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Cardiovascular system > Electrical activity of heart > Flashcards

Electrical activity of heart Flashcards

1
Q

What are cardiac arrhythmias ?

A

Disturbances of normal cardiac rhythm, they are common, often benign, often intermittent but occasionally they are severe

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2
Q

What are the causes of cardiac arrhythmias ?

A

cardiac: MI, coronary artery, LV aneurysm, mitral valve disease, cardiomyopathy, pericarditis, myocarditis, non-cardiac: smoking, caffeine, smoking, alcohol, pneumonia, drugs such as beta 2 antagonist, digoxin, L-dopa, metabolic imbalance such as K+, Ca2+, Mg2+, hypoxia, hypercapnia, metabolic acidosis, thyroid disease

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3
Q

What is the common presentation of arrhythmias ?

A

palpitations, chest pain, pre-syncope/syncope, hypotension, or pulmonary oedema, some arrhythmias might be asymptomatic

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4
Q

What investigations should be performed ?

A

bloods (FBC, U+E, glucose, Ca, Mg), ECG, 24ECG, exercise ECG, ECHO

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5
Q

What are ectopic beats?

A

Early or extra heart beats which can cause palpitations, they are out of place, cells aways from pacemaker get excitable and release electrical signal causing the extra beat, there might be a tiny pause after giving a feeling of missed beat, they are quite common in adults but they do not require treatment as they are clinically insignificant

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6
Q

What are two most common types of ectopic beats?

A

Premature atrial contraction and premature ventricular contraction, they are usually harmless, the cause of often unknown

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7
Q

What stimulants can trigger palpitations?

A

alcohol, caffeine, certain medicines, recreational drugs, tobacco, more likely in pregnancy or menopause

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8
Q

What can cause arrhythmias?

A

They can be caused by chemical imbalance in body such as low blood potassium levels, or injuries to the heart muscle such as heart attack

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9
Q

What is atrial fibrillation?

A

Very common type of arrhythmia of the heart, due to non-coordinated electrical activity in the atria

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10
Q

What would be observed on ECG in atrial fibrillation?

A

No clear P waves, irregular QRS complexes

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11
Q

Describe the physiology of atrial fibrillation

A

The different areas of atria contract at different times, occasionally one signal gets to AV node and causes ventricles to contract, it happens very randomly and usually there are many QRS complexes, the irregular activation of AV node leads to irregular pulse

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12
Q

What are the risk factors for atrial fibrillation?

A

cardiovascular disease, coronary artery disease, valvular disease, essentially anything that can cause inflammation of heart muscle cells in the atria, hyperthyroidism, obesity, diabetes, alcohol consumtopn

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13
Q

Describe the pathological changes that occur in the atria

A

There is injury to the muscle cells in the atria such as inflammation, different cells develop different properties such as short refractory period, there is tissue heterogenity which causes uncoordinated spread of electrical activity, there can also be an area that overtakes of SA node and starts firing signals, over time there is progressive fibrosis and scaring, this leads to persistent AF

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14
Q

What are the three types of atrial fibrillation?

A

paroxysmal AF, persistent AF, long standing AF (longer than 12 months )

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15
Q

What are the symptoms of AF?

A

asymptomatic, or general fatigue, dizziness, SOB, weakness, palpitations, chest pain, pre-syncope

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16
Q

What are the signs of atrial fibrillation?

A

irregularly irregular pulse, irregular volume, if there is haemodynamic instability there is weak pulse and low BP

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17
Q

What are the complications of AF?

A

formation of embolus and risk of stroke

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18
Q

What is the treatment for AF?

A

beta blockers, digoxin, CCB and warfarin, or anti arrhythmic class Ic or class III drugs and cardioversion

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19
Q

What are the more invasive treatment options for AF?

A

implantable pacemakers, radiofrequency ablation

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20
Q

What are the investigations for AF?

A

12 lead ECG, Holter monitor, thyroid function blood test, echo, chest X ray

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21
Q

What is atrial flutter?

A

Atria contraction at very high rates at around 300 bpm, there is re-entrant rhythm that over-rides the SA node and cause atria to contract over and over again

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22
Q

What are the two types of atrial flutter?

A

Type I moves around the tricuspid valve, type II is right or left atrium

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23
Q

Describe the pathology of atrial flutter

A

The cells are more irritable, usually due to underlying cardiac condition, there is change in cells properties, the refractory period is shorter and re-entrant circuit is formed, but it does not move to the ventricles as AV node has long refractory period, there are more atrial contractions compared to ventricular contractions, e.g. ratio 3:1

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24
Q

What are the possible complications of atrial flutter?

A

heart failure, embolus and stroke

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25
Q

What is the treatment for the atrial flutter?

A

Bete blockers or CCB, anticoagulants, or cardioversion, radiofrequency ablation

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26
Q

What is supreventrivcular tachycardia SVT?

A

It is abnormally fast heart rate over 100 bpm, caused by AV node re-entry

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27
Q

What are the symptoms of supra ventricular tachycardia?

A

Dizziness, dyspnoea, palpitations, syncope, feeling faint, fatigue

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28
Q

What type of arrhythmia can be reversed by Valsalva manoeuvre?

A

Supraventricular tachycardia

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29
Q

What does initiates SVT?

A

In SVT the heart rate is not controlled by SA node, the signal arise from somewhere above the ventricles and the signal spreads to the ventricles

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30
Q

How many types of SVT are there?

A

3

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31
Q

What is atrioventricular nodal re-entry tachycardia?

A

It is a type of SVT, there is re-entry circuit formed within AV node or just next to AV node in right atrium, there are slow and quick conducting pathways, signal can get from ventricles to atria and then again to ventricles via node, short circuit is formed.

32
Q

What is the treatment for atrioventricular nodal re-entry tachycardia?

A

ablation mainly, but can also involve medication, it is stopped by Valsalva manoeuvre

33
Q

What is atrial tachycardia?

A

It is type of SVT, signal arise from somewhere in the atria stat drives the heart beat, over-rised the SA node

34
Q

What is Wolf Parkinson White syndrome?

A

Type of SVT in which additional electrical connection between atria and ventricles is formed

35
Q

What is the treatment for SVT?

A

Ablation, medication

36
Q

What are the signs of AVT?

A

NarrowQRS complex, very high heart rate

37
Q

What is ventricular fibrillation?

A

Uncoordinated contraction of ventricles , it is very inefficient, the CO is significantly compromised and the body is not getting enough O2, it can lead to cardiac arrest and sudden death

38
Q

What are the causes of ventricular fibrillation?

A

Due to medication, drugs, electrolyte imbalance and ischaemic changes, electrocution, these leads to tissue heterogeneity

39
Q

What is the pathology of VF?

A

There is abnormal conduction, due to tissue heterogeneity waves of depolarisation spirals around, there is functional re-etry, many circuits can be formed and the conduction is very uncoordinated, the ventricles contract in random fashion

40
Q

What are the signs and symptoms of VF?

A

sudden loss of responsiveness, no normal breathing, in cardiac arrest, pulseless, haemodynamic instability, patients collapse, in cardiac arrest

41
Q

What would the ECG look like in VF?

A

no QRS complexes, many fibrillation waves with erratic rhythm, no discrete features

42
Q

What is the treatment of VF?

A

cardiopulmonary resuscitation and defibrillation, if they survive might be given implantable defibrillator

43
Q

How does defibrillation work?

A

It creates very high energy shock that depolarise everything to at least a critical mass and allow SA to take control again

44
Q

What is ventricular tachycardia?

A

Fast heart beat, HR above 100 bpm, caused by more than 3 premature ventricular contractions, there is not enough time for the ventricles to fill properly and less blood is pumped out as a result

45
Q

What is the pathology that can cause ventricular tachycardia?

A

There can be abnormal focal automaticity, part of cells in ventricle start spontaneously fire action potential, they override AV node and the signal spreads across ventricles, or second option is creation of re-entrant circle due to tissue heterogeneity

46
Q

What are the symptoms of ventricular tachycardia?

A

Palpitations, dizziness, syncope, dyspnoea, patients usually look poorly

47
Q

What are the signs of ventricular tachycardia ?

A

Vey fast heart rate, QRS complexes are broad and no other waves are really visible, they can be monomorphic - they have the same size, or polymorphic - QRS compasses have different size, they are usually regular

48
Q

What investigations are performed for ventricular tachycardia?

A

ECG, echo, bloods (U+E, cardiac enzymes, FBC, CRP), angiogram

49
Q

What is the treatment for ventricular tachycardia?

A

Medication to reduce heart rate, cardioversion, radio frequency ablation, ICD

50
Q

What are the indicators for ICD ?

A

cardiac arrest, sustained VT causing syncope, sustained VT with poor LV function

51
Q

Name the conditions when permanent pacemaker should be implanted

A

AV node ablation, 2nd and 3rd degree AV block with neuromuscular disease, alternating RBBB and LBBB, sinus node disease with symptoms, carotid sinus hypersensitivity

52
Q

What is AV block?

A

Delay or blockage of signal condition at AV node, can be caused by ischaemia, fibrosis

53
Q

What are the common causes of AV block?

A

cardiomyopathies, IE

54
Q

What is first degree AV block?

A

Prolonged PR interval, it is longer than 0.2 s, usually no symptoms and there is no requirement for treatment

55
Q

What is Moritz type I second degree block?

A

PR interval gets progressively longer and eventually one signal is not conducted (ventricular escaped beat), then it starts again

56
Q

What is Mobitz type II second degree block?

A

PR intervals are constant but randomly and occasionally signal is not conducted to the ventricles, usually it is 2nd and 8th are not conducted

57
Q

What are the symptoms of Moritz I?

A

lightheadedness, dizziness, syncope

58
Q

What are the symptoms of Moritz II?

A

fatigue, dyspnoea, chest pain, syncope

59
Q

What is third degree block ?

A

There is no conduction via AV node, ventricular contraction is generated by pacemakers cells in ventricles

60
Q

What are the symptoms of 3rd degree block?

A

syncope, confusion, severe chest pain

61
Q

What is the treatment for AV block?

A

Medication to increase the rate such as atropin, transcutaneous pacing, or implantable pacemaker

62
Q

What is bundle branch block?

A

Block in condition of electrical signal in one of the two branches left or right uncle, most commonly due to fibrosis

63
Q

What are acute causes of fibrosis ?

A

MI, acute ischaemia, myocarditis

64
Q

What are chronic causes of fibrosis?

A

hypertension, coronary heart disease, cardiomyopathy

65
Q

What is RBBB?

A

Right bundle branch block, signal spreads via left bundle, first left side contract then right side, MoRow mnemonics

66
Q

How does the ECG looks in RBBB?

A

MoRoW, M shape in V1, W shape in V6

67
Q

What is LBBB?

A

Blockage of left bundle, signal spreads via right bundle and then to left, right side contracts first then left, WiLliaM mnemonics

68
Q

How does ECG look in LBBB?

A

WiLliaM, W hape in V1, M shape in V6

69
Q

What is the treatment of branch block?

A

Sometimes no treatment, cardiac resynchronisation pacemaker if there is also cardiac failure

70
Q

What is long QT syndrome?

A

Some cells have abnormally long repolarisation, this leads to long QT interval

71
Q

What can cause long QT syndrome?

A

Malfunction of L type Ca channels, or Na and K channels

72
Q

What can arise from long QT syndrome?

A

Torsade de pointes

73
Q

What is Torsade de pointes?

A

It is type of ventricular tachycardia that is polymorhic, QRS complexes seem to be twisting around the base line, the heart rate is around 150-250 bpm

74
Q

What are the symptoms of Torsade de pointes?

A

Palpitations, syncope, dizziness, can lead to sudden cardiac death

75
Q

What are the signs of Torsade de pointes?

A

short-long-short RR intervals, prolonged QT interval and VT that is polymorphic and with broad QRS

76
Q

What is the treatment of Torsade de pointes?

A

drugs, pacing or ICD

Cardiovascular system (18 decks)

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