Cardiogenic Shock

Etiology

Acute or Severe Pulmonary Hypertension (see Pulmonary Hypertension, [[Pulmonary Hypertension]])

Arrhythmia/Conduction Disturbance

Cardiomyopathy (see Congestive Heart Failure, [[Congestive Heart Failure]])

  • Infection
    • Myocarditis (see Myocarditis, [[Myocarditis]])
    • Sepsis-Induced Myocardial Depression (see Sepsis, [[Sepsis]])
    • Hantavirus Pulmonary Syndrome (see Hantavirus, [[Hantavirus]]): unusually produces sepsis with a high SVR and low CO state
  • Endocrine/Metabolic Disturbance
  • Myocardial Ischemia/Infarction
    • Acute Myocardial Infarction (MI) (see Coronary Artery Disease, [[Coronary Artery Disease]]): involving >40% of left ventricular myocardium
    • Myocardial Ischemia/Stunned Myocardium
  • Post-Cardiopulmonary Bypass (see Cardiopulmonary Bypass, [[Cardiopulmonary Bypass]])
  • Restrictive Cardiomyopathy (see Restrictive Cardiomyopathy, [[Restrictive Cardiomyopathy]])
  • Trauma
  • Takotsubo Cardiomyopathy (Stress-Induced Cardiomyopathy) (see Takotsubo Cardiomyopathy, [[Takotsubo Cardiomyopathy]])
  • Tamponade (see Tamponade, [[Tamponade]]): produces diastolic dysfunction
  • Drugs/Toxins

Increased Afterload

Increased Intrathoracic Pressure (with Impaired Right-Sided Venous Return)

  • Herniation of Abdominal Viscera Into Thorax
  • Positive-Pressure Ventilation with High Airway Pressures (see Acute Lung Injury-ARDS, [[Acute Lung Injury-ARDS]])
  • Tension Pneumothorax (see Pneumothorax, [[Pneumothorax]])

Intracardiac Shunt (see Intracardiac and Extracardiac Shunt, [[Intracardiac and Extracardiac Shunt]])

Valvular Disease/Mechanical Disturbance


Diagnosis

  • Echocardiogram: usually diagnostic
  • Swan
    • Cardiac Output (CO): usually decreased
    • Increased Extraction Ratio (Decreased SvO2): in cases with decreased CO

Clinical

  • Hypotension (see Hypotension, [[Hypotension]])
  • Pulseless Electrical Activity (PEA) (see Pulseless Electrical Activity, [[Pulseless Electrical Activity]]): may occur in cases of tension pneumothorax, tamponade

Treatment

Inotropes

  • Norepinephrine: improves myocardial oxygen metabolism (increases myocardial lactate extraction) in patients with cardiogenic shock by increasing perfusion pressure and myocardial oxygen supply
  • Dopamine: worsens myocardial oxygen metabolism because of the associated tachycardia
    • In cardiogenic shock, the use of dopamine increases mortality, as compared to norepinephrine

Intra-Aortic Balloon Pump (IABP)

  • Useful for cases unresponsive to medical therapy
  • Inflates during early diastole (pushing blood toward head and neck arteries and coronary arteries) with rapid deflation prior to systole: decreased afterload (decreased SVR)/ decreased LV-EDP/ modestly decreased aortic systolic pressure -> increased CO
    • In cases of MR or VSD, aortic systolic pressure usually increases modestly
  • Improves myocardial lactate production, arterial BP, and CO
  • Proven to improve survival only in MI patients with complicating ruptured ventricular septum or ruptured papillary muscle

PRBC Transfusion

  • No specific Hct has been documented to improve any clinical factor or outcome
  • However, doubling the Hct (from 20 to 40%) will double plasma viscosity, increasing O2 delivery to coronary arteries but increasing myocardial work

References

  • Effect of isoproterenol, norepinephrine and intraaortic counterpulsation on hemodynamics and myocardial metabolism in shock following myocardial infarction. Circulation 1972; 37:335- 351
  • Effect of dopamine on hemodynamics and myocardial metabolism in shock following acute myocardial infarction in man. Circulation 1978; 57:361-365
  • Comparison of dopamine and norepinephrine in the treatment of shock. N Engl J Med 2010; 362:779-789