- begins after the onset of the QRS wave, which represents electrical activation of the ventricles.
- When ventricular pressure becomes greater than atrial pressure, the AV valves close. Their closure corresponds to the first heart sound. Because the mitral valve closes before the tricuspid valve, the first heart sound may be split.
- Ventricular pressure increases isovolumetrically as a result of ventricular contraction. However, no blood leaves the ventricle during this phase because the aortic valve is closed.
Was this article helpful?