Atrial Fibrillation Flashcards
or atrial flutter
Explain to me what happens in atrial fibrillation
Electrical impulses are generated at sites other than the SA Node in the atria. these sites are called ectopic sites. commonly found at base of pulmonary vessels.
This results in random fibrillations of the atria, not all are contractions.
Because of refractory properties of AV Node, not all contractoins of atria pass through.
So it seems the atria and ventricles are contracting at random intervals to each other.
(youtube vid)
Define atrial fibrillation
DEFINITION: characterised by rapid, chaotic and ineffective atrial electrical conduction. Often subdivided into:
Permanent
Persistent
Paroxysmal
What a re the 3 types of atrial fibrillation?
Paroxysmal AF – irregular pulse that occurs sometimes and then stops. AFib stops by itself and the heart returns to normal rhythm. Recurrent episodes that stop on their own in less than 7 days
episodes lasting longer than 30 seconds but less than 7 days (often less than 48 hours) that are self-terminating and recurrent.
Persistent AF – AFib that does not stop by itself. Needs cardioversion. Recurrent episodes that last more than 7 days.
Permanent AF) – AFib that cannot be corrected by cardioversion. long-term episode
Describe HR in atrial fibrillation?
Can be slow; less than 60 bpm
Or fast; more than 100 bpm
Explain the aetiology and risk factors of atrial fibrillation
There may be no identifiable cause
Secondary causes lead to an abnormal atrial electrical pathway that results in AF
Systemic Causes; Thyrotoxicosis Hypertension Pneumonia Alcohol
Heart Causes ; Mitral valve disease Ischaemic heart disease Rheumatic heart disease Cardiomyopathy Pericarditis Sick sinus syndrome Atrial myxoma
Lung Causes;
Bronchial carcinoma
PE
Summarise the epidemiology of atrial fibrillation
VERY COMMON in the elderly
Present in 5% of those > 65 years
May be paroxysmal
Recognise the presenting symptoms of atrial fibrillation
Often ASYMPTOMATIC
Palpitations Syncope (if low output) SOB Chest pain --fatigue Symptoms of the cause of AF
What is the most common arrhythmia?
AF!
What are the signs of atrial fibrillation on physical examination?
Irregularly irregular pulse
Difference in apical beat and radial pulse
Check for signs of thyroid disease and valvular disease
Name appropriate investigations for AF?
ECG
Bloods
Echocardiogram
What would investigations in AF show?
ECG;
Undulating/Uneven baseline with absent p waves
Irregular intervals between QRS complexes
Atrial flutter = saw-tooth
Bloods; Cardiac enzymes TFT Lipid profile U&Es, Mg2+ and Ca2+
Because there is increased risk of digoxin toxicity with hypokalaemia, hypomagnesaemia and hypercalcaemia
Echocardiogram May show: Mitral valve disease Left atrial dilatation Left ventricular dysfunction Structural abnormalities
What is the difference between atrial fibrillation and atrial flutter?
They are both abnormal heart rhythms. … In atrial fibrillation, the atria beat irregularly. In atrial flutter, the atria beat regularly, but faster than usual and more often than the ventricles, so you may have four atrial beats to every one ventricular beat.
Name 4 cardiac enzymes.
Why do we look at cardiac enzymes in investigation for atrial fibrillation?
Troponin, Creatine kinase, Myoglobin, Lactate dehydrogenase
Atrial fibrillation confers a high risk of events i.e. stroke, HF and mortality.
Troponin is involved in myocyte contractility, elevated levels can foreshadow upcoming cardiovascular events.
Give a brief overview of the management plan for atrial fibrillation
First and foremost, try to treat any reversible causes (e.g. thyrotoxicosis, chest infection)
There are TWO main components to AF management:
- RHYTHM CONTROL; involves cardioversion
1b. RATE CONTROL; involves drugs
Then;
2. Manage stroke risk - anticoagualtion
last resort: ablation
In the management plan for atrial fibrillation what does rhythm control involve?
- If > 48 hrs since onset of AF;
- Anticoagulate for 6 weeks ideally (updt 2021) before attempting cardioversion
1a. If < 48 hrs since onset of AF
- Direct Current cardioversion (2 x 100 J, 1 x 200 J)
- Chemical cardioversion: flecainide or amiodarone
- NOTE: flecainide is contraindicated if there is a history of ischaemic heart disease 2. Prophylaxis against AF;
Sotalol - B blocker Amiodarone - antiarrhytmic (class 3) Flecainide - antiarrhythmic (class 1c) Consider pill-in-the-pocket (single dose of a cardioverting drug (e.g. flecainide) for patients with paroxysmal AF) strategy for suitable patients
Prolonged/ unresponsive to rounds of cardioversion and meds:
- Ablation (of bundles leading to AVN)
- should be followed by pacing ; pacemaker placement
