The ultrastructural changes in atrial cardiac muscle cells of congenital heart disease have

so far

not been reported. This study was concerned with the ultrastructural alterations of right atrial myocardium resected at operation from 15 patients with congenital heart disease. Excepting a small amount of atrial cardiac muscle cells which Seem to be normal

the most muscle cells were hypertrophied and degenerated in all 15 patients. The hypertrophic atrial cardiac muscle cells showed cell diamelers>20m

hypertrophy of nuclei

dilatation of T tubules

mutiple intercalated discs and increase of mitochondria and myofibrils. But the atrial cardiac muscle cells with degeneration showed myofibrillar lysis

abnormal Z bands

mitochondrial swelling and extramembranous disruption

sarcoplasmic reticulum proliferation and dilatation

myelin figures formation and interstitial fibrosis These results suggested that the degree of hypertropy and degeneration of atrial cardiac muscle cells was related to the types

injuried size of congenital heart disease and the age

cardiac functional state of patients