Page 460 - Textbook of Pathology, 6th Edition

444 chronic valvular deformities, while in older patients coronary endocarditis are small (1 to 4 mm in diameter), granular,
artery disease may be superimposed on old RHD. multiple and tend to occur on both surfaces of affected
2. Bacterial endocarditis of both acute and subacute type may valves, in the valve pockets and on the adjoining
supervene due to inadequate use of antibiotics. ventricular and atrial endocardium. The vegetations are
3. Embolism in RHD originates most commonly from mural sterile unless superimposed by bacterial endocarditis.
thrombi in the left atrium and its appendages, in association Unlike vegetations of RHD, the healed vegetations of
with mitral stenosis. The organs most frequently affected are Libman-Sacks endocarditis do not produce any significant
the brain, kidneys, spleen and lungs. valvular deformity. Frequently, fibrinous or serofibrinous
4. Sudden death may occur in RHD as a result of ball pericarditis with pericardial effusion is associated.
thrombus in the left atrium or due to acute coronary Microscopically, the verrucae of Libman-Sacks
insufficiency in association with aortic stenosis. endocarditis are composed of fibrinoid material with
superimposed fibrin and platelet thrombi. The endo-
NON-RHEUMATIC ENDOCARDITIS cardium underlying the verrucae shows characteristic
histological changes which include fibrinoid necrosis,
Inflammatory involvement of the endocardial layer of the proliferation of capillaries and infiltration by histiocytes,
heart is called endocarditis. Though in common usage, if not plasma cells, lymphocytes, neutrophils and the
specified endocarditis would mean inflammation of the pathognomonic haematoxylin bodies of Gross which are
valvular endocardium, several workers designate counterparts of LE cells of the blood. Similar inflammatory
endocarditis on the basis of anatomic area of the involved changes may be found in the interstitial connective tissue
endocardium such as: valvular for valvular endocardium, of the myocardium. The Aschoff bodies are never found
mural for inner lining of the lumina of cardiac chambers, in the endocardium or myocardium.
chordal for the endocardium of the chordae tendineae,
trabecular for the endocardium of trabeculae carneae, and
papillary for the endocardium covering the papillary muscles. NON-BACTERIAL THROMBOTIC
Endocarditis can be broadly grouped into non-infective and (CACHECTIC, MARANTIC) ENDOCARDITIS
infective types (Table 16.6). Most types of endocarditis are Non-bacterial thrombotic, cachectic, marantic or terminal
characterised by the presence of ‘vegetations’ or ‘verrucae’ endocarditis or endocarditis simplex is an involvement of
which have distinct features. the heart valves by sterile thrombotic vegetations.
SECTION III
ATYPICAL VERRUCOUS ETIOPATHOGENESIS. The exact pathogenesis of lesions
(LIBMAN-SACKS) ENDOCARDITIS in non-bacterial thrombotic endocarditis (NBTE) is not clear.
Vegetations are found at autopsy in 0.5 to 5% of cases. The
Libman and Sacks, two American physicians, described a following diseases and conditions are frequently associated
form of endocarditis in 1924 that is characterised by sterile with their presence:
endocardial vegetations which are distinguishable from the 1. In patients having hypercoagulable state from various
vegetations of RHD and bacterial endocarditis. etiologies e.g. advanced cancer (in 50% case of NBTE)
especially mucinous adenocarcinomas, chronic tuberculosis,
ETIOPATHOGENESIS. Atypical verrucous endocarditis is
one of the manifestations of ‘collagen diseases’. Charac- renal failure and chronic sepsis. In view of its association
with chronic debilitating and wasting diseases, alternate
teristic lesions of Libman-Sacks endocarditis are seen in 50% names for NBTE such as ‘cachectic’, ‘marantic’ and ‘terminal’
cases of acute systemic lupus erythematosus (SLE); other
Systemic Pathology
diseases associated with this form of endocarditis are endocarditis are used synonymously.
systemic sclerosis, thrombotic thrombocytopenic purpura 2. Occurrence of these lesions in young and well-nourished
(TTP) and other collagen diseases. patients is explained on the basis of alternative hypothesis such
as allergy, vitamin C deficiency, deep vein thrombosis, and
MORPHOLOGIC FEATURES. Grossly, characteristic endocardial trauma (e.g. due to catheter in pulmonary artery
vegetations occur most frequently on the mitral and and haemodynamic trauma to the valves).
tricuspid valves. The vegetations of atypical verrucous
MORPHOLOGIC FEATURES. Grossly, the verrucae of
NBTE are located on cardiac valves, chiefly mitral, and
 TABLE 16.6: Classification of Endocarditis. less often aortic and tricuspid valve. These verrucae are
usually small (1 to 5 mm in diameter), single or multiple,
A. NON-INFECTIVE
1. Rheumatic endocarditis (page 440) brownish and occur along the line of closure of the leaflets
2. Atypical verrucous (Libman-Sacks) endocarditis but are more friable than the vegetations of RHD.
3. Non-bacterial thrombotic (cachectic, marantic) endocarditis Organised and healed vegetations appear as fibrous
nodules. Normal age-related appearance of tag-like
B. INFECTIVE appendage at the margin of the valve cusps known as
1. Bacterial endocarditis ‘Lambl’s excrescences’ is an example of such healed
2. Other infective types (tuberculous, syphilitic, fungal, viral, lesions.
rickettsial)