cardiogenic shock

see also:

• the shocked hypotensive patient
• return of spontaneous circulation (ROSC) post-arrest
• acute myocardial infarction (AMI/STEMI/NSTEMI)
• cardiac tamponade
• pulmonary embolism (PE)

• cardiogenic shock is shock due to a cardiac cause
• it is said to be the most common cause of death in hospitalised patients

• ischaemic - especially, acute myocardial infarction (AMI/STEMI/NSTEMI)
  • the most common cause of persistent shock
  • occurs in 5% to 8% of people hospitalised with ST elevation myocardial infarction (STEMI) and 2.5% of non‐STEMI cases ¹⁾
  • when cardiogenic shock complicates an acute myocardial infarction, the reported mortality rate is between 85% and 90%
• myocardial stunning (eg. post C-VF)
• other causes of cardiomyopathy
• reversible ventricular dysfunction which have good long‐term prognosis as long as can be supported until recovery:
  • acute myopericarditis
  • Takotsubo cardiomyopathy
  • peripartum cardiomyopathy

• see cardiac arrhythmias

• pulmonary embolism (PE)
• aortic dissection
• valvular disease eg. mitral stenosis, sbe
• ventricular septal rupture
• ventricular outflow obstruction eg. hypertrophic cardiomyopathy (HCM or HOCM)
• air embolism
• cardiac tamponade

• low blood pressure with inadequate organ perfusion:
  • persistent hypotension (systolic blood pressure less than 80 mmHg to 90 mmHg or mean arterial blood pressure 30 mmHg lower than baseline, for more than 30 minutes)
  • poor urine output
  • lactic acidosis
  • impaired cognition ranging from anxiety, restlessness, altered mental state to coma
• usually, a rapid, weak, thread pulse
• JVP elevation
• signs of sympathic stimulation - hyperventilation, cutaneous vasoconstriction causing cool, clammy, mottled skin
• possibly, acute pulmonary oedema (APO), cardiac arrhythmias

• reduction in Cardiac Index to:
  • less than 1.8 L/minute/m² without haemodynamic support
  • less than 2.0 L/minute/m² to 2.2 L/minute/m² with support
• elevated filling pressures (left ventricular end‐diastolic pressure (LVEDP) greater than 18 mmHg or right ventricular end‐diastolic pressure (RVEDP) greater than 10 mmHg to 15 mmHg)
• a pulmonary capillary wedge pressure greater than 15 mmHg in the setting of adequate or elevated filling pressure

• ~50% overall mortality
  • 89-95% mortality if complicates heart attack
  • ~100% mortality if refractory cardiogenic shock despite maximal vasopressors, inotropic support and IABP
• survivors generally have a very different life to pre-illness
  • many have severe psychological stress / nightmares
  • may need to re-locate housing to be near a tertiary medical centre

• search for reversible causes of shock (see below) and manage cardiac arrhythmias
• cardiogenic shock is an indication for emergent DC reversion of atrial fibrillation or ventricular tachycardia (VT)
• consider bedside echo
• IV inotropes
• consider emergent transfer to cath lab for angioplasty if acute myocardial infarction (AMI/STEMI/NSTEMI)
• consider ECMO, short term VAD or intra-cardiac impeller as a temporary bridge to either:
  • recovery
  • declaration of outcome if unclear
  • definitive VAD
  • heart transplantation
• intracardiac impeller devices (eg. Impella^TM):
  • consider temporary intra-cardiac impeller for a few days to a week or so (as of 2019, impeller is replacing intra-aortic balloon pumps)
    • generally need to be under 70yrs age
    • and cause is amenable to sufficient improvement of cardiac function to allow surviving when the impeller is needed to be removed
  • unlike ECMO, it doesn't increase afterload and thus tends to be better at improving myocardial oxygen consumption
  • unlike, IABP, it provides ventricular “unloading” which is an active process reducing volume and pressure by pumping blood from the right or left ventricle to the pulmonary artery or aortic root, respectively. This has a range of beneficial effects such as reduced afterload, reduced wall tension, decreased myocardial oxygen demand
  • unlike IABP, the impeller does not require ECG or arterial waveform triggering, facilitating stability even in the setting of ongoing tachyarrhythmias or electromechanical disassociation ²⁾
  • RP version for RV is NOT suitable if either:
    • acute infection
    • RA, RV or PA thrombus
    • mechanical valves in R heart
    • unrepaired ASD, PFO or aortic dissection
    • PA conduit
    • mod-severe pulm stenosis or insufficiency
    • documented DVT or presence of IVC filter
    • R sided support or ECMO
    • HIT or sickle cell
    • anatomic issues
  • complications
    • most common complications include limb ischemia (0.07-10%), vascular injury and bleeding requiring blood transfusion (0.05-50%)
    • shear stress from the impeller (especially at very high “P” levels) can lead to clinically relevant hemolysis, which in worst case scenario can cause renal failure. Risk is 5-10% in 1st 24hrs.
    • Stroke risk seems to be 2.4-6.3%.
    • risk of access site infection and sepsis
    • mitral regurgitation secondary to injury of the papillary muscles or chordae have been reported
    • the pigtail end within the LV can provoke ventricular arrhythmias
    • may have higher costs and risks of bleeding, stroke, and death than IABP
• may be eligible for ventricular assist device (VAD) if available and appropriate
• some may be eligible for cardiac transplant