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tached by a small pedicle to the posterior curtain of the mitral valve.

This patient had for many years suffered from repeated attacks of cardiac breathlessness; in one of these paroxysms she died suddenly, the concretion having been carried upwards into the infundibulum, and having obstructed the arterial stream.

A third pathological condition in cardiac apnœa consists of changes occurring externally to the heart, on its pericardial lining. Thus there may be ossification, as in the case described at pages 231-5; or there may be adhesion; or, again, there may be rapid serous effusion. I remember one remarkable instance of this latter kind. A man was seized suddenly with symptoms of breathlessness, pain shooting through his body, cramps, and extreme coldness. Cholera was dreaded at the time; and, as the patient died without medical aid, it was assumed that he had succumbed to the epidemic. On making the post mortem examination, I found the pericardium distended with serum, and no other reason to account for the fatal result; the effusion of course being amply sufficient.

In all the examples given above, there has been such a change from the normal state, that the circulation has become mechanically arrested, either by failure of muscular power, or by internal obstruction to the course of the blood, or by external obstruction to the mechanical action of the heart. I might probably greatly enlarge on these points; I might show other lesions leading to the same result; but the illustrations given are fair types, and those most commonly seen.

There are, nevertheless, a class of cases in which cardiac apnoea exists, and of which the one given at pages 235-6 is an example, where no structural lesion of the heart, external or internal, is present, but where the central organ of the circulation suddenly ceases its function by a spasmodic contraction of its walls. In these instances, the heart is found small, firm, and empty; its cavities virtually obliterated by approximation of their surfaces. This pathological state, uncommonly rare, must have for its cause either a modified condition of blood, by which the tonic contraction is excited, or a modified condition of the nervous system acting upon the organ, to produce spasm through its nervous supply. Up to this time, however, not the slightest clue has been obtained as to the nature of the morbid changes by which the result is brought about.

Lastly, in those forms of cardiac apnoea where the symptoms have been induced by the introduction of a poison from without into the body, we may find the heart, according to the nature of the poison, spasmodically contracted on both sides, or relaxed on both sides and full of blood, or contracted on the left side and relaxed and full of blood on the right. Thus, in poisoning by strychnine, the first of these conditions may be obtained; in poisoning by aconite, the second; and in poisoning by inhalation of chloroform, the third. In these cases the blood, for many hours after death, remains fluid, and generally dark.

Although I have noted the morbid conditions of the heart and blood as holding the place of primary

importance in the pathology of cardiac apnoea, there are one or two points of a general kind which must not be overlooked. As a rule, after the form of death under our consideration the external surface of the body is left blanched and free from ecchymosis. If death shall have taken place in the midst of one of the paroxysms, the body will be left rigid, and this rigidity may pass into rigor mortis without any period of relaxation. But if the death take place after the subsidence of muscular contraction or

during a paroxysm in which the muscles of the body generally are not involved, then the body is left free of rigidity, and as though, indeed, it were in a state of gentle sleep. In these cases rigor mortis is slow in its development.

Irrespectively of those lesions which may exist in other organs than the heart, and which may indicate a general degeneration of the body, such as atheroma of the vessels of the brain, fatty degeneration of the liver, and degeneration of the kidneys, but little can be added as specifically denoting, from pathology, the preexistence of cardiac apnoea. But inasmuch as, in a large majority of cases, the fatal paroxysm is due to an arrest of the flow of blood through the right side of the heart, so, even in cases where there is no structural lesion of other organs, there is usually found a considerable amount of venous congestion, particularly in the liver, kidneys, spleen, and brain. Even the muscles may share in this congestion, and present a darkened surface, from which fluid blood readily exudes. The condition of the lungs, how

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ever, often differs from that of the other vascular organs in this respect. For, if the circulation be arrested absolutely on the right side of the heart, then, the current of blood passing through the pulmonary artery being cut off, the lungs may be left not only free from congestion, but bloodless; while the other vascular organs are largely congested. In cases, on the other hand, where the obstruction has commenced on the left side of the heart, and the current of the blood has been cut off in its passage through the aorta, the lungs may be the chief seat of congestion; the other vascular organs being, by contrast, moderately free of blood.

CAUSE AND CAUSATION OF CARDIAC APNEA.

In considering the cause and causation of the symptoms known in their collected sense under the term cardiac apnoea, we turn in every case to some one or other of the morbid conditions of the heart or blood for a predisposing cause. These conditions may, as we have seen, be varied; but they have all this great feature in common, that they imply a deficiency either in the propelling power of the heart or in the sustaining power of the blood.

One or other of these predisposing causes present, any additional cause may prove the excitant which shall have for its tendency the sudden development of the predisposing cause. Thus, in examples of degenerated heart, mental shock and anxiety, too long a deprivation of food, sudden exertion, passion, sudden fear, diarrhoea, over-repletion-any one of

these may act as an excitant of the paroxysm. That these excitants differ widely the one from the other is true; but the difference involves no paradox, for a heart enfeebled may be stopped as readily by calling it into a sudden action which it is not prepared to meet, as by withdrawing from it that sustainment of which it is not able to lose a tithe.

But, perhaps, the most frequent of all exciting causes is profound sleep. In the early hours of the morning, when the influence of the sun has been longest from the earth, and when the physical forces have to a considerable extent relaxed under the effects of sleep; when, in simple terms, the action of the heart, even in the healthy man, is at its minimum of propelling power, then are those who are predisposed to cardiac apnoea most readily affected; then not unfrequently they die, perhaps without awaking, or not dying, they awake in the midst of a paroxysm, the chest fixed and the body more or less tetanic. For this same reason, in cases far advanced, the inability to sleep, owing to the recurrence of the paroxysm, becomes, as we have seen, one of the most characteristic manifestations of the affection.

From this it happens that even events, trifling when they occur in the organism of a sound man, may turn the scale fatally in one disposed to cardiac apnœa. For instance, flatulency leading to distension of the stomach, produces in the healthy individual but a temporary inconvenience, a little pain and fulness in waking hours, and at most a disturbed dream or nightmare during sleep. But in a man with a heart

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