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Old 11-20-2010
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Drug Pharmacology Question

I'm just watching the Kaplan videos for CK.

In talking about Mitral Stenosis, he says that salt restriction and DIURETICS are best for preload reduction and ACE INHIBITORS are no good for preload reduction. ACE INHIBITORS are only good for ventricular emptying whereas MS is a problem with ventricular filling and therefore DIURETICS are the best option.

Could someone explain why diuretics are good for preload reduction and not ACEi? And also why ACEi are only good for emptying, not filling of LV?
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Old 11-20-2010
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ACEi also lower at2 which is an arterial constrictor thus reducing afterload and facilitating ventricular emptying. They are also mild diuretics. On the other hand diuretics do only one job: lower vascular volume, thus reducing the preload only. Hope this helped
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Old 11-20-2010
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Thank you for your answer.

I understand that diuretics lower volume, and therefore preload (or EDV).

However, the ACEi, I don't fully understand yet. ACEi have two main functions:
1 reduce in aldosterone secretion (by inhibiting ACE and lowering A2), therefore decreased Na retention, therefore decreased intravascular volume (like diuretics)
2 reduce in A2, which vasodilates and facilitates ventricular emptying by decreasing the pressure/force by which the ventricle needs to contract to pump blood through the more dilated vasculature.

If ACEi reduce intravascular volume (1), then how come they don't help preload?
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Old 11-21-2010
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Quote:
Originally Posted by karansaraf View Post
Thank you for your answer.

I understand that diuretics lower volume, and therefore preload (or EDV).

However, the ACEi, I don't fully understand yet. ACEi have two main functions:
1 reduce in aldosterone secretion (by inhibiting ACE and lowering A2), therefore decreased Na retention, therefore decreased intravascular volume (like diuretics)
2 reduce in A2, which vasodilates and facilitates ventricular emptying by decreasing the pressure/force by which the ventricle needs to contract to pump blood through the more dilated vasculature.

If ACEi reduce intravascular volume (1), then how come they don't help preload?
They do reduce intravascular volume however to my knowledge this is not the main action. I guess if you want to reduce volume you should directly go with diuretics. I.e it's like aspirin and steroids. If you really want immunosuppression you go with steroids, not simple antiinflammatories.
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