_Morbid Anatomy of the Muscular Substance of the Heart._
Dr. Baillie, speaking of inflammation of the substance of the
heart, says, "When the pericardium covering its surface is
inflamed, the inflammation sometimes passes a little way into
the substance of the heart:" and then he gives these as the
characteristic marks of such inflammation--that "it (the substance
of the heart) becomes much more crowded with small vessels than in
its natural state, and there are sometimes to be seen a few spots
of extravasated blood." Now, this undue vascularity, and these few
extravasated spots, where inflammation unquestionably belongs to
a contiguous structure, may be deemed sufficient evidence of the
muscular substance of the heart participating, or beginning to
participate, in the same disease; but, absolutely and exclusively,
it may be doubted whether more is not required to give a certain
assurance of its inflammation. Here, as elsewhere, we must look
for some of the proper products of inflammation; or for some of
the permanent changes of texture which naturally result from it,
according to its several modes of disorganizing.
It is a very rare event to find pus among the products of
inflammation of the substance of the heart: yet this event has
occurred twice to my observation. In one instance the whole heart
was deeply tinged with dark-coloured blood, and its substance
softened; and here and there, upon the section of both ventricles,
innumerable small points of pus oozed from among the muscular
fibres. This was the result of a most rapid and acute inflammation,
in which death took place after an illness of only two days. In
another instance, after death, which terminated an illness of
long duration and characterized by symptoms referable to the
heart, a distinct abscess was found in the substance of the left
ventricle, closed externally by a portion of adherent pericardium,
and connected internally with an ossified portion of the lining
membrane.
This diffusion of pus, or rather its formation in innumerable
separate points, throughout the muscular structure of the heart, by
a rapid and acute inflammation, is a singular occurrence. No such
case has ever fallen within the knowledge of the most experienced
in morbid anatomy, of whom I have made inquiry; neither has any
such (as far as I can learn) been recorded in books[10].
A single collection of pus[11], constituting an ulcer or abscess of
the heart, and resulting from chronic inflammation, is also a rare
occurrence, yet not so rare but that a specimen of it may be found
in most collections of morbid anatomy[12].
But independent of the formation of pus, softening and attenuation,
as well as induration and thickening of the muscular substance of
the heart, do, in different cases, according to the circumstances
under which they are found, both bespeak inflammation.
Together with the unequivocal evidence of inflammation in other
parts of the heart, the muscular fibres have at the same time been
found very soft and loose, and easily torn; and with this looseness
of texture the heart has sometimes presented a dark and almost
black appearance, and sometimes it has been almost blanched and
colourless. The deep dark tinge shews that the muscular substance
is unnaturally loaded with blood; whereas the absence of colour
shews that it is destitute of its natural quantity. These different
appearances do, in fact, belong to different stages of the same
disease. The first indicates inflammation of the muscular substance
in its present state of activity; the second, an irreparable
disorganization of the muscular substance left by inflammation,
when it has been unarrested in its earliest stages. The first is
found when death takes place _in a few days after_ the accession
of the disease; the second, when the patient survives the first
attack, and dies at a remoter period.
The inflammation, which produces softening and attenuation of the
muscular structure, is, I believe, always of an acute kind.
But induration and thickening of the muscular substance of
the heart is also the result of inflammation. This must be
distinguished from hypertrophy, or mere augmentation of bulk, of
which we shall speak hereafter. In this induration, which proceeds
from inflammation, there is, besides increase of bulk and firmness,
a manifest alteration of texture. A substance[13] is produced
offering a peculiar resistance to the knife. This condition
unquestionably must result from an interstitial deposition of new
matter among the muscular fibres. From concomitant circumstances,
as well as from its own character, I presume that it proceeds
from chronic, not from acute inflammation. I confess that I never
saw a specimen of what I now allude to. It is described with some
minuteness by Corvisart; but it may be presumed to be very rare,
since Laënnec admits that it never fell under his observation.
These opposite states of softening and attenuation in one case, and
induration and thickening in another, are known to those conversant
with morbid dissection as the evidences of inflammation in other
parts of the body besides the muscular substance of the heart.
But there are changes of structure incident to the muscular
substance of the heart which are independent upon inflammation,
or, perhaps, upon any process which can properly be called morbid.
They consist of simple augmentation and simple diminution of bulk
and consistence. This simple augmentation of bulk and consistence
is owing exclusively to a more ample development of natural
structure. The muscular substance is more red than natural, its
carneæ columnæ are increased in thickness, and its proper fibrous
texture is every where more strikingly manifest; but there is no
interstitial deposition of matter new in its kind. It has been
called hypertrophia of the heart, and the name conveys a tolerably
just idea of its actual condition.
The simple diminution of bulk and consistence is a condition the
exact opposite of the former. The muscular substance is less red
than natural; its proper fibrous texture less distinguishable; but
there is still the appearance of muscle shrunk and withered, as
if from an insufficient supply of nourishment. It may be called
atrophia of the heart.
Conjoined with augmentation, as well as with diminution of strength
and bulk in the walls of the heart, there is almost always an
increase in the capacity of its cavities; and in whichsoever part
of the heart the walls are thus augmented or diminished, it is the
cavity appertaining to the same part which undergoes the increase
of capacity. Hence it appears either that one of these conditions
is the immediate and necessary consequence of the other, or that
both are the simultaneous effects of the same causes.
Dilatation of any cavity of the heart, with thickening of its
walls, is called _active dilatation_; and dilatation of any cavity,
with attenuation, is called _passive_[14].
Active dilatation may appertain to every cavity of the heart
simultaneously; and so may passive dilatation. But such occurrences
are very rare: for one cavity being naturally more liable to this
species of dilatation, and another to that, it most frequently
happens that specimens of both conditions are found in the
different cavities of the same heart.
The left ventricle is much more liable to active dilatation than
the right; and the right ventricle more so than either of the
auricles; and of the auricles unquestionably the left. Upon the
whole, perhaps, the fact may be truly stated thus--that the left
ventricle commonly gains an increase of bulk and strength, with an
increase of capacity; and that all the other cavities, at the time
that they expand, are rather apt to become attenuated.
It sometimes (though rarely) happens, that, with an increase of
strength and bulk in its muscular structure, the left ventricle
suffers a diminution of capacity in its cavity. In a case reported
by Laënnec, the left ventricle was an inch and a half thick at
its broadest, and an inch thick at its thinnest part; and yet its
cavity was only capable of containing an unblanched almond. I have
seen the same condition in a less degree.--(_Laënnec_, vol. ii.
698.)
The circumstances under which these opposite conditions, this
hypertrophy and atrophy of the heart, with the enlargement or
diminution of its cavities, arise, must be explained hereafter. At
present I would only remark that they are often found conjoined
with actual disease in other structures of the heart, such as
osseous or cartilaginous thickening of internal lining, adhesion
of the pericardium, and ossification of the coronary arteries, to
which they owe their origin; and, moreover, that they are often
found where the heart is otherwise perfectly sound in texture, and
where their cause must be sought in other parts of the body.
The heart is liable to undergo a simple dilatation of its cavities
without either thickening or attenuation of its muscular substance.
This simple dilatation is sometimes of the whole organ, sometimes
of one side, and sometimes only of one auricle or ventricle. When
it is of one cavity only, it may be complicated with active or
passive dilatation of another, or of all the rest.
There is reason to believe that the heart sometimes undergoes a
temporary dilatation, and again returns to its natural capacity;
but that the dilatation can only subsist for a short time without
becoming permanent.
The power of thus enlarging its cavities, and restoring them to
their natural condition, belongs more especially to the right side
of the heart.
A large accumulation of fat is sometimes met with about the heart.
The healthy heart is always more or less marked upon its external
surface with streaks of white, and this appearance results from
the deposition of fat in the cellular texture, which unites the
serous covering with the subjacent muscular structure. It is found
principally where the venæ cavæ unite to form the right auricle;
also at the base of the ventricles, and along the line which
marks the boundary between the two, and around the origin of the
great blood-vessels as they emerge from the heart. But when fat
is deposited in more than these situations, and in more than the
natural quantity, it is not so much added to the healthy substance
of the heart, as existing at its expense and detriment, and the
muscular structure is that which especially suffers. The fibre
of the fat heart is pale and wasted, like that of a paralytic
limb.--_Mus. of the Coll. of Surg._ 327.
A rupture of the heart is sometimes met with; but all the cases of
reputed rupture are not such in reality. An aperture in the walls
of the heart, through which blood escapes into the cavity of the
pericardium, may result from ulceration as well as from rupture,
or from a mixed process of one and the other; but whatever be the
precise nature of the process by which this perforation of the
heart is effected, it is undoubtedly of rare occurrence.
Where it has been found, there has generally been at the same time
some peculiar condition of the organ, which might be presumed
favourable to its production. Its muscular substance has been
so soft and loose of texture, that it could be pierced through
by the weight of a probe[15]; or it has been converted into, or
greatly intermixed with fat[16]; or its muscular fibres have been
absolutely defective, leaving a certain transparent space, where
the internal lining and the pericardium have been in contact,
and served to maintain the completeness of the cavity, until the
rupture has taken place[17].
Not that a rupture has not been found where the texture of
the parts has seemed to offer no natural facilities to its
occurrence--as in the case related by Harvey himself, who found a
lacerated aperture in the left ventricle, capable of admitting his
finger, through which blood had escaped into the pericardium, the
walls of the ventricle being increased in thickness and strength,
while an obstacle existed at the entrance of the aorta[18]. Here
the heart must have torn itself asunder by the simple violence of
its contraction, in contending against the impediment to the egress
of blood from its cavity. This is an effect which would hardly be
thought capable of being thus produced; but I can well believe it
possible after having seen one of the recti muscles of the abdomen
literally torn in twain, in a man who died of tetanus[19].
[To be continued.]