Fungal endocarditis is a severe infection affecting the inner lining of the heart, known as the endocardium, or the heart valves. This condition occurs when fungi enter the bloodstream and attach to these delicate heart structures, causing inflammation and damage. While relatively uncommon, accounting for approximately 1% to 3% of all infective endocarditis cases, it represents a serious health challenge.
Causes and Risk Factors
Fungi are not typically found circulating in the bloodstream, but they can enter the body through various pathways, eventually traveling to the heart. Once there, they can adhere to and colonize the heart’s inner surfaces or valves, leading to infection. The most frequent fungal culprits include Candida species, responsible for over 50% of cases, and Aspergillus species, which account for about 25% of fungal endocarditis instances.
Several factors increase an individual’s susceptibility to this infection. Medical interventions significantly raise the risk, particularly the presence of prosthetic heart valves or pacemakers, which provide surfaces for fungi to attach. Central venous catheters and prolonged intravenous therapy also create entry points for fungi into the bloodstream.
Individuals with weakened immune systems are more vulnerable to fungal infections spreading to the heart. This includes patients undergoing chemotherapy, those with HIV/AIDS, or individuals receiving immunosuppressant drugs for conditions like organ transplants. Intravenous drug use is another significant risk factor, as it can introduce fungi directly into the bloodstream through contaminated needles or substances.
Identifying Symptoms
The signs of fungal endocarditis often begin subtly, presenting as general, flu-like symptoms that can be misleading. People may experience fever, chills, persistent fatigue, and aching in their muscles and joints. Night sweats and unexplained weight loss can also occur, making the initial diagnosis challenging.
As the infection progresses, more specific symptoms related to heart function may emerge. A new or changing heart murmur, which is an unusual sound heard during a heartbeat, is a common indication. Individuals might also experience shortness of breath, especially with exertion, and chest pain that worsens with breathing, reflecting the heart’s struggle to function effectively.
The Diagnostic Process
Confirming a diagnosis of fungal endocarditis requires specific medical investigations to identify the fungal pathogen and assess heart damage. Blood cultures are a primary diagnostic tool, where blood samples are grown in a laboratory to isolate and identify the specific fungus causing the infection. Persistently positive blood cultures can strongly suggest underlying endocarditis.
An echocardiogram, which uses sound waves to create images of the heart, is another important diagnostic procedure. This ultrasound of the heart allows medical professionals to visualize fungal growths, known as vegetations, on the heart valves or inner lining. Transthoracic echocardiography (TTE) is a non-invasive initial test, but a transesophageal echocardiogram (TEE), performed by inserting a probe down the esophagus, often provides clearer and more detailed images of the heart structures and vegetations.
Treatment Approaches
Treating fungal endocarditis is a complex process that involves a two-pronged approach due to the infection’s severity and fungal characteristics. The first line of defense involves administering long-term, high-dose intravenous antifungal medications. These powerful drugs, such as lipid formulations of amphotericin B or echinocandins for Candida infections, are delivered directly into the bloodstream to control the widespread infection throughout the body.
Antifungal medication alone is often insufficient to fully resolve the infection, especially because fungi can form resistant biofilms on heart valves. Therefore, surgical intervention is necessary to remove the source of the infection. This procedure involves debridement, where infected heart tissue and fungal vegetations are carefully removed.
During surgery, the damaged heart valve is often repaired or, more commonly, replaced with an artificial valve to restore proper heart function. This surgical removal of infected material and valve replacement is considered essential for improving patient outcomes and reducing mortality. The combination of aggressive antifungal therapy and surgical debridement aims to eliminate the infection and prevent further cardiac damage.
Prognosis and Complications
Despite aggressive and combined treatment with both antifungal medications and surgery, fungal endocarditis is associated with a high mortality rate, often exceeding 50% to 70%. This condition can cause severe complications.
One major complication is heart failure, which can result from extensive damage to the heart valves, impairing the heart’s ability to pump blood effectively. Fungal vegetations on the heart valves are prone to breaking off, leading to embolic events. These fragments can travel through the bloodstream and block blood flow to other organs, potentially causing a stroke if they reach the brain, or damaging kidneys, spleen, or limbs.
The infection can also spread beyond the heart, leading to sepsis. This severe condition can cause organ dysfunction and is a significant contributor to the poor prognosis.