Cardiac Cycle - Reduced Ejection (Phase 4)

Aortic and Pulmonic Valves Open; AV Valves Remain Closed

• Approximately 200 msec after the QRS and the beginning of ventricular contraction, ventricular repolarization occurs as shown by the T-wave of the electrocardiogram. Repolarization leads to a decline in ventricular active tension and therefore the rate of ejection (ventricular emptying) falls. Ventricular pressure falls slightly below outflow tract pressure; however, outward flow still occurs due to kinetic (or inertial) energy of the blood.
• Left atrial and right atrial pressures gradually rise due to continued venous return from the lungs and from the systemic circulation, respectively.

Jump to other phases:

• Phase 1 - Atrial Contraction
• Phase 2 - Isovolumetric Contraction

• Phase 3 - Rapid Ejection
• Phase 5 - Isovolumetric Relaxation
• Phase 6 - Rapid Filling
• Phase 7 - Reduced Filling

Revised 04/05/07