heart failure
What is heart failure?
What are the risk factors for heart failure?
What are the symptoms of heart failure?
How is heart failure treated?
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heart failure, chronic, progressive condition in which the heart is unable to generate sufficient cardiac output to maintain adequate systemic circulation and meet the metabolic demands of the body. Heart failure does not signify cardiac arrest (when the heart unexpectedly stops contracting due to a problem in the conduction of electrical signals), but rather impaired pumping capacity. As circulatory efficiency declines, blood may accumulate in the pulmonary and systemic circulation, resulting in symptoms such as shortness of breath and peripheral edema..
Heart failure is a major health concern in countries worldwide. Although reliable data on the prevalence of heart failure is lacking for some parts of the world, it is estimated that globally more than 60 million people are affected by it.
Risk factors
Risk factors for heart failure consist primarily of conditions or behaviors that damage the heart muscle or increase strain on it over time. Examples include certain lifestyle factors, such as tobacco smoking, alcohol consumption, physical inactivity, and a diet that predisposes individuals to high cholesterol and hypertension (high blood pressure). A family history of heart failure or having certain underlying conditions, particularly heart attack, diabetes, cardiac valve insufficiency (leaking) or stenosis (narrowing), also increase risk. Older age (65 years or over) is strongly linked to heart failure because the heart and blood vessels undergo gradual structural and functional changes over time, and the likelihood of accumulated damage increases.
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Pathology and symptoms
Heart failure is classified using several complementary systems that describe symptom severity, disease progression, and cardiac function.
- The New York Heart Association (NYHA) functional classes (I–IV) categorize patients according to the degree to which symptoms limit physical activity.
- The American Heart Association/American College of Cardiology (AHA/ACC) stages (A–D) describe structural progression, ranging from individuals at risk for heart failure to those with advanced disease.
- Heart failure is also categorized by left ventricular ejection fraction, distinguishing heart failure with reduced ejection fraction (HFrEF), mildly reduced ejection fraction (HFmrEF), and preserved ejection fraction (HFpEF). Classification by ejection fraction is further subdivided into systolic, in which the heart muscle is weakened and cannot contract forcefully enough to adequately pump blood, and diastolic, in which the heart muscle is stiff and does not relax properly, limiting filling despite normal contraction.
When heart failure occurs, the ability of the heart to contract is decreased (systolic dysfunction), or the heart becomes stiff and does not relax normally (diastolic dysfunction); in some cases both conditions exist together. When less blood is pumped out of the heart with each contraction, the body activates compensatory mechanisms to maintain circulation to vital organs. One of the most significant responses occurs in the kidneys, which retain sodium and water in an effort to increase blood volume and increase pressures within the heart, thereby supporting cardiac output.
As a result of these reflex actions, patients with heart failure usually show signs of fluid accumulation in the lungs (pulmonary edema) and body tissues (systemic edema), leading to weight gain and swelling of the extremities and abdominal organs. This condition is known as congestive heart failure. Patients with congestion in the lungs or chest cavity suffer from shortness of breath, even with mild exertion or while lying flat. The heart’s response to the systemic effects of circulatory failure is to enlarge the chambers (cardiomegaly) and increase the muscle mass (hypertrophy).
Treatment
Management of heart failure typically begins with the treatment of contributing conditions and the use of medications to counteract maladaptive physiological responses that worsen heart strain. Such medications include angiotensin-converting enzyme (ACE) inhibitors or related agents to lower blood pressure and reduce workload, beta-blockers to regulate heart rhythm and protect the heart muscle, aldosterone antagonists to limit sodium retention, and vasodilators to ease resistance in the blood vessels. Diuretics are used to help eliminate excess fluid, relieving edema, while drugs such as digoxin and digitoxin may be prescribed to strengthen heart contractions. . (These latter drugs evolved from digitalis, which was introduced in the 18th century as one of the first effective remedies for congestive heart failure, known at the time as “dropsy.”)
Lifestyle measures are also essential. Patients are typically advised to restrict sodium intake, avoid tobacco and excessive alcohol use, maintain a healthy weight, and engage in appropriate physical activity. Although many therapies can slow progression and improve quality of life, long-term outlook depends on the underlying condition and the severity of heart dysfunction at the time of diagnosis.
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