Arrhythmia: Atrial fibrilation (Complete) Flashcards
Define atrial fibrilation
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).
Atrial fibrilation is most common at which ages?
At advancing ages >80 years
What are cardiac causes of atrial fibrilation? (4)
Ischaemic heart disease
Hypertension
Rheumatic heart disease (mainly the mitral valve)
Myocarditis
What are non-cardiac causes of atrial fibrilation? (6)
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)
What are the four main types of atrial fibrilation?
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
What are the main symptoms of atrial fibrilation?
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
What are the main signs of atrial fibrilation? (4)
Irregularly irregular pulse
Single waveform on JVP
Variable intensity of heart sounds on auscultation
Features suggestive of HF due to AF
What presentation of AF indicates the need for immediate treatment?
If there is AF alongside ventricular tacchycardia (known as Fast AF)
What investigations should be conducted for patients suspected of having AF? (5)
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)
What is the management plan for patients with Fast AF? (3)
ABCDE approach
If haemodynamically unstable (e.g. shock, syncope, chest pain, pulmonary oedema): Immediate synchronised DC cardioversion
Treat reversible causes:
Infection: ABs
Dehydration: IV fluids
Electrolyte imbalance: Replace electrolytes
When is DC cardioversion offered in management of AF?
If patient is haemodynamically unstable
* Systolic BP <90
* Syncope
* HF or myocardial ischaemia
If patient has an acute new AF which has presented <48 hours then can be cardioverted with sedation
What is the main management plan for AF?
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)
Why is rythm control not initiated for patients presenting >48 hours after initial symptoms?
Sudden correction to sinus rythm could result in dislodging of clot increasing likelihood of stroke.
Hence rythm control is an elective procedure after 4-6 weeks on anticoagulant
What is the target heart rate for patients with AF on rythm control?
<110bpm
What is the main beta-blocker used in treatment of AF? What are some of the contraindictions for using this medication?
Bispropolol
Contraindictions:
COPD and Asthma
Hypotension (will drop the BP)
Name an example of a rate-limitting calcium channel blocker in ryhthm management of AF
Diltiazem
Rate-limitting Calcium-channel blockers used in treatment of AF is contraindicted in which type of patient? (2)
Patients with HF
Avoided in young patients (due to increase in cardiac mortality)
What medication can be given to patients to treat AF if beta-blockers or CCB are contraindicted?
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 cardiac mortality
What are the main clinical signs of digoxin toxicity?
Visual changes
* Yellow-green discoloration
* Haloes
* Blurriness
Nausea/vomiting
Diarrhoea
Confusion
Fatigue
Palpitations
Syncope
What ECG changes are suggestive of digoxin toxicity?
Downsloping ST depression - ‘Reverse Tick’
T wave changes (inversion)
Biphasic/flattened and shortened QT interval
Slight PR interval prolongation
looks like salavdor dali moustache
What scoring system is used to determine risk of embolism/stroke in patients with AF?
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)
What scoring system is used to measure bleeding risk in patients when considering anticoagulant treatment?
HAS-BLED or ORBIT score
List examples of DOACs
Apixaban
Rivaroxaban
Dabigatran
What are some of the complications that can arise from AF or its treatment? (3)
Heart failure
Systemic emboli: Stroke, Mesenteric ischaemia, Acute limb iscahemia
Bleeding: GI, Intractranial [Due to anticoagulation]
Why does digoxin require close monitoring?
Has a very narrow window between therapeutic effects and toxicity
(Small dose increases can have toxic effects)
What ECG changes are characteristic of digoxin treatment?
Down-sloping ST deppresion
N.B. Digoxin alters resting membrane potential in the ventricles leading to downsloping appearance
What are some complications of amiodarone?
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
Give 2 examples of drugs which have adverse interactions with amiodarone
Warfarin (amiodarone decreases warfarin metabolism so increases INR)
Digoxin (Increases digoxin levels so increased risk of toxicity)
What are some presentations of digoxin toxicity?
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)
How are patients with >48 hours AF treated if they are being considered for long term rhythm control?
Give rate control (e.g. beta-blocker or CCB)
Give anticoagulation for at least 4 weeks before attempting rhythm control (typically electrical cardioversion)
What is management for patients post electrical cardioversion if succesful?
If AF <48, no further anticoagulation needed
If AF >48 and hence done as elective procedure, must anticoagulate for at least 4 weeks.
