Snapshot A 65-year-old man is brought into the emergency room after being found at home unconscious. His family did not witness the event but report that his past medical history includes hypercholesterolemia, diabetes, and hypertension. Vital signs are significant for a blood pressure of 86/50 mmHg. On physical exam, he has jugular venous distension and cool extremities. An electrocardiogram reveals ST elevations in leads II, III, and aVF. (Myocardial infarction) Introduction Clinical definition shock secondary to dysfunction of the heart and pump failure the heart is unable to generate sufficient cardiac output to maintain tissue perfusion Epidemiology Risk factors coronary artery disease Etiology Cardiomyopic myocardial infarction (MI) (most common cause) cardiomyopathy myocarditis drug-induced Arrhythmias Mechanical septal defect or ruptured valve blunt cardiac trauma Pathogenesis an underlying event (such as MI) results in ↓ cardiac output, which causes ↓ perfusion to tissue ↓ cardiac output and blood pressure causes ↑ catecholamines, which ↑ vasoconstriction and ↑ myocardial oxygen demand ↑ renin-angiotensin-aldosterone system, which ↑ vasoconstriction and retention of sodium and water ↑ shunting of blood to the brain and vital organs, which causes ↓ perfusion to peripheral organs Presentation Symptoms symptoms depend on etiology myocardial infarction chest pain dyspnea arrhythmias palpitations syncope Physical exam mental status change hypotension tachycardia pulmonary edema diffuse lung crackles distended jugular veins cool extremities ↓ urine output Imaging Echocardiography indication identify etiology of cardiogenic shock findings dilated ventricles decreased ejection fraction any anatomic abnormalities Studies Electrocardiography (ECG) indication identify etiology of cardiogenic shock findings any arrhythmias or myocardial infarction Pulmonary artery catheterization findings ↑ pulmonary capillary wedge pressure (PCWP >15 mmHg) ↑ systemic vascular resistance ↓ cardiac output Differential Different Types of ShockShock TypeSkinWedge Pressure (PCWP) (Preload)Systemic Vascular Resistance (SVR) (Afterload)Cardiac OutputHypovolemic Cold and clammy skin ↓↓ ↑ ↓Cardiogenic↑↑↓Obstructive ↑ or ↓ ↑ ↔ or ↓↓Distributive Warm or dry skin ↔ or ↓ ↓↓ ↓ or ↑ Diagnosis Making the diagnosis most cases are clinically diagnosed Treatment Management approach always assess the ABCs – airway, breathing, and circulation identify and treat the underlying cause (e.g., revascularization in the case of myocardial infarction-induced cardiogenic shock) Conservative supportive indications hypotension PCWP < 15 mmHg modalities fluid bolus oxygen Medical intravenous inotropic drugs indication maintain perfusion drugs dopamine (first line) dobutamine norepinephrine Complications Pulmonary edema Acute renal failure