Therefore, an isovolumetric contraction is one in which the volume of fluid remains constant.

Isovolumetric contraction is a term used in cardiac physiology to refer to an event occurring in early systole, during which the ventricles contract with no corresponding volume change.

Ventricular pressure continues to rise in isovolumetric contraction with maximal pressure generation (max dP/dt) occurring during this phase, until the pulmonary and aortic valves open in the ejection phase.

The isovolumetric contraction lasts for about 0.03 s, but this short period of time is enough to build up a sufficiently high pressure that will eventually overcome that of the aorta and the pulmonary trunk upon opening of the semilunar valves, therefore allowing the correct unidirectional flow of blood.