Atrial fibrillation

Question 1

Atrial fibrillation

definition

range of bpm

what rhythm of heatrtbeat and why

Answer 1

Uncoordinated atrial contraction, typically at approx. 300-600 bpm

Delay at the AVN means that only some of the atrial pulses are conducted to the ventricles, resulting in an irregularly irregular heartbeat

Multiple wavelets with a chaotic reentry within the atria causes bombardment of the ventricles.

The most common sustained cardiac arrhythmia.

Question 2

pathophysiology of atrial fibrillation

Answer 2

• Atrial dilatation, volume overload or fibrosis
• Discrepancies in refractory periods (Creation of long conductive and slow conductive pathways)
• Uncoordinated relaxation/ contraction
• Partial contraction
• Numerous depolarisation waves spread out in all directions electrically neutralising what is picked up on ECG- therefore no P waves

Question 3

Causes of AF:

cardiac

non-cardiac

Answer 3

Cardiac

1. Ischaemic heart disease (most common cause in the uk)
2. Hypertension
3. Rheumatic heart disease
4. Peri/myocarditis

Non-cardiac

1. Dehydration
2. Endocrine (hyperthyroidism)
3. Infective (sepsis
4. Pulmonary causes (pneumonia or PE)
5. Environmental toxins (e.g., alcohol abuse)
6. Electrolyte disturbances (e.g., hypokalaemia)

Question 4

classifications of AF

Answer 4

1. Acute (<48 hours)
2. Paroxysmal (<7 days and intermittent)
3. Persistent (> 7 days but is amenable to cardioversion)
4. Permanent (>7 days but not amenable to cardioversion)

+ if HR is > 100 this is considered to be fast AF

Question 5

symptoms of AF

Answer 5

1. Palpitations
2. Angina
3. SOB
4. Dizziness

Question 6

Signs of AF

Answer 6

1. Irregularly irregular pulse with variable volume pulse
2. Single waveform on JVP
3. Apical to radial pulse deficit
4. On auscultation there may be variable intensity of first heart sound
5. Features of underlying cause (e.g., hyperthyroidism)
6. Features of AF complications (e.g., HF)

Question 7

complications

Answer 7

• Causes turbulent blood flow so increases thrombus formation >>> stroke or MI
• Incomplete filling of ventricles leads to a decreased cardiac output and can lead to heart failure

Question 8

diagnosis of AF (3)

Answer 8

ECG

Echocardiography

TFTs

Question 9

diagnosis of AF via ECG

Answer 9

1. Absent P waves
2. Fibrillatory F waves between QRS complexes (irregular in timing and morphology)
3. Baseline undulations
4. Irregularly irregular R-R intervals

Question 10

basic ECG physiology

• standard Pr interval
• QRS duration
• standard ST interval
• QT interval

Answer 10

Standard PR interval_;_ 0.12 0.20 seconds // 3-5 small squares

QRS duration; 0.08 0.12 secs // 2-3 small squares

Standard ST interval; 0.08 0.12 secs // 2-3 small squares

Q-T interval; 0.35 0.43 secs

Question 11

principles of investigation and. management- SSSS

Answer 11

1. Stroke risk
2. Symptom severity
3. Severity of AF burden
4. Substrate severity

Question 12

methods to detect AF

Answer 12

Question 13

History for AF

Answer 13

Question 14

management of AF

Answer 14

ABCDE- if unstable then initiate immediate DC cardioversion

Consider reversible causes:

Infection- give antibiotics and fluids

Dehydration- give fluids

Replace abnormal electrolytes

Start to think of rate control, rhythm control or electrical cardioversion

Question 15

When to offer rate control in AF

Answer 15

First line in everyone unless patient:

• Has a reversible cause to AF
• Has heart failure thought to be caused primarily by AF
• Has new-onset AF

Question 16

how do you manage someone in acute AF who has syncope, shock, heart failure or angina?

Answer 16

DC cardiovert them

if this fails use amiodarone

do not delay this to start anticoagulation

Question 17

how do you treat someone who has been in AF <48 hours and is stable?

Answer 17

rate or rhythm control (rate go to)

for rhythm, DC cardiovert or give flecainaide (unless ACS). start LMWHeparin

Question 18

how would you treat someone in who has been in AF for >48 hours or unclear time of onset ?

Answer 18

rate control (e.g., bisprolol or diltiazem)

if you choose rhythm control they must have been anticoagulated for at least 3 weeks prior

Question 19

What is rate control

Answer 19

1. A rate limiting calcium channel blocker (e.g., dilitiazem or verapamil) as initial monotherapy (better than beta blocker if asymptomatic)
2. A B-blocker (e.g., bisprolol) (they can’t be used in people with hypotension) OR
3. Consider digoxin (cardiac glycoside which increases the force of contraction and slows rate) monotherapy for people with paroxysmal AF or heart failure, only if they live a sedentary lifestyle

Question 20

What is rhythm control

Answer 20

1. Chemical cardioversion
   
   1. Flecainide (preferrable in younger patients// “pill in the pocket”), dofetilide, propafenone, amiodarone (controls both rate and rhythm)
   2. Adenosine for SVT
2. Electrical DC cardioversion (+sedation)
   
   1. When patient haemodynamically unstable

Lower rate to at least 120 first and try to anticoagulate (heparinised) them first if they have been in AF for 48 hours+

Shouldn’t be cardioverted if they’ve been in AF for 48hrs+ unless anticoagulated for 3 weeks min

atrial ablation possible in those that have an identifiable cause.

Question 21

What is HAS-BLED

Answer 21

Score for assessing risk- balance to anticoagulation

Question 22

what is CHA2DS2-VASc

Answer 22

Question 23

management for preventing stroke risk

Answer 23

long-term anti-coagulation therapy

1. NOAC- Novel Oral Anti-Coagulant
   
   1. -direct thrombin inhibitor (e.g., Dabigatran)
   2. -factor Xa inhibitors (e.g., Rivaroxaban, apixaban, edoxaban)
2. Vitamin K antagonist
   
   1. -warfarin (especially valvular AF)
3. Low molecular weight heparin

Question 24

ECG for Afib

Answer 24

Question 25

atrial flutter

Answer 25

• Circus movement also, travelling in a single large wave
• Rapid rate of atrial contraction at 200 350 bpm
• Signals reaching the atria are too fast for all of them to be conducted
• Therefore 2;1/ 3;1 ratio of Pwaves to QRS
• Sawtooth baseline