Heart failure cells are -
Heart failure cells (siderophages) are hemosiderin containing macrophages in alveoli that are seen in left ventricular failure and denote previous episodes of pulmonary edema.

Left-sided heart failure

The major morphological and clinical effects of LVF are due to increased back pressure in the pulmonary circulation and the consequences of diminished peripheral blood pressure and flow,
The extracardiac organs involved commonly are -

1. Lung (most common)
2. Kidney
3. Brain
Lung

The pressure in the pulmonary veins increases and transmitted retrogradely to capillaries and arteries,
This results in pulmonary congestion and pulmonary-oedema → Wet lung.
There is perivascular and interstitial translate, particularly in the interlobular septa → responsible for Kerley's B lines on X-rays.
Edematous fluid accumulates in alveoli.
Iron-containing proteins and hemoglobin leak out from the capillaries and are phagocytosed by macrophages and converted to hemosiderin.
Hemosiderin - containing macrophages in the alveoli (called siderophages, or heart failure cells) denote previous episodes of pulmonary edema.
The clinical manifestations of LVF are primarily due to these changes in lungs —> Dyspnea, orthopnea, paroxysmal nocturnal dyspnea.

Kidney

Decreased cardiac output causes a reduction in renal perfusion.
If it is severe enough to impair the excretion of nitrogenous product (BUN, Creatinine), Prerenal ARF (Prerenal azotemia) may be precipitated.

Brain

Reduced perfusion to the brain may cause hypoxic/ischemic encephalopathy.
Lipofuscin granules in cardiac cells
Pigmented alveolar macrophages
Pigmented pancreatic acinar cells
Pigment cells seen in liver