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Cardiology Y1 > Atrial Fibrillation > Flashcards

Atrial Fibrillation Flashcards

1
Q

What is Atrial fibrillation?

A
  • Contraction of the atria is uncoordinated, rapid and irregular
  • Due to disorganised electrical activity which overrides normal, organised activity of SAN
  • disorganised activity in atria also leads to irregular conduction of electrical impulses in the ventricles
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2
Q

What will disorganised electrical activity in ventricles cause?

A
  • irregular irregular ventricular contractions
  • tachycardia
  • HF due to poor filling during diastole
  • Inc risk of stroke
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3
Q

How can an ischaemic stoke occur from atrial fibrillation?

A

tendency for blood to collect in the atria and from blood clots (stasis), clots can become emboli and travel to brain to block cerebral arteries

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4
Q

How does atrial fibrillation present?

A
  • usually asymptomatic but can have:
  • palpitations
  • breathlessness
  • syncope
  • symptoms of associated conditions e.g. stroke, sepsis or thyrotoxicosis
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5
Q

What are the two possible diagnosis from irregularly irregular pulse?

A

1) atrial fibrillation

2) Ventricular ectopics

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6
Q

How should irregularly irregular pulse diagnosis be differentiated?

A
  • ECG

- Ventricular ectopics disappear when heart rate is high e.g. during exercise

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7
Q

How would AF show on ECG?

A
  • absent P wave
  • narrow QRS
  • irregularly irregular ventricular rhythm
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8
Q

What are the two types of AF?

A

Valvular - AF when patients have moderate or severe mitral stenosis or mechanical heart valve (which is likely to have lead to the atrial fibrillation)
Non-valvular - AF without valve pathology or with mitral regurgitation or aortic stenosis

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9
Q

What are the common causes of AF?

A
  • Sepsis
  • Mitral Valve Pathology
  • Ischaemic Heart disease
  • Thyrotoxicosis
  • Hypertension
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10
Q

What are the two aspects of AF that need to be treated?

A

1) Rate and rhythm control

2) Anticoagulation to prevent stroke

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11
Q

What are the medications used for rate control in AF?

A

1) Beta blocker
2) CCB
3) Digoxin (only in sedentary people)

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12
Q

when should rate control not be the first line treatment for AF?

A
  • there is reversible cause of AF
  • AF is new onset
  • AF is causing HF
  • they remain symptomatic even after effective rate control
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13
Q

Why is slowing heart rate good for patients with AF?

A
  • The higher the heart the less time is available for ventricles to fill with blood so reducing the CO
  • Slower heart rate extends diastole so ventricles have more time to fill
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14
Q

When is rhythm control offered to patients?

A

(when not using rate control):

  • there is reversible cause of AF
  • AF is new onset
  • AF is causing HF
  • remain symptomatic despite effective rate control
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15
Q

What are the two ways normal sinus rhythm can return?

A

1) single ‘cardioversion’ event that returns normal rhythm

2) long term medical rhythm control that sustains normal rhythm

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16
Q

When should you use delayed cardioversion and when should you use immediate cardioversion?

A

immediate - if AF onset is shorter than 48 hours ago severely haemodynamically unstable
delayed - AF present for more than 48 hours and stable

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17
Q

Why is anticoagulation medication essential before delayed cardioversion?

A
  • anticoagulants prevent blood clot forming

- if blood clot formed, reverting back to the normal sinus rhythm has high risk of mobilising clot and causing stroke

18
Q

What are the two options for cardioversion?

A

1) pharmacological

2) Electrical

19
Q

What is the first line pharmacological cardioversion?

A 
Flecanide 
amiodarone (used in patients with structural heart disease)
20
Q

What does electrical cardioversion involve?

A

patient put under general anaesthetic and cardiac defibrillator used to shock patient

21
Q

What are the three medications used for long term rhythm control?

A

1) Beta blockers
2) Dronedarone (used when already have had successful cardioversion)
3) Amiodarone (used in patients with HF or LV dysfunction)

22
Q

What is Paroxysmal AF?

A
  • AF comes and goes in episodes

- episodes not lasting more than 48 hours

23
Q

How is Paroxysmal AF treated>

A
  • Can still be anti coagulated depending on CHADSVASc score
  • Can also use ‘pill in pocket’ approach where take flecanide is given to take whenever symptoms appear
  • ‘pill in pocket’ only used when no structural heart disease and infrequent episodes
24
Q

When should flecanide be avoided?

A

patients with atrial flutter as can cause 1:1 AV conduction and significant tachycardia

25
Q

Why is anticoagulant medication important for AF?

A
  • atrial blood is often stagnant in left atrium particularly in atria appendage
  • leads to thrombus formation
  • embolus can travel up carotid arteries to brain
  • casting ischaemic stroke
26
Q

What is the major risk of anticoagulants?

A
  • higher risk of serious bleed

- usually risk of stroke significantly outweighs risk of bleeding (bleed easier to treat)

27
Q

What scoring system is used to assess risk of serious bleed?

A

HASBLED

  • Hypertension
  • Abnormal renal/liver function
  • Stroke
  • Bleeding
  • Labile INRs (whilst on Warfarin)
  • Elderly
  • Drugs/alcohol
28
Q

What is used to assess wether a patient with AF should be started on anticoagulants?

A

CHA2DS2-VASc (if have one or more risk factors of these shouldn’t take ACs, some are worth 2 points so shouldn’t take if worth 2)

  • Congestive HF
  • Hypertension
  • Age >75 (worth 2)
  • Diabetes
  • Stroke or TIA previously (2)
  • Vascular disease
  • Age 65-74
  • Sex female
29
Q

What is the MoA of warfarin?

A
  • antagonises Vitamin K
  • Vitamin K essential for functioning of several clotting factors
  • prolongs prothrombin time (time it take for blood to clot)
30
Q

How is the extent of anti-coagulation by Warfarin measured?

A
  • INR (international normalised ratio)
  • compares prothrombin time of patient to prothrombin time of normal healthy adult
  • INR 1 = normal
  • INR 2 = Prothrombin time double normal
31
Q

What is the target INR for AF?

A

2-3 i.e. blood should be clotting 2 to 3 times slower than the normal person

32
Q

What common things will affect INR outside warfarin?

A
  • antibiotics as affect activity of P450 enzymes which metabolise Warfarin
  • Leafy green vegetables (contain Vit K)
  • Cranberry juice and alcohol (affect P450)
33
Q

What is the half life of Warfarin

A

1-3 days

34
Q

How can Warfarin be reversed in an emergency?

A

Give Vitamin K

35
Q

Give two examples of anticoagulants?

A
  • Warfarin

- NOACS/DOACS (novel anticoagulants) (now called Direct Oral anticoagulants)

36
Q

Name a DOAC?

A

Apixaban
Dabigatran
Rivaroxaban

37
Q

Why are DOACs currently used less?

A
  • still on patent so very expensive compared to warfarin

- coming off patent soon so will be far cheaper

38
Q

What is the half life of apixaban?

A

12hours

39
Q

How can DOACs be reversed?

A
  • apixaban and rivaroxaban = Andexanet alfa

- dabigatran = Idarucizumab

40
Q

What are the advantages of DOACs compared to warfarin?

A
  • No monitoring required
  • No major interactions
  • equal if not slightly better at preventing stroke in AF
  • equal if not slightly lower risk of bleeding than warfarin

Cardiology Y1 (12 decks)

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