Drugs and Arrythmias Flashcards
Three types of rhythm disturbances + other
Ectopics
Too fast-tachycardia
Too slow- bradycardia
Disorganised- re-entrants
Device indications:
Pacemaker; defibrillator; CRT
Pacemaker: High grade AV block, sinus node disease- bradycardias
Defibrillator: Aborted sudden cardiac death/sustained VT in heart disease; high risk of SCD
CRT: LBBB, cardiomyopathy
Ectopic beat:
Atrial versus ventricular origin
Treatment
- atrial narrow complex, ventricle broad, as ot conductive system
- Most associated with reassurance. Some suppressive drug therapy if required, withdrawals of other drugs.
Common arrhythmia treatments
Assessment; reassurance; drug therapy; withdrawal of a drug; management of underlying condition; device; intervention (surgical/ablation)
Class 1 drugs
1A, 1B, 1C
Are sodium channel agents, typically blockers
1A: Quinidine, procainamide. Prolong AP
1B: Phenytoin, lidocaine, shorten AP
1C: Flecainide*, encainide, propafenone. slow conduction. Most common, little to no effect on refractory period.
Class 2 drugs
side effects
When to use
Beta blockers, slow HR. Metoprolol, atenolol, propanolol. Slows AV conduction fatigue and bradycardia Contraindictaed for asthma, not COPD Atrial and ventricular arrythmias
Class 3 drugs
Amiodarone side effets
sotalol and amiodarone can cause?
prescribed for
Potassium channel blockers/increase repolarisation. Sotalol (beta blocker low dose with class 3 activity high dose), amiodarone (also a dirty drug, with properties across other classes). Prolongs AP
Amiodarone can potentiate warfarin, raising INR higher. Need to adjust
Sotalol and amiodarone can cause pro-arrthymias
Atrial/ventricular arrythmias
Class 4 drugs
Slow calcium channel blockers
Verapamil; nifedipine; diltiazem
note verapamil ankle oedema
Other drugs/ calss 5 sort of
Digoxin: increases parasympathetic activity, slows atrial rate and AVN conduction
Adenosine: IV administration, AVN block (with some SAN effect)
Pro-arrthymia
Often caused by drugs such as sotalol and amiodarone
Can be fatal
Mechanism: prolongation of repolarisation, causing EAD’s such as in long QT (can develop into torsadesde pointes)
Increased risk of proarrythmia in heart failure
AV Nodal re-entrant tachycardia
What is it
treatment
Circuit in AV node, rapid raising heartbeat, is an SVT. Narrow complex, is a safe SVT
Ectopic trigger
Mechanical therapy
Medical therapy: adenosine for AV block and abortion, beta blocker/calcium antagonists
Ablation therapy
AV re-entrant tachycardia
Tachycardia with AVN part of its circuit.
Narrow complex SVT if going through AVN, if originates other way, broad complex
WPW??
Medical/ablation therapy
Atrial fibrillation points
- Varying symptoms
- rate versus rhythm control
- Anticoagulation issues.
- Restoring sinus rhythm for example does not lower risk of stroke.
- For a high heart rate, want to slow AVN conduction, so beta blockers, calcium channel, maybe even amiodarone, pacemaker, ablation
VT/VF:
Support; antiarrythmics; device; intervention
- Anti-ischaemic, ACEi
- BB, CCB, class 3, class 1 with ICD backup
- ICD, pacemaker
- surgery (CABG), ablation
Amiodarone: side effects, toxicity
A dirty drug, blue discolouration of face, nose
Side effects: myalgias, gait disturbance, insomnia, longer PR as potentiates warfarin (lower warfarin), digoxin toxicity (lower digoxin)
Toxicity: liver failure/toxicity (maintain by LFT’s), pulmonary fibrosis, thyroid toxicity, renal failure, corneal deposits and photosensitivity
