Chapter XV: Section VI: The Aorta and Arteries Generally

[=Notice=: 1. _Before Opening Vessel_—size; course; condition of
external coat and surrounding tissues. 2. _After Opening
Vessel_—character of blood within; coagulated or not; size, color,
consistence, etc., of clot; size of canal; thickness of walls; rigid
or flexible. _Lining Membrane_—smoothness; transparency, etc.;
readiness of detachment; thickness, etc.; if rough, the apparent
cause; fibrinous, atheromatous or calcareous deposits. _Middle
Coat_—its thickness; color; deposits within, and their character.
_External Coat_—general condition.

ANEURISMS:—1. _External Characters_—size; shape; is the dilatation
lateral or general in its relation to the vessel? Openings as seen
externally; size, position, etc.; blood effused; quantity, etc. _After
opening, notice_—contents; blood fluid or coagulated; fibrinous
contents; laminations; their thickness; number; density; dryness;
difference between outer and inner layers. Channel for blood: size;
character of inner surface; how formed? Walls of aneurism: how formed;
by all, or one coat of artery. Size of artery above and below
aneurism.]

The diseases of the aorta, and of arteries generally, which may claim attention in a post-mortem examination, are _inflammation_, _fatty degeneration_, _calcification_, _aneurism_, and _rupture_.

=Inflammation.= This process may be found involving either the outer or inner coats of arteries. In the former case the walls appear thickened and infiltrated with a soft, jelly-like substance, which appears, at a more advanced stage in some cases, to degenerate into a purulent condition, while in others, great thickening of the coats, or even obliteration results. Inflammation of the inner coat generally precedes atheromatous or calcareous deposits, and is mostly confined to old persons. The roughened inner surface thus produced, may serve to collect fibrinous shreds from the blood, and thus be the occasion of the formation of emboli.

Inflammation of arteries may result from injuries, from the presence of emboli, or may be spontaneous in its origin. While the more frequent seat of the disease is in the aorta, it may occur in any other artery.

=Fatty Degeneration=, or atheromatous disease of arteries, is an important affection of those vessels, and is usually associated with aneurism. It is seen more frequently in the arch of the aorta, and consists in the presence of fine white streaks, situated in the substance of the lining membrane. The disease may be found in children as young as from three to seven years of age, but is more common with adults. As the disease advances, the middle coat becomes involved. The streaks gradually change into large, white, opaque patches. The middle coat becomes thinned, loses its elasticity, assumes a gray, semi-transparent appearance, and, at a later stage, becomes soft and cheesy, and sometimes even undergoes a form of liquification into a creamy fluid resembling pus, but dependent upon the abundant formation of fat globules, with scales of cholesterine and granular matter.

While these destructive changes are going on in the inner and middle coats, and tending to their rupture, by a conservative process, the outer coat, upon which the strength of the vessel mainly depends, becomes thickened and strengthened by the accumulation of plastic matter.

=Ossification.= Ossification of the aorta, like that of the coronary and other arteries, consists rather in a process of _calcification_. The deposits are largely confined to the arch, and consist mainly of patches of calcareous matter of various sizes. We seldom find the whole circumference of the vessel involved, as in the case of smaller arteries. The aortic valves will generally be found more or less loaded with the same deposits.[17]

=Aneurism.= This disease is said to occur more frequently in the aorta, than in any other artery. It may be developed in any portion of this vessel or its principal branches, but is more commonly found in the arch. The walls of the vessel being weakened by fatty degeneration, they become less and less able to resist the pressure of the contained blood, and gradually yielding to the systolic force of the heart, become more and more distended, until the complete aneurismal sac is formed.

Aneurism may be either _true_, in which there is a dilatation of all the coats of the vessel, or _false_, where there is rupture of the inner, and perhaps also of the middle, and dilatation of the outer coat alone. The latter form, when developed upon the aorta, may become very large, and by pressure, cause absorption of the sternum, costal cartilages and ribs, and even of the clavicle.

In some cases, the inner and middle coat having ruptured, the blood instead of being confined in a sac formed by the outer coat, becomes diffused between the middle and outer, or between the layers of the middle coat, thus constituting what is known as _dissecting_ aneurism. In these cases, the blood may extend the whole length of the aorta, and even upwards upon the carotids to their bifurcation.

In an examination of an aneurismal sac, the _true_ aneurism will be recognized by the walls presenting all the coats of the artery, and generally by the indication of the presence of atheromatous and calcareous deposits, which are confined to the inner and middle coats. In these cases also, the communication between the sac and the aorta is large and free. If the aneurism be _false_, however, there will be an absence of those deposits, the opening into the artery will be comparatively small, and the inner and middle coats will terminate abruptly at its margin.

The interior of aneurismal sacs will usually be found containing a quantity of fibrine deposited from the blood, and arranged in concentric layers. In color, these fibrinous layers are of a light buff, the outer layers being dry and firm, while the inner ones are softer and more moist, and the central portion, at the same time, filled with a dark mass of coagulated blood. A spontaneous cure will sometimes be effected by a complete blocking up of the sac with fibrinous deposits, thus preventing further dilatation or danger of rupture.

The following case, which has been before reported,[18] shows a combination of both true and false aneurism, with spontaneous cure of the latter:

CASE.—_Spontaneous cure of aneurism of ascending portion of arch of
aorta, with death from bursting of aneurism of descending portion into
the œsophagus._

Mr. H——, of this city, aged sixty years, while walking in his yard one
day after a hearty dinner, was taken with a sudden sensation of
faintness and nausea, which was soon followed by vomiting the contents
of his stomach, with a considerable quantity of blood. After entering
his house, the vomiting was frequently repeated, and at each effort
large quantities of pale blood ejected. Sinking rapidly, in an hour he
was dead.

Twenty-four hours after, I made a post-mortem examination. Upon
exposing the chest, found at the right border of the sternum, just
below the clavicle, a hard, inelastic tumor beneath the skin, of the
size of a small orange. While not adherent to the integument, it
appeared firmly attached to the walls of the chest beneath. Upon
turning aside the integument and pectoral muscles, the tumor was found
connected by a long pedicle to parts within the chest; absorption of
considerable portions of the sternal ends of the first and second
ribs, with the side of the sternum, having resulted from pressure of
the tumor upon those parts, and finally permitting its appearance
beneath the skin.

The removal of the sternum at once demonstrated the aneurismal
character of the tumor by showing its connection with the ascending
portion of the arch of the aorta, while a section of the same,
exhibited the interior filled with dense concentric layers of
fibrinous matter, separable from one another, the outer layers being
dry and hard, while the inner portion was less firm and moist. This
aneurism was plainly of the _false_ variety. The neck of the tumor was
not much larger than the thumb, and of sufficient length to reach from
the arch of the aorta to the dilated sac beneath the skin, outside the
chest.

A further examination of the aorta brought to light a second and
_true_ aneurism of the descending portion of the arch, the dilatation
involving all the coats of the vessels, and which, having _burst into
the œsophagus_, explained at once the cause of the hæmorrhage and
sudden death.

Upon inquiring of the family, I learned that the tumor upon the chest
had been known to have existed for fifteen or twenty years; that for
some years the pulsations of the tumor were strong, but that for many
years all beating had ceased; that he had never discontinued his work,
that of a carpenter, and in fact, it had given him so little trouble
that he had never consulted a physician in regard to it. For a year or
so previous to death, he had been troubled with a cough, particularly
upon exercising, but otherwise had been in good health.

A remarkable and interesting feature of this case was, the little
inconvenience experienced by the patient from so grave a malady, and
one usually attended with great suffering.

=Rupture.= Spontaneous rupture of the aorta is a very rare occurrence, and probably never happens except the coats have first been weakened by disease. Hence, in all of these cases, there will be found atheromatous softening, and generally thinning of the walls by dilatation. In this condition, some violent muscular effort may result in rupture at the most weakened point, and this will be generally at that portion of the aorta within the pericardium, the external coat being weaker here than at any other point.

Where the dilatation of the diseased and weakened vessel has resulted in the formation of an aneurism, rupture of this will be the more frequent termination. This may take place into the œsophagus, as in the case reported, or into the trachea, the pericardium, either pleural cavity, or upon the surface of the body.

Rupture of the coronary arteries, of the arteries of the brain, various branches of the abdominal aorta, and arteries of the extremities, have occasionally been found, when softened by fatty degeneration or atheromatous disease.