Atropine first, then the risk factors for asystole
Expansion
Adverse features demanding immediate treatment: shock, syncope, myocardial ischaemia and heart failure.
Treatment ladder
- Atropine 500 micrograms intravenously, repeated to a maximum of 3 mg
- Transcutaneous pacing, or isoprenaline or adrenaline infusion
- Transvenous pacing, with expert help
Risk factors for asystole, which mandate treatment even without adverse features:
- Recent asystole
- Mobitz II second degree block
- Complete heart block with broad QRS
- Ventricular pause over 3 seconds
“Atropine works at the node, not below it.” In an infranodal block, atropine may increase the atrial rate without improving conduction, worsening the block, which is why Mobitz II and complete heart block go straight to pacing.
Atropine is also ineffective after cardiac transplantation, since the heart is denervated.
Pacemaker codes run chamber paced, chamber sensed, response: VVI paces and senses the ventricle and inhibits on sensing; DDD is dual chamber.
Reversible causes should be sought throughout: drugs (beta blockers, digoxin, calcium channel blockers), hyperkalaemia, hypothyroidism, hypothermia, raised intracranial pressure and inferior myocardial infarction.