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 - Northwestern Memorial Hospital - Chicago

About Heart Failure

Many people mistakenly believe that heart failure means that the heart has stopped or is about to stop. According to the Heart Failure Society of America, heart failure (HF) simply means that the heart is not pumping blood through the body as well as it should. As the heart's pumping action weakens, blood backs up into the blood vessels around the lungs and causes seepage of fluid into the lungs. The fluid causes congestion and makes it hard to breathe. Many people with heart failure also have swollen legs and feet. That is why heart failure is sometimes called congestive heart failure.


What causes heart failure?

Heart failure often occurs when another problem or disorder makes the heart weak or stiff so it doesn't pump or fill normally. The most common cause of heart failure is a heart attack (coronary artery blockage). When a patient has a heart attack, the heart does not work well. Other causes of heart failure include, but are not limited to:

  • High blood pressure (hypertension)
  • Thyroid disease
  • Heart valve disease
  • Alcohol use
  • Myocarditis (infection of the heart muscle)
  • Idiopathic dilated cardiomyopathy (this means that the heart muscle is functioning poorly, but the exact cause is not known)

What does it mean when my heart does not squeeze or relax normally?

The heart squeezes (contracts) and then relaxes with each heartbeat. The contraction part of this cycle is called systole (SIS'to-le). The relaxation portion is called diastole (di-AS'to-le). When the heart does not squeeze well, this is called systolic dysfunction. When the heart is stiff and does not relax well, this is called diastolic dysfunction. Patients can have systolic dysfunction, diastolic dysfunction or both.

Systolic versus Diastolic Left Ventricular Dysfunction
Left Ventricular Systolic Dysfunction: Impaired contraction of the left ventricle.
Left Ventricular Diastolic Dysfunction: Impaired relaxation of the left ventricle.

Ejection Fraction
One way to measure the heart's ability to contract is by checking its ejection fraction. The ejection fraction is the percent of blood the heart squeezes out in one beat. A normal ejection fraction is between 50 and 70 percent. A low ejection fraction is often less than 40 percent.

What are symptoms of heart failure?

Common symptoms of heart failure are shortness of breath (dyspnea), loss of energy (fatigue), rapid weight gain, swelling of the legs and feet, loss of appetite, bloating (swelling) in the abdomen, a dry hacking cough (most often when lying flat), and difficulty sleeping.

The American College of Cardiology and the American Heart Association developed a staging system to identify patients during the course of their disease. This includes people:

  • At high risk for heart failure but who do not actually have heart failure
  • With abnormal heart function who have never developed symptoms of heart failure
  • With abnormal heart function who previously or currently have symptoms of heart failure
  • With advanced heart disease and severe heart failure symptoms on optimal medical therapy

The staging system includes specific treatments that are targeted at each stage. These treatments can reduce illness and death from heart failure.

Stage A
HF Risk Factors/No Heart Disease/No Symptoms

Stage B
Heart Disease with No Symptoms/Asymptomatic LV Dysfunction

Stage C
Heart Disease with Prior or Current HF Symptoms

Stage D
Advanced Heart Disease/Continued HF Symptoms on Medical Therapy/Require Special Interventions

For patients who have Stage C or Stage D heart failure (presence of symptoms), doctors often classify patients' heart failure according to how severe their symptoms are. The table below describes the most common classification system, the New York Heart Association (NYHA) Functional Classification. It places patients in one of four categories based on how much they are limited by their heart failure symptoms during physical activity.

Class I
No symptoms and no limitation in ordinary physical activity.

Class II
Mild symptoms and slight limitation during ordinary activity. Comfortable at rest.

Class III
Marked limitation in activity due to symptoms, even during less-than-ordinary activity. Comfortable only at rest.

Class IV
Severe limitations. Experiences symptoms even while at rest.


For more information regarding heart failure or to obtain a consultation, please contact the Center for Heart Failure at 1-866-662-8467.

Last UpdateMarch 16, 2011