Isovolumetric contraction
![Wiggers diagram of the cardiac cycle, with isovolumetric contraction marked at upper left.](/Images/godic/202501/21/Wiggers_Diagram.svg5036.png")
In cardiac physiology, isovolumetric contraction is an event occurring in early systole during which the ventricles contract with no volume change (isovolumetrically). This short-lasting portion of their contraction takes place during a moment when the heart valves are all closed.