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Old 03-25-2011
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Heart Why edema in hypertension!

In heart failure, patients are suffering from edema because the heart can't pump out enough, effective circulating volume is reduced and RAS is activated and total volume is increased and so the pressure is increased, edema occurs. due to starling law

Hypertension is literally having increased pressure, but why hypertension patient doesnt have edema like heart failure patient.


I know it is stupid question but somebody help me!!
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Old 03-25-2011
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of course i mean primary hypertension without heart failure or kidney problem.
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Old 03-25-2011
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The development of edema is due to the increase of Starling forces which promote the movement of fluid to interstitium and to maintain the edematous state, it requires retention of salt and water by kidney (due to RAA system activation). Without the involvement of kidney, the development of edema will be self limited as the movement of fluid from intravascular to interstitium would reduce the Starling forces that originally promoted the edema.

In primary hypertension, there is no activation of RAA system (unlike in CHF) since kidney has the ability to maintain renal blood flow through autoregulation.
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Old 03-25-2011
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You can also think of the pulmonary (right-sided) circulation and systemic (left-sided) circulation as two separate systems connected in line with each other (I picture it as a circle, myself - try drawing it). Pulmonary hypertension leading to edema is from a blockage just beyond in the cycle - blood is caught between a strong pump and a broken pump, so it backs up in the pulmonary circulation. And as harlesmd said, the systemic circulation doesn't know what's going on in the pulmonary; it just knows that the pressure is a little low, so it holds water to raise the pressure. Essential hypertension is less of a backup because it's just more fluid in the system but the pumps are still working. It could theoretically lead to edema, but you'd have to have a huge amount of extra fluid.

hope that helps
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Old 05-30-2011
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Default Thanks a lot for this information

Same thing is happen with my uncle
thanks for this unique information.


Smith Alan
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Old 01-06-2012
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please elaborate on that a little more i couldnt follow this doubt has been bugging me since a long time now. why dont patients with hypertension have edema?? increased hydrostatic forces in the capillaries should push fluid out into the tissues right?!
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Old 01-06-2012
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Quote:
Originally Posted by tanu_ag90 View Post
please elaborate on that a little more i couldnt follow this doubt has been bugging me since a long time now. why dont patients with hypertension have edema?? increased hydrostatic forces in the capillaries should push fluid out into the tissues right?!
You are confusing urself,,,!! Edema in HF occurs due to raised hydrostatic pressure in the capillaries that pushes the fluid out of capillaries,.. but in hypertension the pressure is significantly raised in the Medium and Large sized vessels, the micro-circulation is effected at last and thats too is not in the range to push the fluid out of the capillaries and cause edema...!!! Hope it'll help.!!
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Old 01-09-2012
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cool that makes sense...thanks i had another doubt related to hemodynamics...
I read this from Guyton textbook of physiology- apparently the cardiac output is determined by the total peripheral resistance...the blood flow to each tissue is determined by the local resistance there and the systemic arterial pressure...the cardiac output is inversely proportional to the total peripheral resistance. But once the blood is out of the heart- its gotta go somewhere right? the blood will face resistance only once it reaches the arterioles...so how can arteriolar resistance decrease cardiac output? if the total peripheral resistance is suddenly increased- where is that remaining blood gonna go if the heart pumps out lesser? and does this mean that hypertensive patients have low cardiac output?
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Old 01-09-2012
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Quote:
Originally Posted by tanu_ag90 View Post
cool that makes sense...thanks i had another doubt related to hemodynamics...
I read this from Guyton textbook of physiology- apparently the cardiac output is determined by the total peripheral resistance...the blood flow to each tissue is determined by the local resistance there and the systemic arterial pressure...the cardiac output is inversely proportional to the total peripheral resistance. But once the blood is out of the heart- its gotta go somewhere right? the blood will face resistance only once it reaches the arterioles...so how can arteriolar resistance decrease cardiac output? if the total peripheral resistance is suddenly increased- where is that remaining blood gonna go if the heart pumps out lesser? and does this mean that hypertensive patients have low cardiac output?
In hypertension , there is arteriolar resistance and so capillaries are basically underfilled. Hence there is no edema in HT.


In early stages of hypertension, the heart compensates the arteriolar resistance by hypertrophy. But later as the severity increases, the heart decompensates and starts dilating. the excess blood which u say wil then get collected in heart and back flow to pulmonary.

the cardiac output wil decrease once heart fails.
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Old 01-22-2012
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thank u that totally makes sense
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