11. Peri-arrest arrhythmias

Question 1

life-threatening features that indicate a patient with an arrhythmia is unstable?

Answer 1

shock (SBP <90, pallor, sweating, cold extremities, confusion)

syncope (TLOC due to global reduction in blood flow to the brain)

heart failure (pulmonary oedema/ raised JVP/ peripheral oedema)

myocardial ischaemia (typical ischaemic chest pain/ evidence of MI on ECG)

extremes of heart rate

Question 2

why do tachyarrhythmias reduce cardiac output so much?

Answer 2

because diastole becomes very short and the heart does not have time to fill properly

Question 3

1) treatment of a tachyarrhythmia with life threatening features?

2) if this fails and adverse features persist?

Answer 3

1) synchronised cardioversion

2) 300mg amiodarone IV over 10-20 minutes and attempt further synchronised cardioversion (this loading dose can be followed by an infusion of 900mg over 24hr)

Question 4

T/F: synchronised cardioversion should be carried out under conscious sedation or general anaesthesia

Answer 4

true

Question 5

a synchronised cardioversion shock means delivering the shock to coincide with the ___ wave

Answer 5

R
(an unsynchronised shock could coincide with the T wave and cause VF)

Question 6

for synchronised cardioversion of a broad complex tachyarrhythmia, start with what energy level?

Answer 6

120-150J and increase in increments if this fails

Question 7

T/F: for AF, start at the minimum defibrillator output

Answer 7

false - MAXIMUM

(atrial flutter and regular narrow-complex tachycardia will often be terminated by lower energy shocks- start with 70-120J)

Question 8

preferable pad position for AF/ atrial flutter?

Answer 8

A-P

Question 9

if the QRS duration is more than __ small squares wide, this is a broad complex tachycardia

Answer 9

3
(>0.12s)

Question 10

2 causes of broad complex tachycardia?

Answer 10

ventricular in origin
or supraventricular rhythm with aberrant conduction i.e. BBB

Question 11

treatment of VT with no adverse features?

Answer 11

300mg IV amiodarone over 10-60 minutes
follwed by 24hr infusion of 900mg amiodarone

Question 12

irregular broad complex tachycardia is most likely to be what?

Answer 12

AF with BBB

Question 13

treatment of torsade de pointes? (if no adverse features)

Answer 13

immediately stop all drugs known to prolong the QT interval

correct electrolyte abnormalities, especially hypokalaemia

give IV magnesium sulfate 2g IV over 10 mins

Question 14

causes of irregular narrow-complex tachycardia?

Answer 14

most likely AF, sometimes atrial flutter with variable AV conduction

Question 15

T/F: significant sinus tachycardia should be slowed with cardioversion or anti-arrhythmic drugs

Answer 15

false - it is a physiological response to stress, treat the cause as just slowing the heart will make things worse

Question 16

T/F: paroxysmal SVT is usually benign

Answer 16

true - unless there is additional structural heart disease

Question 17

stepwise treatment of regular narrow-complex tachyarrhythmia? (in the absence of adverse features)

Answer 17

1) vagal manouvres - carotid sinus massage or valsalva terminate up to a quarter of episodes)
2) adeonise 6mg as a very rapid bolus followed by a flush > then 12mg >then 18mg
3) verapmil 2.5-5mg IV over 2mins or a beta blocker such as metoprolol
4) consider synchronised cardioversion

Question 18

rarely, a very rapid narrow-complex tachycardia can impair cardiac output to such an extent that the pulse may be impalpable and consciousness is impaired or lost

treatment of this?

Answer 18

immediate synchronised cardioversion

(an exception to the non-shockable branch of the ALS algorithm)

Question 19

irregular narrrow complex tachycardia
1) caused by?
2) treatment if life threatening features?

Answer 19

1) most likely fast AF, could also be atrial flutter with variable AV conduction
2) synchronised cardioversion - aim to give anticoagulation prior to this (LMWH or unfractioned heparin)

Question 20

immediate management options for irregular narrow-complex tachycardia with no adverse features?

Answer 20

rate control by drugs
rhythm control by drugs (chemical cardioversion)
rhythm control by synchronised cardioversion
treatment to prevent complications (anticoagulation)

Question 21

people who have been in AF for >____hrs should not be treated by cardioversion (electrical or chemical) until what has been done?

Answer 21

48hrs
until anticoagulated for at least 3 weeks (or unless trans-oesophageal echo detects no evidence of atrial thrombus)

(this is because the longer you’re in AF, the greater the likelihood of atrial thrombus developing)

Question 22

if cardioversion is needed urgently in someone who’s been in AF fpr >48hrs, what should first be given?

Answer 22

either LMWH in therapeutic doses or IV bolus injection of unfractioned heparin followed by continuous infusion to maintain the APTT at 1.5-2 times the reference value

continue heparin and commence oral anticoagulation after successful cardioversion

Question 23

rate control options in fast AF?

Answer 23

usually beta blocker

diltiazem may be used if beta blockers contraindicated or not tolerated

digoxin can be used in heart failure patients but this takes longer than beta blockers to act

Question 24

when are drugs for chemical cardioversion in fast AF, like propafenone or flecainide, contraindicated?

Answer 24

heart failure
left ventricular impairment
ischaemic heart disease
prolonged QT interval

Question 25

T/F: amiodarone is often the most successful drug for chemical cardioversion in fast AF

Answer 25

false
propafenone and flecainide often more successful

Question 26

treatment of bradycardia with adverse features?

Answer 26

usually start with pharmacological treatment - IV atropine 500mcg IV repeated every 3-5 mins if necessary to a total of 3mg

cardiac pacing if bradycardia with adverse signs persists

Question 27

2 line drugs for bradycardia of specific causes
1) for beta blocker/ CCB induced bradycardia
2) digoxin toxicity
3) for bradycardia complicating acute inferior wall MI, spinal cord injury or cardiac transplantation

Answer 27

1) IV glucagon
2) digoxin-specific antibody fragments
3) aminophylline

other 2nd line options include isoprenaline, adrenaline, or dopamine

Question 28

T/F: atropine if first line management for bradycardia in cardiac transplant patients

Answer 28

false - do NOT give to these patients (their hearts are denervated and will not response to vagal blockade by atropine)