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Year One - Cardiovascular System > Atrial Fibrillation > Flashcards

Atrial Fibrillation Flashcards

1
Q

What is atrial fibrillation (AF)?

A

It is where the contraction of the atria is uncoordinated, rapid and irregular

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2
Q

What is the most common arrhythmia?

A

AF

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3
Q

Describe the pathophysiology of AF

A

It is due to disorganised electrical activity that overrides the normal, organised activity from the sinoatrial node

This disorganised electrical activity in the atria also leads to irregular conduction of electrical impulses to the ventricles

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4
Q

What are the three classifications of AF?

A

Paroxysmal

Persistent

Permanent

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5
Q

What is paroxysmal AF?

A

It is when the AF comes and goes in episodes, usually not lasting more than 48 hours

They do not last longer than 7 days

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6
Q

What is persistent AF?

A

It is when the AF comes and goes in episodes that do not self terminate

These episodes usually last greater than 7 days

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7
Q

What is permanent AF?

A

This is when there is continuous AF which cannot be cardioverted or if attempts to do so are deemed inappropriate

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8
Q

What are the five causes of AF?

A

mrs SMITH

Sepsis

Mitral valve pathology

Ischaemic heart disease

Thyrotoxicosis

Hypertension

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9
Q

How does AF usually present?

A

Asymptomatically

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10
Q

What are the six clinical features of AF?

A

Irregularly, Irregular Pulse

Increased Heart Rate, 300 – 600bpm

Palpitations

Dyspnoea

Syncope

Chest Pain

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11
Q

What other condition also results in the presentation of an irregular, irregular pulse?

A

Ventricular ectopics

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12
Q

How do we differentiate between AF and ventricular ectopics?

A

Ventricular ectopics disappear when the heart rate gets over a certain threshold

Therefore, a regular heart rate during exercise suggests a diagnosis of ventricular ectopics

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13
Q

What investigation is used to diagnose AF?

A

ECG scan

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14
Q

What are the three signs of AF on ECG?

A

Absent P waves

Narrow QRS complex tachycardia

Irregularly irregular ventricular rhythm

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15
Q

What are the two aims when managing AF?

A

Rate/rhythm control

Reducing stroke risk

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16
Q

What do we usually chose to control in AF - rate or rhythm?

A

It is first line to control rate rather than rhythm

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17
Q

In what three circumstances do we chose to control rhythm over rate in AF?

A

There is a reversible cause for their AF

The AF is of new onset (within 48 hours)

The AF is causing heart failure

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18
Q

What do we aim to reduce the heart rate to in AF? Why is this important?

A

< 100bpm

It extends the time during diastole when the ventricles can fill with blood, increasing CO

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19
Q

What are the three management options used to control rate in AF?

A

Beta-blocker

Calcium channel blocker

Digoxin

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20
Q

What is the first line management option used to control rate in AF? Name an example

A

Beta-blocker

Atenolol 50-100mg once daily

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21
Q

What is a common contraindication for beta-blockers?

A

Asthma

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22
Q

What CCB is used to control the rate of AF? When is it contraindicated?

A

Diltiazem

Heart failure

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23
Q

When is digoxin administered to control rate in AF?

A

In sedentary patients - who do no/very little physical exercise

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24
Q

What is the mechanism of action of digoxin?

A

It inhibits the Na/K ATPase pump

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25
Q

How do we aim to control rhythm in AF? What is this called?

A

We aim to return the patient to normal sinus rhythm

Cardioversion

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26
Q

What are the two types of cardioversion?

A

Immediate

Delayed

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27
Q

When is immediate cardioversion conducted?

A

In cases where the AF has been present for less than 48 hours or they are severely haemodynamically unstable

28
Q

When is delayed cardioversion conducted?

A

In cases where the AF has been present for more than 48 hours and they are stable

29
Q

Prior to delayed cardioversion, what do we administer to patients? Why?

A

Anticoagulants for 3 weeks

48 hours prior to cardioversion patients may have developed a blood clot in the atria and reverting them back to sinus rhythm carries a high risk of mobilising that clot and causing a stroke

30
Q

What are the two options for cardioversion?

A

Pharmacological

Electrical

31
Q

What two drugs are used in pharmacological cardioversion?

A

Flecainide

Amiodarone

32
Q

When is amiodarone selected in pharmacological cardioversion?

A

Structural heart disease

33
Q

What is electrical cardioversion?

A

It involves rapidly shocking the heart back into sinus rhythm using a cardiac defibrillator machine

These patients are sedated or given general anaesthetic prior to the procedure

34
Q

What is electrical cardioversion synchronised to? Why?

A

R wave

This is to prevent delivery of a shock during the vulnerable period of cardiac repolarisation when ventricular fibrillation can be induced

35
Q

When is electrical cardioversion preferred over pharmacological cardioversion?

A

In haemodynamically unstable patients, with decompensation

36
Q

What drug should patients be administered following electrical cardioversion? For how long?

A

Anticoagulants

Lifelong

37
Q

What three drugs are used to manage rhythm of AF long term?

A

Beta blockers

Dronedarone

Amiodarone

38
Q

What is the first line long term rhythm control drug?

A

Beta blockers

39
Q

What is the second line long term rhythm control drug?

A

Dronedarone

40
Q

When is amiodarone used to control rhythm long term?

A

In patients with heart failure or left ventricular dysfunction

41
Q

What drug class is used to reduce the risk of stroke in AF patients?

A

Anticoagulants

42
Q

How can AF result in the development of a stroke?

A

The uncontrolled and unorganised movement of the atrium leads to blood stagnating in the left atrium, particularly in the atrial appendage

This stagnated blood leads to a thrombus

This clot then embolisms and travels within the blood

It travels from the atria, to the ventricle, to the aorta then up in the carotid arteries to the brain

It can then lodge in the cerebral arteries and cause an ischaemic stroke

43
Q

What type of stroke does AF cause?

A

Ischaemic

44
Q

What scoring system is used to assess whether a patient should be put on anticoagulants?

A

CHAS2DS2-VASc

45
Q

What is the CHA2DS2-VASc score?

A

Congestive heart failure (1 point)

Hypertension (1 point)

Age > 75 (2 points)
Age 65-74 (1 point)

Diabetes (1 point)

Prior Stroke/TIA/VTE (2 points)

Vascular disease (1 point)

Sex Female (1 point)

46
Q

What management option is suggested in patients with a CHA2DS2-VASc score of 0?

A

No treatment

47
Q

What management option is suggested in patients with a CHA2DS2-VASc score of 1?

A

Males - CONSIDER anticoagulation

Females - no treatment (this is because their score of 1 is only reached due to their gender)

48
Q

What management option is suggested in patients with a CHA2DS2-VASc score of 2?

A

OFFER anticoagulation

49
Q

What is the first line anticoagulant used in AF?

A

Direct oral anticoagulants (DOACs)

50
Q

What are the four DOACs used in AF?

A

Apixaban

Dabigatran

Edoxaban

Rivaroxaban

51
Q

Which DOAC is preferred in individuals with renal impairment?

A

Apixaban

52
Q

What is the second line anticoagulant used in AF?

A

Warfarin

53
Q

What is the mechanism of action of Warfarin?

A

It is a vitamin K antagonist

This prolongs the prothrombin time, which is the time it takes for blood to clot

54
Q

What is the function of vitamin K?

A

It is essential for the functioning of several clotting factors

55
Q

Why is it important that we monitor Warfarin regularly?

A

It is affected by the cytochrome P450 system in the liver. Therefore INR will be affected by drugs that influence the activity of the P45O system

It is affected by foods, particularly those containing vitamin K (leafy green vegetables) and those that affect P450 (cranberry juice, alcohol)

56
Q

How do we monitor Warfarin?

A

INR (international normalised ratio)

57
Q

What is the INR?

A

It is a calculation of how the prothrombin time of the patient compares with the prothrombin time of a normal healthy adult

58
Q

What INR reading indicates a normal prothrombin time?

A

1

59
Q

What is the target INR reading for AF?

A

2-3

60
Q

How do we reverse the effects of Warfarin when the INR is too high or bleeding has occurred?

A

Vitamin K

61
Q

What anticoagulant is contraindicated in AF?

A

Aspirin

62
Q

What scoring system is used to establish a patient’s risk of major bleeding whilst on anticoagulants/prior to administration?

A

HAS-BLED

ORBIT

63
Q

What is the HAS-BLED score?

A

It is a score based on…

Hypertension

Abnormal renal and liver function

Stroke

Bleeding

Labile INRs

Elderly

Drugs/alcohol

64
Q

What do NICE guidelines recommend in terms of assessing bleeding risk?

A

They state that a history of falls, old age and alcohol excess should not result in anticoagulation withholding

65
Q

How do we manage paroxysmal AF?

A

A ‘pill in the pocket’ approach with flecanide

This is where they take a pill to termite their AF when they feel the symptoms of AF staring

66
Q

When is flecanide contraindicated? Why?

A

Atrial flutter

It causes 1:1 AV conduction and results in a significant tachycardia

67
Q

Do we start individuals with paroxysmal AF on anticoagulation?

A

Yes - we calculate their CHA2DS2-VASc score and consider a DOAC

This is relevant is only a single episode

Year One - Cardiovascular System (20 decks)

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