Lecture 6 - Bernoulli Equation: Arterial Stenosis

Question 1

Bernoulli Equation?

Answer 1

p + 1/2 * rho *v^2 + rho * g *z = constant

Question 2

Bernoulli assumptions

Answer 2

No viscous losses and blood flow
is steady

Question 3

effective area of valvular stenosis equation?

Answer 3

As = Q * sqrt(rho / 2 * deltaP)

Question 4

What is Vena Contracta and when is it formed?

Answer 4

Vena contracta is the point in a fluid stream where the diameter of the stream is the least, and the fluid velocity is at its maximum (after exiting a hole)

Jets and vena contracta are formed when blood flow emerges from an opening such as a valve

It is the result of the inability of the fluid to turn a sharp corner

Question 5

Contraction Coefficient?

Answer 5

Ajet / Avalve

Question 6

What is stenosis.

Answer 6

Localized constriction in an artery, usually caused by atherosclerotic plaque or congenital defects.

Consists of converging, narrow and diverging sections. (Like a ‘pinch’)

Question 7

Which fluid laws apply at each section of a stenosis?

Answer 7

Converging - Bernoulli

Narrow - Poiseuille

Diverging - None

Question 8

What phenomena can occur distal to a stenosis? Why?

Answer 8

Increased arterial diameter (post-stenotic dilation)

Unclear - possibly abnormal shear stress, turbulent
flow, and wall vibrations leading to extracellular matrix remodelling in vessel wall