Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually
involves the heart valves. Other structures that may be involved include the interventricular
septum, the chordae tendineae, the mural endocardium, or even the surfaces of intracardiac devices.
Endocarditis is characterized by a prototypic lesion, the vegetation, which is a mass of
platelets, fibrin, microcolonies of microorganisms, and scant inﬂammatory cells. In the subacute
form of infective endocarditis, the vegetation may also include a center of granulomatous
tissue, which may fibrose or calcify. There are multiple ways to classify endocarditis.
The simplest classification is based on etiology: either infective or non-infective, depending
on whether a microorganism is the source of the inflammation or not. Regardless, the diagnosis
of endocarditis is based on clinical features, investigations such as an echocardiogram,
and blood cultures demonstrating the presence of endocarditis-causing microorganisms.
Infective endocarditis
Since the valves of the heart do not receive any dedicated blood supply, defensive immune
mechanisms cannot directly reach the valves via the bloodstream. If an organism attaches
to a valve surface and forms a vegetation, the host immune response is blunted. The lack
of blood supply to the valves also has implications on treatment, since drugs also have difficulty
reaching the infected valve. Normally, blood flows smoothly past these
valves. If they have been damaged the risk of bacteria attachment is increased.
Rheumatic fever is common worldwide and responsible for many cases of damaged heart valves. Chronic
rheumatic heart disease is characterized by repeated inflammation with fibrinous resolution.
The cardinal anatomic changes of the valve include leaflet thickening, commissural fusion,
and shortening and thickening of the tendinous cords. The recurrence of rheumatic fever is
relatively common in the absence of maintenance of low dose antibiotics, especially during
the first three to five years after the first episode. Heart complications may be long-term
and severe, particularly if valves are involved. While rheumatic fever since the advent of
routine penicillin administration for Strep throat has become less common in developed
countries, in the older generation and in much of the less-developed world, valvular
disease from undertreated rheumatic fever continues to be a problem.
In an Indian hospital between 2004 and 2005, 4 of 24 endocarditis patients failed to demonstrate
classic vegetation. All had rheumatic heart disease and presented with prolonged fever.
All had severe eccentric mitral regurgitation. One had flail posterior mitral leaflet.
Non-infective endocarditis Nonbacterial thrombotic endocarditis, also
called marantic endocarditis is most commonly found on previously undamaged valves. As opposed
to infective endocarditis, the vegetations in NBTE are small, sterile, and tend to aggregate
along the edges of the valve or the cusps. Also unlike infective endocarditis, NBTE does
not cause an inflammation response from the body. NBTE usually occurs during a hypercoagulable
state such as system wide bacterial infection, or pregnancy, though it is also sometimes
seen in patients with venous catheters. NBTE may also occur in patients with cancers, particularly
mucinous adenocarcinoma where Trousseau syndrome can be encountered. Typically NBTE does not
cause many problems on its own, but parts of the vegetations may break off and embolize
to the heart or brain, or they may serve as a focus where bacteria can lodge, thus causing
infective endocarditis. Another form of sterile endocarditis, is termed
Libman-Sacks endocarditis; this form occurs more often in patients with lupus erythematosus
and is thought to be due to the deposition of immune complexes. Like NBTE, Libman-Sacks
endocarditis involves small vegetations, while infective endocarditis is composed of large
vegetations. These immune complexes precipitate an inflammation reaction, which helps to differentiate
it from NBTE. Also unlike NBTE, Libman-Sacks endocarditis does not seem to have a preferred
location of deposition and may form on the undersurfaces of the valves or even on the
endocardium. Diagnostics
Examination of suspected infective endocarditis includes a detailed examination of the patient,
and especially careful cardiac auscultation, various blood tests, ECG, cardiac ultrasound.
In the overall analysis of blood revealed the typical signs of inflammation. It is also
necessary to sow twice venous blood in order to identify the specific pathogen. Negative
blood cultures, however, does not exclude the diagnosis of infective endocarditis. The
decisive role played by echocardiography in the diagnosis, with which you can reliably
establish the presence of microbial vegetation, the degree of valvular and violations of the
pumping function of the heart. References
External links Endocarditis
Endocarditis, Embolic Stroke