MORBID ANATOMY OF VEINS.
Veins are subject to a variety of morbid changes, which are naturally incident to blood vessels of their particular organisation and functions, occasioning a remarkable contrast in their pathology with that of arteries.
Thus veins are much more subject to diffuse inflammation than arteries, and the products of their inflammation being carried in the blood to the heart, are conveyed all over the body ; they moreover offer peculiar facilities for the introduction of morbid materials into the cir culation, and from both these circumstances wide-spread and diffuse disease is the result— conditions which have no parallel as the conse quence of arterial disease. Again, an injury to a vein, such as a punctured wound,is followed by cicatrization ; and any dilatation of its tube interferes only partially with its functions; whereas in an artery, from the vigorous and pulsating character of the circulation in it, a wound is only to be healed by obliteration of the vessel, and any dilatation of it causes an aneurism — a progressive and destructive disease.
From the time of Hippocrates, some of the diseases of veins —varix and hmmorrhoids have been recognised ; but it was not till John Hunter, in 1793, published his paper on the diseases of veins in the " Transactions of a Society for the Improvement of Medical and Chirurgical Knowledge," that any light was thrown upon that most important of these diseases — phlebitis.
Since then the subject has received a large share of attention at the hands of some of our most distinguished pathologists : and Hodg son, Travers, Breschet, Bovillaud, Rihers, Ar nott, Lee, and hosts of others, have all added their quota towards its elucidation.
The diseases of veins divide themselves into phlebitis, with which may be considered the effects of wounds and ligatures ; varix and hemorrhoids ; rupture ; disease of valves ; phle bolites ; calcareous degeneration ; fatty tumours; entozoa.
Phlebitis. —Phlebitis may be conveniently divided into plastic and suppurative. They, however, frequently exist together, are pro duced by the same cause, or give rise to each other.
Veins possess peculiar facilities for the pro duction of certain of their diseases, especially inflammation of their lining membrane, caused by the introduction of morbid materials into their cavities ; which is a very general cause of the disease now under consideration.
They are peculiarly subject to being opened, on account of their superficial position, and their being submitted to the surgical opera tion of venesection ; and it must be remem bered how large a superficies of the venous cavity is exposed at every parturition to the contact of those fluids which are secreted in the healing of the placental wound. The veins si tuated in the osseous tissues present peculiar facilities for the introduction of morbid mat ters into the circulation, on account of the patency of their cut extremities, caused by the adhesion of their walls to the unyielding tissue in which they are embedded. Again, the di rection ofe th current of the circulation to wards the heart, is not likely to expel any materials that are introduced into the vein, but would rather tend to carry them on into the mass of the circulating fluid.
The absorbing function of veins is often re ferred to as a cause of the introduction of morbid matters into the circulation, and this especially as it regards pus, but it cannot be strictly said that pus is absorbed in cases of purulent phlebitis ; and I apprehend that the distinction laid down by Hunter*, on this point, is perfectly correct. It appears to me impossible for any one acquainted with the structure of the coats of blood-vessels, and the anatomy of a pus-cell, to imagine that pus, as such, can be introduced within a vein by any process analogous to absorption. It is true that pus may enter a vein bodily, and as pus ; and it is equally true that pus may be absorbed ; but the former is by Introduction through some lesion in the vessel's walls, and in the latter the fluid is in some way altered be fore it can pass through the tunics of the vein, if, indeed, a vein be here the agent of absorp tion. When pus is absorbed, as from a bubo, or in empyema, it is attended with a different series of symptoms and consequences from those which arise when it is introduced bodily, and pus is, in these cases, not to be found in the veins ; and it must be remembered that all the circumstances — a wound secreting pus and an open vein, or, what is tantamount to the same, such inflammation of a vein as leads to secretion of pus in its cavity, — are uniformly present where the characteristic results of phlebitis occur. The same thing is imitated by injecting pus into the veins—with like results.