (+ve).

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7
Q

ECG: where would you place lead 3?

A

Left arm (-ve) to left leg (+ve).

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8
Q

Eindhovens triangle

A

An imaginary formation of the 3 limb leads in a triangle shape.

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9
Q

ECG: where would you place lead aVR?

A

Left arm and left leg (-ve) to right arm (+ve).

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10
Q

ECG: where would you place lead aVF?

A

Right arm and left arm (-ve) to left leg (+ve).

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11
Q

ECG: where would you place lead aVL?

A

Right arm and left leg (-ve) to left arm (+ve).

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12
Q

ECG chest leads: In which intercostal space would you place V1 and V2? (Precordial leads)

A

The 4th intercostal space. V1 is right of the sternum and V2 in left.

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13
Q

ECG chest leads: In which intercostal space would you place V3-V6. (Precordial leads)

A

The 5th intercostal space. V3 is left of the sternum, V4 is in the mid-clavicular line, V5 is left of V4 and V6 is under the left arm.

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14
Q

What is an ECG?

A

Representation of electrical events at cardiac cycle

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15
Q

What can an ECG identify?

A

Arrhythmias
Myocardial ischemia and infarction
Pericarditis
Chamber hypertrophy
Drug toxicity

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16
Q

SA node

A

Dominant pacemaker with an intrinsic rate of 60-100 bpm

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17
Q

AV node

A

Back up pacemaker with an intrinsic rate of 40- 60 bpm
Allows for delay

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18
Q

Ventricular cells

A

Back up pacemaker with an intrinsic rate of 20-45 bpm

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19
Q

If electrical impulse travels towards electrodes what does it produce?

A

Upright positive deflection

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20
Q

What is the flow of impulse condition?

A

SA node > AV node > Bundle of His > bundle branches > Purkinje fibres

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21
Q

PR interval

A

Atrial depolarisation + delay in AV junction

Delay allows time for atria to contract before ventricles

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22
Q

Normal ECG

A

Look at slide 23 of Normal ECG’s

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23
Q

Horizontally on an ECG what is one small box worth?

A

0.04s

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24
Q

Horizontally on an ECG what is one large box worth?

A

0.2s

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25
Q

Vertically on an ECG what is one large box worth?

A

0.5mV

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26
Q

What does an ECG measure?

A

Measuring the difference in electrical points between 2 points

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27
Q

What is a bipolar lead?

A

2 Different points on the body

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28
Q

What are unipolar leads?

A

One point on the body and a virtual reference point with zero electrical potential, located in the center of heart

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29
Q

How many leads done the standard ECG have?

A

3 standard limb leads
3 augmented limb leads
6 precordial leads

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30
Q

What are the augmented unipolar limb leads?

A

AVR, AVL, AVF

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31
Q

Where is V7, V8, V9 placed and why?

A

On the back inferior to scapula
For left vetricle as LV is mostly posterior

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32
Q

Which leads show the lateral electrical signals of the heart?

A

I, aVL, V5, V6

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33
Q

Which leads show the electrical signals of the inferior surface of the heart?

A

II, III, aVF

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34
Q

Which leads show the electrical signals of the anterior surface of the heart?

A

V3, V4

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35
Q

Which leads show the electrical signals of the septum of the heart?

A

V1, V2

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36
Q

Features of P wave:

A

Always positive in lead I and II
Always negative in a lead aVR
< 3 small sqaures in duration
< 2.5 small squares in amplitude
commonly biphasic in lead V1
Best seen in leads II
3 small squares wide and tall

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37
Q

What can you see on the ECG for right atrial enlargement?

A

Tall (>2.5mm) pointed P waves (P pulmonale)

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38
Q

Left atrial enlargement

A

M shaped P wave in limb leads

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39
Q

What indicates P Pulmonale?

A

Peaked P wave taller than 2.5mm in the limb leads indicates P pulmonale

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40
Q

What is the PR interval

A

Consists of atrial depolarisation and conduction from atria to ventricles

Normally 120-200 ms

Prolonged in disorders of AV node and specialised conducting tissue

Shorter in younger patients or in pre-excitation (Wolf-Parkinson-White)

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41
Q

What is a short PR interval indicative of?

A

Wolff parkinson white syndrome
Accessory pathway allows early activation of the ventricle
Broad QRS complex typical of WPW - BYPASSES Atrial node

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42
Q

What is a long PR interval indicative of?

A

First degree heart block

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43
Q

Which leads can non-pathological Q waves be found?

A

I, III, aVL, V5 and V6

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44
Q

Features of QRS complexes?

A

R wave in lead V6 smaller than V5
Depth of S wave should not exceed 30mm
Size of complexes related to myocardial mass

Predominantly negative S wave in V1, transitioning to positive R wave by V6

Normal frontal axis -30 to +90 (positive in leads I, II)

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45
Q

What is a pathological Q wave defined by?

A

2mm deep and 1mm wide
25% amplitude of the subsequent R wave

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46
Q

Indications of left ventricular hypertrophy

A

S wave in V1 and R in V5 or V6 > 35mm
R wave of 11 to 13 mm or more in lead aVL

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47
Q

Features of ST segment

A

Flat (isoelectric)
Elevation or depression of ST segment by 1mm or more
Normally isoelectric
Can be elevated in early repolarisation, myocardial infarction, pericarditis/myocarditis,

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48
Q

What is the “J” junction?

A

Point between QRS and ST segment

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49
Q

T wave features?

A

Asymmetrical
Must be atleast 1/8 but less than 2/3 of R wave
Amps rarely exceed 10mm
Follows direction of QRS deflection
Height of T wave normally less than QRS

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50
Q

Abnormal T waves look like what?

A

Symmetrical, tall, peaked, biphasic or inverted

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51
Q

What is QT interval

A

Total duration of ventricular depolarisation and repolarisation
Decreases when HR increases
HR 70bpm - QT <0.40s
0.35s to 0.40s

QT can be corrected to be shorter or faster

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52
Q

U wave

A

Related to after depolarisations which follow repolarisation
Small, round, symmetrical and positive in lead II with amplitude <2mm
Direction same as T wave
More prominet at slow HRs

53
Q

2 rules of determing HR

A

rule of 300/1500
10 second rule

54
Q

Rule of 300

A

Count number of big boxes between 2 QRS complexes and divide this into 300 (smaller boxes with 1500)
for regular rhythms

55
Q

10 second rule

A

ECGs record 10 seconds of rhythms per page
Count number of beats present on ECG
X6
For irregular rhythms

56
Q

QRS axis represents?

A

Overall direction of hearts electrical activity

57
Q

Abnormalities of QRS axis hint at what?

A

Ventricular enlargement
Conduction blocks

58
Q

Normal QRS axis (Look at intro to ECG powerpoint for this shit)

A

-30 degrees to -90

59
Q

Left axis deviation in QRS

A

-30* to -90*

60
Q

Right axis deviation (RAD)

A

+90 to +180

61
Q

What is the conducting system of the heart?

A

1.The SAN generates an electrical impulse.
2.This generates a wave of contraction in the atria.
3.Impulse reaches AVN.
4.There is a brief delay to ensure the atria have fully emptied.
5.The impulse then rapidly spreads down the Bundle of His and Purkinje fibres.
6.The purkinje fibres then trigger coordinated ventricular contraction.

62
Q

What is the amplitude of deflection based on?

A

related to mass of myocardium

Bigger mass of myocardium gives bigger deflection

63
Q

What is the width of the deflection reflecting?

A

reflects speed of conduction

64
Q

When do we get a positive deflection?

A

Positive deflection is towards the lead/vector

After this look arrhythmia lecture please for the flashcards

65
Q

Whats one large square worth?

A

200 ms

66
Q

Two squares (400ms) =
Three squares (600ms) =
Four squares (800ms) =
Five squares (1000ms) =

A

150bpm
100bpm
75 bpm
60bpm

67
Q

Where are the limb leads and what part of the heart do they look at?

A

Limb leads on left
Look at frontal plane

68
Q

Limb leads frontal plane

A

Slide 13

69
Q

Where is most of the heart?

A

2/3 on the left side of the chest
1/3 on the right side of chest

70
Q

What is the normal QRS axis?

A

-30 to +90 degrees

71
Q

What does Left axis deviation -30 to -90 degrees show?

A

Left anterior fascicular block
Left bundle branch block
Left ventricular hypertrophy

72
Q

What does Right axis deviation 90 to 180 degrees show?

A

Left posterior fascicular block
Right heart hypertrophy/strain

73
Q

What can a low amplitude of P wave show?

A

Atrial fibrosis, obesity, hyperkalaemia

74
Q

What can high amplitude of p wave show?

A

Right atrial enlargement

75
Q

What does a bifid p wave show?

A

Left atrial enlargement

76
Q

Alternative pacemaker foci for p wave?

A

Focal atrial tacycardias
‘wandering pacemaker’

77
Q

What can a broad QRS show?

A

Ventricular conduction delay / bundle branch block
Pre-excitation

78
Q

What do small QRS complexes show?

A

Obese patient
Pericardial effusion
Infiltrative cardiac disease
More myocardium than expected

79
Q

What can tall QRS complexes show?

A

Left ventricular hypertrophy
(S wave in V1 and R wave in V5/V6 >35mm)
Thin patient

80
Q

What can Excessively rapid or slow repolarisation show?

A

can be arrhythmogenic
“Long QT” or “Short QT” syndromes
Congenital, drugs, electrolyte disturbances

81
Q

Where are T waves usually inverted?

A

T waves usually inverted in aVR, can be inverted in III

82
Q

T wave changes (inversion) show what?

A

Ischaemia/infarction
Myocardial strain (hypertrophy)
Myocardial disease (cardiomyopathy)

83
Q

What are (ventricular) tachycardia caused by?

A

Atrial fibrillation, Atrial Flutter
Supraventricular tachycardia

Ventricular tachycardia
Ventricular fibrillation

84
Q

Supraventricular rhythms

A

Slide 38

85
Q

What does an ECG show for ventricular tachycardia?

A

QRS comples lot broader – his purkinje system not being used for ventricular depolarisation

86
Q

What does bradycardia cause?

A

Conduction tissue fibrosis
Ischaemia
Inflammation/infiltrative disease
Drugs

87
Q

What is bradycardia caused by?

A

Sinus node disease
AV node / distal conduction problems

88
Q

First degree heart block

A

If pr interval is longer than 200ms but 1 p wave for each QRS is first degree AV block

89
Q

2nd degree heart block

A

P no QRS P QRS P no QRS second degree AV block

90
Q

3rd degree heart block

A

Complete heart block – no relationship between P wave and QRS – ventricles and atria are doing independent activity – 3rd degree

91
Q

What is mobitz type 1?

A

PR interval gradually increases until AV node fails completely and no QRS wave anymore

Starts again - PR gradually lengthens

92
Q

What is mobitz type 2?

A

Sudden unpredictable loss of AV conduction and loss of QRS-
Due to loss of conduction in Bundle of His and Purkinje fibres

PR interval contant but every nth QR constant is missing

93
Q

Characteristics of Left branch bundle block

A

V1 wave - looks like a W
V6 wave - looks like M
RV activated first in front of LV instead of simulatenously

Remember wiLLiam

94
Q

Characteristics of RIGHT branch bundle block

A

V1 wave - looks like a M
V6 wave - looks like W
LV activated first in front of RV instead of simulatenously

Remember maRRow

95
Q

ECG for ischaemia:

A

T wave flattening inversion
ST segment depression

96
Q

ECG for infarction:

A

ST segment elevation
Q waves – old infarction

97
Q

What leads show the RCA territory?

A

inferior leads

98
Q

What leads show the anterior surface of heart?

A

anterior leads

99
Q

What leads show the circumflex territory?

A

lateral leads

100
Q

ECG hyperkalaemia?

A

Tall T waves, flattening of P waves, broadening of QRS… eventually ‘sine wave pattern’

101
Q

ECG Hypokalaemia?

A

Flattening of T wave, QT prolongation

102
Q

ECG hypercalcaemia?

A

QT shortening

103
Q

ECG hypocalcaemia?

A

QT prolongation

104
Q

What do you see in atrial fibrillation ECG?

A

irregular ventricular response

105
Q

Atrial flutter ECG?

A

saw tooth waves

106
Q

Pericarditis ECG?

A

Global ST elevation with saddle shape appearance – suggestive of pericarditis
PR depression which is only really seen in pericarditis

107
Q

What do ectopic beats look like?

A

2 sinus beats and a beat that comes early – eg of broad appearance when ventricles doesn’t activate by his- purkinje system

108
Q

Features of ectopic beats?

A

Very Common
Non sustained beats arising from ectopic regions of atria or ventricles
Generally benign

109
Q

How can you help with ectopic beats?

A

Most patients will gain symptomatic relief from reassurance/betablockers

110
Q

What can high burden VE and AE cause?

A

High burden VE can cause heart failure
High burden AE can progress to AF

111
Q

Who do you refer for ectopic beats?

A

High burden ectopy (>5%, though risk prob not increased till >20%)
Refractory to BB
Structural heart disease
Syncope

112
Q

Whats the commonest sustained arrhythmia?

A

Atrial fibrillation (AF)

113
Q

Features of AF?

A

Paroxysmal (self terminating) OR
Persistent (continues without intervention)

Rapid chaotic firing causes
-Loss of atrial mechanical contraction
-Irregular often rapid ventricular response

114
Q

What is the medical treatments for AF?

A

Treat underlying cause:
Alcohol, Thyroid disease, Hypertension, Valve disease, Heart failure, Obesity, Excessive exercise, Infection etc.

Rate control (accept AF):
Beta blockers
Calcium channel blockers
(Digoxin)

Restore sinus rhythm acutely:
Electrical cardioversion (acutely / after anticoagulation)
Pharmacological cardioversion (flecainide / amiodarone)

115
Q

How can we maintain sinus rhythm?

A

Flecainide
Dronedarone
Sotalol
Amiodarone

116
Q

What can AF do?

A

Lack of mechanical contraction in atrium can lead to clot in ventricles which can travel to the brain leading to stroke

117
Q

What can AF do?

A

Lack of mechanical contraction in atrium can lead to clot in ventricles which can travel to the brain leading to stroke

118
Q

Direct Xa inhibitors?
Stops conversion of prothrombin to thrombin

A

Rivaroxaban
Apixaban
Edoxaban

119
Q

Direct thrombin inhibitor?

A

Dabigatran

120
Q

What do you do for someone with Supraventricular tachycardia?

A

Advice on valsalva manoeuvres
Can try beta blocker/CCB

Who to refer:
Frequent / sustained episodes
Needed adenosine for termination
Abnormal ECG (pre-excitation)

121
Q

What are accessory pathways?

A

Congenital remnant muscle strands between atrium and ventricle

122
Q

What can accessory pathways cause on ECGs?

A

Can be manifest (pre-excitation on ECG)
Or concealed (ECG normal, only conduct retrogradely and only detected at EP study)

123
Q

Ventricular tachycardia ECG

A

Broad QRS complex
Concordance here
NO1 feature is the fact that P wave is independent to QRS complex
P wave rate is slower than the ventricular wave

124
Q

What is an electrical storm?

A

3 or more sustained episodes of VT or VF, or appropriate ICD shocks during a 24-hour period

High risk / poor prognosis

Manage on CCU/ITU

125
Q

What is an electrical storm?

A

3 or more sustained episodes of VT or VF, or appropriate ICD shocks during a 24-hour period

High risk / poor prognosis

Manage on CCU/ITU

126
Q

What is the treatment for electrical storm?

A

Correct any provoking factors e.g. electrolyte (K/Mg), ischaemia, infection, heart failure
Beta blockers, sedation
Amiodarone +/- lignocaine
Overdrive pacing

General anaesthesia / Neuraxial blockade
Catheter ablation

127
Q

Narrow complex tachycardias?

A

SVT
AF/flutter

128
Q

Broad comples tachycardias?

A

VT
SVT with BBB/preexcitation

129
Q

Sinus node disease and bifascicular block ECG

A

PR interval is prolonged

Cardiovascular (14 decks)

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