Cardiogenic Shock

Matthew Alonso

Definition

  • Impairment of CO due to primary cardiac disorder that results in end-organ hypoperfusion and hypoxia
  • Mortality of up to 40-50%

Etiology

  • Cardiomyopathic: acute myocardial infarction with LV dysfunction (most common cause), exacerbation of heart failure, PHTN exacerbation, myocarditis, myocardial contusion, drug-induced
  • Arrhythmogenic: atrial tachycardias (atrial fibrillation/flutter, AVRT, AVNRT), VT/VF, complete heart block, 2nd degree heart block
  • Mechanical: valvular insufficiency, valvular rupture, papillary muscle rupture, critical valvular stenosis, ventricular septal wall defect, ruptured ventricular wall aneurysm, atrial myxoma, HOCM

Presentation and diagnostic criteria

  • Signs of end-organ hypoperfusion - AMS, cold and clammy skin, decreased UOP (<30cc/hr), and elevated lactate (>2).
  • SBP < 90 mmHg for >30min or needing vasopressors to achieve this goal
  • Drop in MAP >30mmHg below baseline or MAP <60mmHg
  • Cardiac index <1.8L/min/m2 without hemodynamic support or <2.2L/min/m2 with support
  • PCWP >15mmHg

SCAI Classification

  • Stage A: At Risk – Normotensive with normal perfusion
  • Stage B: Beginning (Pre-shock) - Hypotension without hypoperfusion. CI >2.2
  • Stage C: Classic Cardiogenic Shock – Hypotension and hypoperfusion. Clinical signs cold, clammy skin, altered mentation, and decreased urine output, elevated lactate. CI <2.2, PCWP >15
  • Stage D: Deteriorating – Worsening hemodynamics despite initial interventions, requiring escalating use of pressors or MCS to maintain SBP and end-organ perfusion.
  • Stage E: Extremis – Refractory hypotension and hypoperfusion requiring multiple simultaneous acute interventions, often experiencing cardiac arrest requiring CPR and/or ECMO.

Evaluation

  • EKG, CBC, CMP, BNP, troponin, lactate
  • Echocardiogram: assess EF and valves
  • LHC if ischemic (see ACS)
  • Hemodynamic monitoring via Swan-Ganz or PA catheter:
    • No benefit for general shock but does improve in-hospital mortality for those with cardiogenic shock
    • PA catheter hemodynamic profile:
      • Cardiac index < 2.2 with support or <1.8 without support, cardiac power <0.6, SVR >1200 initially, then may drop <800 as systemic inflammation causes vasodilation, SVO2 (mixed venous O2 sat) <60%, RVEDP >10
      • LV-dominant: PCWP >RA (CVP), PAPi >1.5 (pulmonary artery pulsatility index = (Pulmonary Artery Systolic Pressure - Pulmonary Artery Diastolic Pressure) / Right Atrial Pressure)
      • RV-dominant: RA >15, PCWP <15, PAPi <1.5
      • Bi-V-dominant: RA >15, PCWP >15, PAPi <1.5
      • PAPi < 0.9 predicts RV failure and that pt will likely need RV support. PAPi <1.85 predicts RV failure in pts with LVADs
      • CPO < 0.6 strongest independent hemodynamic correlate of mortality in CS
      • See right heart cath section for interpreting PA catheter profiles
      • While on CCU rotation, CCU swan sheet provided by Chiefs prior to start. Equation is built into the spreadsheet, although you will need to make sure to input patient specific height and weight metrics in top right corner of sheet.
      • On CCU, update swan sheet Q4H for patients with active Swan-Ganz or PA catheters. Utilize hemodynamics/filling pressures that correlate with timing of draw of MVO2 as this is the value that was zeroed by nursing staff.
      • Thermodilution: uses temperature gradient between two points along PA catheter.
      • Clinical conditions that compromise accuracy of thermodilution measurements due to underestimation or overestimation of cardiac output: valvular regurgitation, intracardiac shunts, and very low flow states

Management (medical & mechanical circulatory support)

Medical management: focus on optimizing preload, afterload, and contractility

  • Preload: IV diuresis – hypotension IMPROVES with diuresis in cardiogenic shock
  • Afterload: IV – nitroglycerine, nitroprusside; PO – captopril, hydralazine, isosorbide dinitrate; vasoconstricting pressors (norepinephrine, vasopressin, phenylephrine) if needing BP support
  • Contractility - Inodilators (increase contractility, decrease afterload – milrinone, dobutamine) or inoconstrictors (increase contractility and afterload – epinephrine, norepinephrine)

Mechanical circulatory support indications:

  • Shock refractory to >1 pressor
  • Shock 2/2 MI (physiology: unloads LV, increases systemic perfusion, increases myocardial perfusion, and provides hemodynamic support during PCI)

Types of mechanical circulatory support (MCS)

Intra-aortic Balloon Pump

V-A ECMO

Tandem Heart

Impella
Mechanics of Support Balloon pump placed in the proximal aorta that inflates during diastole (increasing coronary perfusion) and deflates during systole (LV afterload reduction) Blood from femoral vein is oxygenated and pumped to femoral artery

LV: blood aspirated from LA to femoral artery

RV: blood aspirate from RA to PA

Impella 5.5 & CP: Blood aspirated from LV and ejected to aortic root

Impella RP: Blood aspirated from IVC and delivered
Flow 0.5-1 L/min 4-6 L/min 4-5 L/min 2.5-5 L/min
Support LV BiV LV, RV, or BiV LV or RV (RP)
Hemodynamics

Reduces afterload and LVEDP -> decr cardiac work, O2 consumption Increases SV Increases coronary perfusion

 Increases afterload Reduces SV Reduces LV preload and PCWP Improves tissue perfusion Increases afterload Reduces SV Reduces LV preload and PCWP Improves tissue perfusion Reduces SV Reduces preload and PCWP Improves tissue perfusion
Complications Infection, stroke, thrombocytopenia, balloon malpositioning leading to ischemia, aortic rupture, air embolism Circuit thrombosis, LV dilation. Hypothermia, air embolism, bleeding, thrombocytopenia Tamponade d/t perforation, bleeding, femoral AV fistula, thromboembolism, ASD, limb ischemia Pump migration, bleeding, hemolysis, thrombocytopenia, aortic regurg, stroke, perforation, VT/VF, vascular injury

Possible contraindications to mechanical circulatory support (right or left sided support):

  • Severe aortic regurgitation, intracardiac shunt via ASD, VSD, or PFO, severe RV dysfunction, LA or ventricular thrombus, aortic dissection, severe peripheral arterial disease/inability to achieve adequate vascular access, uncontrolled sepsis, severe coagulopathy or bleeding diathesis

Daily management of MCS devices:

  • Ensure optimal placement of device with daily CXR (IABP) / Echo (Impella)
  • Anticoagulation (based on device)
  • Hematoma monitoring at device site
  • Check distal pulses to monitor for limb ischemia
  • Check urine color to monitor for hemolysis (Impella)
  • IABP: Ensure that the balloon inflation and deflation are synchronized with the cardiac cycle. Inflation should occur at the onset of diastole (middle of the T-wave on ECG) and deflation at the onset of systole (peak of the R-wave on ECG).
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