Rapid Review·Cardiovascular
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Shock
T1Must knowCardiogenic Shock
Focus on
A cold, wet patient: hypotension with pulmonary edema, distended neck veins, cool extremities and oliguria — low output with high filling pressures. Most often a large anterior MI. Reperfuse immediately, support with norepinephrine and dobutamine or a mechanical device, never a beta blocker or a big fluid bolus — and remember the mechanical complications and RV infarct as the exceptions that change the plan.
Key takeaways
What it is and what causes it
Cardiogenic shock
pump failure: cardiac index under 2.2 L/min/m2 with a pulmonary capillary wedge pressure (PCWP) over 15 to 18 mm Hg and a systolic pressure under 90 (or vasopressors to hold it), plus hypoperfusion.A spiral
low output triggers vasoconstriction, which adds afterload to a failing ventricle, and ischemia and dysfunction feed each other.Mortality
30 to 50 percent.Acute myocardial infarction (MI) is the cause in about 80 percent
a large anterior infarct losing over 40 percent of left-ventricular mass, right-ventricular infarction, or a mechanical complication (papillary muscle, septal or free-wall rupture; Post MI Complications).Other causes
fulminant Myocarditis, Takotsubo Cardiomyopathy, Peripartum Cardiomyopathy, acute severe valvular regurgitation (endocarditis, dissection), critical aortic stenosis, sustained arrhythmia, Beta-Blocker Toxicity and calcium-channel blocker overdose, post-cardiotomy stunning, septic cardiomyopathy.Clinical features and diagnosis
Cold and wet
hypotension, tachycardia, cool clammy mottled extremities, pulmonary edema with crackles, orthopnea and hypoxemia, jugular venous distension, an S3, oliguria, confusion and a narrow pulse pressure.A new murmur
means a mechanical complication.Right-ventricular shock
hypotension with jugular venous distension and clear lungs (Acute Coronary Syndrome).Immediate tests
electrocardiogram (ST-elevation infarction, arrhythmia), troponin, lactate, renal and liver function, blood gas, chest radiograph.Bedside echocardiography is the decisive test
ejection fraction, regional wall motion, right-ventricular function, valves, effusion, mechanical complications.Urgent coronary angiography
when infarction is the cause.Pulmonary artery catheter
high PCWP, low cardiac index, high systemic vascular resistance, low mixed venous saturation.Management
Treat the cause first
emergency revascularization (percutaneous coronary intervention, or bypass surgery for suitable anatomy) for infarction with shock is the only therapy with proven survival benefit; culprit lesion first.Cause-specific fixes
surgery for mechanical complications (balloon pump or Impella as a bridge), pericardiocentesis for tamponade, cardioversion or pacing for arrhythmia, antidotes for drug toxicity, valve surgery for acute regurgitation.Norepinephrine first
the first-line vasopressor (less tachycardia and arrhythmia than dopamine).- Add dobutamine (or milrinone, especially with beta blockade or pulmonary hypertension) for low output once the pressure allows.
- Epinephrine for refractory cases. Dopamine is out (higher mortality; Vasopressors & Inotropes).
No blind fluid boluses
the left ventricle is already overloaded.- Small 250 mL boluses only for right-ventricular infarction or a clearly low PCWP.
- Loop diuretics and nitrates once the pressure is restored.
Mechanical circulatory support
for shock refractory to drugs, or as a bridge.- Intra-aortic balloon pump (contraindicated in significant aortic regurgitation and dissection), Impella, venoarterial extracorporeal membrane oxygenation, durable ventricular assist device.
Positive-pressure ventilation
for pulmonary edema it lowers preload and afterload, so it helps left-ventricular failure but is dangerous in right-ventricular failure and tamponade.Withhold negative inotropes
beta blockers, non-dihydropyridine calcium-channel blockers and other negative inotropes until the shock resolves; no nitrates or morphine in right-ventricular infarction.Prognosis
depends on the speed of revascularization; survivors move to reduced-ejection-fraction therapy (Heart Failure) and device evaluation.Hours after a large anterior infarction, a patient is cold, confused and hypotensive with crackles to the mid-lung fields and distended neck veins. What catheter findings are expected, and which treatment is the only one proven to improve survival?
Cardiogenic shock: high PCWP, low cardiac index, high systemic vascular resistance, low mixed venous saturation. Emergency revascularization is the only therapy with proven survival benefit; support with norepinephrine, then dobutamine, and mechanical support if refractory. No big fluid boluses and no beta blockers.
How it's tested
Anterior STEMI, BP 75/50, cold legs, crackles to the mid-lung fields, urine output 5 mL/h: cardiogenic shock — immediate PCI; norepinephrine for pressure, dobutamine for output; no fluid bolus, no beta blocker.
Inferior STEMI with hypotension, JVD and clear lungs: RV infarction — a cautious fluid bolus, reperfusion, avoid nitrates; the one cardiogenic shock that gets fluid.
Day 4 post-MI, sudden shock with a new holosystolic murmur and thrill: ventricular septal rupture — echo, balloon pump, emergency surgery.
Which pressor first in cardiogenic shock: norepinephrine — dopamine causes more arrhythmias and deaths.
Cardiogenic shock refractory to norepinephrine and dobutamine at a PCI center: mechanical support (Impella or VA-ECMO) as a bridge.
Go deeper
Guidelines: 2025 ACC/AHA Acute Coronary Syndromes Guideline · 2022 AHA/ACC/HFSA Heart Failure Guideline
Related Step 2 pages: Approach to Shock, Acute Coronary Syndrome, Post MI Complications, Vasopressors & Inotropes, Heart Failure, Hemodynamics: Preload, Afterload & Contractility
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