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Intra-operative crises · Core14 / 21

Complete heart block before an urgent ureteric stent79-year-old woman, 58 kg, two weeks of dizzy spells

Complete heart block: bradycardia algorithm, pacing and failure to capture

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Know this first

  • A new broad-QRS complete block is usually infranodal; atropine is unlikely to work.
  • Atropine 1 mg every 3–5 minutes, maximum 3 mg, if tried.
  • Infranodal block is paced first; adrenaline 2–10 mcg/min or isoprenaline 2–10 mcg/min bridge to a transvenous wire.
  • Hypokalaemia potentiates digoxin toxicity; digoxin-Fab treats life-threatening toxicity.
  • Transcutaneous pacing may give electrical without mechanical capture.

The patient

79-year-old woman, 58 kg, two weeks of dizzy spells; now fever and loin pain from an obstructed infected kidney. ECG: complete heart block with a broad-complex escape rhythm at 36/min. Drugs: bisoprolol, digoxin. K+ 3.2 mmol/L. Urgent cystoscopy and ureteric stent tonight. Vitals: BP 96/54, HR 36, SpO2 95% on air, temperature 38.6 °C.

The examiner asks

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  1. Consider

    What are your concerns?

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    • A 79-year-old with complete heart block and urosepsis, for an urgent ureteric stent tonight. Patient
    • At 79, septic and bradycardic, she has little reserve and a high delirium risk.
    • A broad escape at 36 means block below the AV node; atropine is unlikely to help. Disease
    • Bisoprolol and digoxin both slow conduction, so I treat them as reversible causes. Stem trigger
    • Her potassium of 3.2 makes any digoxin toxicity worse. Disease
    • An infected obstructed kidney needs draining tonight; it can't wait for a permanent pacemaker. Surgery

  2. Prepare

    How will you prepare her?

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    • Digoxin level now; potassium 20–40 mEq IV over 30 minutes by pump, with ECG monitoring. Disease
    • Bisoprolol and digoxin held; cardiology asked for a temporary transvenous wire before induction.
    • Pacing pads on before induction, connected and tested. Crisis
    • Isoprenaline infusion at 2–10 mcg/min ready as a chemical pacemaker.
    • If digoxin toxicity is confirmed and she is unstable, digoxin-Fab is the antidote. Disease
    • Arterial line before induction; antibiotics after blood cultures.
    • If the wire is delayed: pacing with capture confirmed, or isoprenaline running, before induction. Crisis

  3. Crisis

    The cardiologist is delayed. At induction, HR falls to 28 and BP to 62/30. What do you do?

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    • Adult bradycardia algorithm: HR 28 with shock, so she is unstable. (Crisis)
    • Call for help, oxygen, stop the anaesthetic agents, tell urology to wait.
    • Pace now: the pads are on; infranodal block is paced first.
    • Atropine 1 mg only while pacing starts; her broad escape rarely responds.
    • Adrenaline 2–10 mcg/min, or isoprenaline 2–10 mcg/min, while pacing is set up.
    • Cardiology to theatre for a transvenous wire; urology's fluoroscopy is already here.
    • Reversible causes in her: digoxin, bisoprolol, low potassium, sepsis and hypoxia.

  4. Crisis

    Pacing spikes run at 70/min, but no broad QRS follows each spike and the arterial line shows HR 30, BP 58/30. What now?

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    • Failure to capture: spikes without a QRS and pulse after each one. Crisis
    • Turn the output up until every spike captures; judge capture by the arterial trace, not the ECG.
    • Check pad contact; anteroposterior pads may capture better than anterolateral.
    • Adrenaline infusion keeps her pressure up while pacing is fixed.
    • If her pulse goes: CPR, and adrenaline 1 mg every 3–5 minutes.
    • Transvenous wire under fluoroscopy as soon as cardiology arrive.
    • Afterwards: coronary care, permanent pacemaker review, digoxin-Fab if toxicity is confirmed. After surgery

Fatal mistakes

  • Inducing her without pacing ready.
  • Relying on atropine alone for broad-complex complete heart block.
  • Missing digoxin toxicity with a low potassium.
  • Trusting pacing spikes on the ECG without a pulse.

Checked against: Miller 10e · Faust · Stoelting 8e · AHA guidelines: adult advanced life support (2025) · AHA guidelines: special circumstances of resuscitation (2025)

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