List five causes of cardiogenic shock following myocardial infarction.    (25% marks)

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College answer

  • Left or Right ventricular failure
  • Severe mitral regurgitation
  • Septal rupture
  • Cardiac tamponade/ventricular free wall rupture
  • Arrhythmia (brady or tachy)
  • Drug induced

Discussion

This is an exercise in generating differentials for causes of shock which are applicable to the post-MI period. Thus:

Differential Diagnosis of Shock following MI

Artifactual or spurious

  • Inaccurately measured blood pressure
  • Noradrenaline line is not connected

Mechanical support failure

  • IABP augmentation failure
  • VA ECMO malfunction

Hypovolaemic

  • Loss of blood
    • Retroperitoneal (post angio)
    • Pulmonary / intrathoracic (ventricla damage post angio)

Cardiogenic

  • Ischaemic LV dysfunction
  • Sudden "valve failure", eg. papillary muscle rupture
  • Septal or ventricular rupture
  • Cardiac contusion (commotio cordis) following CPR
  • Drug overdose (of negative inotropes)
  • Rate problem: too fast or too slow
  • AF (loss of atrial kick)
  • Severe acidosis (myocardial depression)

Distributive

  • Anaphylaxis to angio contrast
  • Drug overdose (of vasodilators)
  • Reperfusion "post arrest" syndrome

Obstructive

  • Valve obstruction (thrombosis, myxoma)
  • LVOT or RVOT obstruction
  • Cardiac tamponade due to perforation or rupture