A CASE

OF

DISSECTING ANEURISM OF THE AORTA.

BY

C. HILTON FAGGE, M.D., M.R.C.P.;

ASSISTANT-PHYSICIAN TO GUY'S HOSPITAL.

Received May 25th.-Read June 22nd, 1869.

EARLY in May, 1869, I was requested to assist at the post-mortem examination of a gentleman, Mr. N―, æt. 71, who had died from disease of the heart. Two other medical men were present at the autopsy: Dr. Beeby, of Bromley, who had attended the patient during his fatal illness, and Mr. Oliver Chalk, of London.

I was informed that Mr. N- had led a very active life, and had continued to take horse exercise up to four or five months before his death, although his medical attendants had recognised, some years before, that he had disease of the heart, a loud bruit having been discovered, audible over a large part of the chest. Since the commencement of the present year he had been suffering much from dyspnoea, and had been gradually failing in health; but he had had no dropsy, or only a very little oedema of the ankles. He sank very gradually, having been almost moribund during a whole fortnight.

These were nearly all the facts concerning Mr. N—'s illness that I learnt before the post-mortem examination. They pointed to the probability that the disease, if

valvular, would be found rather in the aortic valves than in the mitral.

The body was spare and thin, but not extremely emaciated; there was no dropsy.

The head was not examined, nor the spine.

On opening the thorax, it was at once seen that the anterior part of the arch of the aorta was much larger than natural; and, as this was the first seat of the disease, it will be well at once to proceed to the description of the appearances presented :—

When the canal of the aorta was laid open, a most remarkable condition was observed. At a distance of less than an inch above the aortic valves, the inner and middle coats1 were divided in the whole circumference of the tube, so as to form an oval aperture with a smooth slightly everted margin, projecting into the cavity of what had been supposed to be the arch, but was now seen to be a large aneurismal sac, formed (mainly, at any rate) from the external coat of the aorta. The separation of the aortic coats extended on one side (in front and towards the right) down to the base of the heart, thus coming into close proximity to the base of the right ventricle. On the left side, and behind, no such separation existed; and here only the edge of the divided coats and the different appearance of the lining membrane served to mark off the inner surface of the aorta from that of the aneurism. About an inch and a half above the truncated extremity of the aorta, another large opening into the aneurism was seen, which led into the continuation of the arch. This aperture, also, was oval, and its slightly everted edge was perfectly smooth, except posteriorly, where a portion of it had been frayed off into an irregular tail, or process, of no great size. From this point two channels,-the one aneurismal, the other the aortic arch-ran on for nearly three

This expression is probably not strictly correct, since Dr. Peacock. has shown that the middle coat is in reality split by the dissecting process, and that part of its structure can be found in the outer wall of the sac. For convenience, however, I have adhered to the ordinary way of describing such

cases.

inches side by side; but the sac of the aneurism preponderated so greatly in size that the arch seemed, as it were, to be imbedded in its anterior wall. Of the three main branches of the aortic arch, the left carotid and the left subclavian came off normally; the blood had not, to any extent, forced a passage between the coats of these arteries, only there were slight indentations in the wall of the aneurism, which marked the origins of the two branches, and indicated a slight tendency to the extension of the dissecting process along their tracks. The root of the innominate artery presented a different condition. Round the great part of its circumference the inner and middle coats of the aorta were completely torn away from it, so as to form an oval communication between the aneurismal sac, and the interior of the arch. The innominate artery, in fact, appeared to arise more directly from the former than from the latter. The aperture of communication was like those above described, smooth, even, and with an edge slightly everted.

A little below the origin of the left subclavian artery the outline of the aortic arch became more marked on the inner surface of the aneurism, and its canal almost immediately afterwards opened a second time into the sac. Here there was again a sharply-defined edge, indicating that the inner layers of the aortic coats had been torn through in their whole circumference; but the aperture was flattened and oblique, and was evidently smaller than that by which the blood entered the arch.

Beyond this the blood was, for a space, confined only by the aneurismal coats, but about an inch lower, the tube of the aorta recommenced by an oval smooth opening, just like those above described.

There was, thus, again a double channel, a sort of double aorta, and throughout the whole length of the main arterial canal this disposition was preserved. The anterior of the two channels was that of the original aorta; the posterior was that of the dissecting aneurism. This last quickly diminished in size below the aortic arch, and throughout

the mediastinum and along the lumbar vertebræ, its calibre was probably about equal to that of the aorta in front of it. On transverse section the form of the two channels were very different; that of the aorta was circular or oval, that of the aneurism semilunar. To employ a comparison made use of by Professor Henderson in reference to a similar preparation, their cut faces looked like those of the two ventricles of the heart when divided transversely; the form of the left ventricle answering to that of the aorta, the form of the right ventricle to that of the aneurism in this case.

Below the bifurcation of the aorta, the disposition differed somewhat on the two sides of the body. The left common iliac was at first double, but the septum was maintained only for about a quarter of an inch, below which the aneurismal channel opened into the artery by a smooth aperture. In the right common iliac artery the channel was double throughout its whole length; but immediately below its division into the external and internal iliac arteries, an oval ring was seen in the external iliac artery, leading from the one tube into the other; and this formed the termination of the aneurism. The external iliac artery thus derived its blood, partly from the aneurismal channel, partly from the common iliac trunk in front of it. The internal iliac was altogether single, and seemed to have received its blood entirely from the aneurismal channel.

The state of the lining membrane and coats of the aorta varied greatly in different parts of its course. Commencing with the aortic valves, these were much diseased. Two of them were blended together, the line of union being marked on the upper aspect of the single valve which resulted by a thick mass containing much calcareous deposit. The interval between the valves was thus converted into a slightly sinuous transverse slit. The sinuses of Valsalva were much dilated, forming quasi-aneurismal pouches. The lining membrane of the aorta was smooth, up to the point where it was first torn across, and the coats were almost free from atheromatous change. The lining membrane of the arch, again, was

almost perfectly smooth.

The surface of the aneurismal

sac, on the other hand, was markedly uneven, and contained a good deal of atheroma. There was no coagulum in the

interior of the sac, with the exception of a mass about two inches in diameter, and of no great thickness, which lay in the angle between the base of the aorta and the aneurismal wall, where it was, of course, out of the line of the blood stream.

In the lower part of the chest, and in the abdomen, the appearances presented by the inner surfaces of the aorta and of the aneurism contrasted curiously with those observed above. Here the interior of the aorta itself was much roughened by plates of atheroma, and contained a good deal of coagulum, adherent to its surface in patches. The aneurismal channel, on the other hand, had a remarkably smooth and polished lining-as smooth and polished as the lining of any healthy artery could be-except where there was an occasional patch of atheroma. Nor was it merely a lining membrane which had thus been developed in the new canal; the subjacent tissue, the fibres of which ran transversely like those of the middle coat of the aorta, was also to some extent a new formation. apparent from the fact that the fibres were easily traceable across the angles which marked the lateral limits of the separation of the aortic coats. In horizontal sections the channel of the aneurism was indeed seen to be surrounded by a ring of some considerable thickness, which passed all round it, and must therefore have been developed subsequently to the formation of the aneurism. Under the microscope this tissue was seen to be made up of fibres identical in appearance with those of elastic tissue.

This was

It did not appear that any of the branches of the abdominal aorta had prolongations from the aneurism, so far as could be determined after removal, when some of them were found to have been cut away. Nor did any of the arterial branches open into or communicate with the aneurism, with the exception of the small posterior branches, namely the intercostal and lumbar arteries. Some of these were found