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Aortic Pressure During Cardiac Cycle



During Ventricular Systole

At the end of isovolumetric contraction → aortic valve opens

Ventricles push blood into aorta

pressure in aorta increases

with continued ejection of blood → the pressure in aorta increases beyond that in left ventricular pressure

In spite of higher pressure in aorta, the aortic valve does not close for a while because the inertia of moving blood keeps the cusps open

Then ejection gets slower

Blood flow gets slower

Pressure in ventricles falls

Small 'Backflow' of blood

Closes the aortic valve

Blood again starts moving in forward direction

Last 3 events (i.e. backflow → closure of valve → forward flow) produce a notch in the pressure recording → called dicrotic notch or incisura


During Ventricular Diastole

Blood keeps moving forward from aorta into circulation

Pressure gradually falls

Next cycle begins with ventricular systole


Pressure Values
  • Pressure in aorta ranges…

    • from 80 mmHg at the end of diastole

    • to 120 mmHg during systole.

  • Pressure curve in pulmonary artery is similar but values are lower.

    • Lowest pressure is 7 mmHg

    • highest is 25 mmHg.

 

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