Atrial Fibrillation Flashcards
How does the SA node usually work?
Produces organized electrical conductivity coordinating contraction of the atria
How does SA node work in A fib?
Contraction of atria is uncoordinated, rapid & irregular. This is due to disorganised activity from SA node
What does a lack of P waves on an ECG convey?
Lack of P waves, reflecting lack of coordinated atrial electrical conductivity
-This leads to irregular conduction of electrical impulses to ventricles
What does irregular conduction of electrical impulses to ventricles result in?
- Irregularly irregular ventricular contractions
- Tachycardia
- Heart failure
- Risk of stroke
Presentation of A fibrillation?
Patients often asymptomatic however can present with
- Palpitations
- SOB
- Syncope (dizziness/fainting)
- Symptoms of associated conditions
Differential diagnosis for an irregularly irregular pulse?
- Atrial fibrillation
- Ventricular ectopics
How do you decide between A Fib and ventricular ectopics?
Differentiated using ECG.
Ventricular ectopics disappear when heart rate goes above a threshold for example in exercise
What does A Fib look like on an ECG?
Absent P waves
Narrow QRS complexes (tachycardia)
Irregularly irregular ventricular rhythm
Assumption for patients with valvular AF?
If they have AF but also mitral stenosis/mechanical valve the assumption is vascular pathology has lead to A Fib.
Non-valvular atrial fibrillation is?
AF without valve pathology
Causes of A fib + pneumonic?
mrs SMITH gets AFIB S- Sepsis M-Mitral valve disease I- Ischaemic heart disease T- Thyrotoxicosis H- Hypertension
2 principals of treating AF?
Control rhythm or rate
Anticoagulation (prevents stroke)
Why do you need to control heart rate in AF?
Increased HR means less time for ventricles to fill up with blood and decreased CO
Aim is to get HR under 100BPM
What should all AF patients have as first line treatment?
Rate control
Reasons why rate control shouldn’t be used as first line treatment for AF?
AF has reversible cause
AF is of new onset
AF is causing HF
They remain symptomatic despite rate control
Drug options for rate control?
- Beta blockers: 1st line (atenolol)
- CCB diltiazem (not preferable in HF)
- Digoxin (only in sedentary people)
Who is rhythm control for?
All patients who can’t have rate control for specific reasons
Aim of rhythm control?
Return patient to normal sinus rhythm