Arrhythmias Flashcards
Lidocaine/mexiletine
Indication: arrythmias
- ventricular tachycardia
Class: Ib
Action:
- fast binding offset kinetics
- blocks the open/inactive Na+ channels (fast beating/ischaemic tissue)
- decrease phase 0 depolarisation - decrease conduction velocity in ischaemic tissue
ECG: prolong QRS
Side effects:
- CNS: dizziness, drowsiness
- abdominal upset
Route:
- lidocaine iv only
- mexiletine oral only
Flecainide
Indication: arrythmias
- paroxysmal AF - pill in pocket
- pharmacological cardio version in AF (IV) - no structural HD
- supraventricular arrythmias
- premature ventricular contrcations
- wolff-parkinson-white syndrome
Class: 1c
Action:
- very slow binding offset kinetics
- block open/inactivated Na+ channels - slow phase 0 in normal tissue
- increase threshold, decrease automaticity
- increase APD and refractory period in rapdily depolarizing atrial tissue
ECG: increase PR, QRS, QT
Side effects:
- pro-arrythmia and sudden death especially with chronic use
- AVOID in atrial flutter - 1:1 conduction through AV node causing ventricular tachycardia
- CNS and GI effects (local anesthetics)
Route: oral or iv
Propanolol/bisoprolol/metoprolol/esmolol
Indiction: arrythmias
- tachycardia
- re-entry arryhthmias
- atrial fibrilation - slow AVN conduction, protect ventricles
- CAN give in stable heart failure, NOT in partial AV block or acute heart failure
Class: II
Actions:
- act at beta 1 receptors in the heart (block sympathetic effect)
- pacemaker cells = decrease phase 4 depolarization, decrease AVN conduction velocity
- non pacemaker cells = increase APD and refractory period
ECG: increase PR, decrease HR
Side effects:
- bronchospasm - non selective beta2 receptors in the lungs
- hypotension
Route:
- propanolol/metoprolol = oral or iv
- bioprolol = oral
- esmolol = iv only (very short acting/half life)
Amiodarone
Indication
- rhythm control in AF with heart failure (normal = beta blocker)
- pharmacological cardio version in AF with structural HD
Class: III
Action:
Non pacemaker cells=
- K+ block - increase APD and refractory period
- Na+ block - decrease phase 0, decrease conduction
Pacemaker cells =
- beta and Ca+ block - decrease phase 4 depolarisation, decrease AVN conduction
ECG: increase PR, QRS, QT, decrease HR
Side effects:
- bradycardia
- pulmonary fibrosis
- hepatitis and jaundice
- thryoid disease
- slate grey skin
- nausea, constipation, taste disturbance
- hyperlipidaemia
- reduce dose of digoxin and monitor warfarin more closely
Route: oral or iv
Sotalol
Indication: arrythmias
- supraventricular and ventircular tachycardia
Class: III
Action:
- K+ block - increase APD and refractory period
- beta blocker - decrease phase 4 depolarisation, decrease AVN conduction
ECG: increase QT, decrease HR
Side effects:
- proarrythmia
- fatigue and insomnia
Route: oral
Verapamil/diltiazem
Indication: arrythmias
- supraventricular tachycardia - control ventricles and convert to normal sinus rhythm (re-entry around AVN)
Class: IV
Action:
- Ca+ channel blocker
- decrease phase 0, decrease conduction through AVN
- increase refractory period in AVN
- negative chronotropic and inotropic effects
ECG:
- increase PR
- increase/decrease HR - depends on BP response and baroreflex
Side effects:
- hypotension, decreased CO, sick sinus
- asystole - if partial AV block and beta blocker present
- GI problems - constipation
Route:
- verpamil = oral or iv
- diltiazem = oral
Adenosine
Indication: arrythmias
- SVTs
Class: V
Action: slows cardiac conduction through the AV node. Interrupts AV node/accessory pathway during SVT and resets it back to sinus rhythm
Route: rapid iv bolus (very short half life)
Dose: 6mg then 12mg then 12mg
Interaction: dypiramidole - inhibits reuptake of adenosine causing longer blocking of AVN/systole
Other:
- impending sense of doom - brief period of asystole/bradycardia
- avoid in asthma/COPD/heart block/severe hypotension - bronchoconstriction
Ivabradine
Indication: arrythmias
- stable angina if patient on monotherapy and cannot tolerate addition of CCB/beta blocker e.g hypotenisve
- sinus tachycardia
- reduce HR in heart failure and angina
Action: HCN channel blocker
- blocks funny current in SAN
- slows SAN
- DOESN’T effect blood pressure
Side effects:
- flashing lights
- avoid in pregnancy
Route: oral
Digoxin
Indication: arrythmias
- AF rate control (beta blocker first line)
- heart failure with arryhtmia present
Class: cardiac glycoside
Action:
- enhances vagal activity - slows AV conduction and HR
- block Na+/K+ ATPase, increase intracellular Na+, decrease activity of NCX, increase intracellular Ca+, increase force of contraction
Side effects:
- v dependent on renal function - decrease function can increase blood levels and cause extreme bradycardia
- needs monitoring and risk of toxicity
Atropine
Indication: bradycardia/AV node block
Dose: 500 micrograms IV
Action: anitmuscarinic - inhibits parasympathetic nervous system
Side effects: pupil dilatation, urinary retention, constipation dry eyes, dry mouth
