CARDIAC OEDEMA:
It occurs in congestive heart failure. The venous pressure and consequently the capillaries pressure is raised. Oedema in the legs and feet occurs in those who habitually stands and walk over the sacrum in those who sit and the lower part of the back and buttocks in those who lie. The kidneys are involved and the secretion of sodium is diminished. An important factor causing oedema is the inability of the kidney to excrete sodium.
Oedema due to Lymphatic Obstruction is most characteristically,though not invariably seen in the arms after radial mastectomy as the surgeon has removed the lymph glands which drain the auxillary area. This type of oedema form also occurs in elephantiatis due to the filariasis caused by a tropical s.arasite which blocks  the lymphatics.