quick question about coronary arteries

[neoserenity333]

do they fill better or worse with increased diastolic pressure?

thanks!

p.s. i'm just kind of confused from Goljan's explanation about all the stuff that happens after you have a decreased cardiac output. He says the arterioles constrict because of catechols, resulting in maintenance of diastolic pressure. But that it's good news for the coronaries b/c they get filled then. I know that's when they get filled, but wouldn't they also constrict from the alpha1 effect?

good luck to all who are taking it soon!

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[crazy_cavalier]

do they fill better or worse with increased diastolic pressure?

thanks!

p.s. i'm just kind of confused from Goljan's explanation about all the stuff that happens after you have a decreased cardiac output. He says the arterioles constrict because of catechols, resulting in maintenance of diastolic pressure. But that it's good news for the coronaries b/c they get filled then. I know that's when they get filled, but wouldn't they also constrict from the alpha1 effect?

good luck to all who are taking it soon!

I don't think direct alpha1 effect is significant on the coronaries.

AFAIK, constriction of the coronaries is primarily due to them "getting squished" during systole and dilation of the coronaries is primarily due to metabolic byproduct (ADP, adenosine) accumulation

 

[neoserenity333]

thanks!

 

[The Angriest Bird]

AFAIK, constriction of the coronaries is primarily due to them "getting squished" during systole and dilation of the coronaries is primarily due to metabolic byproduct (ADP, adenosine) accumulation

Yeah, that's how I think of it too, even though I doubt this is the correct physiology.

Coronary muscles are unique because they are the only arteries that are in the muscles that power the arteries (heart). So, when the heart is contracting (systole), while every artery in the body is "blown open", the coronary artery gets squeezed.

Another thing. When heart rate increases, it's the diastole that gets shortened the most. So, coronary arteries have less time to be filled. Therefore, one important aspect of treating heart failure is to lower the heart rate, by using a beta-blocker such as metoprolol/atenolol.

 

[Ingersoll]

another thing to consider is the filling pressure of the coronary arteries. When the diastolic pressure in the aorta is higher (the time during which the coronaries are primarily filling), the filling pressure will be higher and vice versa.

At least that's how I think it is... as with everything, don't trust it 100%

 

[neoserenity333]

another thing to consider is the filling pressure of the coronary arteries. When the diastolic pressure in the aorta is higher (the time during which the coronaries are primarily filling), the filling pressure will be higher and vice versa...

Ah! I think I was getting "diastolic [blood] pressure" confused with "[end] diastolic pressure"... makes total sense now after your clarification
So hopefully I got it right this time:
- coronaries fill better at higher diastolic blood pressures
- coronaries fill worse at higher LV end diastolic pressures

Thanks all for your input.