Medical Velocity of blood through aorta

[engineer23]

Does anyone know the velocity of blood through the aorta? I have a problem that involves an ultrasound probe and I need to know which velocites of blood I should design for. I know cardiac output is stroke volume x heart rate, but a) what are the range of values for stroke volume and b) how do I correlate flow rate to velocity?

Thanks!

 

[engineer23]

OK, I think I had an epiphany since I posted a few minutes ago...Cardiac output is 5L/min...I can convert this to cubic feet min and divide by the cross sectional area of the aorta to get a velocity. But what are the upper and lower limits on the radius of the aorta?

 

[Dale]

The blood flow in the aorta is highly pulsatile and even goes retrograde during part of diastole. Also the aorta is highly distensible (in healthy people) and so the cross sectional area of the aorta is not constant either. Basically, your epiphany is a nice idea, but the reality is a little more complicated.

A good rule of thumb is that the peak flow velocity is about 100 cm/s, but again this is the peak velocity not the average velocity. Also, the peak velocity depends on orientation (standing vs. supine) and metabolic state (resting vs. exercise) http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=481953

 

[Gokul43201]

On a side note, the earliest definitions of kinetic energy and the first suggestion of the law of conservation of mechanical energy arose from measurements that Bernoulli was performing on the flow velocity of blood (when he noticed that if you cut off a limb, the height to which the blood spurted out was proportional to the square root of the flow speed ).