Cardiac Events + Sounds

Atrial Systole Major Events

• Atria contract

• Final phase of ventricular filling

Isovolumetric Ventricular Contraction

• Ventricles Contract

• Ventricular pressure increases

• Ventricular pressure is constant (all valves are closed)

Rapid Ventricular Ejection

• Ventricles contract

• Ventricular pressure increases and reaches maximum

• Ventricles eject blood into arteries

• Ventricular volume decreases

• Aortic pressure increases and reaches maximum

Reduced Ventricular Ejection

• Ventricles eject blood into arteries (slower rate)

• Ventricular volume reaches minimum

• Aortic pressure starts to fall as blood runs off into arteries

Isovolumetric Ventricular Relaxation

• Ventricles relaxed

• Ventricular pressure decreases

• Ventricular volume is constant

Rapid Ventricular Filling

• Ventricles relaxed

• Ventricles fill passively with blood from atria

• Ventricular volume increases

• Ventricular pressure low and constant

Reduced Ventricular Filling (or Diastasis)

• Ventricles relaxed

• Final phase of ventricular filling

P wave

Atria contract (atrial systole)

PR interval

Final phase of ventricular filling (atrial systole)

QRS Complex

Isovolumetric ventricular contraction

ST segment

Rapid ventricular ejection

T wave

Reduced ventricular ejection

Mitral valve closes

Isovolumetric ventricular contraction

Aortic valve opens

Rapid ventricular ejection

Aortic valve closes

Isovolumetric ventricular relaxation

Mitral valve opens

Rapid ventricular filling

First heart sound

Mitral and tricuspid valves close

Second heart sound

Aortic and pulmonary valves close

Third heart sound

Ventricular filling

Fourth heart sound

Atrial filling