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
How is rhythm control achieved?
Single cardioversion event
Long term medical rhythm control
What is immediate cardioversion?
AF presents less than 48 hours or patient is severely haemodynamically unstable
What is delayed cardioversion?
AF presents for more than 48 hours & they are stable
What is necessary for delayed cardioversion?
Patient should be on anti-coagulants for minimum 3 weeks prior & have rate control
2 types of cardioversion?
Pharmacological Cardioversion
Electrical Cardioversion
1st line pharmacological cardioversion?
Flecanide. amiodarone
Second line pharmacological cardioversion?
- Sedation/general
- Using cardiac defibrillator to drive controlled shocks until sinus rhythm
1st line long term rhythm control?
Beta blockers
Dronedarone
Amiodarone
What is paroxysmal AF?
AF that comes and goes in episodes of usually less than 48 hours
How should paroxysmal AF patients be treated?
Consider pill in pocket approach
- take only when they feel AF symptoms coming on
- Need to have infrequent episodes without underlying structural heart disease and also fully understand how to identify an episode and when to take treatment
What is usually used for paroxysmal AF?
Flecanide
Why do you need to take anti-coagulants in AF?
Because the uncontrolled movement of atria results in blood stagnating in left atrium which eventually leads to thrombus which then mobilises and becomes an emblous in the blood
This travels to atria-ventricles-aorta- Carotid arteries- brain
What does an embolus eventually possibly block?
Cerebral arteries resulting in ischaemic stroke
What is warfarin?
Vitamin K antagonist
How to measure how anti-coagulated a patient is on warfarin?
INR (international normalised ratio)
What does an INR of 1 mean?
Normal prothrombin time
What does an INR of 2 mean?
Twice as long to forma blood clot
What are NOACs?
NOvel anticoagulants
Examples of DOACs?
Rivaroxaban
Dabigatran
Apixaban
What are DOACs?
Direct acting anti-coagulants
no way to reverse their effects although they lower bleeding risk and have a relatively short half life
Advantages of NOACs compared to warfarin?
- No monitoring required
- No major interaction problems
- Slightly better at preventing strokes in AF
- Slightly less risk of bleeding
What is used to assess whether patient with AF should go on anti-coagulants?
CHA2DS2VASc score
Higher the CHA2DS2VASc score the ———–risk of having a stroke?
Higher
0 CHADSVASC score?
No anti coagulation needed
1 on CHA2DS2VASc score?
Consider anti-coags
2 on CHA2DS2VASc score?
Offer anti-coagulation
CHA2DS2VASc score pneumonic?
C- Congestive heart failure H- Hypertension A- Age over 75 (2) D- Diabetes S- Stroke/TIA (2) V- Vascular disease A- Age (65-74) S- Sex (female)
Assessment tool for establishing patients risk of major bleeding whilst on Anti-coags?
HASBLED
Pneumonic of HASBLED?
H- Hypertension A- Abnormal renal & liver function S- Stroke B- Bleeding L- Labile INRs E- Elderly D- Drugs or alcohol
