Synopsis
Classify bradyarrhythmias, identify imminent asystole and use atropine, chronotropic infusions and pacing in the correct conditional branch.
- Bradycardia is a rate, not a diagnosis; athletes and sleep can be physiological, while symptoms and conduction level determine urgency.
- First-degree AV block: every P conducts with a constant PR over 200 ms.
- Mobitz I: progressive PR lengthening before a dropped QRS; Mobitz II: fixed PR intervals with sudden non-conducted P waves.
Key red flags
Mobitz I has progressive PR prolongation then a dropped QRS; Mobitz II has constant conducted PR intervals with unexpected dropped QRS. Mobitz II indicates RCUK asystole risk even after symptoms improve.
Investigation priorities
Identify symptomatic low output and deterioration while treatment is prepared.
Management branches
Bradycardia without shock, syncope, ischaemia, severe heart failure or immediate post-ROSC state.
- Perform ABCDE, monitor, obtain 12-lead and identify reversible causes.
- If none of recent asystole, Mobitz II, complete block with broad QRS or pause over 3 seconds is present, observe and treat the cause.
Key medicines
Atropine IV500 micrograms IV; repeat every 3-5 minutes if needed to a maximum total of 3 mg.
Isoprenaline IV infusionRCUK starting rate 5 micrograms/min IV; titrate under continuous expert monitoring to perfusion and heart rate while pacing is arranged.