Prognosis depends on the infecting organism and the development of complications. Adverse sequelae generally begin within the first weeks after onset of the infectious process and can include glomerulonephritis due to glomerular trapping of antigen-antibody complexes, with http://ebooksmedicine.net
Fig. 11.20 Majorformsofvegetativeendocarditis.Theacuterheumaticfeverphaseofrheumaticheartdisease(RHD)ismarkedbytheappearanceofsmall,warty,inflammatoryvegetationsalongthelinesofvalveclosure;astheinflammationresolves,substantialscarringcanresult.Infectiveendocarditis(IE)ischaracterizedbylarge,irregular,oftendestructivemassesthatcanextendfromvalveleafletsontoadjacentstructures(e.g.,chordaeormyocardium).Non-bacterialthromboticendocarditis(NBTE)typicallymanifestswithsmall-tomedium-sized,bland,nondestructivevegetationsatthelineofvalveclosure.Libman-Sacksendocarditis(LSE)ischaracterizedbysmall-tomedium-sizedinflammatoryvegetationsthatcanbeattachedoneithersideofthevalveleaflets;thesehealwithscarring.
hematuria, albuminuria, or renal failure (Chapter 14). Clinical features of septicemia, arrhythmias (suggesting extension to underlying myocardium and conduction system), and systemic embolization bode ill for the patient. Left untreated, IE generally is fatal. However, with appropriate long-term (6 weeks or more) antibiotic therapy and/or valve replacement, mortality is reduced. For infections with low-virulence organisms (e.g., Streptococcus viridans or Streptococcus bovis), the cure rate is 98%, and for enterococci and Staphylococcus aureus infections, cure rates range from 60% to 90%; however, infections with aerobic gram-negative bacilli or fungi are associated with fatality rate of approximately 50%.
Nonbacterial thrombotic endocarditis (NBTE) is characterized by the deposition of sterile thrombi on cardiac valves, typically in those with an underlying hypercoagulable state. Although NBTE can occur in otherwise healthy individuals, a wide variety of diseases associated with general debility or wasting are associated with an increased risk for NBTE—hence the alternate term marantic endocarditis. In contrast to infective endocarditis, the sterile valvular lesions of NBTE are nondestructive (
Fig. 11.22
The vegetations in NBTE are typically small (1 to 5 mm in diameter) and valvular damage is not a prerequisite. Indeed, the condition usually occurs on previously normal valves. Rather, hypercoagulable states are the usual precursor to NBTE; such conditions include chronic disseminated intravascular coagulation, hyperestrogenic states, and those associated with underlying malignancy, particularly mucinous adenocarcinomas. This last association probably relates to the procoagulant effect of circulating mucin and/or tissue factor elaborated by these tumors. Endocardial trauma, such as from an indwelling catheter, also is a well-recognized predisposing condition.
Although the local effect on the valve usually is trivial, NBTE lesions can become clinically significant by giving rise to emboli that can cause infarcts in the brain, heart, and other organs. NBTE also can serve as a potential nidus for bacterial colonization and the consequent development of infective endocarditis.