Page 288 - Concise Pathology for Exam Preparation ( PDFDrive )

11 Disorders of the Heart 273

2. Infective
(a) Bacterial endocarditis
(b) Other infective types (tuberculous, syphilitic and fungal)

Atypical Verrucous (Libman–Sacks) Endocarditis
Pathogenesis
This type of endocarditis is characterized by formation of sterile vegetations in patients of
collagen vascular diseases (SLE, systemic sclerosis and thrombotic thrombocytopenic pur-
pura). These lesions are essentially composed of fibrinoid material thought to result from
activation of complement system and recruitment of Fc receptor bearing cells.

Gross Pathology
• Small (1–4 mm in diameter), single or multiple, granular-pink vegetations typically seen
in the mitral and tricuspid valves
• Both surfaces of affected valves, adjoining ventricular and atrial endocardium are involved.
• Healed lesions do not produce any significant valvular deformity.

Microscopy
• Verrucae composed of fibrinoid material (fibrin 1 platelet thrombi) are pathognomonic.
• Valves show areas of necrosis, proliferating capillaries, histiocytes, plasma cells, lympho-
cytes and neutrophils.

Nonbacterial Thrombotic/Cachectic/Marantic Endocarditis
Pathogenesis
Not clear; typically show presence of sterile thrombotic vegetations in association with:
(a) Chronic debilitating diseases, eg, cancers, particularly, mucin-secreting adenocarcino-
mas (which show increased blood coagulability or DIC due to the procoagulant effect
of mucin) and nonmucin-secreting malignancies, eg, promyelocytic leukaemia (pro-
myelocyte granules contain procoagulant substances)
(b) Hyperestrogenic states, severe burns or sepsis, which promote hypercoagulability
(c) Endocardial trauma due to an indwelling catheter
Gross Pathology
• Small (1–5 mm in diameter) single or multiple vegetations seen along the line of closure
of the leaflets
• More friable than vegetations of RHD
• Healed vegetations form fibrous nodules

Microscopy
Bland thrombi (platelets and inflammation) without accompanying inflammatory reaction
or bacteria
Complications
Embolization may result in infarcts in brain, lung, spleen and kidney.

Bacterial Endocarditis

Caused by invasion of heart valves or mural endocardium by a microbe. May be classified
into acute or subacute types depending on the virulence of the organism and cardiac status
of the patient.

(a) Acute bacterial endocarditis
(i) Destructive, necrotizing and ulcerative invasion by highly virulent bacteria
(ii) Usually affects normal valves
(iii) Death within days to weeks in 50% patients, despite antibiotics and surgery

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