Page 472 - Textbook of Pathology, 6th Edition

456 lesions such as anomalous coronary arteries, metabolic IV) LÖEFFLER’S ENDOCARDITIS. Also known by the
derangements influencing myocardial function etc. more descriptive term of ‘fibroplastic parietal endocarditis
b) It may occur due to haemodynamic pressure overload such with peripheral blood eosinophilia’, the condition is
as in congenital septal defects and coarctation of the aorta. considered by some as a variant of the entity described above,
c) It may be an expression of genetic disorder as noticed in endomyocardial fibrosis. However, it differs from the latter
twins, triplets and siblings. Association of endocardial in following respects:
fibroelastosis with various congenital malformations in the a) There is generally a peripheral blood eosinophilic
heart or elsewhere further supports the genetic theory. leucocytosis.
d) Some workers consider this disease a form of connective b) The inflammatory infiltrate in the endocardium and in
tissue disorder. the part of affected myocardium chiefly consists of
e) Certain factors causing myocardial injury may initiate the eosinophils.
endocardial disease such as in thiamine deficiency (beri-beri c) The condition has a worse prognosis.
heart disease) or from preceding idiopathic myocarditis. V) OTHER FORMS OF RESTRICTIVE CARDIOMYO-
f) Lymphatic obstruction of the heart has been suggested by PATHY. Besides above, restrictive cardiomyopathy may
some as the causative mechanism.
result from various diverse causes as under:
MORPHOLOGIC FEATURES. Grossly, the characteristic i) Haemochromatosis due to iron overload from multiple
feature is the diffuse or patchy, rigid, pearly-white transfusions, haemoglobinopathies.
thickening of the mural endocardium (Fig. 16.33,C). Left ii) Myocardial sarcoidosis.
ventricle is predominantly involved, followed in iii) Carcinoid syndrome.
decreasing frequency by the left atrium, right ventricle iv) Scleroderma.
and right atrium. Quite often, the valves, especially of the v) Neoplastic infiltration in the heart.
left heart, are affected. Some cases contain mural thrombi.
Enlargement of the heart is present and is mainly due to B. SECONDARY CARDIOMYOPATHY
left ventricular hypertrophy but the volume of the This is a group of myocardial diseases of known etiologies
chamber is decreased. or having clinical associations. This, however, excludes well-
Microscopically, the typical finding is the proliferation defined entities such as ischaemic, hypertensive, valvular,
of the collagen and elastic tissue (fibroelastosis) pericardial, congenital and inflammatory involvements of the
SECTION III
comprising the thickened endocardium. The fibroelastosis heart. The main entities included in this group are described
generally does not extend into the subjacent myocardium. elsewhere in the text and are listed below:
The lesion is devoid of inflammatory cells.
1. Nutritional disorders e.g. chronic alcoholism, thiamine
III) ENDOMYOCARDIAL FIBROSIS. This form of deficiency causing beri-beri heart disease (Chapter 9).
restrictive cardiomyopathy is a tropical condition prevalent 2. Toxic chemicals e.g. cobalt, arsenic, lithium and
in Africa, especially in Uganda and Nigeria, but some cases hydrocarbons.
occur in South India, Sri Lanka, Malaysia and tropical South 3. Drugs e.g. cyclophosphamide, adriamycin, cate-
America. It is seen in children and young adults. The clinical cholamines.
manifestations consist of congestive heart failure of unknown 4. Metabolic diseases e.g. amyloidosis, haemochromatosis,
cause just as in adult variety of endocardial fibroelastosis. glycogen storage diseases, hypo-and hyperthyroidism, hypo-
The etiology of the condition remains obscure but the and hyperkalaemia.
Systemic Pathology
geographic distribution suggests the role of certain factors 5. Neuromuscular diseases e.g. Friedreich’s ataxia, muscular
like malnutrition, viral infections and heavy consumption dystrophies.
of banana (rich in serotonin). 6. Infiltrations e.g. from leukaemia and carcinoma.
7. Connective tissue diseases e.g. rheumatoid arthritis, syste-
MORPHOLOGIC FEATURES. Grossly, endomyocardial mic sclerosis, dermatomyositis, lupus erythematosus.
fibrosis is characterised by fibrous scarring of the ventri-
cular endocardium that extends to involve the inner third
of the myocardium. The atrioventricular valve leaflets are PERICARDIAL DISEASE
often affected but the semilunar valves are uninvolved.
Mural thrombi may be present. The heart may be normal- Diseases of the pericardium are usually secondary to, or
sized or hypertrophied but the volume of the affected associated with, other cardiac and systemic diseases. They
chambers is diminished due to fibrous scarring. are broadly of 2 types:
Microscopically, the endocardium and parts of inner third I. Pericardial fluid accumulations
of the myocardium show destruction of normal tissue and II. Pericarditis
replacement by fibrous tissue. The condition differs from
endocardial fibroelastosis in having mononuclear PERICARDIAL FLUID ACCUMULATIONS
inflammatory cell infiltrate and lacking in elastic tissue. Accumulation of fluid in the pericardial sac may be watery
The superficial layer may show dense hyalinised or pure blood. Accordingly, it is of 2 types: hydropericardium
connective tissue and even calcification. (pericardial effusion) and haemopericardium.