An in-depth report on the causes, diagnosis, treatment, and prevention of heart failure.
Cardiomyopathy; Congestive heart failure
Heart failure is a condition in which the heart does not pump enough blood to meet the needs of the body’s tissues. Heart failure can develop slowly over time as the result of other conditions (such as high blood pressure and coronary artery disease) that weaken the heart. It can also occur suddenly as the result of damage to the heart muscle.
Common signs and symptoms of heart failure include:
- Shortness of breath
- Wheezing or cough
- Fluid retention and weight gain
- Loss of appetite
- Abnormally fast or slow heart rate
Treatment for heart failure depends on its severity. All patients need dietary salt restriction and other lifestyle adjustments, medication, and monitoring. Patients with very weakened hearts may need implanted devices (such as pacemakers, implantable cardiac defibrillators, or devices that help the heart pump blood) or surgery, including heart transplantation.
Doctors usually treat heart failure, and the underlying conditions that cause it, with a combination of medications. These medications include:
- Angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs)
- Beta blockers
- Aldosterone blockers
- Hydralazine or nitrates
Other medications that may be helpful include:
- Aspirin and warfarin
Decision Making in Advanced Heart Failure
For patients with advanced heart failure, symptom relief, quality of life, and personal values are as important to consider as survival, according to a 2012 scientific statement from the American Heart Association (AHA). The AHA notes that while technology has increased the treatment options for advanced heart failure, “doing everything is not always the right thing.” The guidelines emphasize a patient-centered approach to treatment and the importance of patients discussing with their doctors their preferences, expectations, and goals.
Heart failure is a condition in which the heart does not pump enough blood to meet the needs of the body’s tissues. To understand what occurs in heart failure, it helps to be familiar with the anatomy of the heart and how it works. The heart is composed of two independent pumping systems, one on the right side, and the other on the left. Each has two chambers, an atrium and a ventricle. The ventricles are the major pumps in the heart.
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The Right Side of the Heart. The right system receives blood from the veins of the whole body. This is "used" blood, which is poor in oxygen and rich in carbon dioxide.
- The right atrium is the first chamber that receives blood.
- The chamber expands as its muscles relax to fill with blood that has returned from the body.
- The blood enters a second muscular chamber called the right ventricle.
- The right ventricle is one of the heart's two major pumps. Its function is to pump the blood into the lungs.
- The lungs restore oxygen to the blood and exchange it with carbon dioxide, which is exhaled.
The Left Side of the Heart. The left system receives blood from the lungs. This blood is now rich in oxygen.
- The oxygen-rich blood returns through veins coming from the lungs (pulmonary veins) to the heart.
- The heart receives the oxygen-rich blood from the lungs in the left atrium. the first chamber on the left side.
- Here, it moves to the left ventricle. a powerful muscular chamber that pumps the blood back out to the body.
- The left ventricle is the strongest of the heart's pumps. Its thicker muscles need to perform contractions powerful enough to force the blood to all parts of the body.
- This strong contraction produces systolic blood pressure (the first and higher number in blood pressure measurement). The lower number (diastolic blood pressure) is measured when the left ventricle relaxes to refill with blood between beats.
- Blood leaves the heart through the aorta, the major artery that feeds blood to the entire body.
The Valves. Valves are muscular flaps that open and close so blood will flow in the right direction. There are four valves in the heart:
- The tricuspid regulates blood flow between the right atrium and the right ventricle.
- The pulmonary valve opens to allow blood to flow from the right ventricle to the lungs.
- The mitral valve regulates blood flow between the left atrium and the left ventricle.
- The aortic valve allows blood to flow from the left ventricle to the aorta.
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The Heart's Electrical System. The heartbeats are triggered and regulated by the conducting system, a network of specialized muscle cells that form an independent electrical system in the heart muscles. These cells are connected by channels that pass chemically-triggered electrical impulses.
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Description of Heart Failure
Heart failure is a process, not a disease. The heart doesn't "fail" in the sense of ceasing to beat (as occurs during cardiac arrest). Rather, it weakens, usually over the course of months or years, so that it is unable to pump out all the blood that enters its chambers. As a result, fluids tend to build up in the lungs and tissues, causing congestion. This is why heart failure is also sometimes referred to as "congestive heart failure."
Ways the Heart Can Fail. Heart failure can occur in several ways:
- The muscles of the heart pumps (ventricles ) become thin and weakened. They stretch (dilate ) and cannot pump the blood with enough force to reach all the body's tissues.
- The heart muscles stiffen or thicken. They lose elasticity and cannot relax. Insufficient blood enters the chamber, so not enough blood is pumped out into the body to serve its needs.
- Sometimes the valves of the heart are abnormal. (Valves open or close to control the flow of blood entering or leaving the heart). They may narrow, such as in aortic stenosis. causing a back up of blood, or they may close improperly so that blood leaks back into the heart. The mitral valve (which regulates blood flow between the two chambers on the left side of the heart) often becomes leaky in severe heart failure -- a condition called mitral regurgitation.
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- The very mechanisms that the body uses to compensate for inefficient heart pumping can, over time, change the architecture of the heart (called remodeling ) and finally lead to irreversible problems.
The specific effects of heart failure on the body depend on whether it occurs on the left or right sides of the heart. Over time, however, in either form of heart failure, the organs in the body do not receive enough oxygen and nutrients, and the body's wastes are removed slowly. Eventually, vital systems break down.
Failure on the Left Side (Left-Ventricular Heart Failure ). Failure on the left side of the heart is more common than failure on the right side. The failure can be a result of abnormal systolic (contraction) or diastolic (relaxation) action:
- Systolic. Systolic heart failure is a pumping problem. In systolic failure, the heart muscles weaken and cannot pump enough blood throughout the body. The left ventricle is usually stretched (dilated). Fluid backs up and accumulates in the lungs (pulmonary edema). Systolic heart failure typically occurs in men between the ages of 50 - 70 years who have had a heart attack.
- Diastolic. Diastolic heart failure is a filling problem. When the left ventricle muscle becomes stiff and cannot relax properly between heartbeats, the heart cannot fill fully with blood. When this happens, fluid entering the heart backs up. This causes the veins in the body and tissues surrounding the heart to swell and become congested. Patients with diastolic failure are typically women, overweight, and elderly, and have high blood pressure and diabetes.
Failure on the Right Side (Right-Ventricular Heart Failure). Failure on the right side of the heart is most often a result of failure on the left. Because the right ventricle receives blood from the veins, failure here causes the blood to back up. As a result, the veins in the body and tissues surrounding the heart to swell. This causes swelling in the feet, ankles, legs, and abdomen. Pulmonary hypertension (increase in pressure in the lung's pulmonary artery) and lung disease may also cause right-sided heart failure.
Ejection Fraction. To help determine the severity of left-sided heart failure, doctors use an ejection fraction (EF) calculation, also called a left-ventricular ejection fraction (LVEF). This is the percentage of the blood pumped out from the left ventricle during each heartbeat. An ejection fraction of 50 - 75% is considered normal. Patients with left-ventricular heart failure are classified as either having a preserved ejection fraction (greater than 50%) or a reduced ejection fraction (less than 50%).
Patients with preserved LVEF heart failure are more likely to be female and older, and have a history of high blood pressure and atrial fibrillation (a disturbance in heart rhythm).
Heart failure has many causes and can evolve in different ways.
- It can be a direct, latest-stage result of heart damage from one or more of several heart or circulation diseases.
- It can occur over time as the heart tries to compensate for abnormalities caused by these conditions, a condition called remodeling .
In all cases, the weaker pumping action of the heart means that less blood is sent to the kidneys. The kidneys respond by retaining salt and water. This in turn increases edema (fluid buildup) in the body, which causes widespread damage.
High Blood Pressure
Uncontrolled high blood pressure (hypertension) is a major cause of heart failure even in the absence of a heart attack. In fact, about 75% of cases of heart failure start with hypertension. It generally develops as follows:
- The heart muscles thicken to make up for increased blood pressure.
- The force of the heart muscle contractions weaken over time, and the muscles have difficulty relaxing. This prevents the normal filling of the heart with blood.
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Hypertension is a disorder characterized by consistently high blood pressure. In adults, high blood pressure is diagnosed when the systolic blood pressure (the "top" number, which represents the pressure generated when the heart beats) is 140 or higher or the diastolic blood pressure (the "bottom" number, which represents the pressure in the vessels when the heart is at rest) is 90 or higher.
Coronary Artery Disease and Heart Attack
Coronary artery disease is the end result of a process called atherosclerosis (commonly called "hardening of the arteries"). It is the most common cause of heart attack and involves the build-up of
unhealthy cholesterol in the arteries. with inflammation and injury in the cells of the blood vessels. The arteries narrow and become brittle. Heart failure in such cases most often results from a pumping defect in the left side of the heart.
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People often survive heart attacks. but many eventually develop heart failure from the damage the attack does to the heart muscles.
Valvular Heart Disease
The valves of the heart control the flow of blood leaving and entering the heart. Abnormalities can cause blood to back up or leak back into the heart.
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In the past, rheumatic fever, which scars the heart valves and prevents them from functioning properly, was a major cause of death from heart failure. Fortunately, antibiotics and other advances have now made this disease a minor cause of heart failure in industrialized nations. Birth defects may also cause abnormal valvular development. Although more children born with heart defects are now living to adulthood, they still face a higher than average risk for heart failure as they age.
Cardiomyopathy is a disorder that damages the heart muscles and leads to heart failure. There are several different types. Injury to the heart muscles may cause the heart muscles to thin out (dilate) or become too thick (become hypertrophic). In either case, the heart doesn't pump correctly. Viral myocarditis is a rare viral infection that involves the heart muscle and can produce either temporary or permanent heart muscle damage.
Dilated Cardiomyopathy. Dilated cardiomyopathy involves an enlarged heart ventricle. The muscles thin out, reducing the pumping action, usually on the left side. Although this condition is associated with genetic factors, the direct cause is often not known. (This is called idiopathic dilated cardiomyopathy.) In other cases, viral infections, alcoholism, and high blood pressure may increase the risk for this condition.
Hypertrophic Cardiomyopathy. In hypertrophic cardiomyopathy, the heart muscles become thick and contract with difficulty. Some research indicates that this occurs because of a genetic defect that causes a loss of power in heart muscle cells and, subsequently, lower pumping strength. To compensate for this power loss, the heart muscle cells grow. This condition, rare in the general population, is often the cause of sudden death in young athletes.
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Restrictive Cardiomyopathy. Restrictive cardiomyopathy refers to a group of disorders in which the heart chambers are unable to properly fill with blood because of stiffness in the heart. The heart is of normal size or only slightly enlarged. However, it cannot relax normally during the time between heartbeats when the blood returns from the body to the heart (diastole). The most common causes of restrictive cardiomyopathy are amyloidosis and scarring of the heart from an unknown cause (idiopathic myocardial fibrosis). It frequently occurs after a heart transplant.
Severe Lung Diseases
Chronic obstructive pulmonary disease (severe emphysema) and other major lung diseases are risk factors for right-side heart failure.
Pulmonary hypertension is increased pressure in the pulmonary arteries that carry blood from the heart to the lungs. The increased pressure makes the heart work harder to pump blood, which can cause heart failure. The development of right-sided heart failure in patients with pulmonary hypertension is a strong predictor of death within 6 - 12 months.
An overactive thyroid (hyperthyroidism) or underactive thyroid (hypothyroidism) can have severe effects on the heart and increase the risk for heart failure.
Nearly 6 million Americans are living with heart failure. About 670,000 new cases of heart failure are diagnosed each year. Although there has been a dramatic increase over the last several decades in the number of people who suffer from heart failure, survival rates have greatly improved.
Coronary artery disease, heart attack, and high blood pressure are the main causes and risk factors of heart failure. Other diseases that damage or weaken the heart muscle or heart valves can also cause heart failure. Heart failure is most common in people over age 65, African-Americans, and women.
Heart failure risk increases with advancing age. Heart failure is the most common reason for hospitalization in people age 65 years and older.
Men are at higher risk for heart failure than women. However, women are more likely than men to develop diastolic heart failure (a failure of the heart muscle to relax normally), which is often a precursor to systolic heart failure (impaired ability to pump blood).
African-Americans are more likely than Caucasians to develop heart failure before age 50 and die from the condition.
Family History and Genetics
People with a family history of cardiomyopathies (diseases that damage the heart muscle) are at increased risk of developing heart failure. Researchers are investigating specific genetic variants that increase heart failure risk.
People with diabetes are at high risk for heart failure, particularly if they also have coronary artery disease and high blood pressure. Some types of diabetes medications, such as rosiglitazone (Avandia) and pioglitazone (Actos), have been associated with heart failure. Chronic kidney disease caused by diabetes also increases heart failure risk.
Obesity is associated with both high blood pressure and type 2 diabetes, conditions that place people at risk for heart failure. Evidence strongly suggests that obesity itself is a major risk factor for heart failure, particularly in women.
Smoking, sedentary lifestyle, and alcohol and drug abuse can increase the risk for developing heart failure.
Medications Associated with Heart Failure
Long-term use of high-dose anabolic steroids (male hormones used to build muscle mass) increases the risk for heart failure. The drug itraconazole (Sporanox), used to treat skin, nail, or other fungal infections, has occasionally been linked to heart failure. The cancer drug imatinib (Gleevec) has been associated with heart failure. Other chemotherapy drugs, such as doxorubicin, can increase the risk for developing heart failure years after cancer treatment. (Cancer radiation therapy to the chest can also damage the heart muscle.)
Nearly 290,000 people die from heart failure each year. Nevertheless, although heart failure produces very high mortality rates, treatment advances are improving survival rates.
Cardiac Cachexia. If patients with heart failure are overweight to begin with, their condition tends to be more severe. Once heart failure develops, however, an important indicator of a worsening condition is the occurrence of cardiac cachexia. which is unintentional rapid weight loss (a loss of at least 7.5% of normal weight within 6 months).
Impaired Kidney Function. Heart failure weakens the heart’s ability to pump blood. This can affect other parts of the body including the kidneys (which in turn can lead to fluid build-up). Decreased kidney function is common in patients with heart failure, both as a complication of heart failure and other diseases associated with heart failure (such as diabetes). Studies suggest that, in patients with heart failure, impaired kidney function increases the risks for heart complications, including hospitalization and death.
Congestion (Fluid Buildup). In left-sided heart failure, fluid builds up first in the lungs, a condition called pulmonary edema. Later, as right-sided heart failure develops, fluid builds up in the legs, feet, and abdomen. Fluid buildup is treated with lifestyle measures, such as reducing salt in the diet, as well as drugs, such as diuretics.
Arrhythmias (Irregular Beatings of the Heart)
Atrial fibrillation is a rapid quivering beat in the upper chambers of the heart. It is a major cause of stroke and very dangerous in people with heart failure.
Left bundle-branch block is an abnormality in electrical conduction in the heart. It develops in about 30% of patients with heart failure.
Ventricular tachycardia and ventricular fibrillation are life-threatening arrhythmias that can occur in patients when heart function is significantly impaired.
Angina and Heart Attacks. While coronary artery disease is a major cause of heart failure, patients with heart failure are at continued risk for angina and heart attacks. Special care should be taken with sudden and strenuous exertion, particularly snow shoveling, during colder months.
Shortness of Breath (Dyspnea).
Patients typically report that they feel out of breath after exertion. While this may begin only when climbing stairs or taking longer walks, it can eventually be present even when walking around the home. (Those who have chest pain or feel like a heavy weight is pressing on the chest should also be evaluated for possible angina.)
Orthopnea refers to the shortness of breath patients may have when they lie flat at night. Patients may report that they need to use one or two pillows underneath their head and shoulders in order to be able to sleep. Sitting up with legs hanging over the side of the bed often relieves symptoms.
Paroxysmal nocturnal dyspnea (PND) refers to sudden episodes that awaken a patient at night. Symptoms include severe shortness of breath and coughing or wheezing, which generally occur 1 - 3 hours after going to sleep. Unlike orthopnea, symptoms are not relieved by sitting up.
Fluid Retention (Edema) and Weight Gain. Patients may complain of foot, ankle, leg or abdominal swelling. In rare cases, swelling can occur in the veins of the neck. Fluid retention can cause sudden weight gain and frequent urination.
Wheezing or Cough. Patients may have asthma-like wheezing, or a dry hacking cough that occurs a few hours after lying down but then stops after sitting up.
Loss of Muscle Mass. Over time, patients may lose muscle weight due to low cardiac output and a significant reduction in physical activity.
Gastrointestinal Symptoms. Patients experience loss of appetite or a sense of feeling full after eating small amounts. They may also have abdominal pain.
Pulmonary Edema. When fluid in the lungs builds up, it is called pulmonary edema. When this happens, symptoms become more severe. These episodes may happen suddenly, or gradually build up over a matter of days:
- In addition to shortness of breath, patients sometimes have a cough that produces a pinkish froth.
- Patients may experience a bubbling sensation in the lungs and feel as if they are drowning.
- Typically, the skin is clammy and pale, sometimes nearly blue. This is a life-threatening situation, and the patient must go immediately to an emergency room.
Abnormal Heart Rhythms. Patients may have episodes of abnormally fast or slow heart rate.
Central Sleep Apnea. This sleep disorder results when the brain fails to signal the muscles to breathe during sleep. It occurs in up to half of people with heart failure. Sleep apnea causes disordered breathing at night. If heart failure progresses, the apnea may be so acute that a person, unable to breathe, may awaken from sleep in panic.
Doctors can often make a preliminary diagnosis of heart failure by medical history and careful physical examination.
A thorough medical history may identify risks for heart failure that include:
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