🫀 Chapter 491.1: Cardiogenic Shock
Nelson's Textbook of Pediatrics 22e | Low cardiac output · Hypotension · Inotropes · Milrinone · Dobutamine · Dopamine · Epinephrine · ECMO · VAD · Post-cardiotomy · Myocarditis
📚 Reference: www.paeds.online — Paediatric Resource Hub
📌 Cardiogenic Shock – DefinitionPump failure → inadequate cardiac output → tissue hypoxia. Causes: myocarditis, post-cardiotomy, cardiomyopathy, arrhythmias, myocardial infarction (anomalous coronary artery), septic shock (myocardial depression).
📌 Clinical signs of low outputHypotension (age-adjusted), tachycardia, poor peripheral perfusion (cold extremities, delayed capillary refill), weak pulses, oliguria, altered mental status, metabolic acidosis.
📌 Inotropic agents – MilrinonePhosphodiesterase-3 inhibitor. Inotrope + vasodilator (reduces afterload). Preferred in cardiogenic shock with elevated SVR. Loading dose: 50 mcg/kg IV over 10-60 min, infusion 0.25-1 mcg/kg/min.
📌 Inotropic agents – Dobutamineβ1-agonist, inotrope + mild vasodilator. Increases contractility, HR. Dose 2-20 mcg/kg/min. Less arrhythmogenic than dopamine.
📌 Inotropic agents – DopamineLow dose (2-5 mcg/kg/min): renal vasodilation. Medium dose (5-10 mcg/kg/min): β1 inotrope. High dose (>10 mcg/kg/min): α vasoconstriction. Use with caution.
📌 EpinephrineMixed α/β agonist. Potent inotrope and vasoconstrictor. Used for refractory shock. Dose 0.01-1 mcg/kg/min. Risk of arrhythmias, increased afterload.
📌 VasopressinUsed in catecholamine-resistant vasodilatory shock (sepsis). May cause hyponatremia, cardiac ischemia.
📌 Mechanical circulatory support – ECMOVeno-arterial (VA) ECMO for cardiogenic shock. Indications: refractory shock, cardiac arrest (ECPR), bridge to recovery or transplant. Complications: bleeding, thrombosis, infection.
📌 Ventricular Assist Devices (VAD)Berlin Heart EXCOR (infants), HeartMate 3 (older children). Bridge to transplant or recovery. Paracorporeal or implantable.
📌 Post-cardiotomy shockLow cardiac output after CHD surgery. Treat: milrinone, ECMO if refractory. Risk factors: prolonged bypass, young age, residual lesions.
🔍 Step 1: Recognize hemodynamic profile
Hypotension, tachycardia, narrow pulse pressure. Cold, mottled extremities, delayed capillary refill (>3 sec). Weak peripheral pulses.
📈 Step 2: End-organ hypoperfusion
Altered mental status (lethargy, irritability), oliguria (<1 mL/kg/hr), metabolic acidosis (low pH, elevated lactate). Elevated BUN, creatinine.
🩺 Step 3: Physical examination
Gallop rhythm (S3), new murmur (MR from papillary muscle dysfunction), hepatomegaly, pulmonary edema (rales, wheezing). Jugular venous distention if right HF.
🔄 Step 4: Diagnostic tests
Echocardiogram: LVEF, wall motion, valvular function, tamponade. Labs: troponin, BNP, lactate, ABG. ECG: ischemia, arrhythmias.
🚨 Step 5: Determine cause
Myocarditis, post-cardiotomy, DCM, HCM (obstruction), arrhythmia (tachycardia, bradycardia), coronary anomaly, septic shock (myocardial depression).
1️⃣ Initial resuscitation – Airway, Breathing, Circulation
▪ Secure airway, mechanical ventilation (reduce work of breathing, oxygen demand).
▪ IV access, intra-arterial line for BP monitoring.
▪ Fluid bolus: 10-20 mL/kg isotonic crystalloid cautiously (may worsen pulmonary edema).
2️⃣ Inotropic support (first-line – milrinone)
▪ Milrinone: 0.25-1 mcg/kg/min (load 50 mcg/kg over 10-60 min if not hypotensive).
▪ Dobutamine: 2-20 mcg/kg/min – inotrope, mild vasodilator.
▪ Dopamine: 5-15 mcg/kg/min – β1 inotrope, higher doses α vasoconstriction.
3️⃣ Refractory shock – Epinephrine or vasopressors
▪ Epinephrine: 0.01-1 mcg/kg/min – potent inotrope + vasoconstrictor.
▪ Vasopressin: 0.0005-0.002 U/kg/min – for vasodilatory component.
▪ Norepinephrine: 0.05-2 mcg/kg/min – for profound vasodilation.
4️⃣ Mechanical circulatory support
▪ VA-ECMO for refractory cardiogenic shock (fulminant myocarditis, post-cardiotomy).
▪ VAD as bridge to transplant (DCM, chronic HF).
▪ Indications: inability to wean inotropes, end-organ dysfunction, lactate rising.
5️⃣ Treat underlying cause
▪ Myocarditis: IVIG (controversial), ECMO if fulminant.
▪ Post-cardiotomy: re-explore if residual lesion, milrinone, ECMO.
▪ Arrhythmia: cardioversion, antiarrhythmics.
▪ Tamponade: pericardiocentesis.
6️⃣ Monitoring
▪ Continuous ECG, invasive BP, central venous pressure, pulse oximetry.
▪ Serial lactate, ABG, electrolytes, urine output.
▪ Echocardiogram daily to assess recovery.
7️⃣ Transition & long-term follow-up
▪ Wean inotropes as LV function improves.
▪ Transition to oral heart failure therapy (ACE inhibitors, beta-blockers).
▪ VAD or transplant evaluation if no recovery.
❓ Reflex prompt 1: A 6-month-old post-cardiac surgery, BP 60/30, cold extremities, lactate 8 mmol/L. Next step?
✅ Answer: Start milrinone, assess for residual lesion (echo). Consider ECMO if refractory.
❓ Reflex prompt 2: A 12-year-old with fulminant myocarditis, on high-dose epinephrine, BP 70/40, lactate rising. Next step?
✅ Answer: VA-ECMO (bridge to recovery).
❓ Reflex prompt 3: A 4-year-old with DCM, LVEF 15%, on milrinone and epinephrine, still hypotensive. Next step?
✅ Answer: VAD as bridge to transplant (Berlin Heart).
❓ Reflex prompt 4: A neonate with severe aortic stenosis, cardiogenic shock, ductal-dependent. Next step?
✅ Answer: PGE1 infusion, balloon valvuloplasty, ECMO if needed.
❓ Reflex prompt 5: A 14-year-old with septic shock and myocardial depression, BP 60/40, EF 35%. Inotrope of choice?
✅ Answer: Milrinone + norepinephrine. Dobutamine alternative.
❓ Reflex prompt 6: A 5-year-old post-VSD repair, BP 80/50, narrow pulse pressure, CVP 18, lactate 4. First-line inotrope?
✅ Answer: Milrinone (afterload reduction + inotropy).
📌 Cardiogenic Shock – Core Concepts (Nelson 22e, Chapter 491.1)

1. Definition: Pump failure → inadequate cardiac output → tissue hypoxia. Distinguished from hypovolemic, distributive, and obstructive shock.
2. Etiology:
- Myocarditis (fulminant viral).
- Post-cardiotomy (congenital heart surgery).
- Dilated cardiomyopathy (end-stage).
- Arrhythmias (tachycardia, bradycardia).
- Myocardial infarction (anomalous coronary artery, Kawasaki).
- Septic shock (myocardial depression).
- Obstructive (tamponade, massive PE).
3. Clinical features: Hypotension, tachycardia, narrow pulse pressure, cold extremities, weak pulses, delayed capillary refill, oliguria, altered mental status, metabolic acidosis, elevated lactate.
4. Diagnostics: Echocardiogram (EF, wall motion, tamponade), labs (troponin, BNP, lactate, ABG), ECG (ischemia, arrhythmias).
5. Management – Stepwise:
- ABCs, mechanical ventilation.
- Cautious fluid (10-20 mL/kg).
- Inotropes: milrinone (preferred first-line in cardiogenic shock with high SVR).
- Dobutamine, dopamine (second-line).
- Epinephrine, norepinephrine (refractory shock).
- VA-ECMO for refractory shock (bridge to recovery/transplant).
- VAD as bridge to transplant (chronic HF).
6. Specific scenarios:
- Post-cardiotomy: milrinone, re-explore if residual lesion.
- Myocarditis: IVIG (controversial), ECMO.
- Arrhythmias: cardioversion, antiarrhythmics.
- Tamponade: pericardiocentesis.
7. Monitoring: Invasive BP, CVP, serial lactate, urine output, daily echo.
8. Prognosis: Fulminant myocarditis may recover with ECMO. Post-cardiotomy mortality high if ECMO required. Chronic DCM: transplant.
💡 Clinical pearls:
➤ Milrinone is preferred in cardiogenic shock with elevated SVR (inotrope + vasodilator).
➤ Avoid aggressive fluid boluses (may worsen pulmonary edema).
➤ ECMO should be considered early in refractory shock (before end-organ failure).
➤ Post-cardiotomy shock: always rule out residual lesion (echo).
➤ In neonates with ductal-dependent lesions, start PGE1 while evaluating.