Dental operations
In the past, one in eight cases of infective endocarditis was because of bacteremia caused by dental procedures (in most cases due to Streptococcus viridans, which reside in the oral cavity), such as cleaning or extraction of a tooth. This was thought to be more clinically significant than it actually was. However, it is important that a dentist or a dental hygienist be told of any heart problems before commencing treatment. Antibiotics are administered to patients with certain heart conditions as a precaution, although this practice has changed in the US, with new American Heart Association guidelines released in 2007, and in the UK as of March 2008 due to new NICE guidelines. Everyday tooth brushing and flossing will similarly cause bacteremia, so a high standard of oral health should be adhered to at all times.Although there is little evidence to support antibiotic prophylaxis for dental treatment, the current American Heart Association guidelines are highly accepted by clinicians and patients. Pathogenesis
Damaged valves and endocardium contribute to the development of infective endocarditis. Specifically, the damaged part of a heart valve forms a local blood clot, a condition known as non-bacterial thrombotic endocarditis (NBTE). The platelet and fibrin deposits that form as part of the blood clotting process allow bacteria to take hold and form vegetations. As previously mentioned, the body has no direct methods of combating valvular vegetations because the valves do not have a dedicated blood supply.
This combination of damaged valves, bacterial growth, and lack of a strong immune response results in infective endocarditis.Damage to the valves and endocardium can be caused by:
Altered, turbulent blood flow. The areas that fibrose, clot, or roughen as a result of this altered flow are known as jet lesions. Altered blood flow is more likely in high pressure areas, so ventricular septal defects or patent ductus arteriosus can create more susceptibility than atrial septal defects. Catheters, electrodes, and other intracardiac prosthetic devices. Solid particles from repeated intravenous injections. Chronic inflammation. Examples include auto-immune mechanisms and degenerative valvular lesions.The risk factors for infective endocarditis provide a more extensive list of conditions that can damage the heart. Diagnosis
In general, the Duke criteria should be fulfilled in order to establish the diagnosis of endocarditis. Although the Duke criteria are widely used, they have significant limitations. For example, the sensitivity of the Duke criteria for detecting infective endocarditis decreases when prosthetic heart valves are present.As the Duke criteria rely heavily on the results of echocardiography, research has addressed when to order an echocardiogram by using signs and symptoms to predict occult endocarditis among people who inject drugs and among non drug-abusing patients. However, this research is over twenty years old and it is possible that changes in the epidemiology of endocarditis and bacteria such as staphylococci make the following estimates incorrect. The blood tests C reactive protein (CRP) and procalcitonin have not been found to be particularly useful in helping make or rule out the diagnosis.