The Human Circulatory System



Heart failure — sometimes known as congestive heart failure — occurs when the heart muscle doesn’t pump blood as well as it should. When this happens, blood often backs up and fluid can build up in the lungs, causing shortness of breath.

Heart failure may be right-sided or left-sided (or both). Patients with left heart failure may have symptoms of low cardiac output and elevated pulmonary venous pressure; dyspnea is the predominant feature. Signs of fluid retention predominate in right heart failure. Most patients exhibit symptoms or signs of both right- and left-sided failure, and LV dysfunction is the primary cause of RV failure.

Approx­imately half of patients with heart failure have preserved LV systolic function and usually have some degree of dia­stolic dysfunction. Patients with reduced or preserved sys­tolic function may have similar symptoms and it may be difficult to distinguish clinically between the two based on signs and symptoms.

In developed countries, CAD with resulting myocardial infarction and loss of functioning myocardium (ischemic cardiomyopathy) is the most common cause of systolic heart failure. Systemic hyperten­sion remains an important cause of heart failure and, even more commonly in the United States, an exacerbating fac­tor in patients with cardiac dysfunction due to other causes, such as CAD.

Several processes may present with dilated or congestive cardiomyopathy, which is charac­terized by LV or biventricular dilation and generalized systolic dysfunction

Causes include; alcoholic cardiomyopa­thy, viral myocarditis (including infections by HIV), and dilated cardiomyopathies with no obvious underlying cause (idiopathic cardiomyopathy). Rare causes of dilated cardiomyopathy include infiltrative diseases (hemochro­matosis, sarcoidosis, amyloidosis, etc), other infectious agents, metabolic disorders, cardiotoxins, and medication toxicity.


Valvular heart diseases—particularly degenerative aortic stenosis and chronic aortic or mitral regurgitation— are not infrequent causes of heart failure. Persistent tachy­cardia, often related to atrial arrhythmias, can cause systolic dysfunction that may be reversible with controlling the rate. Diastolic cardiac dysfunction is associated with aging and related myocardial stiffening, as well as LVH, commonly resulting from hypertension.

Conditions such as hypertrophic or restrictive cardiomyopathy, diabetes, and pericardial disease can produce the same clinical pic­ture. Atrial fibrillation with or without rapid ventricular response may contribute to impaired left ventricular filling.


The most common symptom of patients with left heart failure is shortness of breath, chiefly exertional dyspnea at first and then progressing to orthopnea, paroxysmal noctur­nal dyspnea, and rest dyspnea.

Chronic nonproductive cough, which is often worse in the recumbent position, may occur. Nocturia due to excretion of fluid retained during the day and increased renal perfusion in the recumbent position is a common nonspecific symptom of heart failure, as is fatigue and exercise intolerance.

Patients with right heart failure have predominate signs of fluid reten­tion, with the patient exhibiting edema, hepatic congestion and, on occasion, loss of appetite and nausea due to edema of the gut or impaired gastrointestinal perfusion and ascites. Surprisingly, some individuals with severe LV dysfunction will display few signs of left heart failure and appear to have isolated right heart failure. Indeed, they may be clinically indistinguishable from patients with cor pulmonale, who have right heart failure secondary to pulmonary disease.

Patients with acute heart failure from myocardial infarction, myocarditis, and acute valvular regurgitation due to endocarditis or other conditions usually present with pulmonary edema. Patients with episodic symptoms may be having LV dysfunction due to intermittent isch­emia. Patients may also present with acute exacerbations of chronic, stable heart failure. Exacerbations may be caused by alterations in therapy (or patient noncompliance), excessive salt and fluid intake, arrhythmias, excessive activ­ity, pulmonary emboli, intercurrent infection, or progres­sion of the underlying disease.

Risk factors

A single risk factor may be enough to cause heart failure, but a combination of factors also increases your risk.

Risk factors for heart failure include:

  • Coronary artery disease. Narrowed arteries may limit your heart’s supply of oxygen-rich blood, resulting in weakened heart muscle.
  • Heart attack. A heart attack is a form of coronary artery disease that occurs suddenly. Damage to your heart muscle from a heart attack may mean your heart can no longer pump as well as it should.
  • Heart valve disease. Having a heart valve that doesn’t work properly raises the risk of heart failure.
  • High blood pressure. Your heart works harder than it has to if your blood pressure is high.
  • Irregular heartbeats. These abnormal rhythms, especially if they are very frequent and fast, can weaken the heart muscle and cause heart failure.
  • Congenital heart disease. Some people who develop heart failure were born with problems that affect the structure or function of their heart.
  • Diabetes. Having diabetes increases your risk of high blood pressure and coronary artery disease. Don’t stop taking any medications on your own. Ask your doctor whether you should make changes.
  • Some diabetes medications. The diabetes drugs rosiglitazone (Avandia) and pioglitazone (Actos) have been found to increase the risk of heart failure in some people. Don’t stop taking these medications on your own, though. If you’re taking them, ask your doctor if you need to make any changes.
  • Certain other medications. Some medications may lead to heart failure or heart problems. They include nonsteroidal anti-inflammatory drugs (NSAIDs); certain anesthesia medications; and certain medications used to treat high blood pressure, cancer, blood conditions, irregular or abnormal heartbeats, nervous system diseases, mental health conditions, lung and urinary problems, inflammatory diseases, and infections.
  • Alcohol use. Drinking too much alcohol can weaken the heart muscle and lead to heart failure.
  • Sleep apnea. The inability to breathe properly while you sleep results in low blood-oxygen levels and an increased risk of irregular heartbeats. Both of these problems can weaken the heart.
  • Smoking or using tobacco. If you smoke, quit. Using tobacco increases your risk of heart disease and heart failure.
  • Obesity. People who have obesity have a higher risk of developing heart failure.
  • Viruses. Certain viral infections can cause damage to the heart muscle.


Complications of heart failure depend on the severity of heart disease, your overall health and other factors such as your age. Possible complications can include:

  • Kidney damage or failure. Heart failure can reduce the blood flow to your kidneys, which can eventually cause kidney failure if left untreated. Kidney damage from heart failure can require dialysis for treatment.
  • Heart valve problems. The valves of the heart, which keep blood flowing in the right direction, may not work properly if your heart is enlarged or if the pressure in your heart is very high due to heart failure.
  • Heart rhythm problems. Heart rhythm problems may lead to or increase your risk of heart failure.
  • Liver damage. Heart failure can cause fluid buildup that puts too much pressure on the liver. This fluid backup can lead to scarring, which makes it more difficult for your liver to work properly.
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The key to preventing heart failure is to reduce your risk factors. You can control or eliminate many of the risk factors for heart disease by making healthy lifestyle changes and by taking the medications prescribed by your doctor.

Lifestyle changes you can make to help prevent heart failure include:

  • Not smoking
  • Controlling certain conditions, such as high blood pressure and diabetes
  • Staying physically active
  • Eating healthy foods
  • Maintaining a healthy weight
  • Reducing and managing stress


For most people, heart failure is a long-term condition that can’t be cured. But treatment can help keep the symptoms under control, possibly for many years.

The main treatments are:

  • healthy lifestyle changes
  • medication
  • devices implanted in your chest to control your heart rhythm
  • surgery

In many cases, a combination of treatments will be required. 

Treatment will usually need to continue for the rest of your life.


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