Heart failure

Heart failure (HF) is generally defined as inability of the heart to supply sufficient blood flow to meet the body's needs.[1][2][3] It has various diagnostic criteria, and the term heart failure is often incorrectly used to describe other cardiac-related illnesses, such as myocardial infarction (heart attack) or cardiac arrest.
Common causes of heart failure include myocardial infarction (heart attacks) and other forms of ischemic heart disease, hypertension, valvular heart disease and cardiomyopathy.[4] Heart failure can cause a large variety of symptoms such as shortness of breath (typically worse when lying flat, which is called orthopnea), coughing, ankle swelling and exercise intolerance. Heart failure is often undiagnosed due to a lack of a universally agreed definition and challenges in definitive diagnosis. Treatment commonly consists of lifestyle measures (such as decreased salt intake) and medications, and sometimes devices or even surgery.
Heart failure is a common, costly, disabling and potentially deadly condition.[4] In developing countries, around 2% of adults suffer from heart failure, but in those over the age of 65, this increases to 6–10%.[4][5] Mostly due to costs of hospitalization, it is associated with a high health expenditure; costs have been estimated to amount to 2% of the total budget of the National Health Service in the United Kingdom, and more than $35 billion in the United States.[6][7] Heart failure is associated with significantly reduced physical and mental health, resulting in a markedly decreased quality of life.[8][9] With the exception of heart failure caused by reversible conditions, the condition usually worsens with time. Although some patients survive many years, progressive disease is associated with an overall annual mortality rate of 10%.[10]
Contents[hide]
1 Terminology
2 Classification
3 Signs and symptoms
3.1 Symptoms
3.1.1 Left-sided failure
3.1.2 Right-sided failure
3.2 Signs
3.2.1 Left-sided failure
3.2.2 Right-sided failure
3.2.3 Biventricular failure
4 Causes
4.1 Chronic heart failure
4.2 Acute decompensated heart failure
5 Pathophysiology
5.1 Systolic dysfunction
5.2 Diastolic dysfunction
6 Diagnosis
6.1 Imaging
6.2 Electrophysiology
6.3 Blood tests
6.4 Angiography
6.5 Monitoring
6.6 Criteria
7 Management
7.1 Acute decompensation
7.2 Chronic management
7.3 Palliative care and hospice
8 Prognosis
9 Epidemiology
9.1 Gender
9.2 Race
9.3 Age
10 See also
11 References
12 External links
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Terminology
Heart failure is a global term for the physiological state in which cardiac output is insufficient for the body's needs.
This occurs most commonly when the cardiac output is low (often termed "congestive heart failure" because the body becomes congested with fluid).[11]
In contrast, it may also occur when the body's requirements for oxygen and nutrients are increased, and demand outstrips what the heart can provide, (termed "high output cardiac failure") [12]. This can occur in the context of severe anemia, Gram negative septicaemia, beriberi (vitamin B1/thiamine deficiency), thyrotoxicosis, Paget's disease, arteriovenous fistulae or arteriovenous malformations.
Fluid overload is a common problem for people with heart failure, but is not synonymous with it. Patients with treated heart failure will often be euvolaemic (a term for normal fluid status), or more rarely, dehydrated.
Doctors use the words "acute" to mean of rapid onset, and "chronic" of long duration. Chronic heart failure is therefore a long term situation, usually with stable treated symptomatology.
Acute decompensated heart failure is a term used to describe exacerbated or decompensated heart failure, referring to episodes in which a patient can be characterized as having a change in heart failure signs and symptoms resulting in a need for urgent therapy or hospitalization.[13]
There are several terms which are closely related to heart failure, and may be the cause of heart failure, but should not be confused with it:
Cardiac arrest, and asystole both refer to situations in which there is no cardiac output at all. Without urgent treatment, these result in sudden death.
Myocardial infarction ("Heart attack") refers heart muscle damage due to insufficient blood supply, usually as a result of a blocked coronary artery.
Cardiomyopathy refers specifically to problems within the heart muscle, and these problems usually result in heart failure. Ischemic cardiomyopathy implies that the cause of muscle damage is coronary artery disease. Dilated cardiomyopathy implies that the muscle damage has resulted in enlargement of the heart. Hypertrophic cardiomyopathy involves enlargement and thickening of the heart muscle.

] Classification
There are many different ways to categorize heart failure, including:
the side of the heart involved, (left heart failure versus right heart failure)
whether the abnormality is due to contraction or relaxation of the heart (systolic dysfunction vs. diastolic dysfunction)
whether the problem is primarily increased venous back pressure (behind) the heart, or failure to supply adequate arterial perfusion (in front of) the heart (backward vs. forward failure)
whether the abnormality is due to low cardiac output with high systemic vascular resistance or high cardiac output with low vascular resistance (low-output heart failure vs. high-output heart failure)
the degree of functional impairment conferred by the abnormality (as in the NYHA functional classification)
Functional classification generally relies on the New York Heart Association Functional Classification.[14] The classes (I-IV) are:
Class I: no limitation is experienced in any activities; there are no symptoms from ordinary activities.
Class II: slight, mild limitation of activity; the patient is comfortable at rest or with mild exertion.
Class III: marked limitation of any activity; the patient is comfortable only at rest.
Class IV: any physical activity brings on discomfort and symptoms occur at rest.
This score documents severity of symptoms, and can be used to assess response to treatment. While its use is widespread, the NYHA score is not very reproducible and doesn't reliably predict the walking distance or exercise tolerance on formal testing.[15]
In its 2001 guidelines, the American College of Cardiology/American Heart Association working group introduced four stages of heart failure:[16]
Stage A: Patients at high risk for developing HF in the future but no functional or structural heart disorder;
Stage B: a structural heart disorder but no symptoms at any stage;
Stage C: previous or current symptoms of heart failure in the context of an underlying structural heart problem, but managed with medical treatment;
Stage D: advanced disease requiring hospital-based support, a heart transplant or palliative care.
The ACC staging system is useful in that Stage A encompasses "pre-heart failure" - a stage where intervention with treatment can presumably prevent progression to overt symptoms. ACC stage A does not have a corresponding NYHA class. ACC Stage B would correspond to NYHA Class I. ACC Stage C corresponds to NYHA Class II and III, while ACC Stage D overlaps with NYHA Class IV.

Signs and symptoms

Symptoms
Heart failure symptoms are traditionally and somewhat arbitrarily divided into "left" and "right" sided, recognizing that the left and right ventricles of the heart supply different portions of the circulation. However, heart failure is not exclusively backward failure (in the part of the circulation which drains to the ventricle).
There are several other exceptions to a simple left-right division of heart failure symptoms. Left sided forward failure overlaps with right sided backward failure. Additionally, the most common cause of right-sided heart failure is left-sided heart failure. The result is that patients commonly present with both sets of signs and symptoms.

Left-sided failure
Backward failure of the left ventricle causes congestion of the pulmonary vasculature, and so the symptoms are predominantly respiratory in nature. Backward failure can be subdivided into failure of the left atrium, the left ventricle or both within the left circuit. The patient will have dyspnea (shortness of breath) on exertion (dyspnée d'effort) and in severe cases, dyspnea at rest. Increasing breathlessness on lying flat, called orthopnea, occurs. It is often measured in the number of pillows required to lie comfortably, and in severe cases, the patient may resort to sleeping while sitting up. Another symptom of heart failure is paroxysmal nocturnal dyspnea also known as "cardiac asthma", a sudden nighttime attack of severe breathlessness, usually several hours after going to sleep. Easy fatigueability and exercise intolerance are also common complaints related to respiratory compromise.
Compromise of left ventricular forward function may result in symptoms of poor systemic circulation such as dizziness, confusion and cool extremities at rest.

Right-sided failure
Backward failure of the right ventricle leads to congestion of systemic capillaries. This generates excess fluid accumulation in the body. This causes swelling under the skin (termed peripheral edema or anasarca) and usually affects the dependent parts of the body first (causing foot and ankle swelling in people who are standing up, and sacral edema in people who are predominantly lying down). Nocturia (frequent nighttime urination) may occur when fluid from the legs is returned to the bloodstream while lying down at night. In progressively severe cases, ascites (fluid accumulation in the abdominal cavity causing swelling) and hepatomegaly (enlargement of the liver) may develop. Significant liver congestion may result in impaired liver function, and jaundice and even coagulopathy (problems of decreased blood clotting) may occur.

Signs

Left-sided failure
Common respiratory signs are tachypnea (increased rate of breathing) and increased work of breathing (non-specific signs of respiratory distress). Rales or crackles, heard initially in the lung bases, and when severe, throughout the lung fields suggest the development of pulmonary edema (fluid in the alveoli). Cyanosis which suggests severe hypoxemia, is a late sign of extremely severe pulmonary edema.
Additional signs indicating left ventricular failure include a laterally displaced apex beat (which occurs if the heart is enlarged) and a gallop rhythm (additional heart sounds) may be heard as a marker of increased blood flow, or increased intra-cardiac pressure. Heart murmurs may indicate the presence of valvular heart disease, either as a cause (e.g. aortic stenosis) or as a result (e.g., mitral regurgitation) of the heart failure.

Right-sided failure
Physical examination can reveal pitting peripheral edema, ascites, and hepatomegaly. Jugular venous pressure is frequently assessed as a marker of fluid status, which can be accentuated by the hepatojugular reflux. If the right ventriclar pressure is increased, a parasternal heave may be present, signifying the compensatory increase in contraction strength.

Biventricular failure
Dullness of the lung fields to finger percussion and reduced breath sounds at the bases of the lung may suggest the development of a pleural effusion (fluid collection in between the lung and the chest wall). Though it can occur in isolated left- or right-sided heart failure, it is more common in biventricular failure because pleural veins drain both into the systemic and pulmonary venous system. When unilateral, effusions are often right-sided, presumably because of the larger surface area of the right lung