Overview

Heart failure describes the signs and symptoms seen in patients with an impairment of the heart’s ability to pump blood associated with increased natriuretic peptide levels and/or evidence of pulmonary or systemic congestion. Any factor that can cause damage to the heart or increase its workload can lead to heart failure. There are multiple ways it can be classified.

Classification

By timeline

Heart failure can be classified as acute or chronic:

  • Acute (decompensated):
    • Sudden worsening of signs and symptoms of heart failure
    • Can be due to decompensation of chronic heart failure due to intercurrent illness (e.g. myocardial infarction, arrhythmia, infection, severe hypertension, or drugs) or high-output heart failure (discussed below)
  • Chronic heart failure:
    •  Long-term and controlled by managing symptoms

By ejection fraction

Heart failure was previously categorised based on the side of the heart involved (right heart failure vs. left heart failure), however, there are many mixed presentations and left heart failure can cause right heart failure.

A more accurate classification is by measuring the left ventricular ejection fraction (LVEF, the percentage of blood pumped out during a single contraction):

  • LVEF 41-49%: heart failure with mildly reduced ejection fraction (HFmrEF)
  • LVEF <40%: heart failure with reduced ejection fraction (HFrEF)
  • LVEF >50% but has symptoms of heart failure/raised levels of natriuretic peptides: heart failure with preserved ejection fraction (HFpEF)

By systole/diastole

Heart failure was also categorised as ‘systolic heart failure’ and ‘diastolic heart failure’. This has been replaced by classifying patients based on the ejection fraction. As a general rule of thumb:

Generally speaking, HFrEF and HFpEF cause left-sided heart failure due to increased ventricular preload (e.g. backflow of blood into the left ventricle due to aortic regurgitation) or increased ventricular afterload (e.g. aortic stenosis, which leads to more ‘work’ needing to be done by the left ventricle to pump blood out of the heart).

By evidence of sodium and water retention

Congestive heart failure describes heart failure with abnormal sodium and water retention, leading to oedema. This has been removed from the universal definition of heart failure as there can be a wide range of signs and symptoms seen in heart failure, and sodium and water retention is not essential for its diagnosis.

By the site of the heart involved

‘Right heart failure’ and ‘left heart failure’ were previously used to classify heart failure, however, there are many mixed presentations and left heart failure can cause right heart failure. These terms may still be used to describe the end effects of heart failure and the symptoms seen.

Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body. Left-sided heart failure leads to a back up of blood in the lungs leading to pulmonary oedema characterised by:

  • Tachypnoea
  • Dyspnoea
  • Bilateral basal crackles
  • Orthopnoea – shortness of breath when lying down
  • Paroxysmal nocturnal dyspnoea – waking up short of breath at night, usually improved by sleeping upright
  • Laterally displaced apex beat – due to enlargement of the left ventricle
  • Additional heart sounds – S3 and S4

Deoxygenated blood from the body enters the right side of the heart to be pumped to the lungs. Right-sided heart failure is often caused by pulmonary diseases (such as pulmonary stenosis or pulmonary hypertension), leading to increased work on the right ventricle, hypertrophy, and subsequent right heart failure. This leads to the accumulation of fluid in the systemic circulation characterised by:

  • Peripheral oedema (usually ankle/sacral oedema)
  • Raised jugular venous pressure
  • Hepatomegaly with or without splenomegaly
    • Due to liver congestion
    • This can lead to impaired liver function, jaundice, and coagulopathy due to impaired clotting factor synthesis

Failure of one side of the heart can lead to the failure of the other. Left-sided heart failure can lead to pulmonary congestion, which puts more strain on the right side of the heart, which can lead to right-sided heart failure.

By symptomatic severity

The New York Heart Association (NYHA) classifies heart failure based on the severity of symptoms and limitation of physical activity:

  • Class I: asymptomatic
  • Class II: mild symptoms with moderate exertion
    • Comfortable at rest
    • Ordinary physical activity does cause breathlessness, fatigue, or palpitations
  • Class III: symptoms with minimal activity
    • Comfortable at rest
    • Less than ordinary physical activity does not cause breathlessness, fatigue, or palpitations
  • Class IV: symptoms at rest
    • Unable to carry out any physical activity without symptoms
    • Discomfort worsens with physical activity

High-output heart failure

High-output heart failure describes when an intact heart cannot pump enough blood to meet the demands of the body. This can occur in scenarios where the metabolic rate of the body increases such as:

Presentation

As discussed above, although left- and right-sided heart failure are not used to classify heart failure, they can be used to assess signs and symptoms seen:

  • Left-sided heart failure – due to pulmonary congestion:
    • Tachypnoea
    • Dyspnoea
    • Bilateral basal crackles
    • Orthopnoea – shortness of breath when lying down
    • Paroxysmal nocturnal dyspnoea – waking up short of breath at night, usually improved by sleeping upright
    • Laterally displaced apex beat – due to enlargement of the left ventricle
    • Additional heart sounds – S3 and S4
  • Right-sided heart failure – due to systemic congestion:
    • Peripheral oedema (usually ankle/sacral oedema)
    • Raised jugular venous pressure
    • Hepatomegaly with or without splenomegaly
      • Due to liver congestion
      • This can lead to impaired liver function, jaundice, and coagulopathy due to impaired clotting factor synthesis
  • Biventricular failure – failure of one side of the heart can lead to failure of the over:
    • An overlap of the above signs and symptoms may be seen
    • Pleural effusions may occur – this can still happen in unilateral heart failure

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