The 2021 Resuscitation Council (UK) guidelines emphasise that the management of bradycardia depends on:

• 1. identifying the presence of signs indicating haemodynamic compromise - 'adverse signs'
• 2. identifying the potential risk of asystole

Adverse signs

The following factors indicate haemodynamic compromise and hence the need for treatment:

• shock: hypotension (systolic blood pressure < 90 mmHg), pallor, sweating, cold, clammy extremities, confusion or impaired consciousness
• syncope
• myocardial ischaemia
• heart failure

Atropine (500mcg IV) is the first line treatment in this situation.

If there is an unsatisfactory response the following interventions may be used:

• atropine, up to a maximum of 3mg
• transcutaneous pacing
• isoprenaline/adrenaline infusion titrated to response

Specialist help should be sought for consideration of transvenous pacing if there is no response to the above measures.

Potential risk of asystole

The following are risk factors for asystole. Even if there is a satisfactory response to atropine specialist help is indicated to consider the need for transvenous pacing:

• complete heart block with broad complex QRS
• recent asystole