The comparative pathology of primary endocardial fibroelastosis in burmese cats

Endocardial fibroelastosis in a Thoroughbred foal

“…In purebred Burmese kittens, lymphatic dilation was noted only in those less than age 50 days. As the disease progresses, the distended lymphatics may collapse due to disuse or compression, secondary to endocardial thickening (Zook et al 1981). This may account for the lack of lymphatic dilation seen in our case.…”

“…The secondary form of EFE is seen in association with the aforementioned cardiovascular problems, more specifically virus-induced myocarditis, carnitine deficiency (Wolfson et al 1990) and myocardiosis seen with certain glycogen storage diseases (Zook et al 1981) The left ventricle is characteristically affected in EFE. However, involvement of the right ventricle and both atria has been reported (Wolfson et al 1990).…”

“…The mode of inheritance, aetiology and pathogenesis of primary EFE remains unclear. Some suggested theories include hereditary carnitine deficiency (Hanukoglu et al 1986), hypoxia, obstruction of cardiac lymphatics, viral infection and mechanical stress secondary to chronic cardiac dilation (Zook et al 1981). It may also represent a nonspecific response to stress on the fetal myocardium in utero or during early postnatal life (Lurie 1988).…”

“…Alternatively, entrapment of the Purkinje fibres may not have been involved in the pathogenesis of the disease process in our case. Previous reports have hypothesised that the entrapped Purkinje fibres may undergo atrophy due to hypoxic damage or compression from the surrounding tissue (Zook et al 1981;Rozengurt 1994). In one case, involving the sudden death of a horse in association with primary EFE, fibroelastic tissue encompassed these modified cardiac fibres (Hughes and Howard 1984).…”

“…This may account for the lack of lymphatic dilation seen in our case. Entrapment of Purkinje fibres by fibroblasts within the deeper portions of the endocardium may be important as a prequel to sudden heart failure as the fibres begin to degenerate within the surrounding connective tissue (Zook et al 1981). This histological finding was not observed in our case, possibly reflecting the chronicity of the disease process.…”