Bradyarrhythmias and heart block

Management— do this, in order

• Position and oxygen first: lie the patient flat and raise the legs — free preload where stroke volume is nearly fixed, which may abort a vagal bradycardia outright — and correct hypoxaemia, which in children may be the entire treatment.
• Access and monitoring: intravenous access, continuous ECG monitoring, a defibrillator with pacing pads at the bedside, and a 12-lead ECG with a rhythm strip running through every intervention.Doctor / NurseNot available at your setup — Defibrillator.
• Correct the chemistry: potassium, magnesium and calcium; hyperkalaemia causes bradycardia with broad complexes and will arrest the patient before the block does, so tall tented T waves, broad QRS and flat or absent P waves justify treatment on the ECG before the result returns.Doctor / NurseNot available at your setup — Serum electrolytes. Tall tented T waves, broad QRS and flat or absent P waves on the ECG justify treating hyperkalaemia before any laboratory result is available.
• Stop the culprit: withdraw non-essential rate-slowing drugs, including beta-blocker eye drops, before diagnosing intrinsic conduction disease.
• Atropine, adult: 0.5–0.6 mg IV bolus, repeated every 3–5 minutes to a maximum cumulative 3 mg; source ranges differ — 0.5 mg initially (range 0.5–2 mg), or 0.6–1.2 mg repeated as required, and 3 mg in asystole.Doctor / Nurse
• Never give a single atropine dose below 0.5 mg — sub-therapeutic doses cause paradoxical vagotonic slowing.
• Atropine, child: 20 microgram/kg IV/IO, minimum single dose 100 microgram, maximum single dose 600 microgram, and may be repeated once; reserve it for clearly vagal bradycardia and for organophosphate poisoning.Doctor / Nurse
• In complete heart block, atropine 1 mg intravenously usually restores AV conduction temporarily, but if the escape complex is wide or repeated doses are needed, temporary ventricular pacing is indicated.Doctor / Nurse
• If atropine fails — isoprenaline: 2 mg in 500 mL of 5% dextrose at 10–60 mL/hour (4 microgram/mL, about 0.7–4 microgram/min); or a bolus of 20–60 microgram then 2–20 microgram/min; or simply 2–20 microgram/min titrated to the desired rate.Doctor / NurseNot available at your setup — Infusion pump.
• Dopamine 5–20 microgram/kg/min IV, increased by 5 microgram/kg/min every 2–5 minutes (paediatric dose the same, 5–20 microgram/kg/min IV/IO); extravasation causes tissue necrosis.Doctor / NurseNot available at your setup — Infusion pump.
• Adrenaline where the patient is both bradycardic and hypotensive: infusion 2–10 microgram/min IV titrated to rate and blood pressure; in children adrenaline, not atropine, is the first-line drug — bolus 10 microgram/kg IV/IO (0.1 mL/kg of 1:10 000) every 3–5 minutes, or infusion 0.05–0.3 microgram/kg/min.Doctor / NurseNot available at your setup — Infusion pump.
• When drugs fail, pace — transcutaneous pacing is the most expeditious technique. Use it in demand mode for sinus bradycardia below 50 beats/min unresponsive to drugs, Mobitz type II second-degree AV block, third-degree heart block, and bilateral bundle branch block; persistent bradycardia below 40 beats/min despite atropine may also be treated with electrical pacing.Doctor / NurseNot available at your setup — Defibrillator.
• Pad placement and settings: anterior pad over the cardiac apex (cathode) and posterior between the spine and the scapula (anode), or two large adhesive gel pads over the apex and the upper right sternal border; dry wet skin, clip rather than shave thick hair, never place a pad over an implanted device; set the rate to 60–80/min in an adult and increase output from zero in 5–10 mA steps until capture, then add a safety margin.Doctor / NurseNot available at your setup — Defibrillator.
• Confirm capture twice: electrical capture means every pacing spike is followed by a broad QRS and a T wave; mechanical capture means a palpable pulse at the paced rate and a rising blood pressure — palpate the femoral or brachial pulse, never the carotid.Not available at your setup — Defibrillator.
• Analgesia and light sedation for the conscious paced patient, titrated cautiously in hypotension, but never delay pacing for sedation in the peri-arrest patient; percussion pacing — firm rhythmical blows with the side of a closed fist over the lower left sternal edge from about 10 cm, at 50–70/min — bridges seconds while the pacer is set up.Doctor / Nurse
• When the drugs and the pacer are all failing, ask what the patient swallowed: glucagon 5–10 mg IV then 1–5 mg/hour for beta-blocker poisoning; 10% calcium gluconate 10–20 mL IV over 5–10 minutes into a large vein for calcium-channel blocker poisoning; atropine 1.2–2.4 mg IV plus digoxin-Fab for digoxin toxicity; and atropine 1.2–2.4 mg IV in escalating doses for organophosphate poisoning, where the endpoint is drying of secretions and not the heart rate.Doctor / Nurse
• Bradycardia-dependent torsades de pointes: magnesium 2 g intravenously over 2 minutes, correct potassium and magnesium, withdraw every QT-prolonging drug, and raise the rate with an isoprenaline infusion up to 20 microgram/min or atrial pacing at 90–120 beats/min.Doctor / Nurse
• Child: airway, oxygen and ventilation come first and usually suffice; if the rate remains below 60/min with poor perfusion despite effective oxygenation and ventilation, start chest compressions, and use intraosseous access at the same doses if cannulation fails.