flowchart TD
A(Heart Failure: <br> - Low Cardiac Output <br> - Low blood pressure)-->B(Decreased organ perfusion <br> - Renal failure <br> - fatigue);
B-->C(Neurohumoral activation);
C-->D(Epinephrine <br> - Increased Heart Rate);
C-->E(Aldosterone: <br> - Sodium retention <br> - Water retention <br> - Oedema);
C-->F(Renin <br> - Increased afterload);
E-->G(Left Ventricular Remodeling);
F-->G;
A-->H(Lung Congestion: <br> - shortness of breath <br> - PND <br> - Orthopnea <br> - Cough)
A-->I(Liver Congestion: <br> - Liver failure);
G-->A;
D-->G
22 Heart Failure
22.1 Definition
The inability of the heat to provide enough output to the body.
22.2 Causes
Varies, especially in children. They can occur in both structurally normal hearts and in congenital cardiac malformations. There are three main groups of causes:
Ventricular dysfunction results from either systolic or diastolic dysfunction of the ventricles. Systolic dysfunction is more commonly encountered compared to diastolic ones. Examples are:
- Cardiomyopathy (dilated, restrictive and hypertrophic)
- Myocarditis
- Arrhythmias
- Coronary artery anomalies
- Post-op cardiac dysfunction
Volume overload occurs in conditions associated with increased volume (preload) in the heart, especially the ventricles. The ventricle must, therefore, eject an increased blood volume, leading to tachycardia. It may or may not be associated with ventricular dysfunction. Examples include:
- Ventricular septal defect (left to right shunt)
- Atrial septal defect
- Patent ductus arteriosus
- Aortic regurgitation (left ventricle)
- Mitral regurgitation (Left atrium)
Pressure overload is when heart failure is caused by an increased pressure (afterload) in the heart. Ventricles must, therefore, contract against higher pressures. It may or may not be associated with ventricular dysfunction. These include:
- Hypertension
- Aortic valve stenosis
- Pulmonary stenosis
- Coarctation of the aorta
In all these, the result is decreased cardiac output and pulmonary oedema.
22.3 Classification
The symptoms of heart failure vary significantly, with infants and young children having different presentations compared to older children. The classification of heart failure there is not uniform. The most well-known classification is the NYHA, which is appropriate for older children. It is shown below:
| Class | Patient Symptoms |
|---|---|
| Class I (Mild) | No limitation on physical activity. Ordinary physical activity does not cause undue fatigue, palpitation or dyspnoea |
| Class II (Mild) | Slight limitation of physical activity. Comfortable at rest but ordinary physical activity results in fatigue, palpitation or dyspnoea |
| Class III (Moderate) | Marked limitation of physical activity. Comfortable at rest but less than ordinary physical activity causes fatigue, palpitation or dyspnoea |
| Class IV (Severe) | Unable to carry out any physical activity without discomfort. Symptoms of cardiac insufficiency at rest. If any physical activity is undertaken discomfort is increased |
On the other hand, the Ross classification shown below is more suited for infants and young children.
| Class | Symptoms |
|---|---|
| Class I | Asymptomatic |
| Class II | Mild tachypnoea or diaphoresis in feeding in infants Dyspnoea on exertion in older children |
| Class III | Marked tachypnoea or sweating with feeding in infants Marked dyspnoea on exertion Prolonged feeding times with growth failure |
| Class IV | Symptoms such as tachycardia, retraction, grunting, or diaphoresis at rest |
22.4 Pathophysiology
A schematic drawing of the various processes involved is shown below:
22.5 Signs and symptoms
The symptoms of heart failure are variable and age-dependent. For infants, the symptoms include poor feeding, sweating with breastfeeding, prolonged feeding time, tachypnoea, poor weight gain and dyspnoea. For young children symptoms include recurrent respiratory tract infection, recurrent wheezing, fatigue, exercise intolerance, facial and recurrent cough. Older children have symptoms that more resemble those of adults. These include tachypnoea, tachycardia, recurrent wheezing, pedal swelling, palpitations, and vomiting.
Signs of heart failure also vary with age. These include for infants, failure to thrive, tachycardia, tachypnoea, hepatomegaly, displaced apex (cardiomegaly), S3 gallop, oedema (pedal in older children and facial or abdominal distension in older children).
22.6 Investigation
The investigations required are generally towards the likely underlying pathology. Some of them would include:
Chest x-ray: This may show cardiomegaly, increased pulmonary lung markings, pulmonary oedema, pleural effusion and heart shape.
Electrocardiogram: This helps to identify chamber enlargement and dysrhythmias that may be the cause or consequent to the heart failure
Echocardiogram: This identifies and quantifies the function of the ventricle as well as the chamber sizes
Blood test: The complete blood count helps to identify anaemia or polycethemia. The serum urea and creatinine identify possible renal dysfunction. Other tests include BNP (Brain Naturetic Peptide) and Troponin both of which are elevated in heart failure.
Other investigatory modalities: These include Magnetic Resonance Imaging, Cardiac catheterization,
22.7 Treatment of Heart Failure
This is done with some goals:
- Improve the quality of life
- Arrest and possibly reverse the heart failure
- Sustain till other definitive therapeutic interventions are employed, including surgery.
The treatment for heart failure is dependent on the pathophysiology, clinical features and stage of the disease.
22.7.1 Non-pharmacological treatment
This includes fluid restriction in case of congestion and fluid overload, intubation and mechanical ventilation to help support breathing and reduce the workload on the heart and patient. Others include cardiac Resynchronization Therapy, Ventricular Assisted Devices and Extracorporeal Membrane Oxygenation. Heart transplantation is the last option in some cases of heart failure.
22.7.2 Pharmacological treatment
Treatment depends on the clinical presentation and cause of the heart failure. There are 2 main groups to be considered:
22.7.3 Acute decompensated heart failure
| Drug | Action |
|---|---|
| Diuretics | Notable here is furosemide. The aim is to help decongest the lungs, reduce preload by vasodilatation and improve heart failure symptoms. |
| Inotropes | These include adrenaline, noradrenaline, dopamine and dobutamine. They help improve the contractility of the heart, increase heart rate, and increase peripheral vascular resistance, thus maintaining the blood pressure and cardiac output. They are usually Intravenous medications. |
22.7.4 Chronic heart failure
These are usually oral medications given to treat heart failure on an outpatient basis
| Group | Action |
|---|---|
| Diuretics | These are given to decongest the lungs, liver and other edematous organs. The most commonly used is furosemide. |
| Aldosterone antagonists | These counteract the aldosterone effect of water and sodium retention. They decrease afterload while helping in reversing cardiac remodelling. |
| ACE-I/ARB | Angiotensin-converting enzyme inhibitors and Angiotensin II receptor blockers counteract the renin effects of increasing afterload. They thus decrease the afterload and help reverse and prevent cardiac remodelling |
| Digoxin | This is probably the oldest anti-heart failure medication. It has negative chronotropic and positive inotropic effects. Thus increasing contractility and reducing heart rate. |
| \(\beta\) -adrenergic blocking | These are adrenergic-blocking agents that work by decreasing sympathetic activity to the heart, decreasing heart rate, and thus decreasing oxygen demand. Examples are Propranolol, Atenolol and Carvedilol. |
22.8 Complications
Complications of heart failure include renal failure, hepatic failure, pulmonary hypertension, arrhythmia, and thromboembolic effects.