Lecture 25: Stroke and Atrial Fibrillation Flashcards
What is atrial fibrillation?
Supraventricular tachycardia characterised by disorganised atrial electrical activity, resulting in absence of significant atrial depolarisation
What is the ventricular rate during atrial fibrillation?
Rapid and irregular
What is the ECG like during atrial fibrillation?
No P waves
What are the symptoms of atrial fibrillation?
- Feeling breathless or having difficulty beathing
- Dizziness, lightheaded or feeling faint
- Feeling your heart racing (palpitations)
- Tiredness or weakness
- Chest discomfort
- Difficluty exercising
How is atrial fibrillation diagnosed?
- ECG
- Holter monitor
- Loop recorder
- Echo: doesnt diagnose, just shows damage to heart muscle
- Blood results: doesnt diagnose - helps rule out underlying conditions - diabates, hyperthyroidism, anaemia, renal function, high cholesterol
Why does atrial fibrillation need to be managed?
- To reduce the risk of developing embolic stroke – anticoagulants
- Reduce the risk of developing heart failure/ LVSD
What is the CHADSVAS score?
- Chronic heart failure
- Hypertension
- Age
- Diabetes
- Stroke/ TIA
- Vascular diseases (IHD, PAD)
- Sex (female at a higher risk)
What are the treatment options for atrial fibrillation?
- Warfarin
- Direct oral anticoagulant: Apixaban or Edoxaban
What is the standard dose of apixaban?
5mg BD
When do you reduce the dose of apixaban?
If 2 of these are met:
- Age >80
- Weight <60kg
- Creatinine >133micrmol/ l
Reduce to 2.5 mg BD
What is the standard dose of edoxaban?
60mg OD
When do you reduce the dose of edoxaban?
Reduce to 30mg OD if CrCl 15-50ml/ min
What is rate control?
Slowing the heart rate
What is rhythm control?
get back into sinus rhythm
How can symptoms of atrial fibrillation be resolved?
Controlling the ventricular rate in patients with atrial fibrillation can resolve symptoms by using AV blocking drugs
What are the AV blocking drugs?
- beta-blockers
- non-dihydropyridine calcium channel blockers (verapamil)
- digoxin
What is first line treatement for rate control?
Beta blockers (atenolol)
How do beta blockers alleviate symptoms of atrial fibrillation?
Antagonise beta-receptors, resulting in decreased conduction through the AV node, which reduces the heart rate in patients with atrial fibrillation.
How do calcium channel blockers alleviate symptoms of atrial fibrillation?
- reduce AV conduction by antagonising voltage gated calcium channels, decreasing intracellular calcium.
- reduce left ventricular contractility via the same mechanism, and therefore contraindicated in patients with left ventricular systolic dysfunction (LVSD).
How do calcium channel blockers alleviate symptoms of atrial fibrillation?
- reduce AV conduction by antagonising voltage gated calcium channels, decreasing intracellular calcium.
- reduce left ventricular contractility via the same mechanism, and therefore contraindicated in patients with left ventricular systolic dysfunction (LVSD).
What is a rate contorlling drug?
Digoxin
What is 1st line treatment in patients with acute heart failure symptoms and AF?
Digoxin
How does digoxin work?
blocks the sodium/potassium ATPase pump.
How should digoxin be prescribed?
Recommended to use digoxin in combination with a beta-blocker or non-dihydropyridine calcium channel blocker because its effective to reduce ventricular rates at rest but not effective during physical activity.
What are the rhythm controlling drugs?
- amiodarone
- flecainide
What class of drug is amiodarone?
Class III
What class of drug is flecainide?
Class IC
How does amiodarone work?
Blocks potassium channels
What is the half life of amiodarone?
42 days
How does flecainide work?
maintain sinus rhythm or chemical cardioversion
What is a contraindication of flecainide?
Significant coronary artery disease
What is pill in the pocket?
Someone prone to symptoms of AF but doesn’t want to be on long term medication so they keep 2 tablets of flecanide and take whenever they have symptoms
When should Direct Current CardioVersion (DCCV) be done?
If patient:
- haemodynamic unstable
- Has SBP < 90 mmHg
- Has Chest pain / heart failure symptoms
- Reduced conscious level
- Known onset of AF (<48 hours)
What is a stroke?
Stroke is a clinical syndrome characterised by sudden onset of rapidly developing focal or global neurological disturbance which lasts more than 24 hours or leads to death.
What is a transient ischaemic attack?
transient (less than 24 hours) neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without evidence of acute infarction
What is a thrombotic stroke?
Blood clot (thrombus) blocks flow of blood in the brain
What is an embolic stroke?
Fattty plaque or blood clot (embolism) breaks away and flows to the brain where it blocks an artery
What is cerebral hemorrhage?
Break in blood vessel in the brain
What is a lacunar stroke?
Small vessels deep in the brain affected
What is a thrombotic stroke in large vessels?
hyperlipidemia with unstable plaque
What is Cardiogenic (Embolic) stroke
Clot moves from the heart and lodges in a vessel in the brain
What are the initial potential complications of strokes?
- Haemorrhagic transformation of ischaemic stroke
- Cerebral oedema.
- Seizures.
- Venous thromboembolism
- Cardiac complications
- Infections
What are the Long-term potential complications associated with a stroke?
- Mobility problems: Hemiparesis or hemiplegia (weakness on one side of the body), Ataxia (lack of co-ordination of movement), Falls,
Spasticity and contractures. Spasticity is common following stroke and can lead to discomfort, pain, difficulties for carers and restriction of activities. - Sensory problems
- Continence problems
- Pain
- Dysphagia (difficluty swallowing)
- Visual problems
What is acute stroke care?
- Admit to stroke unit
- Imaging - CT scan
- Swallow
- Assess medicines - STOP all anticoagulants, thrombolytics, antiplatelets and NSAIDs pending CT result
What are the complications of a thrombolysis?
- Intra –cerebral haemorrhage
- Angioedema
- Bleeding-minor bleeding is common (IV site)
- Anaphylaxis
What is secondary prevention for stroke?
- Antiplatelets/Anticoagulants: Aspirin given on day of admission
- Blood pressure: don’t want to lower BP too much & reduce perfusion to vital organs
- Cholesterol: Atorvastatin 40 mg – 80 mg is used 1ST line. Statins should NOT be used in patients with haemorrhagic stroke unless risk of vascular event outweighs risk of haemorrhagic event.
- Diabetes: high incidence of stroke in patients with diabetes
- Exercise: overwieght increase risk of stroke, smoking increses risk and alcohol
When should aspirin be avoided?
Avoided for 24 hours post thrombolysis as it would increase the risk of bleeding.
What is given to patients in sinus rhythm with a stroke?
- 14 days aspirin 300 mg then clopidogrel 75 mg daily
- Clopidogrel 75mg (unlicensed in TIAs)
