Thickening of the endocardium is sometimes observed in rats and other animals as a spontaneous or experimentally induced lesion. However, its nature, pathogenesis, and significance are not well understood.
In this study, 480 Sprague-Dawley CD outbred albino rats between the ages of 6 and 25 months were examined grossly and microscopically. Endocardial thickening was observed in six cases. It was diffuse and was caused by proliforation of fibroblast-like cells, most frequently involving the left ventricle.
Endocardial thickening in Sprague-Dawley rats appears to be primarily due to endomyocardial fibrosis. It may represent repair of damage to subendocardial myocardium occurring spontaneously or as a consequence of exposure to chemicals or other agents.
References
1.
1. Wegelius O, Von Essen R: Endocardial fibroelastosis in dogs. Acta Pathol Mierobiol Scand77:66–72, 1969.
2.
2. St Geme Jr JW, Davis CWC, Noren GR: An overview of primary endocardial fibroelastosis and chronic viral cardiomyopathy. Perspect Biol Med17:495–505, 1974.
3.
3. Davies JNP: The heart of Africa. Lab Invest10:205–215, 1961.
4.
4. Bohn FK, Buchanan JW, Kelly DF: The pathologic diagnosis of endocardial fibroelastosis and pulmonary disease in a rat. JAVMA157:1360–1377, 1970.
5.
5. Eliot Jr TS, Eliot FP, Lushbaugh CC, Slager UT: First report of the occurrence of neonatal endocardial fibroelastosis in cats and dogs. JAVMA133:271–274, 1958.
6.
6. Coelho E, Pimentel JC: Diffuse endomyocardial fibrosis. Am J Med35:569–576, 1963.
7.
7. Prior JT, Wyatt TC: Endocardial fibroelastosis: A study of eight cases. Am J Pathol26:969–977, 1950.
8.
8. Black-Schaffer, B, Grinstead CE, Braunstein JN: Endocardial fibroelastosis of large mammals. Circ Res16:383–390, 1965.
9.
9. Davies JNP, Coles RM: Some considerations regarding obscure diseases affecting the mural endocardium. Am Heart J59:600–631, 1960.
10.
10. Sigler FW: Diffuse chronic mitral endocarditis and focal mural endocardial fibroelastosis in dogs given an antihypertensive for one year: presented at a meeting of the Industrial Pathologists Discussion Group, May 12, 1971.
11.
11. Chesney CF, Allen JR: Endocardial fibrosis associated with monocrotaline-induced pulmonary hypertension in non-human primates (Macaca artoides). Am J Vet Res34:1577–1581, 1973.
12.
12. Boorman GA, Zurcher C, Hollander CF, Feron VJ: Naturally occurring endocardial disease in the rat. Arch Pathol96:39–45, 1973.
13.
13. Robbins SL, Cotran R: Pathologic Basis of Disease. 2nd edition, W. B. Saunders Company, Philadelphia, 1979, p. 699.
14.
14. Krahwinkel Jr DJ, Coogan PS: Endocardial Fibroelastosis in a great dane pup. JAVMA159:327–331, 1971.
15.
15. Jubb KVF, Kennedy PC: Pathology of Domestic Animals, Academic Press, New York, 1970, p. 105.
16.
16. Miller AJ, Pick R, Katz LN: Ventricular endomyocardial pathology produced by chronic cardiac lymphatic obstruction in the dog. Circ Res8:941–947, 1960.
17.
17. Miller AJ, Pick R, Katz LN: Ventricular endomyocardial changes after impairment of cardiac lymph flow in dogs. Br Heart J25:182–190, 1963.
18.
18. Selye H: Experimental production of endomyocardial fibrosis. Lancet1:1351–1353, 1958.
19.
19. St Geme Jr JW, Peralta H, Farias E, Davis CWC: Experimental gestational mumps virus infection and endocardial fibroelastosis. Pediatrics48:821–828, 1971.
20.
20. Zoltowska A: Studies on the etiopathogenesis of cardiomyopathy with endocardial fibroelastosis. Histological changes in the heart of animals, induced by immunization with heart tissue homogenate and diptheria-tetanus-pertussis vaccine. Acta Biol Med14:693–707, 1969.
21.
21. Paasch LH, Zook BC: The pathogenesis of endocardial fibroelastosis in Burmese cats. Lab Invest42:197–204, 1980.
22.
22. Kline IK, Miller AJ, Pick R, Katz LN: The relationship between human endocardial fibroelastosis and obstruction of the cardiac lymphatics. Circ30:728–735, 1964.
23.
23. Ivankovic S: Tumors of the heart in Pathology of Tumours in Laboratory Animals. Volume 1, part 2. International Agency for Research on Cancer, Lyon, 1976, pp. 313–315.
