Cardiac function curve showing the relationship between preload and stroke volume (noting that cardiac output = heart rate × stroke volume).

At a lower preload the stroke volume is highly sensitive to changes in preload. At a higher preload, further increases in preload lead to a reduced increase in stroke volume (the Frank-Starling mechanism). Stroke volume is also increased in the setting of increased sympathetic nervous system activation or exogenously administered inotropes. A: At rest in a person with a normal heart B: Increased sympathetic nervous system activation or exogenously administered inotropic therapy.