What is isovolumetric ventricular relaxation?

Isovolumetric ventricular relaxation refers to the phase in the cardiac cycle during which both the mitral/tricuspid and aortic/pulmonary valves are closed and the intraventricular pressure decreases without a change in ventricular volume. Key points about isovolumetric ventricular relaxation:

Timing: It occurs between systole (ventricular contraction) and diastole (ventricular filling).

Valves: The mitral/tricuspid valves (on the left and right sides of the heart, respectively) are closed to prevent regurgitation of blood into the atria. The aortic and pulmonary valves remain closed to prevent backflow into the great arteries.

Pressure Changes: During this phase, the intraventricular pressure drops as the myocardium (heart muscle) relaxes.

Volume Changes: Ventricular volume remains constant because there is no flow of blood into or out of the ventricles.

Significance: Isovolumetric ventricular relaxation allows for the buildup of suction within the ventricles. This negative pressure facilitates the rapid filling of the ventricles during the subsequent phase, known as rapid filling, which is the initial phase of ventricular diastole.

Understanding the phases of the cardiac cycle, including isovolumetric ventricular relaxation, is crucial in assessing cardiac function and diagnosing various heart conditions.