Dicrotic notch is caused by ?

Ans. is 'c' i.e.. Closure of aoic valve Aoic pressure curve With the onset of rapid ejection phase of the ventricular systole, the aoic pressure rises steeply to reach a maximum of about 120 mm Hg. The ejection of blood into the aoa causes a stretch on the aoic walls and makes the blood in the entire aerial system to move at a faster rate. This sets up a pressure wave that travel along the aeries. The pressure wave expands the aerial wall as it travels, and expansion is palpable as the pulse. In the later pa of ventricular systole, the aoic pressure declines and continues to decline throughout the diastole, to reach a minimum of about 80 mm Hg during the isometric contraction of the next cardiac cycle. The elastic recoil of the aoa and the resistance of aerioles help to maintain relatively high aoic pressure during diastole. A notch (incisura or dicrotic notch) is rocorded in the early pa of down strok of the aoic pressure curve. It corresponds to the closure of aoic valve. It is produced by the sudden backward flow of aoic blood followed by the immediate cessation of backtlow due to closure of the aoic valves.