Appendix C

Key Cardiovascular Variables and Their Normal Determinants¹

$P¯A=CO×TPR$

CO = SV × HR

SV = EDV − ESV

Ejection fraction = SV/EDV

$SV←pumpventricular={ (+)↑cardiac preload (via effect on EDV)(+)↑cardiac contractility (via effect on ESV)(−)↑cardiac afterload (via effect on ESV)$

Cardiac preload ∝P_CV(“∝” means “is proportional to”

$PCV←volumecentral blood={ (+)↑total blood volume(+)↑peripheral venous tone(+)skeletal muscle pump(+)respiratory pump(−)standing(−)↑cardiac output$

Venous tone ←{(+)↑ sympathetic activity (via NE, α-receptors)

Contractility $←cellsventricular{(+)↑$ sympathetic activity (via NE, β-receptors)

Cardiac afterload $∝P¯A$

$HR←firing rateSA node cell{ (+)↑sympathetic activity (via NE, β-receptors)(−)↑parasympathetic activity (via ACh)$

$TPR←tonearteriolar{ (+)↑sympathetic activity (via NE, α-receptors)(−)↑local metabolites(↑local metabolic rate)$

P_P ∝ SV / C_A