Heart failure a condition where the heart is too weak to meet the body’s circulatory requirements. As a result, blood flow to the organs is compromised.
Heart failure is usually a chronic condition but can occur acutely post-myocardial infarction.
Types of heart failure
Heart failure can be classified according to which side of the heart is affected:
- Left-sided heart failure
- Right-sided heart failure
- Biventricular failure (both of the above affected simultaneously)
In addition, it may be further classified according to whether ejection fraction (stroke volume as a proportion of diastolic volume) is impaired:
- Heart failure with reduced ejection fraction (HFrEF), also known as systolic failure
- Heart failure with preserved ejection fraction (HFpEF), also known as diastolic failure
In 2018, approximately 1.4% of the UK population were diagnosed with heart failure. The average age of diagnosis is 77.
Prevalence increases substantially with age and overall prevalence has increased in recent years.
Heart failure is often secondary to other cardiac disease, most commonly coronary artery disease or hypertension. These conditions cause damage to the heart muscle and surrounding vascular system, predisposing a patient to inefficient cardiac function and, therefore, heart failure.
Acute heart failure
Acute heart failure can be triggered post-myocardial infarction due to damage to the cardiac muscle caused by ischaemia.
Chronic heart failure
Chronic heart failure is often secondary to certain conditions, such as:
- Coronary artery disease
- Valve disease
- Congenital heart disease
- Alcohol or viral induced cardiomyopathies
- Cardiac arrhythmias, particularly atrial fibrillation
Precipitating factors are not directly related to the cardiovascular system but can trigger a decline in cardiac efficiency and predispose a person to heart failure. Precipitating factors for heart failure include:
- Excessive alcohol consumption
- Pulmonary hypertension
Left-sided heart failure
The left side of the heart takes in oxygenated blood from the lungs via the left atrium and pumps this oxygenated blood out to the body. In left-sided heart failure, the left ventricle is inefficient in pumping blood out of the heart, preventing oxygen-rich blood from getting to the rest of the body.
Left-sided heart failure is often secondary to hypertension.
Right-sided heart failure
Right-sided failure occurs when the right ventricle is inefficient in pumping blood towards the lungs.
The right side of the heart takes deoxygenated blood in from the rest of the body via the vena cava and pumps it back towards the lungs via the pulmonary artery.
Right-sided heart failure is often caused by pulmonary disease. Right-sided failure can also develop as a result of left-sided failure; pressure build-up behind left-sided heart failure can lead to pulmonary hypertension, increasing afterload and, consequently, pumping pressure in the right side of the heart.
Heart failure with reduced ejection fraction (HFrEF)
In HFrEF, the ventricles lose their ability to contract. This prevents blood leaving the heart and, therefore, reduces the ejection fraction. This type of heart failure can occur in left-sided, right-sided or biventricular failure.
HFrEF usually occurs when the heart is too weak to pump blood. As a compensatory mechanism, the ventricular muscle hypertrophies and results in an enlarged heart (termed cardiomegaly).
Heart failure with preserved ejection fraction (HFpEF)
HFpEF is less commonly seen in clinic, although its prevalence is increasing. HFpEF presents when the ventricular muscle is too stiff to fill fully with blood. The ventricles can empty fully, so ejection fraction is preserved. However, the ventricles cannot fill enough to adequately perfuse the tissues.
The muscle stiffness seen in HFpEF is often caused by a form of heart disease, such as arrhythmias or coronary artery disease.
The most common symptom associated with all types of heart failure is breathlessness, usually causing a reduction in the ability to exercise or perform daily activities (such as cleaning or walking up the stairs). Features can vary depending on the type of heart failure and the severity of disease.
General features of heart failure include:
- In particular, breathlessness on lying down (called orthopnoea) or breathlessness at night which awakens the patient (called paroxysmal nocturnal dyspnoea), both of which are relieved by sitting or standing upright.
- Fatigue, including a decreased ability to exercise
Left-sided heart failure
Features of left-sided failure occur as the left side of the heart is inefficient at pumping blood, so blood backs up in the blood vessels of the lungs, causing congestion. Features most commonly include:
- Pulmonary oedema
- Crepitations heard on auscultation
Right-sided heart failure
Features of right-sided failure occurs as the right side of the heart is inefficient at pumping blood, so this blood backs up in the body’s venous system. This causes congestion throughout the body, resulting in features such as:
- Oedema of the peripheries, most notably the legs, ankles and abdomen
- Raised jugular venous pressure (JVP)
Compensated vs. Decompensated heart failure
Heart failure can be divided into compensated and decompensated forms, depending on the symptoms experienced by a patient.
In compensated heart failure, symptoms may be less severe and symptoms like oedema may not be present. This is because the heart is able to manage its decreasing function with a range of compensatory mechanisms, such as ventricular muscle hypertrophy, stopping severe symptoms developing.
In decompensated heart failure, the heart can no longer manage its decreasing function and the patient’s symptoms deteriorate. Episodes of pulmonary oedema and a reduction in tolerance to physical activity are often signs of decompensated heart failure. There can be specific causes of decompensation, such as an infection, arrhythmia or recurrent bouts of ischemia damaging the cardiac muscle.
Classification of heart failure
The severity of heart failure is most often classified using the New York Heart Association (NYHA) functional classification system. It classifies heart failure into 4 groups, depending on the patient’s ability to undertake physical activity. The stages are shown below:
|I||Patient has no limitations in daily activity. Normal physical activity does not cause excessive breathlessness or fatigue.|
|II||Patient does not suffer with breathlessness at rest but physical activity causes some breathlessness and fatigue, slightly limiting a patient’s physical activity.|
|III||Patient is not breathless at rest but has marked limitation in physical activity, whereby less than normal daily activity causing breathlessness or fatigue.|
|IV||Patient is breathless at rest and cannot carry out physical activity without discomfort, breathlessness or fatigue.|
Multiple investigations are used to confirm the diagnosis of heart failure, discover the likely type of heart failure, and to possible exclude differentials. Listed below are some typical investigations.
As with many conditions, a battery of blood tests are performed when investigating a possible case of heart failure. These tests include:
|B-type natriuretic peptide (BNP) levels||Increased levels of cardiac BNP (over 100ng/L) suggests damage to the heart muscle and suggest heart failure. BNP levels have a sensitivity of 0.90 and a specificity of 0.73 in detecting chronic heart failure (compared to no heart failure).|
|Full blood count (FBC)||To determine if a patient has an anaemia or any haematological abnormalities.|
|Urea and electrolytes (U&Es)||Electrolyte disturbances may be the cause of some patient symptoms, such as hyperkalaemia causing arrhythmias. Electrolytes can also provide information about renal function, which can be useful when considering the pharmacological treatment of heart failure.|
|Liver function tests (LFTs)||Information on liver function can help when deciding pharmacological treatment. A decrease in hepatic function is a potential complication of heart failure.|
|Thyroid function tests (TFTs)||Hyperthyroidism and hypothyroidism can cause and/or contribute to the development of heart failure|
|Lipid levels||High levels of lipids, and particularly cholesterol levels, can point towards conditions such as hypercholesterolemia and coronary artery disease, which are common contributors to the development of heart failure.|
|Echocardiogram||Uses ultrasound to determine the efficacy of the cardiac muscle and valvular function. An echocardiogram can give lots of useful information about cardiac function, such as: |
The ejection fraction: This fraction is the percentage of blood within the heart that is pumped out by the ventricles with each contraction. It is calculated as the stroke volume divided by the diastolic volume (x100 to create a percentage). In heart failure, this percentage is often decreased to under 45%.
Valve abnormalities: These abnormalities can be a cause or a sign of chronic heart failure.
|ECG||Measures the electrical rhythms to detect potential arrhythmias, which may be a cause or a complication of heart failure.|
|Chest x-ray||Cardiomegaly and pulmonary oedema are often common signs of heart failure observed on chest x-ray. A chest x-ray can also be used to exclude respiratory differentials, such as pneumonia.|
The main goal in managing heart failure is to decrease the amount of work that the heart requires pump blood around the body, preventing worsening of the condition and decreasing hospitalisation.
Relieving the symptoms of heart failure, such as oedema, is also important for making a patient more comfortable and improving quality of life.
General management strategies
Offer lifestyle advice to patients with heart failure, including:
- Maintain a healthy balanced diet (including reducing saturated fat)
- Reduce salt consumption (and avoid salt substitutes containing potassium)
- Stop smoking
- Reduce alcohol consumption (if necessary)
- Increase physical exercise levels (if appropriate)
Co-morbidities, such as hypertension, hypercholesterolemia and diabetes, should also be managed to reduce the risk of worsening heart failure.
Pneumococcal and flu vaccinations should be offered to all patients with heart failure to prevent their condition worsening due to infection.
Treating acute heart failure
Acute heart failure often occurs after a cardiac event, such as a myocardial infarction. Therefore, the cause of acute heart failure should firstly be discovered and treated if necessary.
Patients with acute heart failure may then be offered a range of medication whilst they are in hospital to stabilise their condition. These medications include:
- IV diuretics
- ACE inhibitors
Patients should be monitored closely during hospital treatment, measuring their renal function, electrolytes, heart rate and blood pressure. Once discharged from hospital, a patient may then be managed using chronic heart failure guidelines.
- First-line drugs are ACE inhibitors (e.g. ramipril) and beta blockers (e.g. bisoproplol). Start at a low dose and titrate up, measuring serum electrolytes and eGFR with each dose increase.
- If ACE inhibitors are not tolerated (e.g. the patient develops a cough), replace with an angiotensin II receptor antagonist (e.g. valsartan).
- If therapy fails, add an aldosterone antagonist (spironolactone)
- Third-line treatment options include:
- Hydralazine with nitrate
- Cardiac resynchronisation therapy
HFpEF is often difficult to treat as there is a lack of evidence-based treatments available and treatments used in HFrEF (such as ACE inhibitors) are usually unsuccessful.
Current strategies focus on managing symptoms first, such as offering a low dose of loop diuretic (e.g. furosemide) for oedema. If symptoms do not improve, the patient is often referred to a heart failure specialist for further management.
Treatments for common complications include:
- Oedema: Diuretics (e.g. furosemide) can be used in all types of heart failure.
- Atrial fibrillation: Anticoagulants (e.g. warfarin) can be added to therapy.
Strategies for resynchronising the cardiac rhythm
Patients with certain forms of heart failure may benefit from having a device implanted under the skin which helps to resynchronise the heart rhythm and prevent arrhythmias. Types of devices that may be considered are:
- Implantable cardioverter defibrillators (ICDs): These devices are implanted below the collarbone and have wires that feed into the heart. They analyse the electrical activity of the heart, sensing arrhythmias and delivering electrical pulses to reset the heart rhythm if necessary.
- Cardiac resynchronisation therapy with pacing (CRT-P) devices: These devices are implanted in the upper chest with wires leading into both ventricles and the right atrium. They resynchronise the contraction of the ventricles to a normal contraction rhythm.
- Cardiac resynchronisation therapy with defibrillator (CRT-D) devices: These devices are a combination of ICD and CRT-P devices. They reset the heart rhythm in the event of arrhythmias and can improve ventricular contraction.
These devices are only suitable for certain patients with heart failure, including:
- Those with left sided or biventricular heart failure
- Those with a left-sided ejection fraction of under 35%
- Those with prolonged QRS intervals on ECG
Arrhythmias are a common complication that arise from heart failure. Common arrhythmias include:
- Atrial fibrillation
- Ventricular tachycardia
- Ventricular fibrillation
Valvular damage can also arise due to the compensatory changes in the heart’s shape or size.
Heart failure can also cause thrombotic or embolic complications as inefficient blood flow can cause blood to pool within vessels, forming clots.
The most notable complications that arise from clots include:
- Deep vein thrombosis (DVT)
- Pulmonary embolism.
Inefficient heart function can decrease blood flow to the portal vein, while oedema can compress the portal vein and obstruct blood flow to the liver. This decreased blood flow can lead to decreased hepatic functioning and possible cirrhosis.
Prognosis of heart failure is dependent on the stage of disease. Mild-moderate forms of chronic heart failure have a one-year mortality rate of 20-30%. In more severe forms, this one-year mortality increases to 50%.
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