last updated 31-07-2021

Cardiac output

Factors affecting cardiac output

Since the CO is defined by SV and HR, changes in either of these factors can alter the cardiac output.

Factors affecting stroke volume:

  • Preload, which depends on venous tone and blood volume
  • Contractility (or inotropy), which depends on autonomic innervation and hormones
  • Afterload, which depends on ventricle outflow tract resistance and/or arterial vascular resistance

An increase in preload or contractility/inotropy will result in an increased stroke volume; the fvia increase in the EDV, the latter mediated by a decrease in ESV. An increase in afterload will evoke a decrease in stroke volume via an increase in ESV.

Factors affecting heart rate:

Autonomic innervation and hormones are the main determinants of heart rate.