Congestive Heart Failure: Pathophysiology

congestive heart failure pathophysiology overview and boy is it a vicious cycle congestive heart failure usually starts from some kind of damage or weakening to the heart muscle usually caused by clogged arteries due to coronary artery disease or increased afterload from chronic long-term hypertension this then this weakening of the heart decreases stroke volume stroke volume is the amount of blood pumped by the heart with each beat so if stroke volume goes down down goes cardiac output which is the amount of blood that's pumped by the heart in a minute now the heart has a couple of compensations it will make to try and increase cardiac output one of those is to increase heart rate because if you can increase heart rate you could increase cardiac output however all compensations come with a price tag and in this case the price tag is less time to fill another compensation that we'll see by the heart are structural changes and these are made these structural changes in the heart muscle are an attempt to increase stroke volume one common kind of compensation we see in the heart muscle is called dilated cardiomyopathy in this situation the wall of The ventricle becomes very thin the heart is getting bigger it's trying to pump more blood but this comes at a cost it's actually just getting weaker it's losing its leverage to pump well and you can see that what's going to happen then is as it pumps even less effectively stroke volume drops further perpetuating this vicious cycle of a weakening heart another thing that's sometimes seen a change in the heart muscle during congestive heart failure or leading to it is a thickening of the ventricle wall we call this hypertrophic cardiomyopathy in this situation the walls are getting thicker trying to pump more blood but they're getting stiffer as well and there's less room for blood so they don't F the way a healthy heart should and you can see in this case too that although The ventricle is trying to pump more blood it's actually not succeeding and we have a progressive drop in stroke volume okay now on to the kidney the kidney is exquisitely sensitive to drops and cardiac output as you can see it gets grumpy when it doesn't get enough blood unhappy kidneys that need more blood will release rinin and rein causes the formation of a hormone called Angiotensin Angiotensin stimulates the release of another hormone called aldosterone and aldosterone causes is salt and water retention so you can see that we're getting some fluid accumulation right now if you put it all together and think okay the heart is getting weaker in its compensatory changes while it's trying to increased stroke volume it's actually losing leverage or not feeling well anymore and you're having this Progressive aggressive drop in cardiac output so the drop in cardiac output continually is stimulating the kidneys to continue releasing renin and that continued production of renin is going to cause more and more aldosterone to be in the blood and you can see then that in um as congestive heart failure proceeds you can end up with volume overload if it's the left side of the heart that failed first then what will happen is blood will be waiting to enter the left side of the heart and where is it waiting around it's waiting around in the lungs and blood that sits around or loiters gets itself into trouble and in fact it starts seeping in to the tissues or if it's in the lungs it can cause pulmonary edema and that's where we get that word congestion from there's actually pulmonary congestion too much fluid in the lungs if it's the right side of the heart that failed first or if the left side failed and then the right start right side starts to fail which is typically what happens now in this you have blood waiting around in the periphery trying to get back into the right side of the heart so that's going to be blood draining from the head so we might see jugular vein distension or it might be blood that is down in the lower legs and it's seeping out into the tissues and so now we could have swollen ankles uh as the disease progresses there might even be fluid accumulation occurring in the abdomen we call that aites or in the liver and that would be liver congestion so a general name for that though is peripheral edema where we would see the swollen ankles Etc okay so now that you have an idea of uh what's going on with the comp compensations that ultimately cause a weaker and weaker uh functioning heart and a continual decrease in cardiac output then you can see um how congest heart failure truly is a vicious cycle so in our next video we'll talk about some treatments for congestive heart failure and I'll particularly try to tie together how the treatments get at what is going on uh specifically in this rein Angiotensin aldosterone system and a little bit on the heart how um certain medications can be used to ease the workload on the heart

Channel: Science with Susanna

Views: 301,729

Keywords: CHF, congestive failure, pathophysiology, decompensatory mechanisms

Id: zeSDuiTbM9o

Length: 7min 56sec (476 seconds)

Published: Fri Dec 27 2013