DISEASES OF THE VEINS.
BY ANDREW H. SMITH, M.D.
The principal affections to which the veins are liable are the following: Inflammation (phlebitis), acute and chronic; Dilatation; Narrowing or obliteration; Degeneration; Concretions.
Inflammation.
Idiopathic phlebitis occurs for the most part under one of three conditions: First, as a simple primary inflammation of the tissues composing the walls of the vessel; second, as a participation in an inflamed or diseased condition of surrounding structures; third, as the result of the absorption of poisonous material into the blood.
Like any other structure of the body, the veins are liable to inflammation as a purely local affection. It is nevertheless true that, in the acute form, this inflammation is most likely to occur in connection with certain conditions of the system which seem to act as predisposing causes, although the connection between them and the local phlebitis is not apparent. Thus it occurs (perhaps associated with more or less of lymphangitis) in the puerperal state, in phthisis, in heart disease, and in other conditions of general depression. I have met with it, for example, during recovery from pneumonia after typhoid fever and after suffocative laryngitis. Under these circumstances it constitutes the chief element in the affection known as phlegmasia dolens. Now, none of the above conditions implies, so far as is known, any source of irritation to the venous structures, much less to a limited portion of the venous system; and the only explanation of their association with phlebitis seems to be in the assumption that these conditions favor coagulation of the blood, and that, in these cases, the formation of a clot precedes the local inflammatory process. The location of this clot is probably determined by anatomical conditions.
In other cases, however, the process evidently begins in the wall of the vessel, and the formation of the thrombus is secondary. Any change which interferes with the smoothness of the inner coat, whether by loss of endothelium or by producing inequalities of the surface, will very certainly determine the deposition of fibrin and the formation of a coagulum. The glossy smoothness of the intima seems to require the most perfect nutrition of the subjacent tissues for its maintenance, and its loss produces an immediate slowing and ultimate stoppage of the blood-current. This is admirably shown by the experiments of Nicasse,1 which demonstrate that simply denuding a portion of a vein, and thus cutting off its vascular and nervous supply, induces almost immediately the formation of a thrombus coextensive with the denuded portion.
1 Des Plaies et de la Ligature des Veinse, Thèse, Paris, 1872.