Bradycardia
at the bedside
- full vitals, capillary glucose, cardiac monitor
- definition → HR < 60 bpm; usually matters below 50 bpm; treat by symptoms, perfusion and rhythm, not the number
- confirm → palpate the pulse, exclude probe artefact, 12-lead ECG
- correct hypoxemia first
- pacing pads on early if unstable or high-grade AV block
escalate now if: unstable from the bradycardia, any of
- hypotension or shock
- acutely altered mental status
- ischemic chest discomfort
- acute heart failure / pulmonary edema
- syncope or severe hypoperfusion
- any of these → atropine, then pacing; on a rate-slowing drug → toxicity
focused check
- symptoms → lightheadedness, syncope, chest pain
- drug chart → beta blockers, verapamil / diltiazem, digoxin, amiodarone, sotalol, clonidine; recent dose change, new interacting drug, possible overdose
- causes
- hypoxia
- myocardial ischemia or infarction
- hyperkalemia
- drugs above; lithium, antipsychotics, TCAs
- hypothermia, hypothyroidism
- vagal episode; raised ICP
- intrinsic conduction disease
rhythm on the ECG
| rhythm | features |
|---|---|
| sinus bradycardia | athletes, sleep, vagal tone |
| 1° AV block | PR > 200 ms, every P conducted |
| 2° type I (Wenckebach) | PR lengthens, then a dropped beat; usually benign |
| 2° type II | dropped beats with a constant PR; infranodal, pace early |
| 3° (complete) | P waves and QRS unrelated; pace |
- high-risk features → pause > 3 sec with symptoms, escape rhythm < 40 bpm, syncope with documented bradyarrhythmia, alternating bundle branch block
send now
- K, Mg and Ca; renal function
- troponin if ischemia suspected
- digoxin level if on digoxin; TSH if suspected
treat
stable or asymptomatic
- monitor; treat the cause: hypoxia, hyperkalemia, ACS, drug toxicity
- no atropine for a low rate with good perfusion and no high-grade block
- 2° type II or complete heart block, even if stable → pads on, continuous monitoring, cardiology today
unstable bradycardia
- call and prepare
- senior or resuscitation team; continuous monitoring
- pads on; IV access
- oxygen only if hypoxemic; 12-lead ECG if it does not delay treatment
- atropine 1 mg IV, repeat every 3–5 min, maximum total 3 mg
- Mobitz II or complete heart block → do not delay pacing for repeated atropine
- ACS → use with care, a faster rate can worsen ischemia
- atropine not working → any of, while arranging definitive pacing
- transcutaneous pacing
- epinephrine IV infusion 2–10 mcg/min, titrate to rate and BP
- dopamine IV infusion 5–20 mcg/kg/min
- if pacing
- increase current until electrical capture; confirm mechanical capture (pulse, BP)
- analgesia or sedation if conscious and BP allows; never delay pacing for it
- escalate → cardiology and ICU early; transvenous pacing if still unstable
special cases
- heart transplant → atropine does not work and may harm; pace, catecholamines, specialist now
- beta-blocker or calcium-channel-blocker toxicity → toxicology and ICU now; local poisoning protocol (calcium, high-dose insulin, glucagon)
- digoxin toxicity → stop digoxin, check K, digoxin-specific antibody via toxicology
- hand over → rhythm, rate trend, drugs given, pads on or not, escalation trigger
evidence
| source | type |
|---|---|
| 2025 AHA Adult Advanced Life Support | international guideline |
| 2025 ERC guidance | international guideline |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
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reviewed 17 Aug 2026updated Oct 2026file vital/heart-rate-bradycardia