Cardiogenic Shock

1. Intrinsic cardiac dysfunction

most common: myocardial infarction

heart fails to operate as effective pump: ¯ cardiac output, \¯BP

blood pools “upstream” to failing ventricle

in left heart, leads to pulmonary edema (fluid accumulation in the lungs)

in right heart, leads to ascites (abdominal swelling), edema

other causes:

acute valvular dysfunction (e.g. acute aortic or mitral regurgitation)

arrhythmias (tachyarrhythmias - rapid HR, bradyarrhythmias - slow HR)

cardiomyopathies (problems with the heart muscle, e.g. dilated cardiomyopathy)

compensatory mechanisms

sympathetic activation ( vascular tone and SVR to maintain BP)

release of catecholamines

clinically, similar to hypovolemic shock

skin: cool, mottled (vasoconstriction)

differentiated by measurement of central venous pressure (CVP):

cardiogenic shock: CVP (blood pooling in venous circulation)

hypovolemic shock: ¯ CVP (overall, ¯ circulating blood volume)

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2. Extrinsic (compressive/obstructive) causes

npericardial tamponade

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accumulation of fluid in pericardium

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compression of heart

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inadequate ventricular filling (¯ preload) and ¯ cardiac output

npulmonary embolus

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usually blood clot from lower limbs

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lodges in pulmonary artery or its branches

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obstructs blood flow through the lungs (right heart failure)

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¯ preload delivered to left ventricle (\ ¯ cardiac output)