Flashcards in AF Deck (17):
What is atrial fibrillation?
What is the bpm?
How much does cardiac output fall by?
A chaotic, irregular atrial rhythm at 300-600bpm, the av node responds intermittently, hence irregular ventricular ryhthm.
CO drops by 10-20%
In which demographic is AF common (percentage).
What is the main risk?
How do you reduce this risk?
What should you do on everyone with an irregular pulse?
Elderly (around 9%)
Main risk is embolic stroke.
Warfarin reduces risk from 4%\yr to 1%
Do ECG on everyone with irregular pulse (24 he of dizzy, faint, palpitations)
Common causes of atrial fibrillation
Mitral valve disease
Caffeine or alcohol
Low potassium or magnesium
Associated: obesity, diabetes, CKD
Symptoms of atrial fibrillation
Signs of AF
Irregulary irregular pulse
Apical rate greater than radial
1st heart sound of variable intensity
Signs of LVF (Orthoptera, pink frothy sputum)
Tests for AF
ECG: absent p waves and irregular QRS complex.
Bloods: U&Es, cardiac enzymes, thyroid function.
Consider ECHO to look for atrial enlargement, mitral valve, poor LV function and other structural abnormalities.
Classifications of AF
Initial Episode: <30 secs diagnosed with ECG
Paroxysmal >2 episodes within 7 days
Persistent: over 7 days
Long standing: over 12 months
Permanent: decision by patient and clinician to cease further attempts to restore or maintain SR
What are the aims of AF management?
Ventricular rate control
Correction of rhythm disturbance (in some)
Optimal management of concomitant cardiovascular disease
How is AF related to stroke?
Increases risk by 5%
Af present in 15-20% of acute strokes
Strongest risk factor in 80+
Associated with larger infarcts, increased disability, death, long term care and recurrence
How to assess risk for stoke.
CHF or LVEF <40% 1
Age > 75 2
Vascular disease 1
Age 65-74 1
Sex Category 1
- Overall score of >2 (2.2%\yr stoke) offer oral anticoagualation
- Over 1 consider
DO NOT use aspirin. Review.
How to assess risk for bleed
Abnormal renal and liver function (1 each) 1/2
Liable INRs 1
Elderly (<65) 1
Drugs or alcohol (1 each) 1/2
Maximum 9 points
What is acute AF?
How to manage.
If unwell/haemodynamically unstable:
- Emergency cardioversion, if unreliable try IV amiodarone.
Do not delay to start anti-coagulation.
Treat underlying cause: MI, pneumonia
Control ventricular rate:
1 verapamil 40-120 mg/8h po or Bisoprolol 2.5mg-5.0mg/d po
2. Digoxin or amiodarone
Start full anticoagulation with LMWH, to keep options open for cardioversion even if 48hr limit is running out.
If 48h period has elapsed, cardioversion ok if trans oesophageal echo thrombus-free
Describe cardioversion regime
DC and medical
- Coronary care unit
- General anaesthetic or Iv sedation
Monophasic: 200J, 360J
Relapses are common.
Amiodarone IVI (5mg/kg over 1 hr) or PO (200mg/8hr in 1 wk)
Or flecainide (strong negative ionotrope)
Rate control should normally be offered at 1st line therapy. For which patients would rhythm control be more appropriate?
- symptomatic (reversible cause)
- heart failure due to AF
- new onset A
What drugs are used for rate control?
- Beta- blocker
- calcium channel blocker
- digoxin if fails or non-paroxysmal Af for sedentary patients in heart failure.
- combination therapy of b blocker, diltiazem, digoxin
NB do not give bb with dilitiazem or verapamil without expert advise. Risk Bradycardia.
Describe rhythm control
Flecainide (non structural)
IV amiodarone structural heart disease
Do echo 1st and pre-treat with >4 weeks with amiodarone
Catheter Ablation: of triggers e.g. Pulmonary veins.
Paroxysmal af 'pill in pocket' sotalol or flecainide pr