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.