In (a.k.a. etiology) of heart failure are numerous,

In this first of two lessons, we will cover the main causes, signs, and symptoms of heart failure. We’ll also explore the ways that the left side of the heart and the lungs are affected by this condition.

What Is Heart Failure?

Whether it’s on TV or in real life, you have probably heard the term ‘heart failure.’ But what does that really mean? Why would someone’s heart fail and how does that impact the person as a whole?This lesson focuses on the causes of heart failure, specifically what happens during left-sided heart failure and the impact the condition has on the respiratory system. The other lesson will explain to you how the right side of the heart is involved, how the kidneys play a critical role, and what treatments are used in heart failure and why they make sense based on the pathophysiology of this condition.First, it’s important to define ‘heart failure.’ Heart failure or congestive heart failure (CHF) refers to a state in which the heart has malfunctioned to the point of being unable to pump blood adequately enough to meet the energetic demands of body tissues and organs. Our heart is a pump that pushes blood through the body.

The blood carries nutrients and energy necessary for life. If the heart is unable to perform its duty properly, then we are in a state of heart failure.Think about your local electricity plant; it pumps, in a manner of speaking, electricity. Electricity is necessary to drive the energetic processes of your home.

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If the plant cannot pump enough electricity to your home, then your lights get dim or flicker and the appliances shut down because the plant has failed. Similarly, the body’s appliances (organs) and energetic processes also falter and shut down because the failing heart doesn’t deliver enough energy (or blood) to these places.Before moving on in this lesson, as a very brief review, you should be aware that blood flows through the heart in the following manner: venous (blue-deoxygenated) blood (including that from the jugular veins) enters the right atrium, then goes to the right ventricle. From there it flows into the pulmonary vasculature (the lungs), where it’s oxygenated. From there it proceeds into the left atrium, then the left ventricle, and then the aorta and out into the arterial circulation.

Knowing this will help you to more easily understand the rest of this lesson.

What Causes Heart Failure?

Also, bear in mind that the causes (a.k.a. etiology) of heart failure are numerous, but regardless of the cause, the signs of heart failure are very similar. Major causes for heart failure include:

  • Coronary artery disease, where the heart doesn’t get enough life-giving oxygen due to clogged arteries. This makes it difficult for the heart to function and may lead to a heart attack.

  • Another cause is hypertension, or high blood pressure in the arteries, which makes it difficult for the heart to pump blood out into circulation against this increased force.
  • Congenital or acquired heart defects, such as valve defects, can also lead to heart failure. If heart valves don’t work right, backflow of blood occurs, resulting in excess work for the heart.
  • Furthermore, endocrine disease, such as diabetes mellitus, infections of the heart, drug abuse, obesity, and alcohol consumption are just a few of the things that could cause a heart to fail; there are many others.

What Is Congestive Heart Failure?

Let’s consider one case scenario of heart failure for this lesson: congestive heart failure. Do keep note of something for me.

Depending on the etiology of heart failure, the heart can either thicken (hypertrophy) or expand (dilate), either of which occurs as a result of the underlying cause of the problem, and both result in heart failure.In our case, let’s say that the heart is having trouble pumping blood forward into circulation because a person has high blood pressure. High blood pressure refers to the pressure of blood in arterial circulation. These vessels receive and carry oxygenated blood pumped from the left side of the heart (the left ventricle to be precise).

High blood pressure, or its causes, have many consequences, including increasing the resistance to outflow of blood from the heart.Since the left side of the heart is having a much harder time pumping blood out into the aorta (the body’s biggest artery), then it has to work much harder. When you work really hard, you tire and become exhausted. The left ventricle of the heart, the chamber responsible for pumping all that blood into the aorta also tires, becomes exhausted, and, over time, simply fails. This is termed ‘left-sided heart failure.

‘Think about the consequences of this. If the left ventricle is really exhausted, it can’t pump blood forward as well as it did before. This means the blood entering the left ventricle from the left atrium gets backed up into the pulmonary vasculature of the lungs. The pulmonary vessels then get congested with blood, and this is where the word ‘congestive’ comes into play.

This backup increases the blood pressure in the pulmonary vessels, which we term ‘pulmonary hypertension.’Pulmonary hypertension leads to pulmonary edema, the leakage of fluid into the air spaces of the lungs. This occurs because the body tries to lessen the severity of the pulmonary hypertension by leaking excess fluid in the vessels into the empty spaces in the lungs. It’s kind of like when people try to throw buckets of water from a boat that is taking on too much water. The pulmonary vessels running through the lungs are taking on too much blood and are trying to bail themselves out by throwing out buckets of fluid into the lungs themselves.

Signs of Left-Sided Heart Failure

Unfortunately, those empty spaces in the lungs, now filling with fluid, are normally used for the oxygenation of your blood. This means that the person who has lungs full of fluid could experience:

  • Dyspnea, or shortness or difficulty of breath, since oxygen exchange is impaired due to all of that fluid in the lungs.
  • Furthermore, orthopnea can occur as well. This is difficulty breathing when lying down. This happens because excess fluid flows down with gravity into places like the legs when a person is upright. But when the person lies down, all that excess fluid goes back to the lungs, making it more difficult for the lungs to breathe and the heart to work.

  • Similarly, paroxysmal nocturnal dyspnea, or severe shortness of breath while sleeping, usually relieved when the person sits upright, can occur as well.
  • Crackles in the lungs may be heard; the lung sounds resemble popping bubble wrap or popping popcorn in a kettle.
  • Fatigue can occur because the heart can’t pump enough energy-giving oxygen via the arteries into the tissues that need them. So if your muscles don’t get enough oxygen due to heart failure, you’re obviously going to be a little bit tired. Just like light bulbs fade without electricity, so too does your body.
  • Furthermore, paleness, or bluing (cyanosis), of the skin may occur because the blood isn’t getting oxygenated or circulated properly. Recall that fresh, red, oxygenated blood provides you with a spark of electricity that gives you a healthy pink glow.

    If that spark never arrives because the heart isn’t pumping well and it’s never generated because the lungs don’t oxygenate the blood, then you become pale, or blue like deoxygenated blood.

Unfortunately, the issues of CHF don’t stop there. It is imperative you take a little break, process everything you learned, and come back and watch the next video on heart failure to fully appreciate what a terrible condition this truly is.

Lesson Summary

Let’s review.

Heart failure or congestive heart failure (CHF) refers to a state in which the heart has malfunctioned to the point of being unable to pump blood adequately enough to meet the energetic demands of body tissues and organs. We learned that the causes (a.k.a. etiology) of heart failure include things like coronary artery disease, hypertension, and congenital or acquired heart valve defects.If something like hypertension causes the workload on the left ventricle to increase, it leads to left-sided heart failure, which causes a backup of blood into the lungs, and this, in turn, leads to pulmonary edema, or the leakage of fluid into the air spaces of the lungs.

As a result, left-sided heart failure often causes a person to experience dyspnea, or shortness or difficulty of breath; orthopnea, difficulty breathing when lying down; and paroxysmal nocturnal dyspnea, severe shortness of breath while sleeping, relieved when the person sits upright. In addition to that people can experience crackles in the lungs, fatigue, and paleness, or bluing (cyanosis), of the skin.

Learning Outcomes

Once you have finished reviewing this lesson you should be able to:

  • Explain congestive heart failure
  • Discuss some of the causes of congestive heart failure and pulmonary edema
  • List some of the signs and symptoms of congestive heart failure
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