Indications
- Bradycardia with life-threatening adverse features (shock, syncope, myocardial ischaemia, heart failure — and, in the 2025 guidelines, an arrhythmia immediately post-ROSC) that is refractory or only partially responsive to atropine, per the RCUK 2025 bradycardia algorithm.
- High risk of asystole — recent asystole, Mobitz type II AV block, complete (third-degree) heart block with broad QRS, or ventricular pause >3 seconds — even if currently stable, as a "standby" measure while arranging transvenous pacing.
- Bridging measure while awaiting cardiology and transvenous wire insertion; not a substitute for definitive pacing.
Cautions
Before you start
- Confirm the rhythm on the monitor — pacing a patient who does not need it (e.g. artefact mimicking asystole) causes unnecessary pain.
- Check pad contact and skin — wet, hairy or damaged skin raises threshold and reduces capture reliability.
- Avoid pacing directly over an implanted device if an alternative pad position is available.
Do not delay for
- A conscious, stable patient with adverse features still needs pacing promptly — do not wait for senior review if deteriorating.
- Hypothermic bradycardia can be pacing-resistant; treat the underlying cause alongside pacing.
- Cardiac transplant patients — do not give atropine (risk of paradoxical high-degree block); proceed to pacing/aminophylline per local guidance.
Preparation
- Continuous ECG, SpO2 and non-invasive blood pressure monitoring; IV/IO access secured.
- Explain the procedure to the conscious patient — pacing causes visible muscle twitching and a thumping sensation.
- Prepare analgesia/sedation (e.g. a titrated opioid and/or benzodiazepine such as midazolam) before increasing current, unless the patient is peri-arrest.
- Ensure resuscitation equipment, drugs and a defibrillator/pacer with fresh pads are immediately to hand.
- Call for senior help and arrange transvenous pacing early — external pacing is a bridge, not the endpoint.
Equipment
Pad placement
The anterior-posterior position is generally preferred and reliably avoids interference with defibrillation pad placement if arrest occurs. An antero-lateral (standard defibrillation) position can be used if posterior access is not possible.
Step-by-step technique
Apply pads and connect
Attach anterior and posterior pads to dry, clean skin; connect to the pacing lead and confirm a clear ECG trace on the monitor.
Select demand mode
Use demand (synchronous) mode wherever available — the device senses the patient's intrinsic rhythm and only paces when the rate falls below the set threshold, reducing the risk of R-on-T pacing into a native beat.
Set the rate
Conventions vary: commonly a fixed starting rate of 60–90/min, or a rate set ~30/min above the patient's intrinsic rhythm — either way, adjust to produce an adequate cardiac output.
Give analgesia/sedation
In the conscious patient, give titrated analgesia (and sedation if needed) before increasing current — pacing at capture threshold is uncomfortable.
Increase current to electrical capture
Increase the output current stepwise from a low starting point until each pacing spike is reliably followed by a wide QRS complex and broad T wave on the monitor — this is electrical capture.
Confirm mechanical capture
Electrical capture alone is not enough. Confirm a palpable femoral pulse (less confounded by skeletal muscle twitch than a radial/brachial pulse) synchronous with each paced beat, and/or improving SpO2 trace and blood pressure.
Add a safety margin
Once reliable capture is confirmed, increase the current a further increment (commonly around 10% above threshold, or per device guidance) to maintain a safety margin against drift or skin impedance changes.
Reassess continuously
Re-check capture, pulse, blood pressure and patient comfort regularly; escalate analgesia/sedation as required.
Escalate
Arrange transvenous pacing without delay — transcutaneous pacing is a temporising bridge, not a stable long-term solution, and pad/skin tolerance is limited.
Pitfalls & complications
Common pitfalls
- Mistaking skeletal muscle twitch for mechanical capture — always confirm with a central pulse or ultrasound, not the monitor waveform alone.
- Inadequate analgesia — the commonest reason a conscious patient cannot tolerate pacing at an effective current.
- Poor pad contact (hair, moisture, movement) causing high thresholds or intermittent capture.
Complications
- Pain and skin discomfort/burns with prolonged pacing.
- Failure to capture despite maximum output — consider alternative pad position or urgent transvenous pacing.
- Underlying cause untreated (e.g. hyperkalaemia, drug toxicity, hypothermia) — treat concurrently.
Documentation
- Indication (rhythm, adverse features), atropine doses given, time pacing started.
- Pad position, mode, rate, threshold current for capture, and the current used with safety margin.
- Method of confirming mechanical capture (femoral pulse, SpO2 trace, ultrasound).
- Analgesia/sedation given, ongoing monitoring plan, escalation and referral to cardiology for transvenous pacing.
Pitfalls & pearls
- Femoral pulse check beats radial/brachial for confirming mechanical capture — skeletal twitch from the pacing current can mimic a pulse more proximally.
- Do not chase electrical capture alone; a paced complex without a matching pulse is not working.
- Sedate early rather than trying to "push through" pain at high currents.
- Keep the transvenous pacing conversation going in parallel — do not treat external pacing as the finishing point.
DOPS pointers
RCEM curriculum: Core and Intermediate/Higher Procedural Skill. What assessors look for at each entrustment level:
| 1 | Observed only — can describe the bradycardia algorithm, indications for pacing and pad positions. |
| 2a | Performs with the supervisor present: correct pad placement, demand mode selection, systematic increase to electrical capture. |
| 2b | Performs with supervisor in the department: confirms mechanical capture reliably, titrates analgesia/sedation appropriately. |
| 3 | Indirect supervision: manages failure to capture, escalates promptly for transvenous pacing, treats the underlying cause in parallel. |
| 4 | Independent; can teach and supervise others, including troubleshooting difficult capture and peri-arrest decision-making. |
References
- Resuscitation Council UK. Adult Advanced Life Support Guidelines, 2025 (bradycardia algorithm).
- European Resuscitation Council Guidelines 2025: Adult advanced life support. Resuscitation 2025.
- Craig K. Using transcutaneous cardiac pacing to best advantage: how to ensure successful capture and avoid complications. Br J Cardiol (review, PMC6376978).
- RCEM Curriculum 2021 — Emergency Medicine Specialty Learning Outcomes: core and higher procedural skills (DOPS).