Heart Infection in Children: Myocarditis, Endocarditis & Pericarditis

What Is Heart Infection in Children?

Heart infection in children refers to inflammation or infection of the heart structures, including myocarditis (heart muscle), endocarditis (inner lining and valves), and pericarditis (outer sac). These conditions can impair the heart's ability to pump blood and, if untreated, may lead to serious complications including heart failure.

The heart is a muscular organ that pumps blood throughout the body. It consists of several layers: the myocardium (muscle), the endocardium (inner lining), and the pericardium (outer protective sac). Infections or inflammation can affect any of these structures, leading to different types of heart conditions in children.

Understanding the anatomy of the heart helps explain why different types of heart infections cause different symptoms. When the heart muscle becomes inflamed (myocarditis), the heart's pumping ability is directly affected. When the inner lining is infected (endocarditis), bacteria can damage heart valves and spread to other parts of the body. When the outer sac becomes inflamed (pericarditis), it can cause chest pain and, in severe cases, fluid accumulation that restricts heart function.

Heart infections in children are relatively rare compared to adults, but they can occur at any age. The incidence varies by type: myocarditis affects approximately 1-2 per 100,000 children annually, while infective endocarditis occurs in 0.05-0.12 per 1000 pediatric hospital admissions. However, the true incidence may be higher as many mild cases go undiagnosed.

Types of Heart Infection

Each type of heart infection has distinct characteristics, causes, and treatment approaches. Understanding these differences is important for recognizing symptoms and seeking appropriate care.

Understanding Myocarditis

Myocarditis is the most common type of heart infection in children and deserves special attention. It occurs when the heart muscle becomes inflamed, typically as a result of viral infection. The inflammation can damage heart muscle cells, affecting the heart's ability to contract and pump blood effectively throughout the body.

The inflammatory process in myocarditis can range from mild, causing minimal symptoms, to severe, leading to significant heart dysfunction. In some cases, the immune system continues to attack heart tissue even after the initial infection has cleared, leading to ongoing inflammation and damage. This is why myocarditis sometimes develops weeks after an apparent viral illness has resolved.

Understanding Endocarditis

Infective endocarditis in children is less common than myocarditis but is particularly important because of its association with congenital heart disease. Children born with heart defects, those who have had heart surgery, or those with artificial heart valves are at significantly higher risk. The infection typically occurs when bacteria from another part of the body (such as the mouth during dental procedures) enter the bloodstream and attach to damaged or abnormal heart tissue.

Unlike viral myocarditis, which often resolves on its own, bacterial endocarditis requires aggressive antibiotic treatment and sometimes surgery to prevent serious complications including heart valve destruction, stroke, and spread of infection to other organs.

What Are the Symptoms of Heart Infection in Children?

Symptoms of heart infection in children include unexplained fever, extreme fatigue, rapid or irregular heartbeat, shortness of breath, chest pain or discomfort, poor feeding in infants, swelling in legs or abdomen, and reduced ability to exercise. Symptoms often develop 1-3 weeks after a viral illness and may progress rapidly.

Recognizing the symptoms of heart infection in children can be challenging because many symptoms overlap with common childhood illnesses. However, certain patterns and combinations of symptoms should raise concern, particularly when they occur after a recent viral infection or persist longer than expected.

The presentation of heart infection varies significantly by age. Infants and young children cannot describe their symptoms, so parents must watch for behavioral changes and physical signs. Older children and teenagers can communicate their symptoms more clearly, making diagnosis somewhat easier. Regardless of age, any child who appears seriously ill or has multiple concerning symptoms should receive prompt medical evaluation.

The severity of symptoms often correlates with the degree of heart involvement. Mild cases may cause only fatigue and low-grade fever, while severe cases can lead to obvious signs of heart failure such as significant breathing difficulty, swelling, and inability to perform normal activities.

Early Warning Signs

Early recognition of heart infection symptoms is crucial for optimal outcomes. Parents should be particularly vigilant during and after viral illnesses, as this is when heart infections most commonly develop.

• Persistent fever: Fever lasting more than 3-5 days or returning after initial improvement
• Unusual fatigue: Tiredness out of proportion to the illness, reluctance to play or move
• Rapid breathing: Breathing faster than normal, especially at rest
• Decreased appetite: In infants, poor feeding or taking longer to feed
• Irritability: Inconsolable crying or general discomfort in young children

Symptoms by Age Group

Heart infection symptoms manifest differently depending on the child's age. Understanding these age-specific presentations helps parents and caregivers recognize potential problems more quickly.

Infants (under 1 year): Infants with heart infection may show poor feeding, failure to gain weight, excessive sweating during feeding, rapid breathing, grunting, pale or grayish skin color, decreased wet diapers (indicating poor circulation), and lethargy. They may also have difficulty sleeping or seem unusually fussy. Because infants cannot describe pain or discomfort, these behavioral and physical signs are critical indicators.

Toddlers and young children (1-5 years): Children in this age group may refuse to walk or play, complain of tummy aches (which may actually be referred pain from the heart), vomit without apparent cause, breathe rapidly, and tire easily. They may not be able to articulate chest pain but may point to or rub their chest.

School-age children (6-12 years): Older children can better describe their symptoms. They may report chest pain, palpitations (feeling their heart beating), dizziness, shortness of breath during activities they previously handled easily, and general weakness. They may also notice swelling in their feet or legs.

Teenagers: Adolescents typically present most similarly to adults, with chest pain, palpitations, exercise intolerance, fainting or near-fainting, and flu-like symptoms. They may initially attribute symptoms to overexertion or stress, potentially delaying diagnosis.

Symptoms Specific to Each Type

Myocarditis symptoms often begin with flu-like illness followed by cardiac symptoms. Children may develop chest pain that worsens with deep breathing, palpitations, fatigue, and signs of heart failure (breathing difficulty, swelling). The progression from viral symptoms to heart symptoms typically occurs over days to weeks.

Endocarditis symptoms tend to develop more gradually and may include prolonged unexplained fever, night sweats, weight loss, joint pain, and small painful nodules on fingers or toes. Children may also develop new heart murmurs, and in some cases, symptoms of stroke if infected material breaks off and travels to the brain.

Pericarditis symptoms characteristically include sharp chest pain that improves when sitting up and leaning forward, and worsens when lying down or taking deep breaths. Children may also have fever, and a friction rub sound may be heard with a stethoscope.

What Causes Heart Infections in Children?

Heart infections in children are most commonly caused by viral infections, particularly enteroviruses (including Coxsackie virus), adenoviruses, parvovirus B19, and influenza. Bacterial causes, though less common, include Streptococcus and Staphylococcus. Other causes include autoimmune reactions, certain medications, and toxins.

Understanding what causes heart infections helps explain why they occur and how they might be prevented. The causes differ significantly between the different types of heart infection, with viruses being the predominant cause of myocarditis and pericarditis, while bacteria are the primary cause of endocarditis.

In many cases of myocarditis, the exact cause cannot be determined even after extensive testing. This is called idiopathic myocarditis. Research suggests that some of these cases may involve viral infections that have cleared by the time symptoms appear, or autoimmune mechanisms where the body's immune system mistakenly attacks heart tissue.

Viral Causes

Viruses are responsible for the majority of myocarditis and pericarditis cases in children. These viruses typically cause respiratory or gastrointestinal illness first, and the heart involvement develops as a complication. The mechanism involves either direct viral infection of heart cells or an immune response that damages heart tissue while fighting the infection.

Common viral causes include:

• Enteroviruses (especially Coxsackie B): The most common cause of viral myocarditis, often following a stomach bug or cold
• Adenoviruses: Cause respiratory infections and can affect the heart
• Parvovirus B19: The virus that causes fifth disease (slapped cheek syndrome)
• Influenza viruses: Both influenza A and B can cause myocarditis
• Epstein-Barr virus (EBV): The virus that causes mononucleosis
• Cytomegalovirus (CMV): Particularly in immunocompromised children
• SARS-CoV-2: The virus causing COVID-19 has been associated with myocarditis in some cases

Bacterial Causes

Bacterial infections are the primary cause of infective endocarditis and can occasionally cause myocarditis. Children with congenital heart disease, previous heart surgery, or artificial heart valves are at highest risk for bacterial endocarditis.

The most common bacteria causing endocarditis in children include Staphylococcus aureus (including MRSA), Streptococcus viridans group (often from dental sources), Enterococcus, and various gram-negative bacteria. These bacteria can enter the bloodstream through dental procedures, skin infections, or even routine activities in high-risk children.

Other Causes

While infections cause most heart inflammation in children, other factors can also contribute. Autoimmune conditions such as systemic lupus erythematosus, rheumatoid arthritis, and Kawasaki disease can cause heart inflammation. Certain medications, though rare, may trigger drug-induced myocarditis. Environmental toxins and radiation (typically during cancer treatment) can also damage the heart.

How Is Heart Infection Diagnosed in Children?

Heart infection in children is diagnosed through a combination of clinical evaluation, blood tests (cardiac enzymes, inflammatory markers, blood cultures), electrocardiogram (ECG), echocardiogram (heart ultrasound), and sometimes cardiac MRI. The gold standard for myocarditis diagnosis is cardiac MRI, which can detect inflammation in the heart muscle.

Diagnosing heart infection in children requires a systematic approach combining the child's medical history, physical examination, and various diagnostic tests. Because symptoms can be nonspecific and overlap with many other conditions, healthcare providers must maintain a high index of suspicion, particularly in children who present with cardiac symptoms following viral illness.

The diagnostic process typically begins with a thorough history taking, including recent illnesses, symptoms timeline, and family history of heart disease. Physical examination focuses on vital signs, heart sounds (listening for murmurs, friction rubs, or gallops), signs of heart failure (swelling, liver enlargement), and overall appearance of the child.

Blood Tests

Blood tests provide valuable information about heart damage and inflammation. Several markers are typically measured when heart infection is suspected.

Cardiac enzymes (troponin): Troponin is released when heart muscle cells are damaged. Elevated troponin levels indicate heart muscle injury and strongly support the diagnosis of myocarditis. However, troponin can also be elevated in other conditions, so it must be interpreted in context.

Inflammatory markers: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) indicate inflammation in the body. While not specific for heart infection, elevated levels support the diagnosis when combined with other findings.

B-type natriuretic peptide (BNP): This hormone is released when the heart is under stress. Elevated BNP indicates heart dysfunction and can help assess the severity of cardiac involvement.

Blood cultures: Multiple blood cultures are essential when bacterial endocarditis is suspected. They help identify the specific bacteria causing infection and guide antibiotic selection.

Viral studies: Tests for specific viruses may be performed, including PCR testing for enteroviruses, adenovirus, and other common causes. However, viral testing is often negative by the time heart symptoms develop.

Cardiac Imaging

Electrocardiogram (ECG): This painless test records the heart's electrical activity. In myocarditis, ECG may show various abnormalities including ST-segment changes, T-wave inversions, arrhythmias, and signs of heart enlargement. In pericarditis, diffuse ST elevations are characteristic. Normal ECG does not rule out heart infection, but abnormal findings support the diagnosis.

Echocardiogram: This ultrasound of the heart is crucial for assessing heart function and structure. It can reveal decreased pumping ability (reduced ejection fraction), enlarged heart chambers, abnormal wall motion, valve abnormalities, and pericardial effusion (fluid around the heart). Echocardiography is typically the first imaging test performed and provides immediate, valuable information.

Cardiac MRI: Cardiac MRI has become the gold standard for diagnosing myocarditis. It can directly visualize inflammation in the heart muscle, assess the extent and location of damage, and help distinguish myocarditis from other conditions. Cardiac MRI is particularly useful in children who are stable enough to undergo the procedure, though it may require sedation in younger children.

Other Diagnostic Tests

Chest X-ray: Shows heart size and signs of fluid in the lungs (pulmonary edema). An enlarged heart shadow may indicate myocarditis or pericardial effusion.

Holter monitor: A portable ECG worn for 24-48 hours to detect intermittent arrhythmias that may not appear during a standard ECG.

Endomyocardial biopsy: This invasive test involves taking small tissue samples from inside the heart. While it can provide definitive diagnosis, it is typically reserved for severe cases or when the diagnosis remains uncertain after non-invasive testing.

How Is Heart Infection Treated in Children?

Treatment for heart infection in children depends on the type and severity. It may include supportive care with rest and monitoring, medications for heart failure (diuretics, ACE inhibitors, beta-blockers), anti-inflammatory drugs, intravenous immunoglobulin (IVIG) for certain cases, antibiotics for bacterial infections, and in severe cases, mechanical circulatory support or heart transplantation.

The treatment approach for heart infection in children varies significantly based on the specific type of infection, its severity, and how well the child's heart is functioning. The primary goals of treatment are to support heart function, treat the underlying cause when possible, prevent complications, and promote recovery.

Most children with heart infection require hospitalization, at least initially, for close monitoring and treatment. The length of hospital stay depends on how seriously the heart is affected and how well the child responds to treatment. Some children with mild cases may be managed as outpatients with close follow-up.

Supportive Care

Rest: Physical rest is essential for children with heart infection. Activity increases the heart's workload and can worsen inflammation. Children are typically restricted from physical activity until heart function normalizes, which may take weeks to months. This includes avoiding sports, physical education, and strenuous play.

Monitoring: Continuous cardiac monitoring in the hospital allows early detection of arrhythmias and changes in heart function. Regular echocardiograms track recovery and guide treatment decisions.

Fluid management: Careful attention to fluid intake and output helps prevent fluid overload, which can stress an already weakened heart.

Medications

Several categories of medications may be used depending on the child's condition and specific needs.

Heart failure medications: For children with decreased heart function, standard heart failure medications may be prescribed. Diuretics remove excess fluid and reduce the heart's workload. ACE inhibitors and beta-blockers help the heart pump more efficiently and promote recovery. Digoxin may be used in some cases to strengthen heart contractions.

Anti-inflammatory medications: Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or indomethacin are often used for pericarditis to reduce inflammation and relieve pain. Colchicine may be added to prevent recurrence. In some cases of myocarditis, corticosteroids may be considered, though their routine use remains controversial.

Intravenous immunoglobulin (IVIG): This blood product containing antibodies may be used in certain cases of viral myocarditis, particularly in children with significant heart dysfunction. The evidence for IVIG is limited, but it may help modulate the immune response.

Antibiotics: For bacterial endocarditis, prolonged courses of intravenous antibiotics (typically 4-6 weeks) are essential. The specific antibiotics are chosen based on blood culture results and must effectively kill the bacteria causing infection while achieving adequate levels in heart tissue.

Treatment for Severe Cases

Some children with severe heart infection develop significant heart failure that does not respond adequately to medications. These children may require more intensive support.

Mechanical circulatory support: Devices such as ECMO (extracorporeal membrane oxygenation) or ventricular assist devices can temporarily support heart function while the heart recovers. These are life-saving interventions for children in cardiogenic shock.

Surgery: Surgical intervention may be necessary for endocarditis if infected heart valves are severely damaged, if infection is not controlled with antibiotics, or if there are large vegetations at risk of causing stroke. Valve repair or replacement may be required.

Heart transplantation: In rare cases where the heart is severely damaged and does not recover, heart transplantation may be the only option. This is fortunately uncommon, as most children with myocarditis recover heart function with appropriate treatment.

What Is the Outlook for Children with Heart Infection?

The prognosis for children with heart infection is generally favorable, with 50-80% of children with acute myocarditis recovering completely. Factors affecting outcome include the initial severity, how quickly treatment begins, the underlying cause, and the child's age. Some children may develop chronic heart problems requiring ongoing care.

Parents naturally worry about the long-term outlook when their child is diagnosed with heart infection. While the diagnosis is serious and requires careful management, the news is largely encouraging: most children recover well, especially when heart infection is detected and treated promptly.

The outcome depends on several factors. The initial degree of heart dysfunction is one of the strongest predictors - children who present with mildly decreased heart function generally do better than those with severe heart failure. The underlying cause also matters; viral myocarditis typically has better outcomes than some other forms. Age can play a role, with infants sometimes having more variable outcomes. Finally, how quickly treatment begins affects recovery - early intervention generally leads to better results.

Recovery Statistics

Research provides encouraging data about recovery from pediatric heart infection. Approximately 50-80% of children with acute myocarditis recover completely, with normal heart function on follow-up testing. About 10-20% develop chronic but stable heart problems that may require ongoing medication but don't significantly limit quality of life. Unfortunately, about 10-20% develop more serious chronic heart disease, including dilated cardiomyopathy, which may require ongoing intensive management.

For pericarditis, the prognosis is generally excellent. Most children recover fully, though some may have recurrent episodes that require additional treatment. Endocarditis prognosis depends heavily on the underlying heart condition and whether the infection is controlled before significant damage occurs. With appropriate antibiotic treatment, most children with endocarditis also do well.

Long-term Follow-up

All children who have had heart infection require regular follow-up with a pediatric cardiologist. Follow-up typically includes periodic echocardiograms to monitor heart function, ECGs to check for arrhythmias, and clinical assessments to ensure the child is recovering appropriately.

The frequency of follow-up visits depends on the severity of the initial illness and how well the child is recovering. Children with normal heart function may need visits every few months initially, then annually. Those with ongoing heart dysfunction require more frequent monitoring and may need lifelong cardiology care.

Can Heart Infections in Children Be Prevented?

While not all heart infections can be prevented, risk can be reduced through general infection prevention (hand hygiene, vaccinations), good dental care, appropriate antibiotic prophylaxis for high-risk children before certain procedures, and awareness of warning signs after viral illnesses.

Completely preventing heart infections in children is not possible, since they often result from common viral illnesses. However, there are several strategies that can reduce the risk or help with early detection.

General Prevention Strategies

Infection prevention: Good hand hygiene, avoiding close contact with sick individuals, and staying current with recommended vaccinations help prevent the viral and bacterial infections that can lead to heart involvement. Influenza vaccination is particularly important as flu can cause myocarditis.

Dental health: Good dental hygiene and regular dental care are important, especially for children at risk of endocarditis. Bacteria from dental infections or procedures can enter the bloodstream and infect the heart.

Awareness after viral illness: Parents should watch for new or worsening symptoms in the 1-3 weeks after a viral illness. New fatigue, chest pain, rapid heartbeat, or breathing difficulty should prompt medical evaluation.

Prevention for High-Risk Children

Children with congenital heart disease, previous heart surgery, or artificial heart valves are at higher risk for endocarditis. For these children, specific preventive measures are important.

Antibiotic prophylaxis: Some high-risk children need antibiotics before dental procedures or certain other procedures that may introduce bacteria into the bloodstream. The pediatric cardiologist will advise which children need prophylaxis and when.

Regular cardiology follow-up: High-risk children should maintain regular appointments with their cardiologist. This allows monitoring of heart health and early intervention if problems develop.

When Should You Seek Medical Care?

Seek medical care if your child has unexplained fever lasting more than 3-5 days, unusual fatigue, chest pain, rapid heartbeat, breathing difficulties, or reduced activity tolerance - especially following a recent viral illness. Seek emergency care for severe symptoms like significant breathing difficulty, fainting, or blue/gray skin color.

Knowing when to seek medical care can be challenging for parents. Many symptoms of heart infection overlap with common childhood illnesses, and it's natural to wonder whether a trip to the doctor is necessary. When in doubt, it's always better to have your child evaluated.

Contact Your Healthcare Provider If Your Child Has:

• Fever persisting more than 3-5 days without clear explanation
• Fatigue that seems out of proportion to their illness
• Chest pain or discomfort, especially with breathing
• Palpitations or feeling that the heart is racing or skipping
• Decreased ability to exercise or play
• Swelling in the feet, ankles, or legs
• Persistent rapid breathing
• New symptoms developing after recent viral illness