Cardiogenic Shock


Occurs when a primary cardiac disorder results in a decrease in cardiac output to a level that is insufficient to meet tissue demands for oxygen. Cardiac output is determined by HR and stroke volume.

CO (L/min) = HR (beats/min) x SV (L/beat)

Stroke volume is itself determined by the interrelation of preload, afterload, and contractility. Problems in any of the determinants of CO may cause cardiogenic shock.

Etiology:

Acute myocardial infarction
 Pump failure
 Mechanical complications
 Acute mitral regurgitation secondary to papillary muscle rupture
 Ventricular septal defect
 Free-wall rupture
Right ventricular infarction
Severe depression of cardiac contractility
 Sepsis
 Myocarditis
 Myocardial contusion
 Cardiomyopathy
Mechanical obstruction to forward blood flow
 Aortic stenosis
 Hypertrophic cardiomyopathy
 Mitral stenosis
 Left atrial myxoma
 Pericardial tamponade
Regurgitation of left ventricular output
 Chordal rupture
 Acute aortic insufficiency

Diagnosis

Differential Diagnosis

Differential Dx for Cardiogenic Shock
Acute myocardial infarction
Pulmonary embolus
Chronic obstructive pulmonary disease exacerbation
Pericarditis
Myocarditis
Aortic dissection
Pericardial tamponade
Acute valvular insufficiency
Sepsis
Hemorrhage
Toxins/drugs of abuse

 

ED CARE AND DISPOSITION:

Airway management, Circulatory stabilization, & arrangements for definitive cardiac care occur simultaneously. Cardiology & cardiac surgery should be consulted early. Transfer should be arranged if indicated.

  1. Supplemental O2, ET intubation if need.
  2. IV Access, Cardiac monitor (Rhythm disturbance), Pulse Ox (hypoxemia), CMP (electrolyte imbalance), Hypovolemia should be corrected.
  3. Early revascularization is required for cardiogenic shock due to ischemia.
  4. For chest pain
  5. Severe Hypotension
    Inotropes for depressed LV function:
    Drug Dose Comments
    Dopamine 3-5 mcg/kg/min, titrated up to 20-50 mcg/kg/min prn Use lowest effective dose
    Dobutamine 2-5 mcg/kg/min, titrated up to 20 mcg/kg/min May need dopamine also
    Norepinephrine 2 mcg/min, titrate to response Vasoconstrictor and inotrope
    Milrinone 50 mcg/kg IV over 10 minutes Inotrope and vasodilator;
    lowers blood pressure
    Maintenance infusion of 0.5 mcg/kg/min
     
  6. For mild hypotension w/o hypovolemia: Dobutamine 2.5 - 20 mcg/kg/min.
  7. Milrinone may be considered
  8. As a temporizing measure, intraaortic balloon pump counter-pulsation (if available) should be considered to decrease after load & to augment coronary perfusion.
  9. In the setting of acute mitral regurgitation, afterload reduction via IV Sodium Nitroprusside 0.5 - 10.0 mcg/kg/min should be combined w/ inotropic support via dobutamine 2.5 - 20 mcg/kg/min. An intraaortic pump may also be indicated to augment forward blood flow (contraindicated in severe aortic regurgitation).

 

Treatment of CHF + Hypotension
** Fix the underlying problem

Cause Treatment Comments
Tachycardia Treat the HR (Digoxin, Shock) Afib, VFIB, SVT etc.
Bradycardia Atropine, Pacing,  
Valve problem Valve replacement (pt has murmur) Ischemia, Ruptured corde-tendon, MVR, 
MI CATH lab EKG, Troponin
  RV infarct Aggressive Fluid Load on increase CVP (Increase LV Filling)  
STEMI DO NOT Thrombolize, Need CATH lab for stent.  
Cardiomyopathy Medical Management  
Tox related Glucagon, Digifab, Insulin/Glucose, Ca Chloride Dig OD, Beta Blocker OD
Pt will be bradycardic

Disposition:

  1. Admit ICU, Cardiology consult
Agent Receptor Activity Effects Indication
a1 b1 b2 DA
(Levophed)
Norepinephrine
1-30 mcg/min
+++

 

++ 0 0 SVR ↑↑
CO ↔↓↑
Sepsis
Phenylephrine
(Neo-synephrine)
40-180 mcg/min
+++

 

0

 

0

 

0

 

SVR ↑↑
CO ↔/↑
Sepsis,
Neurogenic shock
Epinephrine +++

 

+++ ++ 0

 

CO ↑↑
SVR ↓ (L)
SVR ↔/↑ (H)
Anaphylaxis,
ACLS,
Sepsis
Dopamine (mcg/kg/min)
Low-dose (0.5-2) 0 + 0 ++ CO ↑
SVR ↑↓
Sepsis,
Cardiogenic shock
Mid-dose(5-10) + ++ 0 ++ CO ↑
High-dose(10-20) ++ ++ 0 ++ SVR ↑↑
Doubutamine
2.5-20 mcg/kg/min
0/+ +++ ++ 0 CO ↑
SVR ↓
Cardiogenic shock
Isoproterenol
2-10 mcg/min
0

 

+++ +++ 0 CO ↑
SVR ↓
Cardiogenic shock w/
bradycardia
Vasopressin
(Adjunct)
0.01-0.04 U/min
        V2 receptors Vasoconstriction
Augments catecholamine

Receptor Functions
Receptor Function
α1  vascular smooth muscle contraction
pupillary dilator muscle contraction (mydriasis), 
intestinal and bladder sphincter muscle contraction
α2 sympathetic outflow, 
Insulin release
 lipolysis, 
platelet aggregation
β1 Heart rate
Contractility
Renin release
Lipolysis
β2 Vasodilation
Bronchodilation 
Heart rate
 Contractility
lipolysis
 Insulin release
 Uterine tone (tocolysis)
Ciliary muscle relaxation
 Aqueous humor production
M1 CNS, enteric nervous system
M2  Heart rate and contractility of atria
M3  exocrine gland secretions (e.g., lacrimal, salivary, gastric acid), 
gut peristalsis, 
bladder contraction,
Bronchoconstriction, 
pupillary sphincter muscle contraction (miosis),
Ciliary muscle contraction (accommodation)
D1 Relaxes renal vascular smooth muscle
D2 Modulates transmitter release, especially in brain
H1 nasal and bronchial mucus production, 
vascular permeability
Contraction of bronchioles
Pruritus
Pain
H2 gastric acid secretion
V1 vascular smooth muscle contraction
V2 H2O permeability and reabsorption in the collecting tubules of the kidney (V2 is found in the 2 kidneys)