Frank–Starling law
![Cardiac function curve
In diagrams illustrating the Frank–Starling law of the heart, the y-axis often describes the stroke volume, stroke work, or cardiac output.
The x-axis often describes end-diastolic volume, right atrial pressure, or pulmonary capillary wedge pressure.
The three curves illustrate that shifts along the same line indicate a change in preload, while shifts from one line to another indicate a change in afterload or contractility.](/Images/godic/202501/18/Starling_RAP_combined.svg0311.png")
The Frank–Starling law of the heart (also known as Starling's law or the Frank–Starling mechanism or Maestrini heart's law) states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant. In other words, as a larger volume of blood flows into the ventricle, the blood will stretch the walls of the heart, causing a greater expansion during diastole, which in turn increases the force of the contraction and thus the quantity of blood that is pumped into the aorta during systole. The increased volume of blood stretches the ventricular wall, causing cardiac muscle to contract more forcefully (the so-called Frank–Starling mechanisms). The stroke volume may also increase as a result of greater contractility of the cardiac muscle during exercise, independent of the end-diastolic volume. The Frank–Starling mechanism appears to make its greatest contribution to increasing stroke volume at lower work rates, and contractility has its greatest influence at higher work rates.