Physiology, Cardiac Cycle

The cardiac cycle is a series of pressure changes within the heart. These pressure changes result in blood movement through different chambers of the heart and the body as a whole. These pressure changes originate as conductive electrochemical changes within the myocardium that result in the concentric contraction of cardiac muscle. Valves within the heart direct blood movement, which leads to the organized propulsion of blood to the next chamber. This rhythmic sequence causes changes in pressure and volume that are often seen graphically in the form of a Wiggers diagram or venous pressure tracings (see Wiggers Diagram). This information is vital to the clinical understanding of cardiac auscultation, pathology, and interventions.