What is stroke volume?

  • The stroke volume (SV) is the amount of blood (mL) ejected per heartbeat by the LV into the aorta (or from the RV into the pulmonary artery) assuming that all the blood leaving the ventricle is ejected into the outflow tract
  • The volume of blood in the LV prior to contraction is the left ventricular end-diastolic volume (LVEDV)
  • The volume of blood remaining in the LV after contraction is the left ventricular end-systolic volume (LVESV)
  • The SV can also be defined as the difference between the left ventricular end-diastolic volume (LVEDV) and the left ventricular end-systolic volume (LVESV)

SV = LVEDV – LVESV

  • Typical values for a 70 kg man are
    • LVEDV = 120 ml
    • LVESV = 50 ml
    • SV = LVEDV – LVESV = 120 ml – 50 ml = 70 ml
    • depending also on patient size, normal range of SV is between 55 and 100 ml
  • Ejection fraction is commonly used as it represents the proportion between the SV and LVEDV. The normal range is 55-70%.

EF (%) = (SV/LVEDV) x 100

  • stroke volume is regulated by preload, afterload, and inotropy