Endocarditis / Эндокардит

Эндокардит
Endocarditis is an inflammation of the heart muscle, the endothelial lining of the heart, the heart
valves, or the connective tissue bed of the heart. This condition is commonly caused by infectious
agents such as bacteria or fungus (infective endocarditis [IE]).
Эпидемиология
IE is a relatively uncommon condition in the United States, with approximately 15 000 cases annually.
The incidence of IE worldwide is estimated at 2 to 10 cases per 100 000 patient-years
and accounts for 1 in 1000 hospital admissions. Untreated IE is fatal despite recent advances in
diagnosis and therapy.
Over the past several decades the incidence of IE has been stable, but the nature of this disease
has changed dramatically. IE was previously related to rheumatic heart disease and poor dental
hygiene. It is now more commonly found to be associated with structural heart disease and prosthetic
cardiac valves, nosocomial infections due to invasive medical procedures, IV drug abuse,
and previous episodes of IE, among others. IE is more common among men (2-3:1 male/female
ratio) and is associated with increasing age.
Патофизиология
IE is often associated with pre-existing valvular abnormalities. Congenital or acquired structural
damage of heart valves causes turbulent blood flow and ulceration of the valvular endothelium.
These endothelial ulcers accumulate thrombi to which the infectious agents adhere. Local inflammation
induces downstream inflammatory protein cascades that lead to the progressive
growth of infected valvular vegetations. In mature vegetations, bacteria often locate below the
surface, and thus become protected from antibiotics and phagocytes. The mitral valve is most
commonly infected (40%), with the aortic valve next (36%), and multivalvular involvement as
the third most common. The pulmonary valve is rarely involved.
Возбудитель
Many bacteria are causative agents of IE. Staphylococci and Streptococci are the most commonly
identified. For patients with native valves that are not IV drug users, Streptococcus viridans is
the most common agent, followed by Staphylococcus and Enterococcus. For IV drug users,
Staphylococcus is most common, followed by Streptococcus, and Enterococcus. Other, less
common microorganisms include HACEK organisms (Hemophilus, Actinobacillus, Cardiobacterium,
Eikenella, Kingella) and fungus. HACEK organisms tend to cause a subacute form of
the disease and can be difficult to isolate.
Диагностика
The diagnosis of IE depends on complete medical history with emphasis on past medical procedures,
previous IE, presence of structural heart disease, incidence of IV drug use, and other
known risk factors, followed by a physical examination of the heart, skin, eyes, dentition, neurologic areas, and sites of any recent medical procedures. New regurgitant heart murmurs occur in
85% of cases. Evidence of new CHF is a poor prognostic finding. Physical signs of small and
large emboli in the eye, conjunctivae, skin, and digits are common. Some classic manifestations
of IE include splinter hemorrhages (longitudinal dark red streaks under the nails), Janeway lesions
(irregular painless small nodes in palms and soles), Osler nodes (tender, larger nodes with
central pallor in hands and feet), and Roth spots (oval retinal hemorrhages with central pallor).
Laboratory studies include blood cultures (3 done within 1 hour, but from 3 separate sites), other
blood chemistry studies (polymerase chain reaction analyses), EKG, CXR, CT and/or MRI, and
echocardiography (transthoracic vs. transesophageal).
Comprehensive IE diagnosis is based on both microbiologic and endocardial involvement, as
well as other minor criteria, as shown in Table 48-1 (commonly known as Modified Duke Criteria).
Лечение
Successful management of IE to facilitate the best possible outcome for the patient involves the
use of a multidisciplinary approach that includes therapy with antimicrobial agents and surgery.
The use of such an approach is necessary since only 50% of all IE cases are successfully managed
with antibiotic therapy. Surgery is most clearly indicated in patients with life-threatening
CHF and/or cardiogenic shock.
Antimicrobial treatment is the first-line treatment for IE. Antibiotics should be selected based on
the isolated organisms. For patients with suspicion of IE in which no organism has yet been isolated,
empiric antibiotics are used. For stable patients with native endocarditis and no history of
IV drug use, penicillin and gentamicin is a good combination. If Staphylococcus is suspected,
such as in the case of IV drug users, nafcillin can be used instead of penicillin. For patients with
penicillin allergy, hemodynamic instability, or residence in communities with high prevalence of
MRSA, vancomycin is used instead of penicillin or nafcillin. Antifungals and/or ampicillin (for
HACEK organisms) may be used for patients that show no improvement despite adequate antibiotic
treatment.
Показания к хирургическому лечению
Strict indications for surgery on IE are not standardized. Widely accepted indications include:1
• Indications for emergent surgery
– Acute AI with early closure of the mitral valve
– Rupture into the pericardium or a heart chamber
• Indications for urgent surgery
– Heart failure with acute AI or MR
– Aortic or perivalvular abscess, aneurysm (as defined by echocardiography, usually TEE)
– Valve obstruction
– Conduction disturbances
– Ineffective antimicrobial therapy
– Unstable prosthetic valve
– Septal perforation
• Indications for elective surgery
– Progressive paravalvular prosthetic leak
– Persistent valve dysfunction and infection after 7 to10 days of appropriate treatment
– Fungal endocarditis