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Y3 Medicine > 3 - ECGs and Bradyarrhythmias > Flashcards

3 - ECGs and Bradyarrhythmias Flashcards

1
Q

What is the protocol for reading an ECG?

A
  1. Confirm patients name and ECG date

2. Rate

3. Rhythm

4. Axis

5. P waves

6. Intervals: PR interval, QRS complex, QT interval, ST segment, T waves

  1. R wave progression
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2
Q

What time interval does each of the following on an ECG represent:

  • 1 small box
  • 1 large box
A

Small box: 0.04 seconds

Large box: 0.2 seconds

1 second is represented by 5 large boxes

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3
Q

How do you calculate the rate on an ECG? (assuming speed is 25mm/s)

A

Regular: 300 ÷ Number of Big squares between R-R

Irregular: Number of QRS complexes on rhythm strip (10 seconds) x 6

Normal is 60-100bpm

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4
Q

How do you work out the rhythm of an ECG?

A

Use card method to mark position of 3 successive R waves and see if all intervals equal

Can be irregularly irregular or regularly irregular or sinus arrhythmia (p waves but irregular)

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5
Q

What is sinus rhythm?

A
  • All QRS complexes preceded with a P-wave
  • Regular rhythm
  • Between 60-100bpm
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6
Q

What is sinus arrhythmia?

A

Slight but regular lengthening and then shortening of RR intervals. All QRS have P waves so sinus node still working

Common in young people, lengthening and shortening corresponds to breathing

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7
Q

What is the difference between AF and atrial flutter?

A

AF: has no p-waves and is irregularly irregular

Atrial flutter: sawtooth baseline with no discernible p-waves but it is regular

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8
Q

What is the axis on an ECG and what is a normal axis?

A

Describes the direction of depolarisation across the heart, should spread from 11 to 5 o clock (-30 and +90)

Need to look at JUST LIMB LEADS/ leads I, II and III. There should be positive deflections for a normal axis.

Most positive deflection should be in II and most negative should be aVR

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9
Q

How do you work out axis on ECG easily?

A

Normal: Lead II or I most positive

Left deviation: aVL/Lead I most positive

Right deviation: Lead III most positive

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10
Q

What are the causes of right and left axis deviation?

A

Right: right ventricular hypertrophy, PE, anterolateral MI, WPW, left posterior fasicle block

(normal in very tall individuals, associated with pulmonary oedema as RVH)

Left: conduction abnormalities, left anterior hemiblock, inferior MI, WPW, LVH

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11
Q

How can you distinguish right and left axis deviation on an ECG?

A

Right: lead I becomes negative and lead II, III/aVF become more positive (Lovers Returning)

Left: lead III and II become negative and lead I more positive (Lovers Leaving)

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12
Q

What are the normal time values for the following and where are these intervals on ECG:

  • PR interval
  • QRS complex
  • QT interval
  • ST interval
A

PR: start of P to start of QRS. 0.12-0.2s (3-5 small squares)

QRS: <0.12S

QT: start of QRS to end of T. Should be 0.38-0.42s

ST interval: end of S to start of T

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13
Q

After looking at rate and rhythm on ECG you look at P waves. What are you looking for?

A
  • Are they present?
  • Are they followed by a QRS
  • Should be upright in II, III, aVF but upside down in aVR
  • Flat, flutter or chaotic baseline?
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14
Q

What is the normal PR interval and what can shorten and lengthen this?

A

3-5 small squares (0.12-0.2 seconds)

Prolonged: Delayed AV conduction e.g heart block

Shortened: fast AV conduction via accessory pathway e.g WPW or SA node in different place

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15
Q

What is a normal QRS complex like and what can cause changes to the QRS complex?

  • Width
  • Height
  • Morphology
A

Should be <0.12s with Q waves being <0.04s wide and <2mm deep

Prolonged QRS: bundle branch block, metabolic disturbance, ventricular origin

Tall QRS (>5mm in limb leads, >10mm in chest leads): LVH

Pathological Q-Waves: following MI

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16
Q

What are the QRS complexes on this ECG showing?

A

Delta wave which is common in Wolf Parkinson White Syndrome

Sign that ventricles are being activated earlier than normal from a point distant to the AV node. Early activation spreads slowly across myocardium causing slurred upstroke of QRS

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17
Q

WPW cannot be diagnosed with the delta wave alone. What other ECG abnormality has to be present?

A

Tachyarrhythmia + Delta Wave

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18
Q

When is a Q wave pathological?

A

> 25% the depth of the QRS that follows it or > 2mm in height and >1mm (40ms) in width.

Single Q wave is ok, need to look for Q in whole territory for evidence of previous MI e.g look at all inferior leads

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19
Q

What is wrong with the QRS complexes in this ECG and why might this have occured?

A

Poor R wave progression

R wave should go from small to big from V1 to V6. Transition of S>R to R>S should be around V3/V4

Poor lead position or previous MI

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20
Q

What is the J point?

A

Where the S wave joins the ST segment

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21
Q

What is the Osborn wave (J wave)?

A

Positive deflection of the J point due to hypothermia, SAH or SEVERE hypercalcaemia

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22
Q

What is a normal ST segment and what is ST elevation/depression?

A

Should be isoelectric

ST elevation: greater than 1 mm (1 small square) in 2 or more contiguous limb leads or >2mm in 2 or more chest leads.

ST depression: >0.5mm in >2 contiguous leads

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23
Q

What is the cause of ST elevation and ST depression?

A

Elevation: full thickness myocardial infarction

Depression: myocardial ischaemia

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24
Q

What do T waves represent and what leads are they normally inverted on?

A

Ventricular repolarisation

Usually inverted in aVR, V1 and V2 and sometimes V3

Abnormal if inverted in I, II, V4-V6

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25
Q

What are the causes of the following:

  • Tall T waves (>5mm in limb leads and >10mm in chest leads)
  • Inverted T waves
  • Biphasic T waves
  • Flattened
A

Tall: hyperkalaemia or STEMI

Inverted: ischaemia, general illness, bundle branch block, PE

Biphasic: Ischaemia and hypokaelaemia

Flattened: hypokalaemia

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26
Q

What is a U wave and what causes these?

A

> 0.5mm deflection after the T wave usually in V2 or V3

Seen in electrolyte imbalances, hypothermia and secondary to antiarrhythmic therapy (such as digoxin, procainamide or amiodarone)

Seen larger in slower bradycardias

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27
Q

What leads are the most positive in normal cardiac axis, left axis deviation and right axis deviation?

A

Normal: II

Left: aVL

Right: III

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28
Q

What does ST elevation across all leads represent?

A

Pericarditis

Saddle shaped

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29
Q

What are some causes of sinus bradycardia?

A
  • IHD
  • Thyrotoxicosis
  • Hypothermia
  • Increased ICP
  • Cholestasis
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30
Q

What are some causes of the following:

  • ST elevation
  • ST depression
  • T wave inversion
A
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31
Q

What are some ECG changes in a PE?

A
  • Sinus tachycardia
  • RBBB
  • Right axis deviation
  • S1Q3T3
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32
Q

What is the Digoxin effect on ECG?

A

- Down-sloping ST depression

- Short QT interval

- Inverted T wave in V5-V6

  • Any arrhythmia e.g ventricular ectopics and nodal bradycardia
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33
Q

What heart territory do all of the 12 leads of the ECG cover and what vessel supplies them?

A
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34
Q

How do hyper and hypokalaemia present on ECG?

A

Hyper

  • Tall tenting T waves
  • Widened QRS
  • Absent P waves
  • Sine

Hypo

  • Small T waves
  • U waves
  • Prominent P waves
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35
Q

How do hypo and hypercalcaemia present on ECG?

A

HypoCa

  • Long QT
  • Small T waves

HyperCa

  • Short QT
36
Q

What are some continuous ECG monitoring methods that can be used to diagnose paroxysmal arrhythmias that may be missed on a single ECG?

A

Telemetry: Inpatient, signals watched by staff on screens so if dangerous arrhytmia can help immediately. Used for those at high risk of arrhythmias e.g post STEMI

Exercise ECG: BP also taken whilst doing standardised exercise

Holter Monitor: Worn for 24h for a week whilst going about normal life

Loop recorder: Placed under the skin (e.g Reveal) and record short period before the event, e.g patient has syncope, can press the button when regains consciousness. Good if events happen months apart

Pacemakers and ICDs

37
Q

How can we split arrhytmias into different categories?

A
  • Bradycardia
  • Narrow complex tachycardia
  • Wide complex tachycardia
  • AF and Atrial flutter

MEMORISE ALGORITHM ON PHOTO

38
Q

What are some causes of arrhythmias in general?

A

Cardiac or Non-cardiac

39
Q

How do patients with arrhythmias present and what questions do you need to ask in the history?

A

Presentation: palpitations, chest pain, presyncope/syncope, hypotension, pulmonary oedema, asymptomatic

History: take history of palpitations including onset/offset/nature, associated symptoms (e.g chest pain, breathlessness), drug history, family history of cardiac disease or sudden death

40
Q

What are the different management options in arrhythmias?

A

Conservative e.g cut down alcohol

Medical e.g betablockers

Interventional e.g pacemakers, ablation of accessory pathways, ICDs

41
Q

Why is syncope during exercise a worrying presentation?

A

Patient may have syndrome predisposing them to sudden cardiac death e.g long QT syndrome

42
Q

What are some tests you can do when a patient presents with palpitations that is likely to be due to an arrhythmia?

A

- Bloods: FBC, U+Es, Glucose, Ca, Mg, TFTs

  • ECG: look for short PR (WPW) or long QT

- 24h ECG monitoring or continuous ECG monitoring

- ECHO for structural heart disease

  • Exercise ECG
43
Q

How do you classify bradycardic arrhythmias based on the aetiology? (<60bpm)

IMPORTANT FLASHCARD TO UNDERSTAND BRADYCARDIAS

A

Based on the pacemaker at fault (sinus node or AV node)

Sinus Node: sinus bradycardia, sick sinus syndrome (tachy-brachy), sinus arrest, vasovagal syncope

AV Node: First degree AV block, Second degree AV block (Mobitz I or II), Complete AV block

44
Q

What are some causes of sinus bradycardia?

A

- Drugs (b-blockers, amiodarone, digoxin)

- Hypothyroidism

- Hypothermia

- Sleep Apnoea

- Increased intracranial pressure

- Athletic

- Rare: rheumatic fever, viral myocarditis, amyloidosis, haemochromatosis, pericarditis

45
Q

Most bradycardias cause by sinus node disease are asymptomatic. If they are symptomatic what is needed?

A

Pacemaker

46
Q

What are some symptoms of bradycardia?

A
  • Asympyomatic
  • Fatigue
  • Nausea
  • Dizziness
  • Syncope
  • Chest pain
  • Breathless
47
Q

What is relative vs absolute bradycardia?

A

Absolute: any heart rate less than 60bpm, can be normal for sleeping athletes

Relative: a heart rate too slow for the haemodynamic state of the patient, doesn’t have to be below 60bpm. (systolic BP<90, HR<40, poor perfusion, poor urine output)

48
Q

How is symptomatic bradycardia managed acutely? (especially after MI)

A
  1. Do ECG and check electrolytes (K+,Mg2+, Ca2+)
  2. Connect to cardiac monitor/telemetry

3. Address cause e.g correct electrolytes, give glucagon if cause by B-blocker

  1. If patient has adverse signs give atropine IV 500mcg every 3-5 minutes up to 3mg
  2. If atropine not working do transcutaneous pacing
49
Q

What is sick sinus syndrome caused by and what are the symptoms?

A

Usually due to sinus node fibrosis, often in the elderly. This can cause sinus bradycardias or tachyarrhythmias like AF

Can get tachy brachy syndrome where they alternate between tachy and bradycardic rhythms

Symptoms: syncope, presyncope, light-headedness, palpitations, breathlessness

50
Q

How is sick sinus syndrome diagnosed and managed?

A

- VTE prophylaxis is episodes of AF detected

- Permanent pacemaker if symptomatic bradycardia or sinus pauses

  • Hard to treat tachy-brachy syndrome as treating one increases the risk of the other
51
Q

What are some causes of 1st, 2nd and 3rd degree heart block?

A

1st and 2nd: normal variant, athletes, sick sinus syndrome, IHD especially inferior MI, acute myocarditis, digoxin, beta-blockers

3rd: IHD especially inferior MI, digoxin toxicity, hyperkalaemia, idiopathic fibrosis, congenital, aortic valve calcification, cardiac surgery infiltration by tumours/granulomas/parasites

52
Q

How does first degree AV block present on ECG and how do you manage it?

A

PR interval >0.2 seconds with no missed beats

  • Check for toxicity if on digoxin
  • No treatment needed unless symptoms of dizziness or syncope then cardiac monitoring should be done to identify higher degrees of heart block
53
Q

How does second degree AV block Mobitz Type I present on ECG and what type of patients may this present in?

A

Progressive lengthening of the PR interval followed by drop in QRS then pattern resets

Can occur in young fit patients with high vagal tone during the night. Also often after inferior MI

54
Q

What is another name for Mobitz Type 1 Second degree AV block?

A

Wenckeback phenomenom

55
Q

How do we managed Mobitz Type I Second Degree Heart block?

A

Rarely proceeds to complete heart block so no therapy needed

If syncope or diziness do cardiac monitoring for higher degrees of heart block

56
Q

How does second degree AV block Mobitz Type II present on ECG and how is it managed?

A

Constant PR interval but then sudden drop of QRS

Can be defined as ratio, e.g 2:1 would be 2 normal for every 1 dropped

Management: risk of progression to complete heart block so permanent pacing needed if drugs excluded

57
Q

How does 3rd degree complete AV block present on ECG?

A

No relationship between P and QRS waves as no conduction between atria and ventricles

Patient is very bradycardic due to ventricular rhythm taking over and can develop haemodynamic compromise

Can be broad complex escape rhythm (block below the AV node and not well tolerated) or narrow complex escape rhythm (block above AV node, often congenital, well tolerated)

58
Q

How is 3rd degree AV block managed?

A

Urgent permanent pacing within 24 hours, unless they are likely to recover normal conduction such as they have had a recent coronary event

59
Q

What are the main causes of 3rd degree heart block and what medicaions can you administer for this?

A

- Digoxin toxicity

- Inferior STEMI (often resolves in hours or days)

- Severe hyperkalaemia

  • Give calcium chloride for hyperK to stabilise membrane
  • If haemodynamically unstable can give atropine 0.5mg up to 3mg
  • Can try isoprenaline if atropine not working
60
Q

What is a junctional rhythm and how does it present on ECG?

A

Has regular narrow QRS waves but no P waves or P waves hidden in QRS

Due to electrical activation occuring near to or within the AV node rather than the SA node

61
Q

What does this ECG show?

A

Intermittent sinus bradycardia on the rhythm strip

Has a tachycardia on other leads so tachy-brady syndrome

Issue at SA node as when AF it is conducted to ventricles

62
Q

What does this ECG show?

A

2:1 heart block (Mobitz Type II)

63
Q

What does this ECG show?

A

Complete heart block as no relationship with QRS.

Narrow escape rhythm

64
Q

What does this ECG show?

A

Complete AV block with broad escape rhythm

More dangerous than narrow escape rhythm as whole AV node not working!!!!

Shows as a bundle branch block

65
Q

How do pacemakers show on an ECG?

A

One pacing wire in ventricle: one spike followed by broad QRS

Two pacing wires: will have spike then p wave and spike followed with broad QRS

66
Q

Where do you place the ECG leads on a patient?

A

V7 placed at posterior axillary line

Make sure you clean the skin with wipe and shave if hairy before placing on leads

67
Q

What does a widened QRS complex mean?

A

>0.12 seconds mean it is originating from the ventricles

Slower pace than if from atria

68
Q

How does RBBB on ECG appear and what are the causes of this?

A

Due to right ventricle being activated by the left ventricle. They cannot be activated at the same time as there is an obstacle in the RBBB.

- Prolonged QRS

- M Pattern in V1 and V1 positive

- Bunny ears

- Wide slurred S wave in V6, hence the W pattern

- T wave inversion V1-V3

- Normal axis

Causes: normal variant, RVH, cor pulmonale, PE

69
Q

How does LBBB appear on ECG and what are the causes of this?

A

Causes: if new onset STEMI, HTN, cardiomyopathy, idiopathic fibrosis, aortic stenosis

- Prolong QRS

- V1 QRS negative (look at chest leads to see when positive)

- M pattern in V6

- Dominant S (W) in V1

- Left axis deviation

Cannot comment on ST segment or T waves if LBBB

70
Q

What are some ways of remembering the ECG findings in LBBB and RBBB?

A

LBBB: WILLIAM

RBBB: MARROW

71
Q

What is bifasicular block and how does it show on ECG?

A

Conduction block between AV node and two of the three fasicles

RBBB + left or right axis deviation

72
Q

What is trifasicular block and how does it present on ECG?

A

Usually bifasicular block plus 1st degree heart block

  • RBBB
  • Left or right axis deviation
  • Prolonged PR interval
73
Q

Complete heart block may be intermittent so may not be seen on ECG. What can be seen on ECG that could indicate a poor conducting system and could mean complete heart block?

A

Bi or trifasicular block

74
Q

What are the causes of low voltage QRS (<5mm in all leads)

A
  • COPD
  • Hypothyroidism
  • PE
  • BBB
  • Pericarditis
  • Pericardial effusion
75
Q

What is the issue with bundle branch block when wanted to read an ECG for a patient with acute chest pain?

A

Can mask ST changes and T wave issues

76
Q

What is normal axis, left deviation, right deviation?

A

Normal: lead II most positive

Left deviation: lead aVL most positive

Right deviation: lead III most positive

77
Q

What does R wave progression mean and what can late R wave transition indicate?

A

Transition of more positive R than S should happen in V3

If late:

  • Prior anterosepctal MI so infarct
  • Inaccurate lead placement
  • LVH
  • Dilated cardiomyopathy
78
Q

What is this ECG abnormality?

A

Looks like ST elevation but it is just high take off

79
Q

What is the QTc interval?

A

QT interval corrected for heart rate

80
Q

If there is a prolonged QRS, what is the first thing you should do?

A

Look in V1 to see if BBB!!

V1 negative in LBBB

V1 positive in RBBB

81
Q

What do very tall R waves indicate?

A

LVH

82
Q

What are some causes of LVH?

A
  • Hypertension
  • Aortic stenosis
  • Hypertrophic cardiomyopathy
83
Q

What do small alternating R waves on an ECG indicate?

A

Pericardial effusion as the heart is swinging in the sac

84
Q

What is the normal QT interval and what are some causes of long QT and short QT?

A

<0.44s or 2 large squares

Long: MI, LVH, HypoK, HypoMg, HypoCa, DKA, Drugs, RBBB/LBBB

Short: HyperCa

85
Q

When is T wave inversion normal?

A

In leads avR and III if in isolation

86
Q

A cardiologist has asked you to start oral amiodarone for a patient who has previously been admitted with ventricular tachycardia. What tests is it important to ensure the patient has had prior to starting treatment

A

- TFT

- LFT

- U+Es: risk of hypoK

- CXR: risk of pulmonary fibrosis

87
Q

What is the treatment algorithm for tachycardias?

A

Y3 Medicine (24 decks)

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