The heart is almost always affected in
idiopathic (primary) hemochromatosis.
In addition cardiac iron deposits occur
in secondary hemochromatosis, which occurs, for example, in patients
who have received multiple blood transfusions for treatment of anemia.
The degree of involvement may be slight
and without evidence of gross changes, but often it is sufficient to
produce a brownish discoloration of the myocardium.
The deposits are more prominent in the
subendothelial than in the subepicardial zone.
Microscopically, hemosiderin granules are identified within myocardial fibers and
occasionally in the connective tissue cells.
In the myocytes, the iron is deposited
in sarcoplasmic siderin granules, which are distinct from lipofuscin
Varying degrees of degeneration, edema, and fibrosis of the
myocardium can be seen.
Electrocardiographic changes and even
cardiac failure may occur.
Arrhythmias may occur as a result of
iron deposits in the fibers of the conduction system.