Cardiac arrhythmias Bradycardias < 60bpm
Aetiology ‘DIVISIONS’
Drugs Anti-arrhythmics, Beta-blockers, CCBs, Digoxin
Ischaemic/infarction
Anti-arrhythmic drugs Vaughan Williams Vagal hypertonia athletes, vasovagal syncope, carotid
classification sinus syndrome
Mechanism of Infection viral myocarditis, rheumatic fever, infective
Class Examples
action endocarditis
Ia Quinidine, Procainamide, Sodium channel Sick sinus syndrome structural damage/fibrosis to SAN,
Disopyramide blocker AVN/conducting tissue (SVT alternating w/ sinus
Note Quinidine toxicity causes Increases AP bradycardia +/- arrest
chinchonism duration Infiltration restrictive/dilated myopathy
(Headache, tinnitus, O HypOthyroid, hypOkalaemia, hypOthermia
thrombocytopaenia) Neurological Raised ICP
Procainamide can cause drug-
Surgery/catheterisation
induced lupus
Septal defect ASD
Ib Lidocaine, Tocainide, Mexilitine Sodium channel
blocker Classification
Decreases AP Sinus bradycardia
duration 1st degree heart block: PR interval > 200ms
Ic Flecainide, Encainide, Propafenone Sodium channel 2nd degree heart block: Wenkebach/Mobitz Type I +
blocker Mobitz Type II
No effect on AP 3rd degree/complete heart block
duration o Junctional: narrow QRS @ ~ 50 bpm
II Propanolol, Bisoprolol, Atenolol, Beta-adrenergic o Ventricular: broad QRS @ ~ 40 bpm
Metoprolol receptor blockers
III Amiodarone, Sotalol, Block potassium Mx If asymptomatic + rate > 40 bpm no Rx
channels
Rate < 40/urgent
IV Verapamil, Diltiazem Calcium channel
1. Rx underlying cause
blockers
2. Atropine 0.6 -1.2 g (max 3g) IV
Isoprenaline IVI
3. Pacing: external
Narrow complex tachycardias/SVT Broad complex tachycardia/VT
Definition Rate > 100 bpm + QRS complex < 120 ms Definition Rate >100bpm + QRS complex > 120 ms
DDx sinus bradycardia, atrial (AF, flutter, atrial tachycardia), AV nodal DDx 1) VT 2) Torsades de points 3) SVT w/ BBB
re-entry tachycardia (AVNRT), AV re-entry tachycardia (AVRT) Aetiology ‘IM QVICK’
Aetiology ‘DIVISIONS’
Drugs Anti-arrhythmics, Beta-blockers, CCBs, Digoxin
Ischaemic/infarction
Anti-arrhythmic drugs Vaughan Williams Vagal hypertonia athletes, vasovagal syncope, carotid
classification sinus syndrome
Mechanism of Infection viral myocarditis, rheumatic fever, infective
Class Examples
action endocarditis
Ia Quinidine, Procainamide, Sodium channel Sick sinus syndrome structural damage/fibrosis to SAN,
Disopyramide blocker AVN/conducting tissue (SVT alternating w/ sinus
Note Quinidine toxicity causes Increases AP bradycardia +/- arrest
chinchonism duration Infiltration restrictive/dilated myopathy
(Headache, tinnitus, O HypOthyroid, hypOkalaemia, hypOthermia
thrombocytopaenia) Neurological Raised ICP
Procainamide can cause drug-
Surgery/catheterisation
induced lupus
Septal defect ASD
Ib Lidocaine, Tocainide, Mexilitine Sodium channel
blocker Classification
Decreases AP Sinus bradycardia
duration 1st degree heart block: PR interval > 200ms
Ic Flecainide, Encainide, Propafenone Sodium channel 2nd degree heart block: Wenkebach/Mobitz Type I +
blocker Mobitz Type II
No effect on AP 3rd degree/complete heart block
duration o Junctional: narrow QRS @ ~ 50 bpm
II Propanolol, Bisoprolol, Atenolol, Beta-adrenergic o Ventricular: broad QRS @ ~ 40 bpm
Metoprolol receptor blockers
III Amiodarone, Sotalol, Block potassium Mx If asymptomatic + rate > 40 bpm no Rx
channels
Rate < 40/urgent
IV Verapamil, Diltiazem Calcium channel
1. Rx underlying cause
blockers
2. Atropine 0.6 -1.2 g (max 3g) IV
Isoprenaline IVI
3. Pacing: external
Narrow complex tachycardias/SVT Broad complex tachycardia/VT
Definition Rate > 100 bpm + QRS complex < 120 ms Definition Rate >100bpm + QRS complex > 120 ms
DDx sinus bradycardia, atrial (AF, flutter, atrial tachycardia), AV nodal DDx 1) VT 2) Torsades de points 3) SVT w/ BBB
re-entry tachycardia (AVNRT), AV re-entry tachycardia (AVRT) Aetiology ‘IM QVICK’
