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Year 3 Cardio > Electrocardiography > Flashcards

Electrocardiography Flashcards

(109 cards)

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1
Q

What is the clinical relevance of the ECG?

A

Conduction abnormalities
Structural abnormalities
Perfusion abnormalities

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2
Q

What are the advantages of ECGs?

A

Relatively cheap and easy to undertake
Reproducible between people & centres
Quick turnaround on results/report

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3
Q

What is a vector?

A

‘a quantity that has both magnitude and direction’

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4
Q

What happens if the wave of excitation travels toward the negative electrode?

A

Downward deflections are towards the anode (-)

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5
Q

What happens if the wave of excitation travels toward the positive electrode?

A

Upward deflections are towards the cathode (+)

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6
Q

What does the isoelectric line represent?

A

represents no net change in voltage. i.e. vectors are perpendicular to the lead.

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7
Q

What does the steepness of the line relate to?

A

Steepness of line denotes the ‘velocity’ of action potential

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8
Q

What does the width of the line relate to?

A

Width of the deflection denotes the ‘duration’ of the event

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9
Q

What is the P wave?

A

The electrical signal that stimulates contraction of the atria (atrial systole)

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10
Q

What is the QRS complex?

A

The electrical signal that stimulates contraction of the ventricles (ventricular systole)

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11
Q

What is the T wave?

A

The electrical signal that signifies relaxation of the ventricles

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12
Q

What comprises the SAN?

A

Autorhythmic myocytes

Small amount of muscle that points more positive than negative

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13
Q

What does the action of the SAN show on an ECG?

A

Deflection is wide (slow)
Not very high (thin muscle)
Positive

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14
Q

What does the action of the AVN show on an ECG?

A

AVN depolarisation
Isoelectric ECG
Slow signal transduction
Protective

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15
Q

What does the action of the bundle branches show on an ECG?

A

Sharp but small downward spike

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16
Q

What does the action of the purkinje fibres show on an ECG?

A

QRS peak

and upward peak

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17
Q

Where do you place the leads?

A 
Lead I (one L) 
Right Arm to Left Arm 
Lead II (two L’s)
Right Arm to Left Leg

Lead III (three L’s)
Left Arm to Left Leg
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18
Q

What is the rule of reading for the leads?

A

English is read left to right and top to bottom.

Polarity does that too.
Drawn as a triangle and reading left to right and top to bottom the first electrode of each pair you reach is the anode (-ve

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19
Q

Where is the V1 electrode placed?

A

Right sternal border

In the 4th intercostal space

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20
Q

Where is the V2 electrode placed?

A

Left sternal border

In the 4th intercostal space

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21
Q

Where is the V3 electrode placed?

A

Halfway between V2 and V4

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22
Q

Where is the V4 electrode placed?

A

Mid-clavicular line

In the 5th intercostal space

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23
Q

Where is the V5 electrode placed?

A

Anterior axillary line

at the level of V4

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24
Q

Where is the V6 electrode placed?

A

Mid-axillary line

at the level of V4

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25
What does each big square represent?
0. 2s | 0. 5mV
26
What does each little square represent?
0. 04s | 0. 1mV
27
What are the three main coronary arteris?
Left circumflex Left anterior descending Right coronary artery
28
What are normal values for R-R interval?
0.6-1.2 seconds
29
What is normal for the duration of the P wave?
80ms | 3 small squares
30
What is normal for the P-R interval?
120-200ms | 5 small squares
31
What is normal for duration of the QRS complex?
<120 ms
32
What is normal for duration of the T-wave?
420 ms
33
What is considered a normal heart rate?
60-100 bpm
34
What is the ECG reporting procedure?
Is it the correct recording? Review the signal quality and leads? Verify the voltage and paper speed? Review the
35
What is the ECG reporting procedure?
Is it the correct recording? Review the signal quality and leads? Verify the voltage and paper speed? Review the patient background if available
36
Can you defibrillate someone in asystole?
Not a shockable rhythm
37
What is sinus rhythm?
Each P-wave is followed by a QRS wave (1:1) | Rate is regular (even R-R intervals
38
What is sinus bradycardia?
Each P-wave is followed by a QRS wave (1:1) Rate is regular (even R-R intervals) and slow (56 bpm) Can be healthy, caused by medication or vagal stimulation
39
What is sinus tachycardia?
Each P-wave is followed by a QRS wave (1:1) Rate is regular (even R-R intervals) and fast (107 bpm) Often a physiological response (i.e. secondary)
40
What is sinus arrhythmia?
Each P-wave is followed by a QRS wave Rate is irregular (variable R-R intervals) and normal-ish (65-100 bpm) R-R interval varies with breathing cycle
41
What is atrial fibrilation?
Oscillating baseline – atria contracting asynchronously Rhythm can be irregular and rate may be slow Turbulent flow pattern increases clot risk Atria not essential for cardiac cycle
42
What is atrial flutter?
Regular saw-tooth pattern in baseline (II, III, aVF) Atrial to ventricular beats at a 2:1 ratio, 3:1 ratio or higher Saw-tooth not always visible in all leads
43
What are the features of first degree heart block?
Prolonged ST segment/interval caused by slower AV conduction Regular rhythm: 1:1 ratio of P-waves to QRS complexes Most benign heart block, but a progressive disease of ageing
44
What are the two types of second degree heart block?
Mobitz I | Mobitz II
45
What are the features of Mobitz I?
Gradual prolongation of the PR interval until beat skipped Most P-waves followed by QRS; but some P-waves are not Regularly irregular: caused by a diseased AV node Also called Wenckebach
46
What are the features of Mobtiz II?
P-waves are regular, but only some are followed by QRS No P-R prolongation Regularly irregular: successes to failures (e.g. 2:1) or random Can rapidly deteriorate into third degree heart block
47
What are the features of third degree heart block?
P-waves are regular, QRS are regular, but no relationship P waves can be hidden within bigger vectors A truly non-sinus rhythm – back-up pacemaker in action
48
What are the features of ventricular tachycardia?
P-waves hidden – dissociated atrial rhythm Rate is regular and fast (100-200 bpm) At high risk of deteriorating into fibrillation (cardiac arrest) Shockable rhythm – defibrillators widely available
49
What are the features of ventricular fibrillation?
Heart rate irregular and 250 bpm and above Heart unable to generate an output Shockable rhythm – defibrillators widely available
50
What are the features of ST elevation?
P waves visible and always followed by QRS Rhythm is regular and rate is normal (85 bpm) ST-segment is elevated >2mm above the isoelectric line Caused by infarction (tissue death caused by hypoperfusion)
51
What are the features of ST depression?
P waves visible and always followed by QRS Rhythm is regular and rate is normal (95 bpm) ST-segment is depressed >2mm below the isoelectric line Caused by myocardial ischaemia (coronary insufficiency)
52
What does aVf stand for?
Augmented vector foot
53
What does aVR and aVL stand for?
Augmented vector Left/Right
54
How does a persons build influence their normal cardiac axis?
Shorter, stockier - normal axis will be more left axis deviate Taller, leaner - normal axis will be more right axis deviated
55
What do you need to work out cardiac axis
Two leads 90 degrees apart
56
What does SOCRATES stand for?
``` Site Onset Character Radiation Associated symptoms Time course Exacerbating and Relieving factors Severity ```
57
What question might you ask when taking a pain history?
Site: Where is the pain? Onset: When did they pain start? Was is sudden or gradual? Character: What is the pain like? An ache? Stabbing? Radiation: Does the move/spread/radiate anywhere? Associations: Are there any other signs or symptoms that come with the pain? Time course: Does the pain follow any pattern in when it presents? Exacerbating/Relieving factors: Does anything make the pain better or worse? Severity: How bad is the pain?
58
When are ECGs most useful?
When you have ECGs over time e.g. 5 years ago Current
59
What are the three classifications of chest pain?
Typical chest pain Atypical chest pain Non-cardiac
60
How do you classify chest pain?
Three questions All three yes = typical 2 yes and 1 no = atypical 1 yes and 2 no = non-cardiac
61
What are the three questions you ask when classifying chest pain?
Is it retrosternal? Is it worsened by exertion? Is it relieved by rest or glyceryl trinitrate?
62
What is a CABG?
Surgically open up the chest. Take a vein from another part of the body and graft it so it reroutes the obstruction or creates a new perfusion pathway.
63
What is balloon angioplasty?
Balloon into leg and blow it up- leave it or erect a drug alluting stent to deliver vascodilators
64
What are p-wave problems?
``` Absent Inverted BIfid (left atrial dilation) Tall (P pulmonale, right atrial dilation) Sawtooth baseline ```
65
What can be wrong with a PR interval?
``` Prolonged Shortened Delta wave (shorted sloped PR interval) - WPW ```
66
What are some normal features of QRS complexes?
``` Should be narrow < 0.12s Not too tall Negative in V1+V2 V3+V4 transition point Tall QRS in V5+V6 ```
67
What can be wrong with the QRS complex?
``` Widened Short Alternating size (electrical alternans) Absent (cardiac arrest) Negative even V5+V6 To big (hypertrophy) ```
68
What is the J point?
When the QRS becomes the ST segment | Should be isoelectric
69
What does an osborn wave mean?
Hypothermia
70
What is the ST segment complex?
Bit between QRS complex and T-wave | Should be isoelectric
71
What is a normal t-wave?
Should be positive in all leads except aVR and V1
72
What are t-wave problems?
Inverted t-waves | Biphasic t-waves
73
What is a U-wave?
Pathological Waveform after the t-wave Young, fit, athletic pts usually Causes e.g. hyperthyroidism, hyper/hypokalaemia
74
What can go wrong with QT interval?
Shortened | Prolonged
75
What are the main features of AF?
Irregularly irregular rhythm Absent p-waves QRS complexes are narrow Baseline is not narrow
76
What are the main features of atrial flutter?
``` Sawtooth baseline Regularly irregular rhythm Absent p waves HR of around 300 Narrow QRS complexes 2:1, 3:1 etc. ```
77
What is a supraventricular tachycardia?
Any tachy that starts above bundle of His Look out for retrograde p waves after QRS
78
What are the features of 1st degree heart block?
Prolonged PR interval Not necessarily a sign of pathology Classically fit, young woman
79
What are the features of 2nd degree heart block? Aka Mobitz type I or Wenckenach phenomenon
Irregularly irregular rhythm Progressively prolonger PR intervals Occasional dropped QRS Usually benign
80
What are the features of Mobitz type II?
PR interval is constant when QRS is present But some p-waves are not followed by QRS Bradycardia Pathological: Damage to conduction system below AV node
81
What are the features of 3rd degree heart block?
Complete cessation of AV conduction P waves and QRS complexes independent QRS can be broad or narrow
82
What are the main features of wolff parkinson white?
Accessory pathway from atria to ventricles Short PR intervals Broad QRS complex with slurring of start (delta wave)
83
What are the ECG changes for pericarditis?
Widespread changes
84
What is really dangerous in WPW?
``` AF and flutter Nothing to slow down the aberrant pathway Can go into VF Need cardiovert Don't give AV node blocking drugs ```
85
What is ventricular fibrillation?
``` Incompatible with life Shockable ACLS Rapid, broad complexes Complexes start big and gets smaller Chaotic Pulseless ```
86
What is ventricular tachycardia?
Monomorphic is most common Fast HR Very broad, consisten ventricular complexes Loss of other features Sometime ocassional normal cycles - capture beat Seen in structural heart disease e.g. prev MI
87
What are the main features of LBBB?
WiLLiaM or ViLheM V1 and V6 Damage to left bundle branch Broad QRS Deep S wave in V1 Notched R wave in V6 Cannot interpret further - other abnormalities won't be seen Concerned about new onset MI
88
What are the main features of RBBB?
``` MaRRoW/ MaRiNe Broad QRS RSR' in V1 Wide downstroke slurred S wave in V6 V1-3 ST depression ```
89
What are the features of torsades de pointes?
Type of polymorphic VT Different morphologies throughout the trace Broad QRS complexed Calcium abnormalities likely cause of prolonged QT Changing amplitudes beat to beat Twisting 'bigger' then 'smaller' appearance
90
What is the management for torsades?
IV Magnesium
91
What is the natural history of a STEMI in terms of ECG changes?
Hyperacute t-waves (mins) ST elevation (0-12 hours) Q-wave develops (1-12 hours) ST elevation with T-eave inversion (2-5 days)
92
When should you be careful about giving nitrates?
RCA infarcts
93
What is suggestive of a posterior MI?
Reciprocal horizontal ST depression in V1-3 No posterior leads so we cannot see the ST elevation there
94
What are the ECG features of a NSTEMI?
Sub total occlusion Widespread ST changes and t-wave inversion
95
What ECG changes are seen in pericarditis?
Inflammation of pericardium Saddle shaped ST elevation PR depressions Maybe tachy
96
What ECG changes are seen in hyperkalaemia?
Tented t-waves Tachycardia
97
What diagnosis is associated with U waves?
Hypokalaemia | T-wave inversion
98
What is the difference between PR interval and segment?
Interval includes the p-wave
99
What should you tell the patient before doing an ECG?
Might need to shave Chaperone Stickers might be cold
100
How would you report an ECG?
This is a 12 lead ECG for X, DOB, date and time Presenting complaint The trace is calibrated at speed 25mm/sec and deflection of 1cm/1mV Rate, rhythm, axis Go through cardiac cycle Abnormalities
101
How do you work out rate on an ECG?
Total number of complexes in 10s x 6
102
What are causes of left axis deviation?
Disease of conduction | e.g. WPW, Inferior MI, Hyperkalaemia
103
What are causes of right axis deviation?
Extra muscle bulk e.g pulmonary HTN, PE Normal in tall, thin adults
104
When do you get broad QRS complexes?
Problem in ventricles and conductions e.g. VT or VF
105
When do you get narrow QRS complexes?
Supra-ventricular e.g. AF, A Flutter pr SVT
106
What are features of SVT?
No p-waves Regular QRS Fast
107
What is monomorphic VT?
All beats look the same
108
What would you see in RBBB?
rSR' in V1 qRs in V6
109
What would you see in LBBB?
rS in V1 R in V^

Year 3 Cardio (12 decks)

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