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 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.