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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
What is the treatment for the atrial flutter?
Bete blockers or CCB, anticoagulants, or cardioversion, radiofrequency ablation
26
What is supreventrivcular tachycardia SVT?
It is abnormally fast heart rate over 100 bpm, caused by AV node re-entry
27
What are the symptoms of supra ventricular tachycardia?
Dizziness, dyspnoea, palpitations, syncope, feeling faint, fatigue
28
What type of arrhythmia can be reversed by Valsalva manoeuvre?
Supraventricular tachycardia
29
What does initiates SVT?
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
30
How many types of SVT are there?
3
31
What is atrioventricular nodal re-entry tachycardia?
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
What is the treatment for atrioventricular nodal re-entry tachycardia?
ablation mainly, but can also involve medication, it is stopped by Valsalva manoeuvre
33
What is atrial tachycardia?
It is type of SVT, signal arise from somewhere in the atria stat drives the heart beat, over-rised the SA node
34
What is Wolf Parkinson White syndrome?
Type of SVT in which additional electrical connection between atria and ventricles is formed
35
What is the treatment for SVT?
Ablation, medication
36
What are the signs of AVT?
NarrowQRS complex, very high heart rate
37
What is ventricular fibrillation?
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
What are the causes of ventricular fibrillation?
Due to medication, drugs, electrolyte imbalance and ischaemic changes, electrocution, these leads to tissue heterogeneity
39
What is the pathology of VF?
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
What are the signs and symptoms of VF?
sudden loss of responsiveness, no normal breathing, in cardiac arrest, pulseless, haemodynamic instability, patients collapse, in cardiac arrest
41
What would the ECG look like in VF?
no QRS complexes, many fibrillation waves with erratic rhythm, no discrete features
42
What is the treatment of VF?
cardiopulmonary resuscitation and defibrillation, if they survive might be given implantable defibrillator
43
How does defibrillation work?
It creates very high energy shock that depolarise everything to at least a critical mass and allow SA to take control again
44
What is ventricular tachycardia?
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
What is the pathology that can cause ventricular tachycardia?
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
What are the symptoms of ventricular tachycardia?
Palpitations, dizziness, syncope, dyspnoea, patients usually look poorly
47
What are the signs of ventricular tachycardia ?
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
What investigations are performed for ventricular tachycardia?
ECG, echo, bloods (U+E, cardiac enzymes, FBC, CRP), angiogram
49
What is the treatment for ventricular tachycardia?
Medication to reduce heart rate, cardioversion, radio frequency ablation, ICD
50
What are the indicators for ICD ?
cardiac arrest, sustained VT causing syncope, sustained VT with poor LV function
51
Name the conditions when permanent pacemaker should be implanted
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
What is AV block?
Delay or blockage of signal condition at AV node, can be caused by ischaemia, fibrosis
53
What are the common causes of AV block?
cardiomyopathies, IE
54
What is first degree AV block?
Prolonged PR interval, it is longer than 0.2 s, usually no symptoms and there is no requirement for treatment
55
What is Moritz type I second degree block?
PR interval gets progressively longer and eventually one signal is not conducted (ventricular escaped beat), then it starts again
56
What is Mobitz type II second degree block?
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
What are the symptoms of Moritz I?
lightheadedness, dizziness, syncope
58
What are the symptoms of Moritz II?
fatigue, dyspnoea, chest pain, syncope
59
What is third degree block ?
There is no conduction via AV node, ventricular contraction is generated by pacemakers cells in ventricles
60
What are the symptoms of 3rd degree block?
syncope, confusion, severe chest pain
61
What is the treatment for AV block?
Medication to increase the rate such as atropin, transcutaneous pacing, or implantable pacemaker
62
What is bundle branch block?
Block in condition of electrical signal in one of the two branches left or right uncle, most commonly due to fibrosis
63
What are acute causes of fibrosis ?
MI, acute ischaemia, myocarditis
64
What are chronic causes of fibrosis?
hypertension, coronary heart disease, cardiomyopathy
65
What is RBBB?
Right bundle branch block, signal spreads via left bundle, first left side contract then right side, MoRow mnemonics
66
How does the ECG looks in RBBB?
MoRoW, M shape in V1, W shape in V6
67
What is LBBB?
Blockage of left bundle, signal spreads via right bundle and then to left, right side contracts first then left, WiLliaM mnemonics
68
How does ECG look in LBBB?
WiLliaM, W hape in V1, M shape in V6
69
What is the treatment of branch block?
Sometimes no treatment, cardiac resynchronisation pacemaker if there is also cardiac failure
70
What is long QT syndrome?
Some cells have abnormally long repolarisation, this leads to long QT interval
71
What can cause long QT syndrome?
Malfunction of L type Ca channels, or Na and K channels
72
What can arise from long QT syndrome?
Torsade de pointes
73
What is Torsade de pointes?
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
What are the symptoms of Torsade de pointes?
Palpitations, syncope, dizziness, can lead to sudden cardiac death
75
What are the signs of Torsade de pointes?
short-long-short RR intervals, prolonged QT interval and VT that is polymorphic and with broad QRS
76
What is the treatment of Torsade de pointes?
drugs, pacing or ICD

Cardiovascular system (18 decks)

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