Atrial Fibrillation & Flutter

Question 1

Define atrial fibrillation

Answer 1

A chaotic, irregular atrial rhythm at 300-600bpm; the AV node responds intermittently, hence an irregular ventricular rate.

Question 2

What does CO drop by in AF and why?

Answer 2

10-20% as ventricles aren’t reliably filled by the atria

Question 3

What are the overall causes of AF?

Answer 3

Any condition resulting in raised atrial pressure, increased atrial muscle mass, atrial fibrosis or inflammation and infiltration of the atrial fibrillation.

Question 4

What is the pathophysilogy of AF?

Answer 4

AF is caused by multiple “wandering” re-entry circuits within the atria, as well as some ectopics often arising from the distal pulmonary vein. These re-entry circuits are often caused by atrial enlargement as a result of an underlying pathology of the heart.

Question 5

Give two bullet points which outline cause of AF

Answer 5

• Re-entry circuits as a reuslt of unidirectional block

- Rapidly firing ectopic focus that drives the atria into fibrillation

Question 6

How is the chaotic contraciton of the atria not conducted to the ventricles/

Answer 6

This chaotic rhythmn is prevented from spreading to the ventricles by refractory tissue at the AV node so that only some of the ventricles are conducted, in a very irregular fashion.

Question 7

Give two reasons AF is potentially dangerous

Answer 7

1) Rapid ventricular rates compromising cardiac output resulting in hypotension and pulmonary congestion (especially in individuals with hypertrophied or stiff left ventricles)
2) The absence of organized atrial contraction promotes blood stasis in the atria leading to an increased risk of thrombus formation

Question 8

Give four symptoms of AF

Answer 8

• Chest pain
• Palpitations
• Dyspnoea
• Faintness

Question 9

When do symptoms of AF come on?

Answer 9

These symptoms will usually come on when ventricular rate is about 140-160

Question 10

What is a pulse deficit?

Answer 10

o Apical ventricular pulse rate is often greater than the radial rate and the 1st heart sound is of variable intensity. This is because ventricle may be unable to produce contraction large enough to generate a pulse wave. This is called a pulse deficit.

Question 11

What signs will you see in on examination in AF?

Answer 11

Patients may have pulse deficit
Patients may have signs of acute stroke due to thrombus formation
Loss of a waves in the jugular venous pulse1

Question 12

What tests do you do to diagnose AF?

Answer 12

ECG
Echocardiography
Thyroid function tests

Question 13

What does the ECG show in AF?

Answer 13

Absent p waves
Irregularly irregular R-R intervals
Sometimes wide QRS complex (could be WPW)

Question 14

How do you diagnose paroxysmal AF?

Answer 14

24 hour ambulatory tape

Question 15

What is AShman phenomenon

Answer 15

AF may cause a phenomenon which mimics ventricular extrasystoles or ventricular tachycardia due to short R-R intervals following long R-R, lengthening the refractory period of the bundle of his and causing an RBBB morphology

Question 16

What is one looking for on electrocardiography of someone with AF

Answer 16

left atrial enlargement, left ventricular wall motion abnormalities suggesting past or present ischemia, valvular disorders and cardiomyopathy.

Question 17

What is the immediate management of acute AF?

Answer 17

• O2
• U+Es
• Emergency cardioversion/IV amiodarone if unavailable
• Treat associated illness

Question 18

How do you control ventricular rate in acute AF

Answer 18

1) Verapamil or bisoprolol
2) Digoxin or amiodarone
Start full anti-coagulation with LMWH

Question 19

What is the process of DC cardioversion in AF?

Answer 19

O2->ITU/CCU->GA or IV sedation-> 200J -> 360J -> 36J0

Relapses back into AF are common and drug cardioversion (Amiodarone/Flecainide) is often preferred

Question 20

What are the three priorities in chronic AF?

Answer 20

rate control, rhythm control and adequate anti-coagulation

Question 21

When would you want good rhythmn control and when do you not care?

Answer 21

rhythm control may be appropriate in symptomatic/younger/idiopathic/AF from a corrected metabolic abnormality.

Otherwise rate control is fine

Question 22

When is rate control prioritised?

Answer 22

Rate control is usually prioritised in patients who have the permanent form of the arrhythmia or have failed cardioversions in the past, and is usually used to produce a block at the AV node.

Question 23

When is rate considered controlled in AF?

Answer 23

HR

Question 24

What three drug classes can be used for rate control?

Answer 24

• B blocker
• Rate limiting Ca2+ blocker
  o Verapamil/Diltiazem
• Digoxin

Question 25

How is DC cardioversion prepared for in AF?

Answer 25

Cardioversion is the first line for rhythm control. It is preceded by taking sotalol or amiodarone for 4 weeks if there is an increased risk of cardioversion failure.

Question 26

How can chemical cardioversion be achieved?

Answer 26

• flecainide is 1st choice if there is no structural heart disease
• IV amiodarone is there is structural

Question 27

Give two alternatives to chemical cardioversion

Answer 27

AV node ablation, maze procedure, pacing and pulmonary vein ablation.

Question 28

What is the acute anti-coagulation in AF?

Answer 28

• Use heparin if AF started

Question 29

What is the chronic anticoagulation in AF?

Answer 29

• Anticoagulation with warfarin and aim for an INR of 2-3
• Aspirin is a less suggested alternative and is used if warfarin is contraindicated.
• Dabigatran (a direct thrombin inhibitor) maybe an alternative to warfarin

Question 30

What scoring system is used to predict stroke risk?

Answer 30

CHAD2DS2 VASc score

Question 31

What does chad2ds2 vasc scoring measure?

Answer 31

• Heart failure
• Diabetes
• Hypertension
• Vascular disease
• Aged> 65
• Female
• AND 2 points for
• Age >75
• Prior TIA, stroke/thromboembolism

Question 32

What is acute AF?

Answer 32

Acute AF is new-onset AF lasting

Question 33

What is paroxysmal AF?

Answer 33

Paroxysmal AF is recurrent AF that typically lasts

Question 34

What is persistent AF?

Answer 34

Persistent AF lasts > 1 wk and requires treatment to convert to normal sinus rhythm.

Question 35

What is permanent AF?

Answer 35

Permanent AF cannot be converted to sinus rhythm. The longer AF is present, the less likely is spontaneous conversion and the more difficult is cardioversion because of atrial remodeling (rapid atrial rate-induced changes in atrial electrophysiology that are dominated by a decrease in atrial refractoriness and may also include increase in spatial dispersion of atrial refractoriness slowed atrial conduction velocity, or both).

Question 36

Define atrial flutter

Answer 36

Atrial flutter is characterized by rapid, regular atrial activituy at a rate of 180-350bpm. Many of these fast impulses reach the AV node during its refractory period and do not conduct to the vevntricles.

Question 37

What is the pathophys of atrial flutter?

Answer 37

In general atrial flutter is caused by reentry over a large anatomically fixed circuit. In the common form of atrial flutter this circuit involves a specific pathway that runs through the interatrial septum and the roof and free wall of the right atrium.

Question 38

Why does atrial flutter have a saw toothed pattern?

Answer 38

The “saw toothed pattern” ocurs because large parts of the atrium are depolarized throughout the cycle given the p waves a sinusoidal appearance.

Question 39

Why does slowing of the atria in atrial flutter cause ventricular tachycardia?

Answer 39

Slowing of the atria in atrial flutter can cause a ventricular tachycardia as the atrial conduction reverts for 2:1 to 1:1.