Arrhythmia: Atrial fibrilation (Complete)

Question 1

Define atrial fibrilation

Answer 1

Type of arrythmia characterised by rapid, uncoordinated atrial contraction (around 300-600 bpm).

(Delay in the AV node means that only some of the atrial impulses reach the ventricles resulting in irregular ventricular response).

Question 2

Atrial fibrilation is most common at which ages?

Answer 2

At advancing ages >80 years

Question 3

What are cardiac causes of atrial fibrilation? (4)

Answer 3

Ischaemic heart disease

Hypertension

Rheumatic heart disease (mainly the mitral valve)

Myocarditis

Question 4

What are non-cardiac causes of atrial fibrilation? (6)

Answer 4

Dehydration

Electrolyte disturbances (E.g. hypokalaemia, hypomagnesaemia)

Endocrine causes (e.g. hyperthyroidism)

Infective causes (e.g. sepsis)

Pulmonary causes (e.g. PE or pneumonia)

Environmental toxins (e.g. alcohol abuse)

Question 5

What are the four main types of atrial fibrilation?

Answer 5

Acute AF: Lasts < 48 hours

Paroxysmal AF: Lasts < 7 days and is intermittent

Persistent AF: Lasts > 7 days but can be cardioverted

Permament AF: Lasts > 7 days and cannot be cardioverted

Question 6

What are the main symptoms of atrial fibrilation?

Answer 6

Palpitations (pounding, fluttering or beating irregularly)

Chest pain (anginal chest pain if they have ischaemic heart disease)

Shortness of breath (due to AF related cardiomyopathy)

Dizziness

Question 7

What are the main signs of atrial fibrilation? (4)

Answer 7

Irregularly irregular pulse

Single waveform on JVP

Variable intensity of heart sounds on auscultation

Features suggestive of HF due to AF

Question 8

What presentation of AF indicates the need for immediate treatment?

Answer 8

If there is AF alongside ventricular tacchycardia (known as Fast AF)

Question 9

What investigations should be conducted for patients suspected of having AF? (5)

Answer 9

Bedside:
ECG: No p-waves
Basic obs: Check haemodynamic stability

Bloods:
FBC
Serum magnaesium
U&Es: Pottasium
Calcium
TFT
CRP: Signs of infection

Imaging:
Echocardiogram (rule out other cardiac pathologies or identify causes)

Question 10

What is the management plan for patients with Fast AF? (3)

Answer 10

ABCDE approach

If haemodynamically unstable (e.g. shock, syncope, chest pain, pulmonary oedema): Immediate DC cardioversion

Treat reversible causes:
Infection: ABs
Dehydration: IV fluids
Electrolyte imbalance: Replace electrolytes

Question 11

When is DC cardioversion offered in management of AF?

Answer 11

If patient is haemodynamically unstable

If patient has an acute new AF which has presented <48 hours then can be cardioverted with sedation

Question 12

What is the main management plan for AF?

Answer 12

Rate control:
Beta-blocker (e.g. bispropolol)
Rate-limitting calcium-channel blocker (e.g. dilitazem).

N.B. Do not offer in patients with reversible causes, have HF secondary to AF or new-onset AF.

Rhythm control: Used for patients with longstanding history of AF or if AF > 48 hours

Electrical cardioversion

Pharamcological: (e.g. Flecanide, amiodarone [lots of side-effects], soltalol).

Anticoagulation
DOAC or Warfarin
Based off of risk (CHA2DS2-VASc score) and bleeding risk (HASBLED score)

Question 13

What is the main beta-blocker used in treatment of AF? What are some of the contraindictions for using this medication?

Answer 13

Bispropolol

Contraindictions:
COPD and Asthma
Hypotension (will drop the BP)

Question 14

Rate-limitting Calcium-channel blockers used in treatment of AF is contraindicted in which type of patient? (2)

Answer 14

Patients with HF

Avoided in young patients (due to increase in cardiac mortality)

Question 15

What medication can be given to patients to treat AF if beta-blockers or CCB are contraindicted?

Answer 15

Digoxin (Outdated medication used to be 1st line)

(Useful for hypotensive patients or those with HF)

N.B. Avoid in younger patients as it increases cardica mortality

Question 16

What scoring system is used to determine risk of embolism/stroke in patients with AF?

Answer 16

CHA2DS2-VASc score

Score of 2 or more

(Score of 1 in males you can consider but not 1 in females as the point is only due to their sex)

Question 17

What scoring system is used to measure bleeding risk in patients when considering anticoagulant treatment?

Answer 17

HAS-BLED or ORBIT score

Question 18

List examples of DOACs

Answer 18

Apixaban

Rivaroxaban

Dabigatran

Question 19

What are some of the complications that can arise from AF or its treatment? (3)

Answer 19

Heart failure

Systemic emboli: Stroke, Mesenteric ischaemia, Acute limb iscahemia

Bleeding: GI, Intractranial [Due to anticoagulation]

Question 20

Why does digoxin require close monitoring?

Answer 20

Has a very narrow window between therapeutic effects and toxicity

(Small dose increases can have toxic effects)

Question 21

What ECG changes are characteristic of digoxin treatment?

Answer 21

Down-sloping ST deppresion

N.B. Digoxin alters resting membrane potential in the ventricles leading to downsloping appearance

Question 22

What are some complications of amiodarone?

Answer 22

Pneumonitis (Can lead to pulmonary fibrosis due to being lipophillic and accumulating in tissues with high fat content such as in the lungs)

Hypothyrodism and hyperthyroidism (high idodine content)

Liver failure

Grey skin

Corneal deposits

SJS

Question 23

Give 2 examples of drugs which have adverse interactions with amiodarone

Answer 23

Warfarin (amiodarone decreases warfarin metabolism so increases INR)

Digoxin (Increases digoxin levels so increased risk of toxicity)

Question 24

What are some presentations of digoxin toxicity?

Answer 24

Dizziness

Nausea and vomiting

Palpitations (due to arrhythmias)

Bradycardia typically without hypotension

Yellow-green colour disturbance

Visual haloes

Confusion

Hyperkalaemia (note that hypokalaemia is a risk factor for toxicity)

Question 25

How are patients with >48 hours AF treated if they are being considered for long term rhythm control?

Answer 25

Give rate control (e.g. beta-blocker or CCB)

Give anticoagulation for at least 3 weeks before attempting rhythm control (typically electrical cardioversion)

Question 26

What is management for patients post electrical cardioversion if succesful?

Answer 26

If AF <48, no further anticoagulation needed

If AF >48 and hence done as elective procedure, must anticoagulate for at least 4 weeks.