congestive heart failure: pharmacology priyanka sachdev

 congestive heart failure: pharmacology priyanka sachdev 

Congestive heart failure: pharmacology, Priyanka Sachdev. The pathophysiology behind this, and there are actually a few different types of heart failure, believe it or not, there is left heart failure, right heart failure, and that is called high output failure

We are going to talk about left heart failure first, which is by far the most common type of heart failure. Now, we are going to talk about left heart failure.

We want to think about two different types or subtypes. If you think about left heart failure, it is called systolic heart failure and diastolic heart failure

Now, the main reason this patient had heart failure was that the underlying cause was starting to progress to heart failure. If the patient progresses, their contractility will decrease, so the left ventricular myocardium will decrease in contractility.

So the contractility is decreasing, then you have to ask yourself the question, what is causing this left ventricular myocardium to contract? What are the disease processes that are causing it?

So we are going to explain here that the left ventricular myocardium is damaged. The shape or form and the contractility are knocked on here, which is one of the most common causes, which is myocardial infarction

If a patient has an MI, it causes fibrosis of that tissue. Do you lose contractility there? It is a way that others believe it or not, cardiomyopathies that you know.

This is particularly very common, which is related to cardiopathy, because what happens is the actual ventricles become really thin and very weak, which is another one where the contractility is reduced, another one can be myocarditis

But that's relatively uncommon, but we'll put that down too, so another one can be myocarditis, so there can be inflammation of the myocardium, but all of these things would be triggering factors

Which can't cause the heart's contractility to be impaired. The heart, specifically the left ventricle, is not working properly. It cannot push the blood out of the left ventricle and into the aorta very well

And so that's where the problem arises, is that the patient has trouble pumping blood out of the heart, so they have a forward flow problem, so there's a very important formula like that that we're not going to get crazy about, but it helps us get the left side out.

Fraction and this is a very important term so in a person who has systolic heart failure sometimes what happens is when you drop the contraction you drop the contraction

which is called the left ventricular ejection fraction which is basically the amount of blood that you can pump from the heart to the right and when that happens when your left contraction decreases

so your contraction goes down and now your contraction drops. It's harder to get blood out of the heart. When that happens, we have a very specific term

whenever a patient has a decrease in their left ventricular ejection fraction, especially when it's below 40% you know, we call it heart failure with a low ejection fraction, we call it hemiplegia, and usually when that happens.

Less than 40 percent, so when the left ventricular ejection fraction is less than 40, we call it hefrif, which is another way of describing systolic heart failure, but the whole point here is that I want you to understand

is that there can be a decrease in the amount of blood that comes out of the heart, so what do you call it when the volume of blood that you think a heart is pumping decreases

cardiac output, so in these patients, they will start to experience a decrease in cardiac output, which we are going to describe as Co for short, and this is the biggest distinguishing factor here for systolic heart failure or hefrif heart failure

where the low ejection fraction can cause a decrease in contractility due to these diseases when we come here it is another flavor of heart failure which is another flavor of heart failure

which is another problem of heart failure. The feeling that it's really hard to get blood out of the heart, and there are some ways that blood leaves the heart properly

So we call this kind of stroke volume the amount of blood that you're getting out of the heart, and a heart rate that depends on the preload contraction, and what

The last one is afterload, when the afterload goes crazy in these patients, it's hard for them to get blood out of the heart, and the problem here is usually that it

Patients massively increase their afterload, which is the diseases that really increase afterload

and cause these particular types of problems, chronic hypertension can't say how common this particular etiology is

which is probably going to be one of the most common causes by far, so that would be a chronic blood pressure, we'll put chronic here, which is another one you know is right here.

aortic valve aortic semilunar valve what if that valve is super super stenotic and because it's crazy crazy stenotic it's almost hard it's kind of obstructing the forward flow

which also causes afterload aortic stenosis. Here is another common cause, so the other disease would be called aortic stenosis. It's a very common cause.

Afterload is basically anything that makes it difficult for the left ventricle to pump blood out of the heart. These two things are by far the most common things that will cause diastolic heart failure.

Now, what you see in systolic heart failure is a right ventricle that is overdilated, so let's actually write it down here. It's a very complex thing that you need to note.

Hypertrophied. This ventricle is very hypertrophied. So you have what's called hypertrophy. This is a very thick and large left ventricle. We call it left ventricular hypertrophy.

Or sometimes LVH for short. Now, the reason to think about it is that if the pressure in the aorta is actually so high that you have to overcome it, then what is that?

That's when you can thicken the left ventricle; you can do that. Rejuvenate that left ventricle, and you get it to where you're actually able to produce more stroke volume

Now the problem is you reduce the actual space of the left ventricle, and now my problem is I'm not getting a lot of blood into the left ventricle, I can't fill it properly

And so this problem is filling, it was a forward flow, so what I see here is that in this particular disease process, there is a problem of diastolic heart failure

that they have a reduced filling process in the left ventricle.

Ventricular filling, and since I can't fill the ventricles well, that's what's causing the problem now. Here's the thing

Their left ventricular ejection fraction is completely fine; it's usually completely preserved, so this filling process won't affect the ejection fraction

So their left ventricular ejection fraction is usually allowed to be used as a term; this is where we have the term heart failure

Which in the lowercase p is preserved ejection fraction, where if we give it a certain number, it's at least greater than 40%

So, in the population of these patients who have diastolic heart failure, their filling is reduced because their ventricle is super hypertrophied, which is why their left ventricular ejection fraction is called half

And here they have half. The question is, his cardiac output is low because due to less contraction, he will also have less cardiac output. You guys know

why his cardiac output will be low. He will have less cardiac output because, think again about your physiology, guys, it is very important to understand physiology here

. If my filling is low, then I will not preload. What happens to my stroke volume that goes down if stroke volume goes down what happens to my cardiac output

which goes down, so both these patients will have less cardiac output, but the main difference here is that this is a preserved EF because they do not have a problem with the rejected portion; it has less of a problem with contractility of the ejection fraction because they have a lack of dilatation.

ventricle hypertrophy ventricle super high yield can't forget these things understand the causes understand high afterload understand the contractility problem okay

Now we get into something that I think is really important, and I think can often be overlooked when patients have heart failure, because of these problems

So it can get worse and worse if left untreated. Let me tell you why, when your heart rate goes down a little bit, you go back to Physiology here when cardiac output goes down

What we know is that there is always that formula. Do you guys remember the formula for blood pressure? Do?  You have the formula for blood pressure

, that blood pressure is equal to cardiac output times the systemic vascular resistance. In patients who have heart failure, what is the systemic vascular resistance here? Their cardiac output drops

And then if you say that keeping it normal or constant, what will happen to their blood pressure, which will also drop? Then what is the normal compensatory mechanism that our body tries to create?