Atrial Fibrillation

Question 1

Describe in basic terms what AF is

Answer 1

The SA node is disregulated, sending multiple signals, resulting in fibrillation rather that contraction of the atria, resulting in a loss of atrial kick

Question 2

What are some risk factors for AF

Answer 2

HTN, heart disease, valvular disease (pt heart in an ineffective state), obesity, diabetes, genetic predisposition

Question 3

Stress on the atria causes……

Answer 3

Tissue heterogeneity, whereby the cells develop different electrical properties, causing unpredictable electrical signals

Question 4

What dose paroxysmal AF refer too

Answer 4

Intermittent AF

Question 5

Over time paroxysmal AF leads too…..

Answer 5

Over time these episodes lead to more stress on the atria more (calcium overload) leading to progressive fibrosis (scarring) leading to more persistent AF

Question 6

Symptoms of AF

Answer 6

Fatigue, dizzy, SOB, weakness, Palpitations

Question 7

Why are people in AF at an increased risk of stroke

Answer 7

Atria is quivering, not pumping blood effectively, thus blood in the atria can become stagnant.
When clots dislodge they can end up in the brain

Question 8

What class of drug is metoprolol

Answer 8

Beta blocker

Question 9

Beta blocks block…..

Answer 9

The affect of adrenaline or noradrenaline on the sympathetic nervous system

Question 10

What is activated when the SNS is activated

Answer 10

Catecholamines, which stimulates adrenaline and noradrenaline to be thrown at organs leading to increase HR and other affects of adrenaline

Question 11

What receptors are stimulated when fight or flight is activated

Answer 11

Adnergic receptors, alpha and beta

Question 12

Beta blockers antagonise (block)…….

Answer 12

B adrenergic receptors

Question 13

Beta blockers all end in the suffix…

Answer 13

Olol

Question 14

How dose inhibiting B1 help AF

Answer 14

Decreases HR and cardiac output, helping the heart to fill slower and regain an atrial kick, becoming a more effective pump

Question 15

Treatment If the patient is not compromised or is mildly compromised(rate over 120)

Answer 15

Administer 50 mg metoprolol tartrate PO.

Question 16

Treatment if If the patient is moderately compromised

Answer 16

Administer 300 mg of amiodarone IV (over approximately 30 minutes).

Administer a further 150 mg of amiodarone IV over approximately 30 minutes if the ventricular rate remains predominantly greater than 120/minute.

Seek clinical advice if backup is not available for amiodarone, or amiodarone is contraindicated.

Question 17

If the patient is severely compromised

Answer 17

Reconsider the diagnosis because it is very rare for atrial fibrillation or atrial flutter to cause severe compromise.
If the patient can obey commands:

Administer 0.5-1 mg/kg of ketamine IV (up to a maximum of 100 mg) to induce dissociation, and Cardiovert using maximum joules in synchronised mode. Repeat this once if the rhythm fails to revert.

If the patient cannot obey commands:
Cardiovert using maximum joules in synchronised mode. Repeat this once if the rhythm fails to revert.

Question 18

Patients suitable for referral to primary care are

Answer 18

Those who are known to have paroxysmal atrial fibrillation and the rhythm reverts with metoprolol PO alone.

Those who have chronic atrial fibrillation, but the rate is now controlled with metoprolol PO alone and there are no active symptoms of myocardial ischaemia.

Question 19

When do we see severe cardiac compromise in AF

Answer 19

It is rare for atrial fibrillation to be the primary cause of severe cardiovascular compromise. For this to occur it usually requires a combination of a very fast ventricular rate (160-200/minute) and severe heart disease.

If the patient is severely compromised, it is much more likely that there is another underlying condition such as septic shock and the diagnosis must be reconsidered prior to providing specific treatment for the dysrhythmia.

Question 20

Treatment of sepsis induced AF

Answer 20

Amiodarone should only be administered in the setting of sepsis if the patient is normotensive, the ventricular rate has failed to settle with 0.9% sodium chloride IV and cooling, and the patient has significant symptomatic myocardial ischaemia.

Question 21

Metoprolol mechanism of action

Answer 21

Metoprolol is an immediate release beta blocker. It antagonises (blocks) beta-1 receptors in the heart, causing a decrease in heart rate, cardiac output and blood pressure.

Question 22

Metoprolol indication

Answer 22

Adults with mild or no cardiovascular compromise as a result of fast atrial fibrillation or atrial flutter.
Adults with moderate cardiovascular compromise as a result of fast atrial fibrillation or atrial flutter, if amiodarone is not available or is contraindicated

Question 23

Metoprolol contraindications

Answer 23

Known severe allergy.

Hypotension. Metoprolol will further reduce the blood pressure

Question 24

Metoprolol cautions

Answer 24

First degree heart block. Metoprolol may cause bradycardia.

Known sick sinus syndrome without an internal pacemaker in place. Metoprolol may cause bradycardia.

Previous second or third degree heart block without an internal pacemaker in place. Metoprolol may cause worsening of heart block and bradycardia.

Asthma or COPD. Metoprolol may cause bronchospasm and should usually be withheld if the patient regularly takes bronchodilators.

Heart failure. Metoprolol will reduce cardiac output and may make heart failure worse. Pregnancy.

Question 25

Thoughts on metoprolol in pregnancy

Answer 25

Safety has not been demonstrated during pregnancy. The likelihood of administration being required in a woman who is pregnant is so low that personnel must seek clinical advice prior to administration.
May be administered if the patient is breastfeeding. Advise the patient to stop breastfeeding and seek further advice from their lead maternity carer or GP.

Question 26

Dosage of metoprolol

Answer 26

50 mg oral

Question 27

Adverse affects of metoprolol

Answer 27

Nil

Question 28

Onset of metoprolol

Answer 28

10-20 mins

Question 29

Duration of metoprolol

Answer 29

4-6 h

Question 30

Common interactions of metoprolol

Answer 30

The blood pressure effect will be potentiated by other medicines that lower blood pressure. For example, GTN, antihypertensive medicines and amiodarone.
The heart rate effects will be potentiated by other medicines that lower the heart rate. For example, amiodarone and centrally acting calcium channel blockers such as diltiazem.

Question 31

Use of metoprolol when patient is already beta blocked

Answer 31

Patients with chronic or paroxysmal atrial fibrillation/atrial flutter may be prescribed a beta blocker. Personnel should still administer metoprolol as indicated, even if the patient has taken their own beta blocker

Question 32

Mechanism of amiodarone

Answer 32

Amiodarone is an antidysrhythmic with a broad spectrum of activity.
Amiodarone has predominantly class III activity. It prolongs the action potential duration, reduces automaticity and prolongs the refractory period of atrial, nodal and ventricular tissues.
The electrophysiological effects result in a reduction in abnormal electrical activity (for example ectopy), a reduction in electrical conduction, a reduction in heart rate and a stabilisation of the SA and AV nodes.
Amiodarone also causes a small increase in coronary blood flow (although this is not usually clinically significant) and a reduction in myocardial oxygen consumption by reducing inotropy (the force of cardiac contraction).

Question 33

Indications of amiodarone

Answer 33

Cardiac arrest with VF or VT at any time after the first dose of adrenaline.
Adults with sustained VT in the absence of cardiac arrest.
Adults with moderate cardiovascular compromise as a result of fast atrial fibrillation or fast atrial flutter.

Question 34

Contrindactions of amiodarone

Answer 34

Known severe allergy.
Known severe allergy to iodine.
VT secondary to cyclic antidepressant poisoning. In this setting amiodarone administration can be associated with severe worsening of shock, without resolution of the rhythm.

Question 35

Cautions of amiodarone

Answer 35

None if the patient is in cardiac arrest.

Poor perfusion or signs of low cardiac output. Amiodarone reduces inotropy and may cause a significant fall in cardiac output, particularly when administered rapidly.

Hypotension. Amiodarone causes vasodilation and may worsen hypotension, particularly when administered rapidly.

Atrial fibrillation associated with sepsis. Amiodarone may cause a significant fall in cardiac output.

Known sick sinus syndrome without an internal pacemaker in place. Amiodarone slows the heart rate and severe bradycardia may occur following reversion of a tachydysrhythmia.

Previous 2nd or 3rd degree heart block without an internal pacemaker in place. Amiodarone slows the heart rate and severe bradycardia may occur following reversion of a tachydysrhythmia.

Pregnancy.

Question 36

Doseage of amiodarone in AF

Answer 36

Tachydysrhythmia in an adult:
300 mg IV over 30 minutes.
A further 150 mg IV over 30 minutes may be administered if the tachydysrhythmia persists.

Question 37

Admin of amiodarone

Answer 37

Tachydysrhythmia:
Place 300 mg of amiodarone in 100 ml of 5% glucose and label. 1 drop/second via a standard IV administration set will deliver 100 ml over approximately 30 minutes. Slow the rate of infusion if hypotension occurs.
The administration set will need to be flushed with 0.9% sodium chloride to ensure that all of the amiodarone has been administered.
An IV infusion over 30 minutes is the preferred method of administration. However, it is acceptable to dilute 300 mg of amiodarone to a total volume of 20-30 ml using 5% glucose or 0.9% sodium chloride. Administer this IV over 30 minutes and slow the rate of infusion if hypotension occurs.

Question 38

Adverse affects of amiodarone

Answer 38

Hypotension. Lightheadedness. Bradydysrhythmia.

Question 39

Adverse affects of amiodarone

Answer 39

Hypotension. Lightheadedness. Bradydysrhythmia.

Question 40

Amiodarone onset

Answer 40

5-10 mins

Question 41

Amiodarone duration

Answer 41

1-4 hours after a single dose.
Amiodarone is taken up into tissues and slowly released. This may result in a prolonged half-life, particularly when more than one dose has been administered. This is why many references quote a half- life of 10-60 days, but the clinical duration of effect is much shorter than this.

Question 42

Amiodarone preparation

Answer 42

Ampoule containing 150 mg in 3 ml.

Question 43

Common interactions of amiodarone

Answer 43

May potentiate the action of cyclic antidepressants in cyclic poisoning.
May cause bradycardia following reversion of dysrhythmia if the patient is taking a beta-blocker and/or a centrally acting calcium channel blocker (for example diltiazem).

Question 44

If the indication is atrial fibrillation causing moderate cardiovascular compromise, the goal of treatment is

Answer 44

to control the ventricular rate and not to revert the rhythm to sinus rhythm, although treatment with amiodarone may result in reversion of the rhythm to sinus rhythm. If a patient has been in atrial fibrillation for longer than a few days, there is a small risk that this may be associated with emboli leaving the left atrium. This is why amiodarone is reserved for patients with cardiovascular compromise that is clinically significant.

Question 45

Simple explination of amiodarone mechanism

Answer 45

Blocks channels and beta adrpergic receptors, stopping overactive signals thus stabilising heart rhythm