Left ventricular pressure-time curve

See graph 20050607

Phases

Systolic phases

1. Mitral valve closes
2. Isovolumetric contraction
3. Aortic valve opens
4. Isotonic contraction (rapid ejection, then reduced ejection)
5. Protodiastole
   * Pressure falling just before aortic valve closes

Diastolic phases

1. Aortic valve closes
2. Isovolumetric relaxation
3. Mitral valvle opens
4. Rapid filling
5. Diastasis (reduced filling)
6. Atrial systole

Points to note

• a wave - Due to atrial contraction
• c wave - Bulging of MV into LA due to isovolumetric contraction of LV
• x descent - During rapid ejection, the shortening of LV pulls fibrous atrioventricular ring downwards, lengthening LA and increasing LA size
• v wave - Passive filling of LA against closed MV
• y desecent - Opening of MV and rapid filling of LV
• Incisura (the dicrotic notch) - Due to small retrograde flow at the end of ventricular systole hitting against the AV as it closes (kinetic energy of the reverse flow converted into pressure)
• [BL8:p75] Peak of the flow curve occurs where LV pressure curve intersect the aortic pressure curve

Other notes

LV filling

• 60% in rapid filling phase
• 10% in diastasis
• 30% in atrial systole

Difference in the elderly

• Isovolumetric contraction phase, pressure rise not as sharp
• Higher peak pressure during systole
• Lower heart rate
• Wave forms travel more quickly because of stiffer walls

Venous pulse

Except for the c wave, venous pulse pressure curve closely follows the atrial pressure curve