This law is important because it explains how the heart is able to maintain cardiac output (the amount of blood pumped out by the heart each minute) in the face of changing conditions. For example, when a person exercises, the heart rate increases and the stroke volume (the amount of blood pumped out by the heart with each contraction) decreases. However, the Frank–Starling law ensures that the heart continues to pump enough blood to meet the body's needs, even though the filling time of the heart is reduced.
The Frank–Starling law also helps to explain why heart failure can occur. When the heart is unable to stretch properly, it cannot contract forcefully enough to pump sufficient blood around the body. This can lead to a buildup of pressure in the heart and lungs, as well as a decrease in cardiac output.
The Frank–Starling law is a fundamental principle of cardiac physiology and has important implications for the understanding and treatment of heart disease.