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Cardiogenic Shock: 55
Etiopathogenesis & Clinical Recognition

in heart rate remains one of the first compensatory Unless the mesenteric arteries have a pre-existing
mechanisms to maintain tissue perfusion and hence stenosis which may lead to mesenteric ischemia,
is an important clue to the onset of decompensation. ischemic necrosis of the intestines usually occurs
late in the stages of irreversible shock.
Hypotension: Primary pump failure leads to earlier
onset of hypotension in cardiogenic shock compared Brain: Impaired perfusion to brain occurs as an end
to the other forms of shock. This is only one of the result of prolonged or severe shock. This leads to
manifestations of cardiogenic shock and other fea- cell death in the brain, cerebral edema, agitation, sei-
tures have to be sought for before making a diagno- zures, obtundation and finally brain death. Hepatitis
sis of cardiogenic shock. Hypotension could be due can also result in direct transmission of ammonia and
to hypovolemia or peripheral vasodilation (sepsis) or other toxins to the brain resulting in hepatic coma.
drug induced. It is defined in adults by systolic blood Lactic acidosis: Tissue hypoperfusion throughout
pressure < 90mmhg, mean arterial blood pressure the body leads to intracellular accumulation of lactic
<65mmhg or relative drop in systolic BP>40mmhg.
acid and eventually results in lactic acidosis. The det-
Skin: Peripheral vasoconstriction is an important rimental effects of acidosis include endothelial cell
compensatory mechanism for cardiogenic shock. death and failure of peripheral vasoconstriction and
Cold, clammy extremities are a result of this mech- fall in peripheral vascular resistance, further depres-
anism. Prolonged vasoconstriction, compounded by sion of myocardial contractility, elevation of pulmo-
intravenous vasopressors, has known to result in dig- nary arterial pressures and impaired responsiveness
ital gangrene. Backward failure of right heart leads to to the parenteral medications.
congested veins and elevated jugular venous pulse History and clinical examination can result in a rea-
and pressure in the neck which serve as an important sonable recognition of cardiogenic shock.
diagnostic clue to raised right heart pressures.
Lungs: Backward failure of the left heart leads to Symptoms and Signs of Heart Failure and
direct transmission of heart pressures to the pul- Cardiogenic Shock
monary circulation resulting in pulmonary alveolar
edema. Initially there is compensation in form of in- TYPICAL SPECIFIC
creased respiratory rate (tachypnoea) and pulmonary Breathlessness Elevated jugular venous
vascular redistribution. Type 1 respiratory failure sets pressure
in after the compensatory mechanisms fail to main- Orthopnoea Hepatojugular reflux
tain normal arterial oxygen saturation.
Paroxysmal nocturnal Third heart sound (gallop
The combination of findings in the skin and lungs dyspnoea rhythm)
provide quick and vital clues to the stage of heart Reduced exercise toler- Laterally displaced apical
(9)
failure. Forrester et al state that the ‘cold-wet’ va- ance impulse
riety of heart failure represents those in cardiogen- Fatigue, tiredness, in-
ic shock. This bed-side assessment of cardiogenic creased time to recover
shock corresponds to low cardiac index (cold periph- after exercise
eries) and pulmonary congestion (wet lungs). Ankle swelling
Kidneys: Prolonged tissue hypoxia leads to acute re- LESS TYPICAL LESS SPECIFIC
nal injury. This is termed as ‘Cardio-renal syndrome’ Nocturnal cough Weight gain (>2 kg/week)
because of the detrimental effects of cardiogenic Wheezing Weight loss (in advanced
shock on the kidneys. Decreased glomerular filtration HF)
rate leads to decreased intraglomerular pressures Bloated feeling Tissue wasting (cachexia)
and oliguria. Tissue acidosis, necrosis and death may
result in post glomerular obstruction. Loss of appetite Cardiac murmur
Confusion (especially in Peripheral oedema (ankle,
Liver: Intrahepatic pressures tend to be high as a the elderly) sacral, scrotal)
direct result of backward failure of the right heart.
This results in hepatomegaly. Tissue hypoxia leads Depression Pulmonary crepitations
to ischemic hepatic necrosis and hepatitis. Palpitations Reduced air entry and dull-
ness to percussion at lung
Gastro-intestinal system: Intestinal venous conges- bases (pleural effusion)
tion due to backward cardiac failure leads to de- Dizziness Tachycardia
creased bowel movements and decreased appetite.

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