Hea failure cells are

Rising pressure in the pulmonary veins is ultimately transmitted back to the capillaries and aeries of the lungs, resulting in congestion and edema as well as pleural effusion due to an increase in hydrostatic pressure in the venules of the visceral pleura. The lungs are heavy and boggy, and microscopically show perivascular and interstitial transudates, alveolar septal edema, and accumulation of edema fluid in the alveolar spaces. In addition, variable numbers of red cells extravasate from the leaky capillaries into alveolar spaces, where they are phagocytosed by macrophages The subsequent breakdown of red cells and hemoglobin leads to the appearance of hemosiderin-laden alveolar macrophages-- so-called hea failure cells--that reflect previous episodes of pulmonary edema. (Robbins Basic pathology,9th edition.pg no.367)