Cardiogenic Shock¶

Sims Hershey

Definition¶

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

Cardiomyopathic: myocardial infarction with LV dysfunction (most common cause), exacerbation of heart failure, PHTN exacerbation, myocarditis, myocardial contusion, drug-induced
Arrhythmic: atrial tachycardias (atrial fibrillation/flutter, AVRT, AVNRT), VT/VF, complete heart block, 2^nd 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

"Cold and wet" - decreased perfusion due to reduced cardiac output with pulmonary congestion and/or increased left sided filling pressures. May also be "cold and dry" in the setting of normal PCWP with low cardiac output.
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, usually with narrow pulse pressure
Initially, SVR is elevated in the s/o hypoperfusion. SVR then declines in progressive shock due to vasodilation in the s/o systemic inflammation causing elevated NO in the shock state.

EKG
Labs: CBC, CMP, BNP, troponin, lactate
- Evidence of end organ damage: lactic acidosis, acute kidney injury, acute liver injury
Echocardiogram: assess EF and valves
LHC If ischemia (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, cardiac power \<0.6, SVR 800-1600, SVO2 \<60%
  - LV-dominant: RA (CVP) \<15, PCWP >18, PAPi >1.5 (pulmonary artery pulsatility index)
  - RV-dominant: RA >15, PCWP \<18, PAPi >1.5
  - Bi-V-dominant: RA >15, PCWP >18, PAPi >1.5
  - PAPi \< 1 indicates that patient will likely need RV support
  - CP \< 0.5 strongest independent hemodynamic correlate of mortality in CS
  - See right heart cath section for interpreting PA catheter profiles

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

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
Dynamics	Inflates during diastole, deflates during systole	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 2.5, 5.0 & CP: Blood aspirated from LV to aortic root Impella RP: Blood aspirated from IVC and delivered to PA
Flow	1 LMP	4.5 LPM	4-5 LPM	2.5: 2.5 L/min CP: 3.33 L/min 5.0: 5 L/min RP: 4 L/min
Support	LV	BiV	LV, RV, or BiV	LV or RV (RP)
Effects	Reduces afterload Increases stroke volume (SV) Increases coronary perfusion Reduces LV preload and PCWP	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	Thrombocytopenia Thrombosis Arterial obstruction Aortic rupture or dissection Air embolism	Circuit thrombosis LV dilation Hypothermia Gas embolism	Tamponade d/t perforation Thrombosis Embolism (gas or thrombus) Arterial Shunt	Pump migration Hemolysis Aortic regurg LV perf VT/VF

Aortic regurgitation, intracardiac shunt via ASD, VSD, or PFO, severe RV dysfunction, LA or ventricular thrombus, aortic dissection, uncontrolled sepsis, severe coagulopathy or bleeding diathesis