Why does aortic stenosis reduce coronary blood flow?

[studylol]

Hello friends,

Coronary blood flow is determined by length of diastole. I am trying to imagine the mechanism by which AS causes reduced coronary blood flow, but i'm a little stuck.

How does it work?

Thanks.

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[Apoplexy__]

Take a step back at the bigger picture: you're decreasing the size of the aperture by which blood moves to supply the heart (through the aortic valve > aorta > coronary arteries). You're making it more difficult for blood to get through there.

The length of diastole is the most important determinant under physiological conditions, not pathological ones. Under pathological conditions, something else can become the rate-limiting factor.

 

[studylol]

Is that something else reduced systolic blood pressure? Less bp in root of aorta during systole causes less pressure gradient for blood to flow through coronaries, i'm thinking.

 

[Instatewaiter]

Hello friends,

Coronary blood flow is determined by length of diastole. I am trying to imagine the mechanism by which AS causes reduced coronary blood flow, but i'm a little stuck.

How does it work?

Thanks.

it is actually caused by loss of microcirculation and loss of coronary flow reserve.

You lose the downstream flow so your overall coronary flow decreases.