Heart failure used to describe a point at which the heart can’t supply enough food to meet the body’s demand. This can happen in two ways I know the third ventricle can’t come blood hard enough Urine Stone called systolic heart failure or not enough blood fills the ventricles during Diastole called diastolic heart failure.
In both cases, Blood bags up into Dylan’s causing congestion or blood buildup, which is why it’s also often known as congestive heart failure or just CHF. Congestive heart failure affects millions of people around the world and since it means that the body’s need is not being met, it can ultimately lead to death. Part of the reason why so many people are affected by heart failure is that there are A wide variety of heart diseases like ischemia and valvular diseases that can impair the heart’s ability to pump out blood and -over time- can ultimately cause the heart to fail.
Alright first up in systolic heart failure kind of mathematical way to think this one is that the heart needs to squeeze out a certain volume of blood each minute called cardiac Output, which can be rephrased as the heart rate (All the number of Beats in a minute )multiplied the stroke volume( the volume of blood squeezed out with each heartbeat ). The heart rate is pretty intuitive but stroke volume is a little tricky. For example, in an adult, the heart might beat 70 times per minute and the left ventricle might squeeze out 70 ml pipette so 70 x 70 is equal to a cardiac output of 4900 ml per minute, Which is almost 5 liters per minute. So you can notice that not all the blood was pumped out right? An nd the stroke volume is a fraction of the total volume.
The total volume may be closer 110 ml and 70 ml is the fraction that gets ejected Out with each Beat the Other 40 ml kind of lingers in the left ventricle until the next Beat, In this example, the ejection fraction would be 70 ml divided by 110 ml or about 64%, a Normal ejection fraction is around 50 to 70% between 40 to 50% would be borderline, and anything about 40% or less would indicate systolic heart failure because the heart is only squeezing Out a little blood is beat.
So in this example, if the total volume of the left ventricle was 110 ml but only 44 ml was pumped out with each beat( then you have 44 ml divided by 110 ml which is 40 %), then we would say that this person is in systolic heart failure.
Diastolic heart failure Which is where the heart is squeezing hard enough but not feeling quite enough. In this case, again the stroke volume is low but the ejection fraction normal. It’s not filling enough so there’s a low total volume, say about 69 ml, well even though both are low, 44 ml divided by 69 ml is still 64 %.
In this situation, the failures caused by abnormal filling of the ventricles so that the Chamber doesn’t get fully loaded or stretched out in the first place. Another term for this is having a reduced “preload” which is the volume of blood that’s In the right ventricle before the ventricular muscle contracts.
An important relationship between systolic and diastolic function can be understood through Frank-Starling Mechanism, which basically shows that loading up the ventricle with blood during diastole And stretching out the cardiac muscle makes it contract with more force which increases Stroke volume during systole.
This is kinda like how stretching out a rubber band make it snapback even harder, except That cardiac muscle is actively contracting whereas the rubber band is passively going Back to its relaxed state which is a basic difference.
Heart failure can affect the right ventricle or the left ventricle or both ventricles so someone might have right-sided heart failure, left-sided heart failure or both (Which is called by biventricular heart failure ), Each of which can have a systolic or diastolic failure.H having said that, if less blood exists either ventricle it will affect the other since they Work in series, so left sided could cause right sided and vice versa ,so these terms Really refers to the primary problem affecting the heart, basically which one was first .
Usually, left-sided heart failure is caused by systolic dysfunction.T he is typically due to some kind of damage to the myocardium or the heart muscles, which means it can’t contract as forcefully and pump blood as efficiently. Ischemic Heart disease caused by coronary artery atherosclerosis or plaque build up, Is the most common cause. In this case, less blood and oxygen in the blood gets through the coronary artery to the heart tissue, which Damages the myocardium. sometimes, if the coronary is blocked completely and the person has a heart attack, they might be left with scar tissue that doesn’t contract at all, which again means the heart can’t Contract as forcefully.
Long-standing hypertension is another common cause of heart failure.T his is because as arterial pressure increases in the systemic circulation, it gets harder For the left ventricle to pump blood out into that hypertensive systemic circulation.T o Compensate, The left ventricle actually bulks up, And it’s muscle hypertrophy, or Grow so that the ventricle can contract with more force . The increase in muscle mass also means that there is a great demand for oxygen, and, So that even less blood delivered to the tissue.M ore demand and reduced supply means that some of the ventricular muscle starts have weaker contraction leading to systolic failure.
Another potential cause would be dilated cardiomyopathy, where the heart Chambers dialects, or grows in size in an attempt to fill up the ventricle with a larger and larger volume of blood, or Preload stretch out the muscle wall and increase contraction strength, via the Frank-Starling mechanism. Even though This can work for a little while, over time, the muscle walls get thinner and weaker, eventually leading to muscle that is so thinned out that it cause systolic Left side heart failure. Ultimately the ventricle walls need to be the right size relative to the size of the Chamber in order for the heart to work efficiently.
Any major deviation from that can lead to heart failure. Even though systolic Failure is most common in left-sided heart failure diastolic heart failure or fillings dysfunction can also happen. In hypertension, remember how the left Ventricular hypertrophied? Well, that hypertrophy is concentric which means that the new sarcomeres are generated in parallel with existing sarcomeres. This means that as the heart muscle wall enlarges, it crowd into the ventricular chamber space, resulting in less space for blood, meaning that in addition to contributing to systolic dysfunction, hypertension also can cause diastolic heart failure.
Concentric hypertrophy leading to diastolic failure can also be caused by aortic stenosis, Which is a narrowing of the aortic valve opening as well as by hypertrophic cardiomyopathy, an Abnormal ventricular wall thickening often from a genetic cause.R restrictive cardiomyopathy is yet another cause. In this case, the heart muscle gets stiffer and less compliant, and therefore it is not easy for left Ventricle to stretch out and fill with as much blood which leads to diastolic Heart failure.
When the heart doesn’t able pump out as much blood, there is decreased in the blood flow to the Kidneys which activates the renin-angiotensin-aldosterone system, ultimately causing fluid retention. Which fills the heart little more during diastole and increases preload which increases contraction Strength again by the help of Frank-Starling mechanism.
Unfortunately, Just Like The Other strategies, in the long-term, retaining fluid so that more fluid remains in the blood vessel typically leads to a large portion of it leaking into The tissues and can contribute to fluid buildup in the lungs and another part of the body, Which can worsen the symptoms of heart failure. Alright so major, a major clinical sign of the heart not being able to pump enough blood forward to the body is that blood starts to back up into the lungs.
A backup of blood in the Pulmonary vein and capillary beds can increase the pressure in The Pulmonary artery and can also result in a fluid moving from the blood vessels to the Interstitial space causing pulmonary edema or often congestion. In the alveoli of the lungs, all this extra fluid makes Oxygen and Carbon dioxide exchange through blood makes a lot harder, Since a wider layer of fluid takes more time for Oxygen and Carbon dioxide.
To diffuse through and therefore patients have dyspnea- trouble breathing, as well as orthopnea-Which is difficulty breathing when lying down flat since that allows venous Blood to more easily flow back from the legs and the gut to the heart and eventually into The pulmonary circulation. This extra fluid in the lungs causes crackles or rales to be heard on auscultation while the patient breathes.
If enough fluid filled some of these capillaries in the lungs, they can rupture, leaking blood Into the alveoli. Alveolar macrophages then eat up these red blood cells which cause them to take on this brownish color from Iron build-up. And then they are then called” hemosiderin- Laden macrophages “, Also known as” heart failure cells”. For left-sided heart failure, certain medications can be prescribed to help improve blood flow, Like ACE inhibitors which help dilate blood vessels as well as diuretics to help reduce the overall fluid buildup in the body which helps prevent hypertension from worsening the heart failure.
Now let’s switch gears and think about right-sided heart failure which is often caused by left-sided heart failure. Remember how fluid buildup increased pressure in the Pulmonary artery, Well this increased pulmonary blood pressure makes it harder for the right side to pump blood into. In this case, heart failure would be biventricular since both ventricles are affected. Someone can have also isolated right-sided heart failure, though, and an example of this Would be left to the right cardiac shunt. In these cases there might be a cardiac shunt like an atrial septal defect or a Ventricular Septal defect that allow blood to flow from the higher pressure left side to the lower pressure right side, Which increases fluid volume on the right side and can eventually lead to concentric hypertrophy of the right ventricle, making it more prone to ischemia- which is,a systolic dysfunction and have a smaller volume and become less compliant which is a diastolic dysfunction .
Another potential cause of isolated right-sided Failure is chronic lung disease. Lung diseases often make it harder to exchange oxygen. Well in response to low oxygen level or hypoxia, the pulmonary arterioles constrict, Which raises the pulmonary blood pressure. This just like before makes it harder for the right side of the heart to pump against And can lead to right-sided hypertrophy and heart failure. When chronic lung disease leads to right-sided hypertrophy and failures it’s known as Cor pulmonale. With left-sided failure, blood gets back up into the lungs.
With right-sided failure, blood gets back up to the body and so patients have congestion In the veins of the systemic circulation. One common manifestation of this is jugular venous distention, where the jugular vein that brings blood back to the heart takes on more blood and becomes enlarged and distended In the neck. Also in the body ,when blood backs up to the liver and spleen, fluid can move into the Interstellar space within those organs and they can both become enlarged called hepatosplenomegaly, Which can be painful and if the liver is congested for long periods of time, patient can eventually develop cirrhosis a type of liver failure, which would be called cardiac cirrhosis .
Excess interstitial fluid near the surface of the liver and spleen can also move right Out into the peritoneal space as well and since that cavity can take a lot of fluid before there is an increase in pressure, a lot of fluid can build up in the peritoneal Space which is called ascites. Finally, the fluid that backs up into the interstitial space in the soft tissues in the legs causes pitting edema, where the tissue is visibly swollen and when you apply pressure to it, it leaves a “pit” and takes a while to come back to its original place.
This generally affects the legs in the most population of people suffering-+ heart disease, because gravity generally causes the majority of fluid to “pool” in the dependent parts of the body, which is the legs when you’re standing and the sacrum, essentially the lower back, when you’re lying down. Right-sided heart failure can be treated similarly as like left-sided heart failure treated, especially because it’s often a result of left-sided heart failure.
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