Infective endocarditis is an infection that affects the inner lining of the heart, particularly the heart valves, as a result of certain types of bacteria or other microorganisms entering the bloodstream and settling in the heart. Its symptoms may initially be mild, such as fever, fatigue, and chills, but they can gradually worsen if the condition is not diagnosed and treated appropriately. Therefore, recognizing the symptoms, causes, and risk factors of infective endocarditis can help ensure early diagnosis and reduce the risk of serious complications.In this article on Dalili Medical, learn about the causes, symptoms, types, diagnostic methods, medical and surgical treatment options, and the most important ways to prevent infective endocarditis.

What is infective endocarditis?
Infective endocarditis is an infection of the inner lining of the heart, particularly the heart valves. It is most commonly caused by bacterial infections, although in some cases it may result from fungi or other microorganisms.

Is infective endocarditis dangerous?
Yes. Infective endocarditis can be a serious medical condition, especially if it is not diagnosed and treated promptly. It may cause damage to the heart valves, heart failure, or spread of the infection to other organs of the body.

How does infective endocarditis occur?
The infection occurs when microorganisms enter the bloodstream, travel to the heart, and become attached to one of the heart valves or damaged heart tissue. The risk may be higher in people with artificial heart valves or certain implanted cardiac devices.

Can infective endocarditis occur in a healthy heart valve?
Yes. Infective endocarditis can occur even in a previously healthy valve. However, previous heart valve damage or the presence of an artificial valve can increase the risk of infection.

Does having a fever alone mean that a person has infective endocarditis?
No. Fever is a common symptom with many possible causes and does not, by itself, indicate infective endocarditis. Diagnosis requires a comprehensive medical evaluation, which may include blood cultures and echocardiography when the condition is suspected.

Is infective endocarditis contagious?
No. Infective endocarditis is not usually transmitted from person to person like the common cold. It occurs when certain microorganisms enter the bloodstream and then reach the heart and become attached to a heart valve or cardiac tissue.

Does every heart patient need antibiotics before visiting the dentist?
No. Not all people with heart conditions need preventive antibiotics before dental procedures. Antibiotic prophylaxis is recommended for certain high-risk patients who are more likely to develop infective endocarditis and serious complications, depending on their medical condition and the type of dental procedure.

Can infective endocarditis recur after treatment?
Yes. A person can develop infective endocarditis again after recovery. Therefore, medical follow-up and appropriate preventive measures are important, particularly for people who have previously had infective endocarditis.

Can infective endocarditis be cured?
Yes. Infective endocarditis can often be successfully treated, particularly when it is diagnosed early and the appropriate treatment is started promptly. Some cases require surgery in addition to antibiotics to repair or replace the affected heart valve.

When should urgent medical attention be sought?
Urgent medical evaluation is recommended if concerning symptoms occur, such as persistent fever accompanied by shortness of breath, chest pain, fainting, significant deterioration in general health, or sudden neurological symptoms, particularly in people with an artificial heart valve, a previous history of infective endocarditis, or significant heart valve disease.

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Types of Infective Endocarditis

Infective endocarditis can be classified in several ways according to the speed at which the disease develops, the type of heart valve affected, the presence of an artificial valve or implanted cardiac device, and the source of infection.

1. Acute Infective Endocarditis

This type is characterized by symptoms that develop rapidly over a short period, and the condition may be severe from the beginning.

Key features include:

• High fever and chills.
• General weakness and fatigue.
• Rapid deterioration of heart valve function in some cases.
• A risk of serious complications if treatment is not started promptly.
• It may be caused by highly aggressive bacteria, particularly Staphylococcus aureus.

2. Subacute Infective Endocarditis

This type develops gradually over several weeks or months, so the symptoms may initially be mild or nonspecific.

Possible symptoms include:

• Mild or intermittent fever.
• Fatigue and weakness.
• Night sweats.
• Loss of appetite and weight loss.
• Muscle and joint pain.

It may occur more frequently in people with previously damaged heart valves or underlying heart disease, and some types of streptococcal bacteria can cause it.

3. Native Valve Endocarditis

Also known as Native Valve Endocarditis, this type affects one of the patient's original heart valves without the presence of an artificial valve.

It may affect the mitral valve, aortic valve, or other heart valves.

4. Prosthetic Valve Endocarditis

This type occurs in people who have an artificial heart valve or prosthetic material used to repair a heart valve.

It may be classified according to when the infection develops after valve replacement, including:

• Early prosthetic valve endocarditis, occurring relatively soon after valve replacement.
• Late prosthetic valve endocarditis, occurring after a longer period following valve replacement.

These cases require careful evaluation because the infection may involve the prosthetic valve itself or the surrounding tissues.

5. Cardiac Device-Related Endocarditis

Infection may occur in people who have certain implanted cardiac devices, such as:

• Pacemakers.
• Implantable cardioverter-defibrillators (ICDs).
• The leads connected to these devices.

In some cases, treatment may require removal of the infected device or leads in addition to antibiotic therapy.

6. Healthcare-Associated Infective Endocarditis

This type occurs in the context of exposure to healthcare, such as certain hospital stays, intravenous catheters, or medical procedures. The causative bacteria may differ from those responsible for community-acquired infections.

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Causes of Infective Endocarditis

Infective endocarditis is an infection of the inner lining of the heart, particularly the heart valves. It usually occurs when microorganisms, especially bacteria and sometimes fungi, enter the bloodstream and then become attached to a heart valve or an area of damaged cardiac tissue.

What Are the Main Causes of Infective Endocarditis?

1. Bacteria Entering the Bloodstream

The entry of microorganisms into the bloodstream is the main step preceding infection in most cases. Bacteria can enter the bloodstream from various sources, including:

• Dental and gum infections and certain dental procedures.
• Skin infections, wounds, or abscesses.
• Some urinary tract infections.
• Certain respiratory tract infections.
• Intravenous catheters, particularly when used for prolonged periods.
• Some surgical procedures and medical interventions.

Common microorganisms that can cause infective endocarditis include:

• Staphylococcus aureus.
• Various types of Streptococcus, including oral streptococci.
• Enterococcus.
• Other types of bacteria, as well as certain fungi in specific cases.

2. Previous Heart Valve Disease or Damage

The risk of infective endocarditis increases when a heart valve is abnormal or damaged because the affected valve surface may provide a suitable site for microorganisms to attach.

Conditions that may increase the risk include:

• Heart valve diseases.
• Valve stenosis.
• Valve regurgitation.
• Certain congenital heart conditions.
• A previous history of infective endocarditis.

3. Artificial Heart Valves or Prosthetic Material

The risk may be higher in people who have an artificial heart valve or prosthetic material used to repair a heart valve. Microorganisms can attach to these artificial surfaces and cause infection.

4. Intravenous Catheters and Medical Devices

Certain intravenous catheters, particularly those used for prolonged periods, can provide a pathway for bacteria to enter the bloodstream.

In some cases, infection may also be associated with implanted cardiac devices, such as pacemakers or implantable cardioverter-defibrillators (ICDs).

5. Certain Medical Procedures

Some medical procedures may allow microorganisms to enter the bloodstream. However, not every medical procedure causes infective endocarditis, and preventive antibiotics are not necessary for every patient.

The decision to use antibiotic prophylaxis depends on the patient’s level of risk and the type of procedure.

6. Conditions That Increase Susceptibility to Infection

The risk of infective endocarditis may be higher in some people with a weakened immune system or certain chronic medical conditions. However, having these risk factors does not necessarily mean that a person will develop the disease.

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Diagnosis of Infective Endocarditis

The diagnosis of infective endocarditis is based on a combination of clinical information and diagnostic tests. No single symptom or test is sufficient to confirm the diagnosis. Doctors combine the medical history and physical examination, blood cultures, cardiac imaging, laboratory tests, and additional investigations, together with established diagnostic criteria.

1. Medical History and Physical Examination

The doctor evaluates the patient’s symptoms and risk factors and may ask about:

• Fever, chills, and night sweats.
• Fatigue, loss of appetite, or weight loss.
• Shortness of breath or chest pain.
• Previous heart valve disease.
• The presence of an artificial heart valve.
• A previous history of infective endocarditis.
• Recent surgery or medical procedures.
• The presence of implanted cardiac devices.

During the physical examination, the doctor listens to the heart for a new heart murmur or a change in a previously existing murmur. The doctor may also look for certain skin or neurological findings that can be associated with the condition.

2. Blood Cultures

Blood cultures are among the most important tests for diagnosing infective endocarditis because they can help identify the microorganism responsible for the infection and guide the selection of the most appropriate antibiotic.

Several blood samples are usually collected before antibiotics are started, when the patient’s condition allows it. The samples are then analyzed in the laboratory to detect bacteria or fungi and determine their susceptibility to antibiotics.

3. Echocardiography

Cardiac imaging is one of the main diagnostic tools used to detect infection involving the heart valves.

A. Transthoracic Echocardiography (TTE)

This is often the initial echocardiographic examination. It can help detect:

• Vegetations on the heart valves.
• Valve regurgitation or impaired valve function.
• Valve damage or perforation.
• Certain complications around the heart valve.

B. Transesophageal Echocardiography (TEE/TOE)

This technique provides more detailed images of the heart valves and surrounding tissues. It may be particularly important when:

• There is a strong suspicion of infective endocarditis despite an inconclusive TTE.
• The patient has a prosthetic heart valve.
• An abscess or other complication around the valve is suspected.
• A more detailed assessment of the heart valves is required.

4. Blood Tests and Other Laboratory Investigations

Laboratory tests may reveal changes that support the suspicion of infection or inflammation, such as:

• Increased inflammatory markers, including CRP and ESR.
• Increased or decreased white blood cell count.
• Anemia.
• Changes in kidney function.
• Certain abnormalities in urinalysis when the kidneys are affected.

However, these tests cannot confirm infective endocarditis on their own.

5. Additional Imaging Tests

Additional investigations may be needed when the initial tests are inconclusive or when complications are suspected. These may include:

• Computed tomography (CT) scans.
• PET/CT in selected cases, particularly in patients with prosthetic heart valves or implanted cardiac devices.
• Brain or other organ imaging when symptoms suggest that complications of the infection may have spread to other organs.

6. Diagnostic Criteria for Infective Endocarditis

Doctors use the updated Duke diagnostic criteria (Duke Criteria) to help establish the diagnosis. These criteria combine clinical, microbiological, and imaging findings.

Major Criteria Include:

• Positive blood cultures for microorganisms associated with infective endocarditis.
• Evidence of heart valve or surrounding tissue involvement on cardiac imaging.
• Certain other microbiological findings that support the presence of infection.

Minor Criteria Include:

• Predisposing conditions or risk factors for infective endocarditis.
• Fever.
• Certain vascular or embolic complications.
• Certain immunological manifestations.
• Microbiological evidence that does not meet the requirements for a major criterion. 

Symptoms of Infective Endocarditis

Infective endocarditis is an infection of the inner lining of the heart, particularly the heart valves. Symptoms can vary from one person to another. They may develop suddenly over several days in acute cases or gradually over weeks or months in less acute cases.

Most Common Symptoms

1. Fever
Fever is one of the most common symptoms of infective endocarditis. It may be persistent or intermittent and may be accompanied by chills or shivering.

2. Night Sweats
The patient may experience noticeable sweating during the night, sometimes accompanied by an elevated body temperature.

3. Fatigue and Exhaustion
Persistent weakness, fatigue, and reduced ability to perform normal daily activities may occur.

4. Loss of Appetite and Weight Loss
Appetite may gradually decrease, which can lead to unexplained weight loss.

5. Muscle and Joint Pain
The patient may experience generalized muscle aches or pain in certain joints.

6. Headache and General Malaise
Headaches or a general feeling of illness and discomfort may occur.

7. Shortness of Breath
Shortness of breath may develop when the infection affects the function of a heart valve, causing abnormal blood flow or heart failure.

8. Chest Pain or Heart Palpitations
Chest pain or a sensation of rapid or irregular heartbeats may occur, although these symptoms are not present in every patient.

9. Swelling of the Legs or Feet
Swelling may occur because of impaired heart function, particularly when the infection leads to heart failure.

Signs of Endocarditis on the Skin and Nails

Some skin and nail findings may occur, including:

• Small red or purple spots on the skin or inside the mouth.
• Minor bleeding under the nails.
• Small, painful lumps on the tips of the fingers or toes.
• Painless spots that may appear on the palms of the hands or soles of the feet.

These findings alone do not confirm infective endocarditis, as they can also occur with other medical conditions. Therefore, they should not be used by themselves to establish a diagnosis.

Symptoms That May Indicate Complications

In some cases, pieces of infected material from the heart valve may travel through the bloodstream to other organs, causing different symptoms, such as:

• Sudden weakness or numbness on one side of the body or difficulty speaking if the brain is affected.
• Abdominal or flank pain if certain internal organs are affected.
• Changes in urine or swelling due to kidney involvement.
• Severe shortness of breath or sudden deterioration due to severe impairment of heart valve function.

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Treatment of Infective Endocarditis with Medication and Surgery

Treatment of infective endocarditis depends on the type of microorganism causing the infection, the affected valve, the severity of the disease, and whether the valve is native or prosthetic. Treatment requires specialized medical supervision and often begins in a hospital because the choice and duration of antibiotic therapy depend on blood cultures and antimicrobial susceptibility testing.

First: Medical Treatment of Infective Endocarditis

Antibiotic therapy is the main treatment for most cases of infective endocarditis. The medications are selected according to the causative microorganism and its susceptibility to antibiotics.

Examples of antibiotics that doctors may use include:

• Methicillin-susceptible Staphylococcus aureus (MSSA): Oxacillin or nafcillin may be used, or cefazolin in some cases.
• Methicillin-resistant Staphylococcus aureus (MRSA): Vancomycin or daptomycin may be used depending on the patient's condition.
• Antibiotic-susceptible streptococci: Penicillin G or ceftriaxone may be used depending on culture and susceptibility results.
• Enterococcus: Ampicillin combined with another appropriate medication may be used, or a vancomycin-based regimen in some cases of drug allergy.
• Prosthetic valve endocarditis: This often requires a more complex treatment regimen and a longer duration of therapy, depending on the microorganism and the affected valve.

Treatment usually lasts for several weeks and may require intravenous antibiotics, along with monitoring of kidney and liver function, blood counts, and the patient's response to treatment.

Important: Antibiotics should not be taken or dosed without medical supervision. An inappropriate antibiotic choice can lead to treatment failure or antibiotic resistance.

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Second: Surgical Treatment of Infective Endocarditis

Not all patients require surgery. However, surgery may become necessary when the infection causes severe heart valve damage, heart failure, uncontrolled infection, or a high risk of complications.

Main Indications for Surgery

1. Heart Failure

Surgery may be necessary when the infection causes severe damage to a heart valve, such as:

• Severe acute valve regurgitation.
• Valve obstruction.
• Signs of heart failure.
• Pulmonary edema or cardiogenic shock in severe cases.

In some high-risk situations, surgery may be emergency surgery.

2. Uncontrolled Infection

Surgery may be required if the infection persists despite appropriate antibiotic treatment or if complications develop, such as:

• Persistent bacteria in the bloodstream.
• Formation of an abscess around the valve.
• Extension of the infection into tissues surrounding the valve.
• Formation of a fistula or pseudoaneurysm.
• Infection caused by microorganisms that are difficult to eradicate, such as certain fungi.

3. Reducing the Risk of Embolic Complications

Infected masses on the heart valve, known as vegetations, may break off and travel through the bloodstream to other organs. Therefore, surgery may be considered in some patients with large or highly mobile vegetations, particularly when there is a high risk of embolic complications.

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Surgical Procedures Used

1. Heart Valve Repair

When the valve can be preserved, the surgeon may:

• Remove infected tissue.
• Clean the infected area.
• Repair the damaged parts of the valve.

Repairing the patient's natural valve is preferred when it is feasible and safe.

2. Heart Valve Replacement

If the valve is severely damaged and cannot be repaired, the infected valve is removed and replaced with an appropriate prosthetic valve.

The cardiac team determines the most suitable type of valve based on the patient's age, health status, and other factors.

3. Removal of Abscesses and Infected Tissue

When the infection extends into the area surrounding the valve, surgery may be required to remove the infected tissue and abscess, followed by reconstruction of the affected area and repair or replacement of the valve, depending on the extent of damage.

4. Prosthetic Valve Surgery

When a prosthetic valve becomes infected, it may be necessary to remove the infected valve, clean the surrounding area, reconstruct damaged tissues, and implant a new valve when needed.

5. Removal of Infected Cardiac Devices

If the infection is associated with an implanted cardiac device, such as a pacemaker or implantable cardioverter-defibrillator (ICD), removal of the infected device and leads may be necessary. The medical team then determines whether and when the device should be reimplanted after the infection has been controlled.

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Timing of Surgery

The timing of surgery varies from one patient to another:

• Emergency surgery: Performed very urgently in certain cases of heart failure or severe cardiac complications.
• Urgent surgery: Performed within a short period when the infection is uncontrolled or the risk of complications is high.
• Delayed surgery: May be postponed in some stable patients to allow antibiotic treatment to take effect first, provided there is no urgent indication for intervention.

Can Surgery Replace Antibiotic Treatment?

No. In many cases, treatment consists of appropriate antibiotics combined with surgery when indicated. The final treatment plan is determined based on the microorganism, the location of the infection, the condition of the heart valve, and the presence of heart failure, abscesses, or other complications.

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Prevention of Infective Endocarditis

Prevention of infective endocarditis focuses on reducing the chances of bacteria or other microorganisms entering the bloodstream, maintaining good oral and skin health, and following medical recommendations for people at increased risk. It is important to understand that preventive antibiotics are not recommended for everyone and are reserved for certain high-risk individuals and specific situations.

1. Maintaining Good Oral and Dental Health

Good dental and gum care is one of the important ways to reduce the risk of infection. Recommendations include:

• Brush the teeth regularly with an appropriate toothbrush and toothpaste.
• Clean between the teeth using an appropriate method.
• Have regular dental checkups.
• Treat tooth decay and gum infections promptly.
• Pay attention to unusual gum pain, swelling, or bleeding.
• Tell your dentist if you have a prosthetic heart valve, a previous history of infective endocarditis, or another high-risk heart condition.

The goal is to maintain good oral health and reduce infections that may allow bacteria to enter the bloodstream.

2. Preventive Antibiotics Before Certain Dental Procedures

Not everyone needs to take antibiotics before visiting the dentist.

Antibiotic prophylaxis may be recommended for people at the highest risk of serious complications from infective endocarditis, before certain dental procedures involving manipulation of the gum tissue or the area around the tooth root.

People who may benefit from antibiotic prophylaxis include:

• People with a prosthetic heart valve or prosthetic material used for valve repair.
• People with a previous history of infective endocarditis.
• Some patients with certain congenital heart conditions.
• Some heart transplant recipients who have a particular heart valve problem.

The doctor determines the appropriate antibiotic, dose, and timing based on the patient's condition, medical history, and drug allergies.

3. Taking Care of the Skin and Wounds

Wounds or skin infections can provide an entry point for bacteria into the bloodstream. Therefore:

• Clean cuts and wounds properly.
• Keep open wounds covered when necessary.
• Do not squeeze or manipulate boils or abscesses.
• Seek medical attention if signs of infection appear, such as redness, swelling, pain, or discharge.
• Maintain good skin hygiene.

4. Avoiding Tattoos and Body Piercing in High-Risk Individuals

Tattooing and body piercing may increase the risk of infection. Therefore, people at increased risk of infective endocarditis are generally advised to avoid these procedures whenever possible, particularly when adequate hygiene and sterilization cannot be guaranteed.

5. Treating Infections Properly

Bacterial, skin, and other infections should be treated appropriately, particularly in people who have risk factors for infective endocarditis.

Antibiotics should not be used without medical advice because the appropriate antibiotic depends on the type of infection and the patient's condition.

6. Proper Care of Catheters and Medical Devices

When a person has an intravenous catheter or an implanted medical device, they should:

• Keep the catheter site clean.
• Watch for redness, pain, swelling, or discharge.
• Inform the healthcare team promptly if signs of infection appear.
• Avoid removing or handling the catheter without guidance from the healthcare team.

7. Medical Follow-Up for People with Heart Conditions

People at increased risk, including those with:

• A prosthetic heart valve.
• Significant heart valve disease.
• A previous history of infective endocarditis.
• Certain types of congenital heart disease.

should understand their condition and level of risk and should inform their cardiologist and dentist before undergoing any medical or dental procedure.