Aortic Pressure During Cardiac Cycle

At the end of isovolumetric contraction → aortic valve opens

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Ventricles push blood into aorta

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pressure in aorta increases

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

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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

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Blood flow gets slower

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Pressure in ventricles falls

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Small 'Backflow' of blood

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Closes the aortic valve

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Blood again starts moving in forward direction

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

Blood keeps moving forward from aorta into circulation

↓ Pressure gradually falls

↓

Next cycle begins with ventricular systole

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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