Heart failure cells or siderophages are hemosiderin-containing macrophages in the alveoli. The main causes are left heart failure and chronic pulmonary edema.
In left heart failure, the left ventricle can not keep pace with the incoming blood from the pulmonary veins. The resulting backup causes increased pressure on the alveolar capillaries, and red blood cells leak out. Alveolar macrophages ingest the red blood cells, and become engorged with brownish hemosiderin.
In pulmonary edema, alveolar septa get thick and fibrous, again increasing pressure on alveolar capillaries and resulting in leakage of red blood cells which undergo phagocytosis by alveolar macrophages.
Heart failure cells may cause brick-red sputum.
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