Ventricular Arrhythmias Flashcards
what causes ventricular arrhythmias?
SA and AV nodes fail to pace the heart leading to no atrial activity
examples of ventricular arrhythmias
premature ventricular contractions (PVC) idioventricular arrhythmias (ventricular escape rhythm) agonal rhythm VT VF torsades de pointes asystole PEA
what are premature ventricular contractions (PVCs)?
ectopic beats that arise from irritable sites in the ventricles
causes of premature ventricular contractions?
exercise stress caffeine heart disease electrolyte imbalances hypoxia tricyclic antidepressants digoxin toxicity
management of premature ventricular contractions
reduced CO can lead to HF, VT, VF
oxygen
lidocaine
procainamide
what is a ventricular escape rhythm (idioventricular arrhythmia)?
last ditch effort by the ventricles with a rate of 20-40bpm
causes of ventricular escape rhythm
digoxin
MI
metabolic/ hyperkalaemia
cardiomyopathy
management of ventricular escape rhythm
usually leads to cardiac arrest so atropine, pacing
dopamine if hypotension
CPR
define agonal rhythm
<20bpm
frequently seen in unsuccessful resuscitation efforts
causes of agonal rhythm
trauma
acute MI
natural progression to death
management of agonal rhythm
CPR
when is VT seen?
almost always occurs in diseased hearts
what is ventricular tachycardia?
rhythm where 3 or more PVCs arise in sequence at a rate of greater than 100bpm
causes of VT
heart disease myocardial ischaemia prolonged QT electrolyte imbalance digoxin toxicity CHF
management of VT
CPR amiodarone lidocaine cardiovert chronic= ICD or ablation if re-entry
what is VF?
multiple weak ectopic foci in the ventricles
no coordinated contraction as impulses not through normal conduction pathway
causes of VF
AMI untreated VT electrolytes hypothermia drug toxicity/ overdose trauma
management fo VF
CPR
cardiovert
mimicked by electric razor or shivering
what is torsades de pointes?
VT associated with prolonged QT interval
causes of torsades de pointes
prolonged QT VT drugs phenothiazine or tricyclics overdose electrolytes (hypokalaemia and hypomagnesaemia)
what drugs cause prolonged QT
metformin
erythromycin
ramipril
management of torsades de pointes
CPR
eliminate predisposing factors
magnesium sulphate bolus
cardioversion or defib if unstable
what is asystole?
ventricular standstill
causes of asystole
myocardial damage secondary to AMI failure of pacemaker tamponade prolonged VF PE
what is PEA?
absence of pulse and myocardial activity but electrical activity is still present
causes of PEA
hypovolaemia (MOST COMMON) hypoxia acidosis hypo/hyperkalaemia hypothermia toxins tamponade tension pneumothorax thrombosis trauma massive MI overdose on tricyclics
