Heart Failure

What is Heart Failure?

Heart failure (HF) is a condition in which the heart is unable to provide the body with enough blood and nutrients to meet its metabolic needs. Heart failure is usually caused by failure of the heart to function efficiently as a pump. In most cases of heart failure the ventricle (one of two lower chambers of the heart) is no longer able to eject blood adequately. In other cases of heart failure the heart is unable to fill with blood appropriately. HF is usually a progressive disease – it develops slowly – but it is chronic once it is established. It can also be marked with acute episodes during its chronic course, in which symptoms are worse for a short period of time. HF occurs following damage to the heart. Damage can be caused by a heart attack, high blood pressure that has lasted a long time, structural abnormalities of the heart, or viruses. In rare cases heart failure is caused by mutations
in cardiac genes.

HF can be categorized as either systolic or diastolic. In systolic HF, the ventricle fails to pump enough blood to the body’s organs and tissues. Ejection fraction is the percentage of blood ejected from the ventricle with each heart beat (60% is normal but this varies upon the technique used to measure it). It is an index of ventricular function that your doctor may use to assess your heart function. In systolic heart failure the ejection fraction is decreased. Because the heart is no longer able to pump the amount of blood it used to with each beat, fluid begins to build up in the body. It can back up into the lungs and cause congestion in the lungs, making it difficult to breathe. In diastolic HF, the ventricle fails to relax or rest as it should and is unable to fill completely with blood. It is most readily diagnosed by echocardiography which demonstrates failure of the ventricle to relax normally. Diastolic HF can occur even if left ventricular systolic function is normal. In fact in diastolic heart failure the ejection fraction is typically normal or even elevated. Systolic HF is more often seen in younger patients and in those who have had heart attacks. Diastolic HF increases in importance in the elderly and in patients with a history of high blood pressure.

Figure 1: Diagram of the heart

How common is Heart Failure?

Nearly 15 million people worldwide have HF. In the United States alone, almost 5 million people have HF. Approximately 500,000 new cases of HF are diagnosed each year. HF is the sole cause of 12 to 15 million visits to physicians and 6.5 million hospital days each year. During a 10-year period, the number of times patients were admitted to the hospital for HF went up from 550,000 a year to 900,000 a year. Nearly 300,000 patients die each year as a result of HF; this number has increased over the years, despite advances in treatment.

Eighty percent of patients hospitalized for HF are older than 65 years old. Of people over 65 years, 6% to 10% have HF. More Medicare dollars are spent in diagnosing and treating HF than any other disease. Among people 55 to 64 years old, 6.2% of men and 3.4% of women have HF. Between the ages of 65 and 74, the numbers begin to even out, and 6.8% of men and 6.6% of women have HF. By the age of 75 and older, the numbers are nearly 10% for each gender. As our populations continue to increase in age, the HF population also increases.

What are the symptoms of Heart Failure?

Symptoms of HF include:

Difficulty breathing, or shortness of breath, when exercising or at rest
Swollen legs, ankles, or feet from a build-up of fluid (called edema)
Weight gain (from increased fluid retention)
Decreased ability to exercise
Tiredness after normal activities
Cough with activity or at rest.

Once the diagnosis of HF has been made, these symptoms may be used to help classify the disease and monitor the success of therapy.

What causes Heart Failure?

HF develops over time. It begins with some sort of injury to the heart, though this injury is often undetected. With time, the damage from that injury causes the heart (namely, the left ventricle) to become less effective in circulating and pumping the body’s blood. As blood flow out of the heart slows down, blood returning to the heart backs up. As a result, fluid builds up in the body and can cause swelling in the ankles, as well as difficulty breathing if fluid collects in the lungs. Causes of damage to the heart that can start this process include:

High blood pressure – especially when it goes untreated and is long-term
Abnormal heart valve
Coronary artery disease – a narrowing of the arteries that supply blood to the heart
Scar tissue from an old heart attack
Cardiomyopathy – disease in the heart that causes the heart to become enlarged and lose pumping strength
Congenital heart defects – defects present at birth
Infection of the heart or its valves – known as myocarditis or endocarditis
Use of illegal drugs such as cocaine or misuse of anabolic steroids (sometimes used by athletes to build muscle and strength)
Some chemotherapeutic (drug) treatments for cancer
Excessive alcohol use and other cardiac toxins
Rare metabolic diseases

How is Heart Failure diagnosed?

Physical Examination

A physical examination performed by the physician can reveal signs of HF that help lead to diagnosis of the disease. Shortness of breath and swelling in the ankles and feet are commonly found in patients with HF. However, these symptoms may also be present with diseases or syndromes other than HF. In addition, an exercise stress test can be performed to see how the heart responds to exercise. This involves walking on a treadmill or riding a stationary bicycle.

Electrocardiogram (ECG)

The electrocardiogram (ECG) is a painless test that shows the electrical activity of the heart. The ECG shows changes in the heart commonly seen in patients with HF. The ECG can show if there has been any damage done to the heart.

Chest X-ray

A chest x-ray should be a normal part of the battery of tests performed for determining if a patient has HF. The x-ray checks the size of the heart and may show congestion in the lungs due to fluid build-up.

Echocardiogram

The echocardiogram is an ultrasound (sound wave) picture of the heart that provides objective data about the heart valves and the function of the walls of the heart. It allows the physician to watch the heart as it beats and pumps blood. The echocardiogram also measures a patient’s ejection fraction (also called “EF”), which is a measure of how well the heart pumps blood.

Laboratory Tests

Laboratory tests such as complete blood counts, electrolytes, albumin, blood urea nitrogen (BUN), creatinine, glucose, liver enzymes, urinalysis, and thyroid stimulating hormone (TSH) may be needed. Results of the urinalysis, as well as creatinine and BUN levels, may help detect potential kidney disease. TSH levels assess possible thyroid problems that could cause patients to feel tired or to gain weight. Sodium levels in the blood should be known to help direct the patient’s intake of salt through foods. These values, if abnormal, can either cause worsening of HF symptoms or may actually point the way to a different cause of the symptoms.

Physicians can also use B-type natriuretic peptide (BNP) testing to diagnose HF.

What is BNP?

BNP, or B-type natriuretic peptide, is a hormone that is made in the ventricles of the heart. Everyone normally has a small amount of BNP in their blood system. More of it is released into the blood when there is a change in the wall of the left ventricle and when there is an overload of blood volume. These are some of the changes that happen with HF. Because it is made and released in the ventricle when the ventricle is “stressed,” BNP is a better indicator of this stress than other, similar hormones.

By taking a small sample of blood from a patient, doctors and lab technicians can run a test to determine how much BNP is in the blood (the level of BNP in the blood, or BNP level). BNP is measured in picograms per milliliter (pg/mL), and the decision threshold (the point at which patients are typically determined to have HF) is 100 pg/mL. BNP is now added to the list of laboratory tests that can be performed to help diagnose HF. The BNP test has shown to be a reliable test to rule out HF with a high degree of certainty.

BNP levels tend to increase somewhat as patients increase in age. They also tend to be higher in women than in men.

Local laboratories perform their own tests to determine BNP ranges appropriate for the local population of people they serve.

New York Heart Association (NYHA) classification of Heart Failure

Many years ago, in an effort to categorize or classify different stages of HF, the New York Heart Association (NYHA) classification of HF system was created. This is a way to subjectively classify HF according to how symptoms relate to daily activities and patient quality of life. The four classes of this system describe functional limitations based on the amount of effort required to start experiencing symptoms. The system does not describe structural abnormalities or the risk of developing HF. However, BNP levels correspond to and help tell the severity of HF. In patients with heart failure, BNP levels correlate most directly with the severity of heart failure as well as how well (or poorly) the body is compensated. Figure 2 shows the association between BNP levels and severity of HF according to NYHA classes.

Figure 2. Assessment of Severity of Heart Failure with BNP

ACC/AHA Heart Failure Classification System

In 2001, the American College of Cardiology (ACC) and the American Heart Association (AHA) updated guidelines for the diagnosis and treatment of HF. At this time, they also created a new staging system that identifies four stages of HF. This staging system is designed to work with, not to replace, the NYHA classification scheme. Patients described in the NYHA system are found within Stages C and D of the ACC/AHA system. The new system focuses on prevention, evolution, and progression of HF. The reason for this is that when different methods of therapy are begun before the patient actually begins to experience symptoms, the patient’s overall life span and severity of disease can be improved, compared with what it might have been if treatment had not been started early.

In this new system, Stage A describes a person who is at risk for HF but who does not appear to have structural abnormalities of the heart and who has no symptoms of HF (see Table 1). Stage B identifies a patient with a structural abnormality of the heart who has never experienced symptoms of HF. Stage C describes a patient with a structural abnormality of the heart who has symptoms of HF now or has had them in the past. Stage D refers to a patient with end-stage symptoms of HF, in whom normal treatment options do not work, and who requires specialized treatment. Some of these specialized treatments include the use of a machine to keep the blood circulating through the body (mechanical circulatory support), continuous drug infusions, a heart transplantation, or end-of-life hospice care.

This classification system provides a reliable, objective method of identifying patients in the various stages throughout the course of the disease. Each stage is linked to treatments used only in that stage. Patients would usually move from one stage to the next unless disease progression (gradual worsening of the disease) was slowed or stopped by treatment. In any case, once patients have moved to the next stage, they cannot return to the earlier stage.

Table 1. Systems used to classify or describe HF

NYHA Heart Classification System	ACC/AHA Staging System
Class I — Mild • No limitation of activity • No symptoms with normal activity	Stage A • No structural abnormality of the heart • No symptoms of HF
Class II — Mild • Slight limitation of activity • Comfortable with rest or mild exertion	Stage B • Structural abnormality of the heart • No symptoms of HF
Class III — Moderate • Marked limitation of activity • Comfortable only at rest	Stage C • Structural abnormality of the heart • Some symptoms of HF
Class IV — Severe • Complete rest is required; confined to bed or chair • Any activity brings discomfort; symptoms occur at rest	Stage D • Structural abnormality of the heart • Symptoms of HF that do not respond well to normal treatment
NYHA = New York Heart Association ACC = American College of Cardiology	AHA = American Heart Association

How is Heart Failure treated?

Treatment of HF includes a variety of methods. Some are drug-related; some are not. Physicians may suggest several treatments at the same time, such as some lifestyle changes along with new drug therapy. Among the treatments for HF are:

Activity

decrease activities to levels that are tolerated, but exercise regularly as tolerated ; for example, some may take the elevator instead of the stairs to avoid feeling tired or out of breath.

Low salt diet

especially important in more advanced disease.

Fluid intake

the amount of fluids a patient consumes each day must be monitored; reducing fluid intake can help reduce symptoms.

Weight control

patients should weigh themselves regularly (e.g., once a day) to help monitor the amount of fluid in the body; those patients who are overweight should work on reducing their weight.

Drugs

Angiotensin-converting enzyme (ACE) inhibitors – to expand blood vessels and decrease their resistance. ACE inhibitors have been shown to reduce mortality in patients with heart failure.
Beta-blockers – to improve cardiac output (left lower chamber of the heart) and block the effects of neurohumoral factors. Beta-blockers have been shown to reduce mortality in patients with heart failure. They are effective in both systolic and diastolic heart failure.
Digitalis – to increase the pumping ability of the heart.
Diuretics – to help get rid of excess salt and water from the body.
Vasodilators – to expand blood vessels and decrease their resistance.
Natrecor® – used in severe cases of HF to help patients who have trouble breathing even at rest.

Surgery

Valve replacement for a faulty valve.
Heart transplantation for hearts so damaged they cannot be repaired otherwise.
Biventricular pacing – for patients with NYHA III/IV Class heart failure and conduction system defects.
Ventricular Assist Devices – for patients with NYHA Class IV heart failure.

Whatever the method or methods of treatment, patients must take care to follow their physician’s directions for treatment closely and as often as prescribed. This applies to diet, exercise, rest, and drug therapy. Patients should report any changes in symptoms to their physician.

Glossary

BNP testing – a test performed on a small sample of blood to determine the amount of B-type natriuretic peptide (BNP) in the blood

Cardiomyopathy – disease of the heart muscle that causes it to become enlarged and lose strength to pump blood

Chronic – present for a long period of time

Congenital – acquired while developing as a fetus before birth (a birth defect)

Diastolic – referring to the time in which the heart rests or relaxes, when it is not pumping blood

Echocardiogram – an ultrasound picture of the heart in motion

Edema – a build-up of fluid in the body, typically manifest as swelling in the legs (there are many causes of edema)

Electrocardiogram (ECG) – a test that shows the electrical activity of the heart

Ejection fraction (EF) – a measure of how well the heart pumps blood; determined during an echocardiogram, nuclear cardiac study or cardiac catheterization

New York Heart Association (NYHA) classification system – a system of four classes that describe the functional aspects of heart failure

Systolic – referring to the contraction or squeezing of the heart muscle; the movement the heart makes as it pumps blood out of its chambers

Transplantation – surgery to remove an organ (e.g., a heart) from the body when that organ no longer works well enough to support life, to replace it with a like organ (e.g., another heart) that
does work

Valve – a moving, mechanical part of the heart that opens and shuts to help control the flow of blood through the chambers of the heart

Ventricle – one of two lower chambers of the heart. Each heart has two lower chambers, the left ventricle and the right ventricle, and two upper chambers, the left atrium and the right atrium

Helpful Websites

The Internet is rich with information, and that includes health-related information. Here are a few websites that might be helpful:

References

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