Have used lithium for 10+ years with constant edema of ankles. now have chronic venous deficiency. could lithium have caused this as long use.

Unlikely: Lithium causes problem with the balance of na and electrolytes through the kidney and , yes, can cause edema but mostly just electrolyte imbalances. I am not sure it can cause venous insufficiency on its own.

Lithium and veins: Endothelial cells have the key function of participating in the maintenance of open and functional capillaries. Dysfunction of the vascular endothelium is thus a hallmark of human diseases such as peripheral vascular disease (rajendran 2013) however lithium alters the disposition and release of norepinephrine and, as a result, affects adrenergic neurotransmission(beaty 1981) may impair venous flow.