Arrhythmia Flashcards
Class IB
Na channel blockers e.g. Lidocaine
Lidocaine MoA
Block fast Na channels resposible for phase 0 (decrease slope)
Ventricular myocytes
No effect on SAN/AVN
rapidly depolarizing tissue- particularly post MI damage
Lidocaine use
Ventricular tachycardia (ventricular myocyte selective)
Class IC
Flecanide
Flecainide MoA
Stronger decrease phase 0 than Lidocaine
decreases automaticity
increases action potential duration
Flecainide use
Wide spectrum
Flecainide ADR
Pro-arrythmic - give B blocker to prevent ventricular tachycardia
Class II
B blockers e.g. bisoprolol
B blocker MoA
B1 receptor- SAN/AVN
decrease sinus rate, conduction velocity
decrease phase 4 (upstroke of pacemaker)
B blocker ECG effect
Increase PR
decrease HR
B blocker uses
Catecholamine dependent tachycardia (SNS)
AVN re-entry arrhtyhmias
Afib
B blocker ADR
Bronchospasm
Hypotension
B blocker warnings
AV block
Class III
K channel blockers
E.g. Amiodarone
Amiodarone MoA
Increase refractory period and AP duration
decrease phase 0
decrease phase 4 (B block and Ca block)
decrease AV conduction
Amiodarone ECG effects
Increase PR, QRS, QT
decrease HR
Amiodarone ADR
Pulmonary fibrosis
increase LDL
optic neuritis
Amiodarone DDI CYPs
Inhibits CYP2C9, CYP34A (warfarin)
Amiodarone warnings
Thyroid disease- contains iodine.
Sotalol MoA
Class II and III effects
Increase APD and refractory period
Slows phase 4
Slows AV conduction
Class IV
Ca channel blockers e.g. Verapamil
Verapamil MoA
Ca channel underlies upstroke in pacemaker cells.
slows AV conduction
increases refractory period in AVN
Increase phase 4 slope SAN
Verapamil uses
Surpaventricular tachycardia
Re-entry around AV
Verapamil DDI
B blocker- asystole
Adenosine MoA
Binds to A1 receptor
decrease CAMP –> increase K channels –> hyperpolarisation –> decrease HR
slows AVN conduction
Adenosine uses
supraventricular arrhythmia - EMERGENCY
diagnosis of coronary artery disease
Ivabradine MoA
Blocks funny current in SAN- decreases HR
Ivabradine uses
Heart failure
Sinus tachycardia
Digoxin MoA
Inhibits Na/K ATPase
Decrease HR
Increase contractility
Digoxin uses
Atrial fibrillation and flutter
Atropine MoA
Selective mAChR antagonist (M2 in the heart)
blocks vagal activity
Increases HR and AV conduction
Atropine uses
Bradycardia