Endocarditis is a relatively uncommon but very dangerous inflammation, usually caused by infection in vulnerable areas of the endocardium – the innermost layer of the heart’s chambers and valves.
There are several types of endocarditis, ranging from acute forms that appear suddenly to subacute types that develop gradually over time. The condition is usually caused by bacteria that enter the body by various means, such as cuts, minor surgeries and dental procedures.
In the vast majority of patients, endocarditis can be effectively treated with medication and/or surgery. Nevertheless, endocarditis can cause serious damage or even death if left untreated. Because of the dangerous nature of this condition, people at moderate and high risk for endocarditis (e.g., those with any type of valvular heart disease) are strongly advised to take antibiotics both before and immediately after any dental or medical procedure. This preventive action can help to kill any bacteria that enter the bloodstream as a result of the procedure, minimizing the risk of developing endocarditis.
About endocarditis
Endocarditis is a relatively uncommon, but potentially dangerous inflammation, usually caused by infection in vulnerable areas of the endocardium – the innermost layer of the heart’s chambers and valves. It can be caused by bacteria, fungi or other infectious agents. The most common form of endocarditis is caused by bacteria that are somehow introduced into the bloodstream, often from the mouth.
When intact, the endocardium is resistant to infection from these bacteria. However, injury or deformity of the endocardium can cause clots to form on the injured surface. These act as traps for microorganisms, which multiply rapidly at the site of the damage and go on to cause endocarditis. Endocarditis is rare in people with healthy hearts, and most commonly affects individuals who have valvular heart disease, congenital heart disease or a history of rheumatic fever.
There are several types of endocarditis, classified according to the severity of the condition and the underlying cause:
Acute bacterial endocarditis involves a rapid development of symptoms. If the infection is severe, there may be serious damage to the valves and a significant decline in health in only a few weeks.
Subacute bacterial endocarditis entails a more gradual onset of symptoms that could take several months to a year to develop. During that time, it can cause serious damage to heart valves. It typically is not accompanied by the dramatic symptoms seen in the acute form of the disease.
Fungal endocarditis can occur in people with previously damaged heart tissue and in people who have a very low resistance to infection, especially those who are taking drugs that suppress the immune system (e.g., people who have just received an artifical transplant, pacemaker or implantable cardioverter defibrillator). Both fungal and bacterial endocarditis are commonly seen in people with a history of illegal intravenous (I.V.) drug use, because non-sterile needles can introduce a host of microorganisms directly into the bloodstream.
Nonbacterial endocarditis can be caused by some cancers (rarely) and by some autoimmune disorders such as systemic lupus erythematosus.
If the endocarditis is bacterial, it is critical to identify the exact bacteria before treatment. Endocarditis is commonly caused by streptococcus, staphylococcus, pneumococcus or enterococci bacteria. The bacteria most often responsible for endocarditis are staphylococcus aureus. The presence of these virulent bacteria in the blood indicates an automatic screening for endocarditis.
Bacteria can enter the bloodstream through certain dental or medical procedures. An infection from something as simple as a skin cut can provide the opportunity for bacteria to enter the body. In addition, medical conditions such as a gum disease or an intestinal disorder can allow bacteria to enter the bloodstream as well.
Men are somewhat more likely to develop endocarditis than women. The condition is also more prevalent in older individuals. Compared with an overall rate of two per 100,000 people who acquire the condition, the rate for people over 60 can approach 30 per 100,000. This increase may be due to the fact that older Americans are more likely to have preexisting heart conditions such as rheumatic heart disease, mitral valve prolapse, degenerative heart disease or artificial heart valves – conditions that increase the risk of endocarditis. People who inject illegal drugs are at high risk for endocarditis, as are patients infected with HIV, have AIDS or other diseases that affect the immune system. Children are rarely affected by endocarditis.
One of the more serious complications of endocarditis is the development of vegetations within the heart or on the heart valves. Vegetations are clumps of trapped bacteria or fungi, platelets, fibrin strands and immune cells. If pieces of the vegetation break off and enter the bloodstream, they may lodge in a blood vessel(embolism). This blockage can prevent oxygen-rich blood from reaching the tissues on the other side of the blockage, which could be fatal. While 75 to 90 percent of patients properly diagnosed with endocarditis are successfully treated, endocarditis is likely to lead to death if left untreated. According to the American Heart Association, bacterial endocarditis was responsible for more than 2,300 deaths in 1999.
Signs and symptoms of endocarditis
The onset of symptoms from endocarditis varies with the type of disease and the cause of the infection. Individuals with endocarditis may experience the following symptoms:
Fever, which may be low grade, particularly with subacute endocarditis
Chills
Weight loss
Shortness of breath
Persistent cough
Night sweats
Headache
Arthritis, or joint pain
Back or chest pain
Dark red lines of bleeding under the nails (splinter hemorrhages)
Tiny, purplish-red pinpoint spots of bleeding under the skin (petechiae)
Painless bumpy nodules on the palms of the hands and soles of the feet
Tender spots under the skin on the pads of the fingers (Oster’s nodes)
Clinical signs that may be confirmed by a physician include the following:
A new heart murmur or change in the quality of an existing heart murmur
Embolisms, caused by clumps of infectious bacteria or fungi, and blood cells
Enlarged spleen
Stroke
Diagnosis methods for endocarditis
Diagnosing endocarditis is complicated by the condition’s large number of possible signs and symptoms. A physician may suspect endocarditis based on a patient’s medical history and physical symptoms upon examination. However, endocarditis may present the same symptoms as pneumonia, heart attack or many other conditions. Furthermore, because it can be caused by a variety of bacteria, which are difficult to isolate, many physicians begin their diagnosis by ruling out other causes. In general, if a constellation of symptoms is present and there is no other known infection or condition, a physician may narrow down the diagnosis to endocarditis.
The two most common tests to confirm this diagnosis are blood tests and echocardiogram. Blood tests or cultures are used to detect the presence of bacteria, identify the bacteria and determine which antibiotics they are sensitive to. A sample of blood will be placed in a culture bottle containing a nutrient broth that supports the growth of the type of bacteria that commonly causes endocarditis. If the endocarditis is acute, these samples will be taken over a period of an hour. If the endocarditis is subacute, the samples may be taken over a period of days and treatment may be delayed. The object is to culture and isolate the organisms so physicians can identify which organism is responsible for the infection.
It is not easy to capture the bacteria in a blood culture, and physicians have a better chance of doing so when people have a fever, which may happen when large numbers of bacteria enter the bloodstream. Other blood samples may be taken to detect the presence of anemia. In about 2 percent to 5 percent of cases of bacterial endocarditis, the blood cultures are negative. This is especially true among patients who have already been treated with antibiotics. Therefore, negative blood cultures do not necessarily rule out endocarditis, and depending on the other signs and symptoms present, the physician may go ahead and recommend medical therapy.
The blood culture is frequently followed by an echocardiogram, especially among patients at moderate to high risk of endocarditis. This painless, noninvasive test uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is displayed on a video screen, where a physician can study and measure various factors. These include the heart’s thickness, size, function and any buildup of vegetations (clumps of trapped bacteria or fungi layered with platelets, fibrin and immune cells) that may be present. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage (regurgitation), narrowing (stenosis) or damage caused by infection.
In some cases, the physician may need to do a minimally invasive transesophageal echocardiogram. During this test, a flexible transducer is placed down the throat and into the esophagus to create very clear images of the heart and valves without interference from the chest wall or lungs. The goal is to determine if the heart valves have been compromised by the infection.
Other tests that may be ordered during the initial screening might include an electrocardiogram, which measures the heart’s electrical rhythms, or a chest x-ray, which can reveal blood or fluid that has backed up into the lungs.
Treatment options for endocarditis
The treatment for patients diagnosed with endocarditis is intravenous (I.V.) antibiotic therapy. This use of antibiotics requires a significant dose for a long period of time – as long as six weeks, depending on the type of infectious agent causing the disease. It is important that the antibiotics used are the correct ones for the organism that is causing the infection.
Recently, some studies have shown that oral antibiotic therapy may work with certain patients. Oral therapy works if the exact bacterial cause of the endocarditis is known, if the bacteria are susceptible to antimicrobial therapy, and if there is some other reason to avoid I.V. therapy.
More and more frequently, surgery is also used to treat the damage to the heart valves caused by endocarditis. This is especially true:
For patients with heart failure that is related to the heart valves
In cases where repeated antibiotic therapy hasn’t worked
In cases where recurrent emboli (at least two) are present
The most common surgery associated with endocarditis is heart valve surgery repair or replacement.
Prevention methods for endocarditis
There are a number of preexisting conditions that increase a patient’s risk of endocarditis. These conditions include the following:
Heart murmurs, particularly when accompanied by regurgitation
A prior case of endocarditis
The presence of one or more artificial heart valves
Certain heart defects or heart diseases that are present since birth (e.g., patent ductus arteriosus, ventricular septal defect, coarctation of the aorta)
Any type of valvular heart disease (e.g., valvular stenosis, valvular regurgitation, mitral valve prolapse)
The presence of surgical shunts from the aorta to the pulmonary artery
Illegal intravenous (I.V.) drug use
A prior history of rheumatic fever
Excessive alcohol use
Infection with HIV, AIDS or other diseases that affect the immune system
Diabetic patients undergoing hemodialysis
Individuals who are at high risk for endocarditis are strongly advised to take antibiotics before any dental or medical procedure. This preventive action may help to protect patients from bacteria that could be introduced into the bloodstream. Patients should immediately alert all medical and dental professionals of their condition to be sure it is included in their medical records. The American Heart Association has an endocarditis wallet card that a person can carry in order to alert medical workers in the event of an emergency.
Some physicians have begun to recommend that some higher risk patients take antibiotics prior to undergoing tattooing or body piercing due to a possible link with endocarditis. While there is no clinical evidence that indicates endocarditis is caused by these activities, some physicians have reported seeing cases of endocarditis after body piercing and/or tattooing was performed.
In addition, individuals who are at risk for endocarditis should pay special attention to oral hygiene. Brushing and flossing on a regular basis can help prevent the build-up of bacteria in the mouth. Regular cleaning and check-ups by a dentist should also be a part of the preventive plan.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about endocarditis:
How can I tell if I am at risk for endocarditis?
What lifestyle factors might increase my chance of developing endocarditis?
What types of tests will be used to diagnose my condition?
How and when will these tests be performed?
What type of endocarditis do I have?
What are my treatment options for my endocarditis?
What type of antibiotics will I need to take and for how long?
What steps can I take to lessen the chances of developing endocarditis?
Are there any activities I should avoid?
What are some of the signs and symptoms of endocarditis that I need to be aware of?
Do I need to take antibiotics before visiting the dentist?
What types of antibiotics do I need to take? How long before I visit the dentist should I take them?
Are there any other circumstances when I should be taking antibiotics?
How will my condition be monitored throughout my life?
What is my risk of developing endocarditis in the future?
