Cardiac emergencies and arrhythmias

Manage the cardiac emergencies an ICU sees every day: STEMI and NSTE-ACS reperfusion and antithrombotics, acute heart failure and pulmonary oedema, AF with rapid ventricular response, ventricular and wide-complex tachycardia, bradycardia and temporary pacing, and hypertensive emergencies with target-driven BP lowering.

6 topics

01
Acute coronary syndromes: STEMI and NSTE-ACS
ECG within 10 min. STEMI: primary PCI if achievable within 120 min of diagnosis, otherwise fibrinolysis within 10 min and transfer. Load antiplatelets, anticoagulate, and risk-stratify NSTE-ACS for timing of angiography.
8 stepsAlgorithm6 dosesNew
02
Acute heart failure and pulmonary oedema
Profile the patient as warm/cold and wet/dry. Warm-wet: IV loop diuretic plus vasodilator if SBP > 110 and CPAP/NIV for pulmonary oedema. Cold: cardiogenic shock pathway. Always find the trigger.
7 stepsAlgorithm2 dosesNew
03
AF with rapid ventricular response in the ICU
Unstable: synchronised cardioversion (≥ 200 J biphasic). Stable: treat triggers (sepsis, hypovolaemia, K+, Mg2+, catecholamines), then rate control with a beta-blocker or diltiazem if LVEF > 40%, or amiodarone/digoxin if LVEF ≤ 40% or hypotensive. Assess anticoagulation.
7 stepsAlgorithm5 dosesNew
04
Ventricular tachycardia, wide-complex tachycardia and electrical storm
Treat a regular wide-complex tachycardia as VT until proven otherwise. Unstable: synchronised cardioversion. Stable: cardioversion under sedation or IV amiodarone. Torsades: magnesium and remove QT drugs. Electrical storm: sedate, beta-block, amiodarone, correct electrolytes, treat ischaemia.
6 stepsAlgorithm2 dosesNew
05
Bradycardia, heart block and temporary pacing
Look for adverse features and reversible causes (drugs, K+, ischaemia, hypothermia, hypothyroidism, raised ICP). Atropine first; if it fails or the block is infranodal, adrenaline or isoprenaline infusion and transcutaneous then transvenous pacing.
6 stepsAlgorithm2 dosesNew
06
Hypertensive emergencies
Hypertensive emergency means severe BP elevation with acute organ damage. Lower BP with titratable IV drugs to a target and timeline set by the organ involved; avoid precipitous falls except in aortic dissection, pulmonary oedema and eclampsia.
5 stepsAlgorithm3 dosesNew

Drugs in this module

Doses written for this module's context. The same drug may read differently in another module.

Aspirin

Antiplatelet (COX inhibitor)

Indications: All ACS unless contraindicated.
Adult dose: Loading 150-300 mg orally (chewed, non-enteric coated) or 75-250 mg IV; then 75-100 mg daily.
Preparation (India): 75 mg, 150 mg and 325 mg tablets; chewable formulations widely available.
Cautions: Active bleeding, true allergy.

Ticagrelor

P2Y12 inhibitor

Indications: ACS (with aspirin), PCI.
Adult dose: 180 mg loading, then 90 mg twice daily for 12 months (default).
Preparation (India): 90 mg tablets (can be crushed for NG tube).
Cautions: Dyspnoea, bradyarrhythmia, bleeding; not with fibrinolysis (use clopidogrel).

Clopidogrel

P2Y12 inhibitor

Indications: With fibrinolysis; when ticagrelor/prasugrel unavailable or contraindicated; patients on oral anticoagulants.
Adult dose: PCI: 600 mg loading then 75 mg daily. With fibrinolysis: 300 mg loading (75 mg if age > 75 years), then 75 mg daily.
Preparation (India): 75 mg and 300 mg tablets; inexpensive.
Cautions: Variable response (CYP2C19 polymorphism, common in South Asians).

Unfractionated heparin (UFH)

Indirect thrombin and Xa inhibitor

Indications: Primary PCI; adjunct to fibrinolysis; NSTE-ACS when early invasive strategy; AF or LV thrombus when rapid reversal may be needed.
Adult dose: Primary PCI: 70-100 U/kg IV bolus. With fibrinolysis: 60 U/kg bolus (max 4000 U), then 12 U/kg/h (max 1000 U/h), aPTT 1.5-2.0 × control (≈ 50-70 s) for 24-48 h.
Preparation (India): 5000 U/mL (5 mL vials = 25 000 U). Infusion 25 000 U in 50 mL = 500 U/mL.
Cautions: Heparin-induced thrombocytopenia; bleeding; monitor platelets.
Monitoring: aPTT (or anti-Xa) 6 h after start and each change; platelets on alternate days.

Enoxaparin

Low-molecular-weight heparin

Indications: NSTE-ACS; adjunct to fibrinolysis; VTE treatment.
Adult dose: NSTE-ACS: 1 mg/kg SC every 12 h. With fibrinolysis: age < 75: 30 mg IV bolus + 1 mg/kg SC 15 min later then every 12 h (first 2 doses max 100 mg); age ≥ 75: no bolus, 0.75 mg/kg SC every 12 h (first 2 doses max 75 mg). CrCl < 30: 1 mg/kg once daily.
Preparation (India): Prefilled syringes 40, 60, 80 mg; biosimilars available.
Cautions: Accumulates in renal failure; partial protamine reversal only.

Tenecteplase

Fibrinolytic (tPA variant)

Indications: STEMI within 12 h when primary PCI cannot be done within 120 min of diagnosis.
Adult dose: Single IV bolus by weight: < 60 kg 30 mg; 60-69 kg 35 mg; 70-79 kg 40 mg; 80-89 kg 45 mg; ≥ 90 kg 50 mg. Half dose in patients ≥ 75 years.
Preparation (India): 40 mg vials (8000 U) reconstituted to 5 mg/mL; Indian biosimilars available (20, 30, 40 mg).
Cautions: Absolute contraindications: previous ICH or unknown-origin stroke, ischaemic stroke within 6 months, CNS tumour/AV malformation, major trauma/surgery/head injury within 1 month, GI bleed within 1 month, bleeding disorder, aortic dissection, non-compressible punctures within 24 h.

Streptokinase

Fibrinolytic (non-fibrin-specific)

Indications: STEMI fibrinolysis where tenecteplase/alteplase are unavailable or unaffordable.
Adult dose: 1.5 million units IV over 30-60 min.
Preparation (India): 1.5 MU vials; reconstitute in 100 mL NS.
Cautions: Hypotension during infusion (slow or pause), allergic reactions; antibodies form, do not repeat after 5 days. Less effective than fibrin-specific agents.

Glyceryl trinitrate (nitroglycerin)

Nitrate vasodilator

Indications: Acute pulmonary oedema with SBP > 110 mmHg; ongoing ischaemic pain; hypertensive emergency with ACS or pulmonary oedema.
Adult dose: Sublingual 0.4-0.5 mg; IV 10-20 mcg/min, increase by 5-10 mcg/min every 3-5 min, up to 200 mcg/min.
Preparation (India): 5 mg/mL ampoules (25 mg/5 mL). 50 mg in 50 mL NS/D5 = 1 mg/mL (1000 mcg/mL). Use non-PVC tubing if possible.
Cautions: Avoid with SBP < 90, RV infarction, severe aortic stenosis, PDE-5 inhibitor within 24-48 h. Headache; tachyphylaxis.

Furosemide

Loop diuretic

Indications: Congestion in acute heart failure.
Adult dose: Diuretic-naïve: 20-40 mg IV. On oral loop diuretic: IV dose 1-2 × the daily oral dose. Check spot urine sodium after 2 h (target > 50-70 mmol/L) or urine output > 100-150 mL/h over 6 h; if inadequate, double the dose (max ~400-600 mg/day).
Preparation (India): 10 mg/mL, 2 mL ampoules; infusion 250 mg in 50 mL.
Cautions: Hypokalaemia, hypomagnesaemia, ototoxicity with rapid high doses (≤ 4 mg/min).

Amiodarone

Class III antiarrhythmic

Indications: AF rate or rhythm control in critically ill or reduced EF; haemodynamically tolerated VT; electrical storm.
Adult dose: 300 mg (or 5-7 mg/kg) IV over 20-60 min, then 900 mg over 24 h; total ≤ 2.2 g/24 h.
Preparation (India): 150 mg/3 mL ampoules; dilute in 5% dextrose; central line preferred for infusion.
Cautions: Hypotension, bradycardia, phlebitis, QT prolongation; thyroid, liver and lung toxicity with prolonged use; interacts with warfarin and digoxin.

Diltiazem

Non-dihydropyridine calcium channel blocker

Indications: AF/flutter rate control when LVEF > 40%.
Adult dose: 0.25 mg/kg IV over 2 min (≈ 15-20 mg), repeat 0.35 mg/kg after 15 min if needed; infusion 5-15 mg/h.
Preparation (India): 25 mg/5 mL injection (availability variable).
Cautions: Avoid in HFrEF, hypotension, pre-excited AF, wide-complex tachycardia.

Metoprolol

Beta-1 selective blocker

Indications: AF rate control; ACS (tachycardia, hypertension, no heart failure).
Adult dose: IV 2.5-5 mg over 2 min, repeat every 5 min to max 15 mg. Oral 25-100 mg twice daily.
Preparation (India): 5 mg/5 mL injection; tablets 25, 50 mg.
Cautions: Avoid in acute HF, shock, bradycardia, severe bronchospasm, cocaine-related ACS.

Esmolol

Ultra-short-acting beta-1 blocker

Indications: Rate control in AF when titratable control is needed; aortic dissection (with vasodilator); hypertensive emergencies with tachycardia.
Adult dose: 500 mcg/kg over 1 min, then 50-300 mcg/kg/min.
Preparation (India): 100 mg/10 mL vials (10 mg/mL); 2.5 g/250 mL premixed bags in some hospitals.
Cautions: Hypotension; bradycardia.

Digoxin

Cardiac glycoside

Indications: AF rate control, especially with reduced EF or hypotension, as add-on.
Adult dose: IV loading 0.5 mg, then 0.25 mg every 6 h to total 1-1.5 mg (reduce in renal failure and elderly). Maintenance 0.0625-0.25 mg daily by renal function.
Preparation (India): 0.25 mg/mL injection (2 mL = 0.5 mg); 0.25 mg tablets.
Renal / hepatic: Renally cleared: reduce dose; target level 0.5-0.9 ng/mL.
Cautions: Toxicity with hypokalaemia, hypomagnesaemia, hypercalcaemia, amiodarone; avoid in pre-excitation.

Adenosine

Purinergic AV nodal blocker

Indications: Regular narrow-complex tachycardia (SVT); diagnostic in stable regular monomorphic wide-complex tachycardia.
Adult dose: 6 mg rapid IV push with 20 mL flush; then 12 mg (repeat 12 mg once per ESC/AHA practice). 3 mg if central line, heart transplant, or on dipyridamole.
Preparation (India): 3 mg/mL (2 mL = 6 mg) vials.
Cautions: Asthma (bronchospasm), pre-excited AF, irregular or polymorphic WCT; transient asystole is expected.

Atropine

Antimuscarinic

Indications: Symptomatic bradycardia.
Adult dose: 0.5-1 mg IV every 3-5 min to max 3 mg.
Preparation (India): 0.6 mg/mL ampoules.
Cautions: Ineffective in heart transplant and infranodal block (Mobitz II, wide-escape CHB).

Isoprenaline (isoproterenol)

Non-selective beta agonist

Indications: Bradycardia bridge to pacing; bradycardia-dependent torsades.
Adult dose: Infusion 1-10 mcg/min (start 2-5 mcg/min).
Preparation (India): Availability limited; 2 mg/mL or 0.2 mg/mL ampoules depending on supplier.
Cautions: Tachyarrhythmia, hypotension (beta-2 vasodilation), myocardial ischaemia.

Magnesium sulfate

Electrolyte

Indications: Torsades de pointes; adjunct in AF and VT when Mg low.
Adult dose: 2 g IV over 10-15 min; may repeat; aim Mg > 1 mmol/L.
Preparation (India): 50% (500 mg/mL) 2 mL ampoules.
Cautions: Hypotension, loss of reflexes at high levels; caution in renal failure.

Labetalol

Alpha-1 and beta blocker

Indications: Hypertensive emergencies (encephalopathy, stroke, pre-eclampsia, aortic dissection with tachycardia control).
Adult dose: 0.25-0.5 mg/kg IV bolus (typically 20 mg) over 2 min, repeat 20-80 mg every 10 min (max 300 mg); or infusion 1-2 mg/min (some protocols up to 4 mg/min) until target, then reduce.
Preparation (India): 5 mg/mL, 4 mL ampoules (20 mg). Infusion: undiluted 5 mg/mL or 100 mg in 100 mL.
Cautions: Bradycardia, heart block, acute HF, asthma.

Nicardipine

Dihydropyridine calcium channel blocker

Indications: Hypertensive emergencies (stroke, encephalopathy, AKI).
Adult dose: 5 mg/h IV, increase by 2.5 mg/h every 5-15 min to max 15 mg/h.
Preparation (India): Limited availability; check local supply.
Cautions: Reflex tachycardia; avoid in severe aortic stenosis and acute HF.

Sodium nitroprusside

Arterial and venous vasodilator (NO donor)

Indications: Hypertensive emergencies with acute LV failure or aortic dissection (with beta-blocker) when other agents fail.
Adult dose: 0.3-10 mcg/kg/min; use the lowest dose and shortest duration (< 48-72 h).
Preparation (India): 50 mg vials; 50 mg in 50 mL D5 = 1000 mcg/mL; protect from light.
Cautions: Cyanide and thiocyanate toxicity (renal/hepatic failure, high doses); rebound; raises ICP.

6 topics

Acute coronary syndromes: STEMI and NSTE-ACS

Acute heart failure and pulmonary oedema

AF with rapid ventricular response in the ICU

Ventricular tachycardia, wide-complex tachycardia and electrical storm

Bradycardia, heart block and temporary pacing

Hypertensive emergencies

Drugs in this module

Module references (10)