Ultrastructural findings in 350 endomyocardial biopsy specimens and 59
autopsy or explanted hearts from cardiac transplant recipients are re
viewed. Myocyte degeneration can be readily distinguished from necrosi
s by the technique described. Vascular changes of endothelial activati
on, endothelial cell damage, and basement membrane reduplication can b
e readily identified. In addition, the myofilament composition of isch
emic hearts in patients with allograft coronary artery disease is dist
inctive: There is a disproportionate loss of actin over myosin, giving
a coarse appearance to the myofilaments. These changes are useful in
further defining the morphologic features associated with rejection an
d ischemia in cardiac transplant recipients.