Arrhythmias

Question 1

What are the 4 cardiac arrest rhythms?

Answer 1

Ventricular tachycardia
Ventricular fibrillation
Pulseless electrical activity (all electrical activity except VF/VT, including sinus rhythm without a pulse)
Asystole (no significant electrical activity)

Question 2

Which cardiac arrest rhythms are shockable?

Answer 2

VT

VF

Question 3

Which cardiac arrest rhythms are not shockable

Answer 3

Pulseless electrical activity (all electrical activity except VF/VT, including sinus rhythm without a pulse)
Asystole (no significant electrical activity)

Question 4

Tachycardia treatment in an unstable patient

Answer 4

Up to 3 synchronised shocks

Amiodarone infusion

Question 5

Narrow complex tachycardias

Answer 5

AF- rate or rhythm control
Atrial flutter- BB
Superventricular tachycardias- vagal manoeuvres and adenosine

Question 6

Broad complex tachycardias

Answer 6

Ventricular tachycardia- amiodarone

Question 7

Atrial flutter- what is it and how do we treat

Answer 7

It is a re-entrant rhythm in either atrium forming a self-perpetuating loop

Atrial contraction at 300bpm. ventricular contraction at 150bpm

Saw tooth appearance

Rate/rhythm control w BBs or direct current cardioversion

Question 8

How can we treat recurrent atrial flutter?

Answer 8

Radiofrequency ablation of the tricuspid valve isthmus is curative for most patients

Question 9

Supraventricular Tachycardias (SVT) what is it?

Answer 9

Re-entry from ventricles up to atria

Question 10

SVT Mx

Answer 10

Valsalva manoeuvre- blow hard against resistance

Carotid sinus massage

Adenosine (or verapamil)

Direct current cardio version if other options fail

Question 11

Adenosine MOA and method of administration in SVT

Answer 11

Slows conduction through AV node and rests sinus rhythm

Rapid bolus

Causes brief period of asystole or bradycardia

Question 12

Key points to remember about adenosine: cautions and how to administer

Answer 12

Avoid in asthma/COPD/ heart failure/ heart block/ severe hypotension

Warn about feeling of impending doom

Give as fast IV bolus into antecubital fossa

Initially 6mg, then 12mg then a further 12 mg if no improvement between doses

Question 13

Long Term Management of patients with paroxysmal SVT

Answer 13

BBs
Ca channel blockers
Amiodarone
Radiofrequency ablation

Question 14

Wolff-Parkinson White Syndrome- what is it and how do we notice on ECG?

Answer 14

Extra pathway connecting atria and ventricles (Bundle of Kent)

Short PR
Wide QRS
Delta wave- slurred upstroke on QRS complex

Question 15

Wolff-Parkinson White Syndrome definitive treatment

Answer 15

Radiofrequency ablation of accessory pathway

Question 16

What is radiofrequncy ablation?

Answer 16

Catheter up femoral vein
Wire through venous system under X-ray guidance to heart
The ablate the abnormal area of electrical activity

Question 17

Torasdes de pointes- what is it and how do we notice on ECG?

Answer 17

Polymoprhic ventricular tachycardia

Height of QRS get smaller and smaller then larger then smaller etc

Prolonged QT due to prolonged repolarisation

This results in random spontaneous depolarisation in some areas known as afterdepolarisations which lead to ventricular contraction before proper depolarisation

Question 18

What are the 2 outcomes of torsades de pointes

Answer 18

Terminate and revert to sinus

Progress to VT

Question 19

Causes of prolonged QT

Answer 19

Long QT syndrome (inherited)

Medications- antipsychotics, citalopram, flecainide, stall, amiodarone, macrolide ABx

Electrolyte disturbance- hypOkalaemia, hypOmagnesaemia, hypOcalcaemia

Question 20

Mx Torsades

Answer 20

Correct cause eg meds or electrolyte
Mg infusion even if normal Mg

Defib if –> VT

Question 21

Long term mx of prolonged QT syndrome

Answer 21

Avoid danger meds
Correct electrolytes
BB (not sotalol)
Pacemaker or implantable defibrillator

Question 22

How do we manage unstable patients w VT?

Answer 22

Immediate cardioversion
or without pulse
Defib

Question 23

How do we manage stable patients w VT?

Answer 23

Amiodarone
Lidocaine- unless LV impariment
Procainamide

Question 24

1st degree heart block

Answer 24

Delayed conduction through AV node

PR> 0.2 seconds (5small squares or 1 big)

Question 25

What are the 2 types of 2nd degree heart block

Answer 25

Mobitz type 1/Wenckebach’s

Mobitz type 2

Question 26

Mobitz type 1 on ECG

Answer 26

Increasing PR intervals until P wave no longer results in a QRS

Question 27

Mobitz type 2 on ECG

Answer 27

Intermittent interruption of AV conduction so there are missing QRS complexes

Eg 3 P waves to each QRS would be a 3:1 block

Question 28

What is 3rd degree heart block?

Answer 28

Complete heart block!
No relationship between P waves and QRS
risk of asystole

Question 29

1st degree heart block Mx

Answer 29

Asymptomatic doesn’t need treatment, observe

Question 30

Unstable heart block or risk of asystole eg mobitz type 2, complete heart block Mx

Answer 30

Atropine 500mcg IV

If no improvement

Atropine 500mcg IV repeated (up to 6 doses)

Inotropes eg Noradrenalin

Transcutaneous cardiac pacing (defibrillator)

Permanent implantable pacemaker

Question 31

What is the MOA of atropine and SEs?

Answer 31

Atropine is an antimuscarinic
Works by inhibiting parasympathetic nervous system

SEs: pupil dilatation, urinary retention, dry eyes and constipation