What is Aortic Valve Endocarditis (Infective Endocarditis)?
Infective endocarditis happens when an infection takes hold on the inside lining of the heart’s valves. This can occur with natural heart valves, replacement heart valves, or even heart devices such as pacemakers or defibrillators. This condition is a global issue, and over the past few decades, there have been changes in both the types of patients it affects and the main cause of the infection.
In terms of the main cause, a bacteria named Staphylococcus aureus has become more common than Streptococcus, especially in developed regions. This is often associated with healthcare environments and invasive procedures. Patients affected now tend to be older and have more health issues, making the condition more severe. In addition, growing resistance to antibiotics is posing a global challenge to healthcare.
Despite medical advancements in diagnosis and treatment methods, the overall survival rates haven’t improved much. Among all types, an infection of the aortic valve is particularly serious and often leads to high rates of illness and death. In this article, we focus on this type of infective endocarditis.
To be clear, infections can occur in various parts of the heart, including the flaps of the valves or the places where artificial heart components have been implanted. Native valve endocarditis refers to infections of the natural parts of the heart, while prosthetic valve endocarditis refers to infections of replacement parts or other artificial heart components.
What Causes Aortic Valve Endocarditis (Infective Endocarditis)?
Infective endocarditis, an infection of the heart valves, can be influenced by whether the valve is natural or artificial. For artificial valves, the cause of the infection can depend on the timeframe – early phase (less than two months after implantation) or late phase (more than 12 months after implantation).
For natural valves, the most common culprits of the infection are bacteria called Streptococcus viridans and Staphylococcus aureus. For artificial valves during the early phase, the infection is normally caused by coagulase-negative staphylococci (such as Staphylococcus epidermidis) and Staphylococcus aureus. In the late phase, the same bacteria found in natural valves, Streptococcus viridans and Staphylococcus aureus, are usually the cause.
Enterococci bacteria can enter the bloodstream as a result of manipulations in the digestive or urinary tracts. Streptococcus bovis and Clostridium septicum are linked to colon cancer. The HACEK group of bacteria (including Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella) generally infect people with poor dental hygiene or drug users who use contaminated needles.
When infective endocarditis is caused by a fungus, it’s the most serious form of the condition. Those at risk include people with artificial heart valves, intravenous drug users, and individuals with weakened immune systems.
Risk Factors and Frequency for Aortic Valve Endocarditis (Infective Endocarditis)
Infective endocarditis is an infection that can get from your community or from exposure to healthcare environments. This disease shows different trends and patterns in different parts of the world. For example, in developing countries, the main risk factor is rheumatic heart disease, which affects younger patients. There, the infection is usually caused by community-acquired, penicillin-sensitive streptococci.
- In developed countries, risk factors are more diverse and include degenerative valve disease, cancer, intravenous drug use, diabetes, and congenital heart disease.
- The average age of patients in these countries is older than 70.
- Over the last 20 years, cases of infective endocarditis that were caught in healthcare settings and caused by Staphylococcal infection have increased. This increase is due to more use of invasive procedures, implanted cardiovascular electronic devices, long-term intravenous lines, small incision surgeries, and artificial heart valves.
- There has also been a rise in infective endocarditis cases after small-incision aortic valve surgery or non-surgical aortic valve replacement.
Signs and Symptoms of Aortic Valve Endocarditis (Infective Endocarditis)
If a person has aortic valve endocarditis, they may experience a range of symptoms and signs. These can include fevers, chills, difficulty breathing, shortness of breath when lying down (orthopnea), night sweats, fatigue, and weight loss. Other potential symptoms are related to issues with the heart and brain, like a mini-stroke (transient ischemic attack), stroke, heart attack, or heart failure symptoms. On a physical examination, a murmur suggestive of aortic insufficiency might be detected and symptoms of heart failure can be seen if the aortic valve isn’t functioning properly.
There can also be several other possible signs of this condition that reflect the impact on other organs. This can include vision loss, strength loss, and signs like splinter hemorrhages (tiny blood spots under the nails), Osler nodes (painful bumps on the hands or feet), Roth spots (spots on the retina), Janeway lesions (painless red spots on the palms or soles), organomegaly (enlarged organs), and blood in the urine (hematuria) if the kidneys are affected.
- Fevers and chills
- Difficulty breathing
- Shortness of breath when lying down (orthopnea)
- Night sweats
- Fatigue
- Weight loss
- Symptoms of heart and brain issues (like mini-strokes, strokes, heart attacks, or heart failure)
- An aortic insufficiency murmur detected during a physical examination
- Signs of heart failure if the aortic valve isn’t functioning properly
- Vision or strength loss
- Splinter hemorrhages, Osler nodes, Roth spots, and Janeway lesions
- Enlarged organs (organomegaly)
- Blood in the urine (hematuria) if kidneys are involved
Neurological symptoms such as confusion, delirium, paleness (pallor), tiredness (lethargy), irregular heartbeat (arrhythmia), and loss of appetite (anorexia) can also be present. In fact, about one-third of patients may show signs of neurological dysfunction due to an embolic stroke.
Testing for Aortic Valve Endocarditis (Infective Endocarditis)
The Modified Duke Criteria are used by doctors to assess patients suspected of having infective endocarditis. This is a disease that can cause inflammation and infection of the heart. The criteria split patients into three groups – definite infective endocarditis, possible infective endocarditis, or rejected infective endocarditis.
‘Definite infective endocarditis’ might be established using either pathological or clinical methods. Pathological verification involves identifying microorganisms through lab tests or finding active endocarditis in tissue samples. Clinical verification comes from meeting a certain number of major and minor criteria from the Modified Duke Criteria list.
The major clinical criteria include having multiple positive bacteria test results, new valve damage, or the presence of infection-related issues like vegetation (masses of bacteria), abscesses, or separation of valve tissues. The minor criteria include having a heart condition or a history of intravenous drug use, a high fever, evidence of infection in other parts of the body, immune system reactions, and positive bacteria tests that don’t fulfil the major criteria.
‘Possible infective endocarditis’ describes situations where there’s one major and one minor criterion present or if there are three minor criteria present. ‘Rejected infective endocarditis’ is used when other diseases are more likely, or there’s not enough evidence of infection, or symptoms improve quickly with treatment.
Remember that earlier antibiotics treatment can hide signs of infective endocarditis. Additionally, ultrasound testing can help diagnose endocarditis by showing things like abscesses, new heart valve issues, masses on a valve, or issues with artificial heart valves. If a patient shows signs of neurological issues, a head CT scan may be performed. Also, if an ECG shows new conduction blockages, this could mean a severe form of the disease.
Treatment Options for Aortic Valve Endocarditis (Infective Endocarditis)
The American Heart Association (AHA) updated their guidelines for treating infective endocarditis (a heart infection) in 2015. These guidelines suggested specific treatments for different types of the disease, depending on the bacteria strain causing the infection and whether the infection is occurring in a natural or artificial (prosthetic) heart valve.
Treatment methods, described in the AHA 2015 guidelines, can be quite complex, as they depend on factors like the causative bacteria, the bacteria’s susceptibility to antibiotics, and whether the infection is acute or chronic and involves a natural or prosthetic valve. Typically, for chronic infections of natural valves, the treatment is an IV drip of penicillin lasting up to 4 weeks, accompanied by a two-week course of gentamicin for particular types of bacteria.
However, the guidelines caution against using aminoglycosides (like gentamicin) for long periods due to possible kidney toxicity and had no impact on reducing death rates. The same caution goes for rifampin due to potential liver toxicity. However, if the bacteria responsable are sensitive to gentamicin, it might be added to the treatment plan. For artificial valve infections, a combination of vancomycin and aminoglycoside or rifampin is commonly used. For acute cases with a natural valve infection, the disease needs to be treated with either nafcillin (or cefazolin, if allergic to nafcillin) for certain types of bacteria, or with vancomycin for methicillin-resistant types.
When it comes to fungal infections, 5-fluorouracil and amphotericin are typically used, although surgery is often required. Additionally, interruption of anticoagulation might be reasonable for patients with an infected mechanical valve who have also had a central nervous system issue caused by clotting.
Surgery often becomes necessary if the infection is not responding to antibiotics. Surgery is recommended mostly for cases with severe symptoms, such as those causing heart failure, those resulting from extremely resistant bacteria, those causing heart conduction issues, or where there’s a persistent infection resistant to antibiotics. Several surgical options are available to treat aortic valve endocarditis, with the choice dependent on the surgeon’s experience and preference.
Over time, treatment plans for aortic valve endocarditis have evolved. Although aortic valves from donors were commonly used previously, such grafts often led to other problems, necessitating additional surgeries. Today, biological stentless valves are a common choice. These valves have a long shelf life and come in a variety of sizes, although some surgical skill is required to ensure the best outcomes. If the infection is limited to leaflets/cusps, a valve repair should be performed whenever possible. For an infection that has spread beyond the aortic root or has destroyed the annulus, the preferred method is reconstruction with a biological root or an allograft.
What else can Aortic Valve Endocarditis (Infective Endocarditis) be?
When it comes to diagnosing infective endocarditis (an infection of the heart’s inner lining), there are several other conditions that doctors might need to rule out. These include:
- Nonbacterial thrombotic endocarditis: This used to be called marantic endocarditis. It causes small, non-infectious growths on the valve leaflets of the heart. Conditions that can trigger it include certain types of cancer and states where blood clots more easily than it should.
- Libman–Sacks endocarditis: This causes rough, wart-like growths and is linked with systemic lupus erythematosus, which is an autoimmune disease where the body’s immune system attacks its own tissues and organs.
- Vasculitis: This is an inflammation of the blood vessels that can cause changes in the blood flow.
- Connective tissue disease: These are disorders featuring damage or inflammation in the tissues that hold the body together, like ligaments and tendons.
- Fever of unknown origin: This refers to a high body temperature for which doctors haven’t been able to find a cause after extensive testing.
Doctors need to carefully consider these other conditions and conduct thorough examinations to make an accurate diagnosis.
What to expect with Aortic Valve Endocarditis (Infective Endocarditis)
In-hospital death rates for a heart infection known as infective endocarditis are around 20%. Certain factors can increase the risk of death, such as old age, different types of bacteria and fungi causing the infection, severe other illnesses (like end-stage kidney disease requiring dialysis, artificial heart valve infection, severe heart failure, stroke, abscess, severe HIV caused immune system suppression, and infection spreading to the area around the heart valve or causing a heart muscle abscess).
A significant cause of illness and death in people with this type of heart infection is stroke, which is especially true when blood clots move to the brain. In a study of over a thousand patients with infective endocarditis on the left side of their heart, the occurrence of stroke in patients receiving the appropriate antibiotics was roughly five in a thousand patient days in the first week of treatment. This number dropped to roughly two in a thousand patient days in the second week of treatment. This suggests that starting antibiotics early can significantly lower the risk of stroke.
Possible Complications When Diagnosed with Aortic Valve Endocarditis (Infective Endocarditis)
Complications arising from aortic valve endocarditis can be harmful. These can range from congestive heart failure due to damage to the valve, annular abscess, and certain types of aneurysms which can lead to various heart conditions. Further problems can include blockages in the conduction system of the heart, neurological issues due to blood clots or aneurysms, and even the spread of the disease to other organs resulting in them getting damaged.
Here is the list of potential complications in simpler terms:
- Congestive heart failure due to damage to the valve
- Annular abscess
- Mycotic aneurysms leading to pericarditis (swelling of the outer lining of the heart), hemopericardium (blood in the outer lining of the heart), cardiac tamponade (a life-threatening situation when fluid builds up around the heart), or fistulas to the cardiac chambers
- Blockages in the heart’s conduction system
- Neurological complications due to blood clots or aneurysms
- Spread of the disease to other organs like the liver, kidneys, and spleen leading to damage
Preventing Aortic Valve Endocarditis (Infective Endocarditis)
Detecting and treating infective endocarditis promptly is crucial to ensure the best possible recovery. Patients should be informed about what to expect during their healing process, what could increase their risk of getting the condition, what symptoms to watch out for, and how the disease is treated. This knowledge can make a significant difference in managing infective endocarditis.
