Definition of Congestive Heart Failure (CHF)

Heart failure is a condition in which the heart fails to adequately perform its job of pumping blood throughout the body. As a result, the body’s tissues and organs may not get enough nutrients and oxygen.

Typically, the body's response to heart failure causes the retention of sodium and the accumulation of excess fluid, leading to swelling of the lower extremities (edema) and lung congestion. In these cases, heart failure is commonly referred to as congestive heart failure (CHF).

CHF means that the heart has lost some of its pumping ability, but it hasn’t stopped functioning entirely. Lifestyle changes and aggressive medical care are critical to optimizing cardiac function and minimizing your symptoms.

CHF may be more common than you think. In the United States, about 6.2 million adults have heart failure. CHF is a serious condition, but many people are able to manage it under a doctor’s care.

Causes of CHF

CHF is caused by other conditions that damage the heart. Some of these conditions include:

  • Coronary artery disease (CAD): This is the most common type of heart disease. In CAD, cholesterol and fatty deposits block the arteries of the heart, hence some of the heart muscle does not get as much blood as it requires. When this happens the heart muscle may stop working well, making it more difficult to pump enough blood out to the body.
  • , causing the heart to work hard to pump blood. Over time the heart begins to fail.
  • Past heart attacks (myocardial infarction): The heart tissue is damaged during a heart attack, even mild ones. This damaged tissue doesn’t work as well, impacting the heart's ability to pump.
  • High blood pressure (hypertension): If you have uncontrolled high blood pressure, your heart is working harder to overcome that pressure and may become damaged over time.
  • Obesity: Obesity puts you at higher risk of conditions like type 2 diabetes and sleep apnea. If you are obese you are also more likely to develop high blood pressure, high cholesterol levels, and cardiomyopathy, which are all independent major risk factors for CHF.
  • Diabetes: High blood sugars, especially when uncontrolled, can damage the blood vessels and nerves that control the heart. People with diabetes also tend to have higher rates of obesity and hypertension—independent risk factors for CHF.
  • Valvular heart disease
  • Hyperthyroidism (overactive thyroid)
  • Other conditions such as severe anemia and abnormal heart rhythms

These conditions have one common denominator—they all weaken the heart muscle.

When the heart is weakened, it becomes more difficult for it to pump blood forward so blood and fluid back up into the lungs. Fluid in the lungs can cause shortness of breath, a common symptom of congestive heart failure.

If the heart is having serious difficulty with pumping, then you might experience edema or a build-up of fluid in the feet, ankles, and legs. The heart helps to pump blood and fluid against gravity, when it loses that ability, blood fluid pools in the extremities.

Heart Failure Doctor Discussion Guide

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Types of Heart Failure

CHF can be further characterized as left-sided or right-sided heart failure.

Left-Sided CHF

Left-sided heart failure is the most common type of heart failure. Most of the heart’s pumping power comes from the left side. The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body.

If the large and powerful chambers of the left ventricle and left atrium begin to fail, the left side of the heart has to work harder to pump blood. Over time blood can build up in the pulmonary veins leading to shortness of breath and trouble breathing, especially during physical activity. If left untreated, the right side of the heart may begin to fail as well.

The two types of left-sided heart failure are systolic heart failure and diastolic heart failure. In systolic heart failure or heart failure with reduced ejection fraction (HFrEF) the left side of the heart loses its ability to contract and becomes unable to meet the body’s oxygen and nutrient needs over time.

In diastolic heart failure or heart failure with preserved ejection fraction (HFpEF), the left side of the heart retains its ability to pump but stiffening of the heart muscle does not allow it to relax during beats.

Losing the ability to relax during beats means that the left ventricle chamber loses its capacity to adequately fill with blood, so when it pumps less blood is pushed out.

Right-Sided CHF

The right side of the heart delivers deoxygenated blood from the body to the lungs to be replenished with oxygen. As previously mentioned, right-sided heart failure usually follows longstanding left-sided heart failure.

It is quite common for people with right-sided failure to also have edema and ascites or a fluid accumulation in the abdomen such as the gastrointestinal (GI) tract and liver due to backflow of blood and other fluids of the body.

Stages of CHF

The most commonly used classification system is the New York Heart Association (NYHA) Functional Classification system. People are placed into categories based on their physical abilities and limitations:

  • In Stage I there are no limitations of physical activity and therefore no symptoms such as fatigue, heart palpitations, or shortness of breath following physical activity.
  • In Stage II there are slight limitations of physical activity, meaning that you are comfortable at rest, but increased physical activity may cause fatigue, heart palpitations, and shortness of breath.
  • In Stage III there is a marked limitation in your physical activity. You may be comfortable at rest, but even minor increases in physical activity cause symptoms of fatigue, heart palpitations, or shortness of breath.
  • In Stage IV you are unable to carry on any physical activity without discomfort. This is called having symptoms of heart failure at rest. If any physical activity is undertaken, discomfort increases.

If you have trouble breathing, cough up pink or foamy mucus, or have a new irregular or rapid heartbeat, you may be suffering from sudden heart failure and should seek immediate medical attention.

Most cases of CHF are chronic and develop over time. Symptoms to watch for are:

  • New or increased dyspnea or shortness of breath
  • Dizziness, lightheadedness, or feeling like you may faint
  • Sudden weight gain
  • New or increased swelling of the legs, ankles, or feet
  • Sudden fatigue or weakness especially while doing normal physical activities

Healthcare professionals also use an objective A-D assessment:

  • Stage A: Increased risk of heart failure but no structural abnormality
  • Stage B: Structural heart abnormalities but no symptoms
  • Stage C: Structural heart disease and symptoms present
  • Stage D: Refractory heart failure

A Word From Verywell

Studies have shown that aggressive medical care, such as employing several medications and potentially medical device therapy, can significantly improve wellbeing and survival in people with heart failure.

Lifestyle changes can also be helpful. Remember that having a salty meal or skipping your daily diuretic can be all that’s needed to trigger a heart failure flare-up, so remaining diligent in your new routine will be key. Watch closely for changes in your health and be sure to contact a healthcare professional if you develop new symptoms.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Virani SS, Alonso A, Benjamin EJ, Bittencourt MS, Callaway CW, Carson AP, et al. Heart disease and stroke statistics—2020 update: a report from the American Heart AssociationCirculation. 2020;141(9):e139-596.

  2. Centers for Disease Control and Prevention. Heart failure.

  3. American Heart Association. Types of heart failure.

  4. American Heart Association. Classes of heart failure.

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.