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ALS/GIC > Peri-arrest arrhythmias > Flashcards

Peri-arrest arrhythmias Flashcards

1
Q

What does an arrhythmia occuring after initial resuscitation from cardiac arrest suggest?

A

That the patients condition is still unstable and there is a risk of further cardiac arrest

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2
Q

Wat are the 3 main classifications of arrhythmias ?

A

Tachycarrhytmias
Bradyarrhythmias
Arrhythmias with normal heart rates e.g. hypokalaemia.

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3
Q

What should be your general approach to all arrhythmias?

A
  • ABCDE - assess for life-threatening features
  • ECG monitoring
  • 12-lead ECG
  • IV access
  • If hypoxic give Oxygen.
  • Document heart rate and nature of the arrhytmia
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4
Q

What features suggest an arrhythmia is life-threatening ?

A
  • Shock
  • Syncope
  • Heart failure
  • Myocardial ischaemia - chest pain &/or ECG changes
  • Extremes of HR
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5
Q

When heart rate increases what happens to dialstole and systole ?

A

Both are decreased but diastole is shortened to a greater degree

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6
Q

Consider what happens to diastole and systole as heart rate increases and how this might affect cardiac output in a extreme tachycarrhythmia

A
  • Particularly in very fast heart rates >150bpm
  • As HR increases there is a reduction in cardiac output (as diastole is shortened and the heart does not have enough time to fill ==> decreased SV)
  • Aditionally there will be decrease coronary blood flow potentially causing ischaemia
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7
Q

When does the majority of coronary blood flow occur ?

A

Because these vessels traverse the myocardium, myocardial contraction during systole compresses arterial branches and prevents perfusion. Therefore, coronary perfusion occurs more during diastole rather than systole

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8
Q

Regarding bradycardia, HR below what is generally poorly tolerated ?

A

<40bpm

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9
Q

Why do patients with pre-existing heart disease tolerate bradycardia less well ?

A

They cannot compensate for bradycardia by increasing stroke volume (CO = HR x SV).

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10
Q

What are the 4 general tx options for an arrhythmia?

A
  1. No treatment
  2. Simple clinical intervention e.g. vagal manoeuvres, percussion pacing
  3. Drug treatment
  4. Electrical - cardioversion for tachyarrhythmias and pacing for bradycarrhythmias.

If arrhythmia develops due to an underlying condition e.g. AMI, infection, heart failure etc. Make sure to afterwards tx the underlying condition.

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11
Q

Why is electrical mx of an arrhytmia the preferred option over drugs if the patient is unstable ?

A

Because drug tx usually works more slowly and less reliably

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12
Q

Life-threatening signs associated with a tachycarrhythmia are uncommon under what HR?

A

<150bpm

Note - if underlying heart disease or co-morbid they might be unstable with HR’s <150bpm.

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13
Q

If a patient has life-threatening signs associated with a tachyarrhytmia what should you do ?

A

Synchronised cardioversion (upto 3 attempts)

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14
Q

If synchronised cardioversion fails to terminate an arrhythmia and adverse features persist what should you do?

A
  • Give IV amiodarone 300mg over 10-20mins
  • Then attempt further synchronised cardioversion
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15
Q

Why is it important to ensure when cardioverting a tachyarrhythmia it is set to deliver a synchronised shock?

A

So that it coincides with an R-wave. Otherwise there is a risk of coinciding with a T-wave and causing VF.

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16
Q

What should be given to the patient when carrying out synchronised cardioversion?

A
  • Concious sedation e.g. midazolam
  • Or GA.
17
Q

What energy should be selected for broad complex tachyarrythmias ?

What energy should be selected for narrow complex tachyarrythmias ?

A

Broad complext - start with 120-150J
Narrow complex - start with 70-120J. Except AF start with max defibrillator output.

18
Q

If cardioversion is attempted for AF or atrial flutter what defib pad positions should be used? (if feasible)

A

Antero-posterior

19
Q

If a patient has a tachyarrythmia with no life-threatening features and you want to treat it what will you do ?

A

Drug therapy - choice depends on arrythmia type.

20
Q

A regular broad complex tachycardia could be ventricular or supraventricular with bundle branch block in origin. What is the safest approach to treating these arrythmias?

A

To treat all regular broad complex tachycardia as VT unless there has been a prev. diagnosis of SVT with bundle branch block.

Treat with amiodarone 300mg IV over 20-60mins then 900mg over 24hrs. If tachycardia persists after initial 300mg consider DC cardioversion.

21
Q

What is the most likley cause of an irregular broad complex tachycardia?

What are the other potential causes of irregular broad complex tachycardia?

A

AF with bundle branch block.

Others - AF with ventricular pre-exitation (WPW syndrome) or polymorphic VT (TdP)

22
Q

If someone is stable with TdP what is the treatment ?

A
  • IV Mg2+ 2g over 10mins + correct hypokalaemia and stop QT prolonging drugs.
  • Obtain expert help.

Note - often they are unstable and will need cardioversion or usual defibrillation if no pulse.

23
Q

List the potential causes of a regular narrow complex tachycardia ?

Do the same for irregular narrow complex tachycardias.

A
  • Regular narrow complex tachycardias - Sinus tachy, paroxysmal SVT, atrial flutter with reg AV conduction
  • Irregular narrow complex tachycardias - Most likely AF, sometimes atrial flutter with irregular AV conduction.
24
Q

Would you attempt to correct ‘treat’ sinus tachycardia ?

A

NO - this is a physiological response in sick patients, correcting it will usually make them worse.

25
Q

Is paroxysmal SVT usually life-threatening ?

A

No even in WPW patients, but often causes frightening symptoms.

It might be if underlying structural heart disease or coronary disease.

26
Q

What is the typical atrial flutter 2:1 block heart rate?

A

Usually 150bpm (atrial rate is 300bpm ==> ventricular is 150bpm).

27
Q

In the absence of life-threatening features what is the treatment of regular narrow complex tachycardias?

A
  1. Attempt vagal manoeuvres (carotid sinus massage or valsalva manoeuvre) + record a 12-lead ECG during each manoeuvre. Look out for this revealing atrial flutter waves as the HR slows.
  2. If no response then give a rapid bolus of adenosine 6mg IV.
  3. If no response repeat with 12mg IV adenosine and then if needed 18mg.
  4. If adenosine is contraindicated or fails to terminate rhythm then consider giving verapamil 2.5mg IV or a beta-blocker e.g. metoprolol 2.5mg IV.
  5. If narrow complex tachycardia persists then consider sync cardioversion.
28
Q

Vagal manoeuvres or adenosine will terminate almost all paroxysmal SVT’s, what does failure to terminate a regular narrow complex tachycardia with there use suggest?

A
  • It suggests an atrial tachycardia i.e. atrial flutter.
  • Exception to this is if the adenosine wasnt give quick enough or into a peripheral vein.
29
Q

If someone has life-threatening features and a irregular narrow complex tachycardia you would carry out sync cardioversion, what wold you start alongside this but not delay cardioversion in order to give?

A

Anti-coagulation either LMWH or unfractionated heparin.

30
Q

If there are no life-threatening features and someone has a irregular narrow complex tachycardia what tx could you give ?

A

Either:
* Rate control - with beta-blocker, CCB or digoxin
* Chemical cardioversion - propafenone or flecanide (more effective options but cant use if LVSD, IHD or prolonged QTc), amiodarone 300mg IV then 900mg over 24hrs.
* Sync cardioversion.

31
Q

What is the general cut-off time for immediately (on presentation) treating someone with chemical or electrical cardioversion for AF and why?

A

If in AF >48hrs do not cardiovert them until anticoagulated for >= 3weeks or had a trans-oesophageal echo to rule out atrial thrombus.

If life-threatening features however then crack on and cardiovert then anticoagulate for >= 4weeks.

32
Q

If someone with known or undiagnosed WPW presents with pre-exitation AF what should you avoid ?

A
  • Adenosine, diltiazem, verapamil or digoxin.
  • These drugs block AV node and may make exitation worse.
33
Q

What are the causes of bradycardia ?

A
  • Physiological e.g. athletes, sleep
  • Cardiac - AV block or sinus node disease
  • Non-cardiac; vasovagal, hypothermia, hypothyroidism, hyperkalaemia
  • Drug-induced; Beta-blockers, diltiazem, digoxin, amiodarone
34
Q

What is the treatment of bradycardia with life-threatening features?

A
  1. Atropine 500mcg IV can be repeated upto 3mg, given every 3-5mins
  2. If inadequate response consider cardiac pacing. If pacing cannot be achieved promptly consider 2nd line drugs (isoprenaline, adrenaline or dopamine (2.5-10mcg/kg/min).
35
Q

When should you consider using aminophylline instead of atropine for bradycardia tx ?

A

In bradycardia complicating acute MI, spinal cord injuries, or cardiac transplantation.

Do not use atropine for cardiac transplant patients (this is because their hearts are denervated and will not respond to vagal blockade by atropine which may cause paradoxical sinus arrest or high-rade AV block).

36
Q

In life-threatening bradycardia with no response to atropine or atropine is contraindicated what should you do ?

A
  • Transcutaenous pacing.
  • Can do percussion pacing at 50-70bpm whilst setting up cardiac pacing.
37
Q

When should you consider temporary transvenous pacing or early PPM insertion?

A
  • Documented asystole (ventricular standstill >3s)
  • Mobitz type II AV block
  • CHB

ALS/GIC (14 decks)

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