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.