1.01. Cardiac Output Equations

Cardiovascular system reveiew for the USMLE Step 1 exam.

• Equations that describe cardiac output and cardiac performance
• Cardiac output (CO) is the amount of blood volume pumped by the heart per min, typically given in L/min
• CO is equal to stroke volume (SV) times heart rate (HR)
• SV is influenced by preload, afterload, and contractility
• Pulse pressure is the difference between systolic and diastolic blood pressure (PP = SBP-DBP)
• High pulse pressure can be caused by stiffening of the major arteries
• Mean arterial pressure (MAP) is the average arterial pressure during one cardiac cycle
• MAP is equal to CO * TPR and MAP is equal to ⅔ DBP + ⅓ SBP
• Diastolic blood pressure contributes more to MAP than systolic pressure