Chapter 11 Peri-arrest arrhythmias Flashcards

1
Q

How many joules would you use to cardiovert a broad complex tachycardia or atrial fibrillation?

A

120 - 150J ( go up of not effective)

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2
Q

How many joules would you use to cardiovert atrial flutter?

A

70 - 120J

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3
Q

When cardioverting an atrial tachycardia (AF, A-flutter) what is the best position to have the pads in?

A

Anterioposterior

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4
Q

When the sync is on, where on the ECG should the shock be delivered?

A

R wave

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5
Q

Why do you need to hold the shock button for a second or two when the sync is on?

A

The machine is waiting to give the shock on the R wave

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6
Q

Why does the sync turn off automatically after the 1st shock?

A

Incase the patient goes into VF, allows for rapid unsynchronised shock.
Remember to put the sync back on if you need to shock more than once.

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7
Q

If electrical cardioversion fails and adverse features persist, how fast can you give 300mg amiodarone over before trying to shock again?

A

10 -20 minutes

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8
Q

After 300mg amiodarone, what is the loading dose infusion of amiodarone and over what time-frame?

A

900mg amiodarone over 24 hours

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9
Q

A patient has a broad complex tachycardia, haemodynamically stable. You choose to give 300mg amiodarone. Over what time-frame should you give the infusion?

A

20 - 60 minutes

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10
Q

A patient has an irregular broad complex tachycardia. What is the rhythm MOST likley?

A

Atrial fibrilation with a bundle branch block.

also consider AF with ventricular pre-excitation ie wolf-parkinson white syndrome

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11
Q

How quickly should you give 10mmol magnesium to a patient with torsades depointes?

A

10 minutes (watch for and or treat hypotension)

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12
Q

How do you treat torsades de pointes (a form of polymorphic VT)

A

If pulseless: unsynchronised shock
If pulse but unstable: try synchronised shock, if not shocking take off sync
If stable:
1) stop all QT prolonging drugs
2) 10mmol magnesium over 10 minutes
3) Increase HR by overdrive transcutaneous pacing

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13
Q

What are the possible arrhythmias for a narrow complex tachycardia?

A

1) Sinus tachycardia
2) Atrioventricular nodal re-entry tachycardia (AVNRT) = most common
3) Atrioventricular re-entry tachycardia (AVRT) due to WPW syndrome
4) Atrial flutter with regular AV conduction (usually 2:1)

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14
Q

What are the four adverse features that may be seen in a tachyarrhythmia that indicate electrical cardioversion is needed?

A

1) shock
2) syncope
3) myocardial ischaemia
4) heart failure

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15
Q

How many shocks would you give to terminate a tachyarrhythmia before giving amiodarone (an then repeating again)

A

3 shocks, then
300mg amiodarone over 10-20 minutes, then
Repeat shock, then
900mg amiodarone over 24 hours

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16
Q

You assess a patient to have a narrow complex irregular tachyarrhythmia, therefore it is probably AF and you want to treat with IV metoprolol. What dose do you give?

A

1 - 2 mg IV ever 5 minutes up to total of 15mg

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17
Q

What is the IV to oral conversion rate for metoprolol?

What does 1mg IV metoprolol equal orally?

A
1 : 2.5
1mg IV metoprolol = 2.5mg oral
5mg IV metoprolol = 12.5mg oral
10mg IV metoprolol = 25mg oral
15mg IV metoprolol = 37.5mg oral
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18
Q
A patient has atrial fibrilation, you want to slow the rate but they are intolerant to beta-blockers (allergy, previous asthma triggered by beta-blocker). 
What class of drug can you use?
A

Non-dihydropyridine calcium channel blocker

Verapamil 2.5 - 5mg IV over 2 minutes. Can repeat ver 15-30 minutes to max dose 20mg

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19
Q

You have given 150mg IV amiodarone to control AF. How long do you wait before considering another 150mg dose?

A

1 hour

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20
Q

What doses of adenosine do you give for SVT?

A

6mg then
12mg then
18 mg

Monitor and record ECG continuously

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21
Q

A patient was treated for SVT successfully but then goes back into SVT. What might they need before going home?

A

Ant-arrhythmic prophylaxis

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22
Q

You think a patient has SVT (narrow complex tachycardia) but you fail to achieve sinus rhythm with adenosine.
What might the rhythm be?

A

Possible atrial flutter

Control rate with beta-blocker

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23
Q

An ECG shows an irregular narrow complex tachycardia.

What are the possible rhythms?

A
Atrial fibrillation (most likely)
Atrial flutter with variable AV conduction (variable block)
Multifocal atrial tachycardia
24
Q

A patient is sick and has a very fast sinus tachycardia. Will treating the rhythm with cardioversion or drugs help?

A

No

Treat underlying cause for sinus tachycardia

25
Q

A patient has an atrioventricular NODAL re-entry tachycardia. Are they likely to have an underlying heart disease?

A

No
AV nodal re-entry tachycardia AVNT is the most most common SVT and is often seen in people without underlying heart disease
The rhythm is often benign unless there is underlying co-incidental structure heart disease or IHD

26
Q

What is the cause of antrioventricular re-entry tachycardia AVNT?

A

Accessory pathway, Wolf-Parkinson White syndrome
Usually benign rhythm unless additional structural heart disease and when patient has atrial fibrillation (rapid conduction of atrial activity to ventricles)

27
Q

What is the success rate of using vagal manoeuvre to terminate SVT?

A

25%
Record ECG during each manoeuvre
If atrial flutter, transient slowing of ventricular response will reveal flutter waves

28
Q

How do you give adenosine?

A

Rapid IV push through proximal (cubital) vein
Follow with large flush.
Use 3-way tap to give drug then flush

29
Q

What is the success rate of vagal manoeuvres + adenosine in treating SVT?

A

Close to 100%
Consider atrial flutter if you have been unable to treat with both these techniques
(or you are giving adenosine too slowly)

30
Q

A patient has SVT and vagal manoeuvres have failed. They are allergic to adenosine. What drug can you give?

A

Verapamil 2.5 to 5mg IV over 2 minutes every 15 - 30 minutes to max 15mg

31
Q

A patient has a very rapid narrow complex tachycardia. They have no pulse and consciousness is impaired or lost. You have started CPR.
This is technically a PEA arrest. Should you deliver a shock?

A

Yes.
This is one exception from the the ALS algorithm.
This arrhythmia IS treated with cardioversion. Give a SYNCHRONISED shock at 200J.
If this fails give an unsynchronised shock.

32
Q

A patient has a very rapid narrow complex tachycardia. They have no pulse and consciousness is impaired or lost. You have started CPR.
This is technically a PEA arrest. Should you deliver a shock?

A

Yes.
This is one exception from the the ALS algorithm.
This arrhythmia IS treated with cardioversion. Give a SYNCHRONISED shock at 200J.
If this fails give an unsynchronised shock.

33
Q

How many hours of being in AF would make someone high risk of thromboembolism should you choose to cardiovert (chemical or electrical) ?

A

48 hours

34
Q

If you decide to cardiovert a patient in AF who is not anticoagulated. What drug should you commence?

A

Anticoagulation, intially either by LWMH injection at therapeutic dose or unfractioned heparin bolus then infusion.
Need to continue for at least 4 weeks.

35
Q

What is the onset of action and time to maximal effect of IV metoprolol?

A

Onset within 3 minutes, maximal effect 10 minutes

36
Q

After giving IV metoprolol, how long should you wait before giving oral metorprolol?

A

15 minutes
Howeve note effect of 20mg IV metoprolol is halved in health subjects by 6 hours. Duration of action last longer than half life.

37
Q

What is the redistribution and elimination half life of IV metoprolol

A

Redistribution half life Half life 5 -15 minutes

Elimination half life 3 -5 hours

38
Q

How is metorolol metabolised and elimination?

A

Primary hepatic metabolism, caution in hepatic impairment.

Renal elimination

39
Q

A patient is marginally hypotension and symptomtic with fast AF. You decide to cautiously use esmolol IV to see if they will tolerate a beta blocker. How is esmolol metabolised and what is its duration of action?

A

Metabolisedi by red cell esterase within 10 - 20 minutes

40
Q

What is the loading dose and infusion rate of esmolol?

A

500mcg/kg over 1 minute then
50 - 200 mcg/kg/min (increase dose by 50mcg/kg/min ever 4 min until adequate control)

For less aggressive control, omit bolus

41
Q

A patient has fast AF and heart failure. You decide to give IV digoxin. How long till onset of action? How long till peak of action?

A

Onset within 1 hour, peak 6 hours

42
Q

What is the onset of action of IV verapamil. When is the peak effect?

A

Onset 2 minutes

Peak effect 10 -15 minutes

43
Q

What is the initial and then subsequent doses of IV digoxin for rapid digitiliation?

A

IV 250 to 500mcg then
250 mcg ever 4 -6 hours until total dose of 750 to 1500mcg given
Caution renal impairment

44
Q

Why would amiodarone be considered over calcium channel blocker or beta blocker in a patient with borderline hypotension?

A

Less likely to cause hypotension
Better tolerated by critically unwell patients
For rate control, give 150mg IV over 10 minutes

45
Q

How does magnesium provide rate control ?

A

Antagonises calcium channels
10mmol over 30 minutes then 10 mmol over 2 hours
Decreases HR by 10 -15 bpm

46
Q

Is clonidine effectve for acute ventricular rate control?

A

Yes. As effective as digoxin and verapamil

47
Q

Can you give a beta-blocker and calcium channel antagonist together?

A

yes but with caution.

Contraindicated in patients with heart failure or hypotension

48
Q

What are your opteions for emergent/urgent rate control for fast AF in a patient who is hypotensive or has symptomatic heart failure?

A

Drugs: digoxin, amiodarone (but not together, amiodarone increase serum concentration of digoxin)
Cardioversion

49
Q

What is the risk of co-administratin of amiodarone and digoxin?

A

Amiodarone prolongs digoxin elimination half life by 30%

Risk of digoxin toxicity

50
Q

How do you treat a patient with Wolff-Parkinson White syndrome AND fast AF?

A

Direct current cardioversion
Usual rate slowing drugs are ineffective + adenosine, digoxin and non-dihydropyridine calcium chanel blockers are contraindicate as they can trigger ventricular fibrillation

If drug MUST be used, give amiodarone

51
Q

How long should you wait before repeating with 500mcg dose of atropine for symptomatic bradycardia?

A

3-5 minutes to total of 3mg
Note doses of < 500mcg or when given slowly can cause parodoxycal slowing of the HR.
Caution in AMI as increase in HR may worsen ischaemia

52
Q

A patient is bradycaric and you decide to give an isoprenaline infusion. What is the initial rate?

A

IV isoprenaline 5mcg/min

53
Q

A patient is bradycaric and you decide to give an adrenaline infusion. What is the initial rate?

A

IV adrenaline 2 - 10 mcg/min

54
Q

A patient is bradycardic but asymptomatic. What are the ECG rhythms or findings that put the patient at risk of asystole?

A
2nd degree heart block, mobitz type II
3rd degree (complete) heart block with broad QRS
Ventricular pauses > 3 seconds
55
Q

A patinet is bradycardic and as at least one of the following features on their ECG:
2nd degree heart block, mobitz type II
3rd degree (complete) heart block with broad QRS
Ventricular pauses > 3 seconds

Do you they need urgent treatment of their bradycardia?

A

Yes. At risk of asystole. Treat as per symptomatic bradycardia (atropine, isoprenaline or adrenaline infusion)

56
Q

Can you give atropine to patients with cardiac transplants?

A

No
Their hearts are denervated and will not response to vagal blockade
But will put them at risk of paradoxical sinus arrest or high grade AV block