Arrhythmias 2 - Atrial Fibrillation Flashcards
what is atrial fibrillation?
= chaotic and disorganises atrial activity
= irregular heart beat
what 3 things can atrial fibrillation be?
what is the most common type of arrhythmia?
1) paroxysmal
2) persistent
3) permanent (chronic)
= sustained arrhythmias
is atrial fibrillation always symptomatic?
NO
- It can be symptomatic or asymptomatic
when does the incidence of atrial fibrillation increase?
incidence increases with age
what is the mechanism of AF?
= ectopic foci in muscle sleeves in the Ostia of pulmonary veins
how can you terminate AF?
1) anti-arrhythmic drugs
- for pharmacologic cardioverson
2) electrical cardioverson
3) spontaneous reversion to sinus rhythm
describe paroxysmal atrial fibrillation?
= lasting less than 48hours
= often recurrent
describe persistence AF?
= an episode of AF lasting greater than 48hours, which can still be cardioverted to NSR
- unlikely to spontaneously revert to NSR
describe permanent AF?
= inability of pharmacologic and non-pharmacologic methods to restore NSR
what are some associated diseases/casues with AF?
1) Hypertension
2) Congestive heart failure
3) Sick sinus syndrome
= ‘tachy brady syndrome’
4) Coronary heart disease
5) Obesity
6) Thyroid disease
Familial
7) Cardiac Valve disease
8) Alcohol abuse
9) Congenital heart disease
10) Cardiac surgery
11) COPD, Pneumonia,
12) Septicaemia,
13) Pericarditis, tumors
14) Vagal cause – high endurance athletess
what is lone (idiopathic) aF?
= absence of any heart disease & no evidence of ventricular dysfunction
- a diagnosis of exclusion
what could be lone (idiopathic) AF cause?
what is a significant risk factor of AF?
= genetic factors
= stroke
what are symptoms of AF?
when are symptoms the worse?
1) palpitations
2) Pre-syncope (dizziness)
3) syncope
4) chest pain
5) dyspnea
6) sweatiness
7) fatigue
at onset of AF
describe the changes seen on an ECG?
1) Atrial Rate: > 300 bpm
2) Rhythm: Irregularly irregular
3) Ventricular Rate: Variable
- Dependent upon:
= AV node conduction properties
= Sympathetic and parasympathetic tone
= Presence of drugs with act on the AV node
4) Recognition:
- Absence of P waves
- Presence of ‘f’ waves
when might AF with slow ventricular rate co-exist?
may co-exist with periods of fast VR
what might be required to allow for pharmacological control of fast VR?
= pacemaker
when AF goes so fast what happens?
pseudo-regularisation (fat regularisation)
= goes so fast it looks regular
what happens to atrial kick, filling time and cardiac output in AF?
1) lost atrial kick
2) decreased filling times (reduced diastole)
= reduced cardiac output
what can AF result in?
= congestive heart failure, especially in presence of diastolic dysfunction
what does a ventricular rate of < 60BPM suggests?
suggest AV conduction disease
- caution with anti-arrhythmic & rate controlling drugs
- may require permanent pacing
how do you manage AF?
1) rhythm control
= aiming to maintain SR
OR
2) rate control
= aim to accept AF but control ventricular rate
= anti-coagulants for both approaches if high risk for thromboembolism
what 3 drugs could you use to slow down AVN conduction?
= ventricular RATE control
1) digoxin
= increase vagal tone
= slowing down heart rate
2) beta-blockers
e. g. bisoprolol, propanolol, atenolol
3) verapamil, diltiazem
(Calcium channel blockers = heart rate slowing)
= alone or in combination
what 2 things could you do for rhythm control?
1) restoration of normal sinus rhythm (NSR)
2) maintenance of normal sinus rhythm (NSR)
how would you restore NSR?
RHTHYM CONTROL
1) pharmacologic cardioversion (anti-arrhythmic drugs e.g. amiodarone)
2) direct current maintenance of NSR
how would you maintain NSR?
1) anti-arrhythmic drug
2) catheter ablation of atrial focus / pulmonary veins
3) surgery
what does electrical cardio version aim to do?
= immediate restoration of sinus rhythm
Aims to;
- terminates arrhythmia by delivery of dose of electrical current to heart at a specific moment in cardiac cycle
describe the 4 classes ofanti-arrhythmic drugs?
1) reducing Na+ channel current
e. g. lignocaine, quinidine, flecainide, propafenone
- blocks Na+ channel curent
- slowing cardiac depolarisation (phase 0)
- slowing conduction
2) B-adrenergic antagonists
e. g. propanolol
3) action potential prolongation
e.g. amiodaronne
sotalol
drondarone
4) Ca channel antagonists
e. g. verapamil
what are characteristics of torsades de pointes (TdP)?
- HR 200-250BPM
- rhythm = irregular
- long QT interval
- wide QRS complex
- continuously changing QRS morphology
who is at high risk of thrombo-embolism?
1) Valvular heart disease ( MS > MR)
2) Age >75 especially female
3) Hypertension
4) Heart failure (LVEF < 0.35)
5) Previous thromboembolism/ stroke
6) Coronary artery disease, or diabetes and > 60 years old
7) Thyrotoxicosis
what are 2 indications of anti-coagulation in AF?
1) valvular AF
= mitral valve disease: MS and MR
2) non-valvular AF = age > 75 = hypertension = heart failure = pervious stroke/thrombo-embolism = CAD/DM = diabetes
what are the 2 aims for radio-frequency in AF?
1) to maintain SR
- by ablating AF focus (usually in pulmonary veins)
2) for rate control
- ablations of AVN to stop fast conduction to the ventricles
what does left atrial catheter ablation for AF do?
isolates triggers in pulmonary veins by pulmonary in LA vein isolation
+/- lines of block
what is atrial flutter?
= rapid and regular form of atrial tachycardia
what is atrial flutter usually?
= paroxysmal
how is atrial flutter sustained?
by macro-re-entrant circuit
- circuit is confined to right atrium
- episodes can last from seconds to years
what does chronic atrial flutter usually progress to?
atrial fibrillation
what might an atrial flutter result in?
= thrombo-embolism
how could you treat atrial flutter?
1) RF ablation
2) pharmacological therapy
- slow ventricular rate
- restore sinus rhythm
- maintain sinus rhythm once converted
3) cardioversion
4) warfarin for prevention of thromboembolism
