DISEASES OF THE HEART form a large proportion of the most serious disorders that afflict mankind, in youth as well as in advanced life. For the structure and functions of the organ the reader is referred to ANATOMY and PHYSIOLOGY.
In the early ages of medicine, the absence of correct anatomical, physiological, and pathological knowledge pre-vented diseases of the heart from being recognized with any certainty during life, and almost entirely precluded them from becoming the objects of medical treatment. But no sooner did Harvey (1628) publish his discovery of the circulation of the blood, and its dependence on the heart as its central organ, than derangements of the circulation began to be recognized as signs of disease of that central organ. The earliest indications of this important step in the diagnosis of these diseases are to be found in the instruc-tive records contained in the writings of the great patho-logists of the beginning of the 18th century, of whom the chief in this respect are Lancisi, Morgagni, Senac, and Meckel. There is, however, a limit to the information obtainable in this way; and, though its range has been largely increased in our day by the invention of such instruments as the sphygmograph and cardiograph, &c. it was very easily reached in those early times, when men had only their unaided senses to depend upon, and but little ex-perience to guide them. We need not wonder, then, that after the first great step was taken there was but little further progress made, and medicine had to wait till the beginning of another century, when Corvisart (1806) first made practical use of Auenbrugger's (1761) invention of percussion to determine the size of the heart, enlargement of that organ bulking largely in those days as a substantive disease. Corvisart was also in the habit of listening to the sounds made by the heart, and he may therefore be regarded as the first practical exponent of our modern methods of physical exploration, though scarcely as their founder. For as Auenbrugger invented percussion, so Laennec (1819) was undoubtedly the first to make a scien-tific application of mediate auscultation to the diagnosis of diseases of the chest, and it is to him we trace all the benefits derived from this method of inquiry, though it is to Bouillaud (1824) that we are chiefly indebted for its extension to the diagnosis of diseases of the heart; while it is to the clinical experience, and above all to the practical experiments, of James Hope (1832) that we owe much of that precision we have now attained in our diagnosis of those diseases from abnormalities in the sounds produced during the cardiac movements; just as we have learned from M. Forget (1851) the doctrine of retro-dilatation, which rightly interpreted is capable of greatly informing us as to the origin and progress of heart disease, and from William Stokes (1854) some instructive views on defective heart power as a cause of certain symptoms simulating disease of the brain, which have proved most valuable and suggestive in the diagnosis of diseases of the heart as well as in their treatment.
The half dozen works just alluded to by no means ex-haust the literature of this subject during the past ages, but each of them marks an era, and by their means we may readily trace the progress of cardiac diagnosis during the 130 years intervening between Lancisi and Stokes ; but during the twenty odd years that have since elapsed the literature of this subject has become so unusually copious and exhaustive that it would occupy too much space merely to enumerate the authors' names. Fortunately this further development need not concern us here.
As in former so in recent times the progress made in the diagnosis of diseases of the heart has been entirely based on physics and on physiology, and the heart is an organ so situated and so connected as to render it singularly amenable to these methods of investigation. Resting on the diaphragm, and projected against the anterior chest-wall, the heart is partly within reach, and is otherwise so completely surrounded on three sides by resonant organs (the lungs) that any change in its position or in its size is readily made out by palpation and percussion, while by listening over the cardiac areaauscultationwe can ascertain whether the valves of the heart remain intact, have an unusual strain thrown upon them, or have been rendered incompetent by disease.
As the four openings of the heart lie so close together that a superficial area of half a square inch includes a part of each, it is only by taking advantage of certain well-known laws regulating the conduction of sound that we are able to differentiate the sounds produced at each of these open-ings respectively, and to assign to each a definite position on the chest-wall, where it is heard at its maximum intensity. Physiology, on the other hand, teaches us that each indi-vidual cardiac pulsation, the time of which is marked for us by that impulse against the chest-wall of which we are all more or less conscious, consists of alternate acts of con-traction and dilatation affecting the four cavities of the heart. Some of these acts precede this impulse, some accompany it, and others follow it, and the relation of any sound produced within the heart to these physiological acts is termed its rhythm.
The functional perfection of the heart is thus easily determined by ascertaining that it is of a normal size, that its impulse is neither too strong nor too weak, and that its sounds are normal when listened to, each in its own position of maximum intensity. When these conditions are present, any abnormal cardiac phenomena, such as palpitation, irregular action, &c, are to be regarded as entirely due to abnormal innervation, and not to any actual disease of the heart. On the other hand functional imperfection is readily detected by the occurrence of any abnormality in the phenomena already referred to, especially if accompanied by a blowing sound instead of the usual valve sound in any of the normal auscultatory areas. And an intelligent appreciation of these facts, together with a correlation of the physical with the physiological phenomena, that is, a correct determination of the rhythm of the sounds heard, enables us to ascertain with certainty, not only the valve implicated, but also the mode in which the lesion has affected or is likely to affect the heart and through it the circulation. Having found the heart to be functionally imperfect, we have two alternatives presented to useither the valves are incurably deformed from previous disease, or they are merely functionally imperfect from over-disten-tion of the cardiac cavities, a state of matters which may arise from various causes, and which ts always susceptible of great relief and very often of perfect cure.
The great function of the heart is to keep up such a pressure within the arterial section of the vascular canals as will suffice for the maintenance of the circulation and of all the organic functions of the body dependent upon it. The tendency, however, of all the extrinsic forces connected with the circulation is to equalize the blood pressure throughout the vascular system, and so to bring the circula-tion to a stand-still; and indeed it is in this way that death at last occurs ; whether it happen suddenly or slowly the cause is still the samecessation of the circulation brought about by equalization of the blood pressure throughout the whole of the vascular system, or, as it may be otherwise put, from decline of the arterial (aortic) blood pressure.
Valvular lesions of the heart, however produced, tend, as may be readily understood, to neutralize the cardiac function and to lower the arterial blood pressure, either by permitting an unnatural escape of the blood backward (regurgitation) or by obstructing its onward flow (obstruc-tion). And this action is further intensified by the interference with the cardiac nutrition which necessarily results, first of all directly, from the heart being flushed with blood at a low pressure, and secondly indirectly, from the imperfect performance of all those functions, such as digestion, &c, upon which the formation of healthy blood depends, arising from the same cause.
Valvular disease thus gives the heart more work to do, while it takes from it the power of doing it, putting the organ in a vicious circle. In this way curable disease if neglected may readily lapse into incurability, while to incurable disease there can be but one ending, though, apart from such accidents as embolism or asystole from violent emotion or exertion, that is neither so sudden nor so speedy as is commonly supposed, and indeed usually occurs from gradual asthenia, often accompanied hydropsy, and preceded by a life of more or less active exertion, averaging in many cases not less than twenty years from the primary onset of the disease. During this comparatively long period the disease may have been entirely mute ; that is, the valve lesion has progressed so slowly from its trifling commence-ment that the residual accumulation in the cavity primarily affected has gone on guttatim, and has spread itself back-wards over the other sections of the circulation in the same graduaimanner, the resulting dilatation being so immediately followed by compensating hypertrophy that the sufferer has never been aware of any derangement of his functions. A time comes at last, however, when, from a failure of nutri-tion due to physical causes, the increase in the heart's bulk ceases to be muscular, and it becomes fibrous; then indeed the disease is no longer mute, serious rupture of the compen-sation sets in, and all that art can do is to make the inevit-able declension as gradual as possible. Up to this period any accidental rupture of the compensation, which readily enough occurs from over-exertion, imperfect nutrition from any cause, or from any feverish attack, is as a rule perfectly amenable to appropriate treatment, though the restored com-pensation is always less stable than it had been previously.
Ruptured compensation is often attended by very alarm-ing symptoms, such as great general dropsy and extreme irregularity of the heart's action, but the true measure of the patient's danger lies less in these symptoms than in the condition of the cardiac muscle, and in the circumstances which threaten asystole, that is, arrest of the heart's action.
If in early times the diagnosis of diseases of the heart was a matter of great difficulty, this seemed of less import-ance as their treatment was so hopeless. " A mesure qu'on pénètre," says Senac, "dans les maladies du cur, la medicine parait plus stérile ; que peut-on espérer des médi-caments, par exemple, dans les dilatations du cur 1 " But modem science, which has rendered the heart so accessible from all sides that there is nowadays probably no organ of the body whose diseases can be so readily detected or so accurately discriminated, has not only pointed out the true source of danger in these diseases, but has also put into our hands a remedy by which some are cured who were formerly thought incurable, while many incurables have their downward progress so successfully arrested that they feel themselves to be practically cured. And yet DIGITALIS (q.v.) was all but unknown 100 years ago, while so little was known of its real actionratio medendithat within the last thirty years a living author wrote that the use of digitalis as a diuretic in heart disease was quite " indefensible," as " the failing heart is absolutely incap-able of sustaining the depressing influence of the drug." Nowadays we know digitalis to be the only drug that can be relied on for increasing the power of the heart's contrac-tions, and it also slows them,the result being that the blood pressure is increased throughout the whole arterial system, and that, time being given for the heart itself to be flushed by blood at an increased pressure, its nutrition is improved. The heart not only acts more powerfully under the immediate influenceof the drug, but it becomes more able to act, so that by and by the drug may be left off; though indeed, should the muscular degeneration determinately threaten a rapid progression, tonic doses of the drug may be safely given daily for many years continuously, in spite of all our forefathers' croaking as to the dangers of accumu-lation. But however marvellous the effects of tonic doses of digitalis may be, the virtues of the drug in larger doses are even more wonderful in appropriate cases, for by means of large doses the skilled physician has it in his power permanently to contract many dilated hearts, and so to cure what seemed an incurable disease not only to Senac but even to many of his more modern successors.
There are many other drugs employed in the treatment of diseases of the heart, but there is no other deserving of special mention. Other medicines are employed to relieve pain, aid digestion, dispel flatulence, unload the bowels, improve the blood, or simply as general tonics, and may be catalogued as morphia, chloroform, belladonna, pepsine, asafcetida, aloes, rhubarb, iron, &c.
ANGINA PECTORIS (q.v.) is a painful disease of the heart which has been already described. Palpitation is an extremely rapid and sometimes forcible action of the heart. Irregular and Intermittent Action are sufficiently described by their names ; irregular action may be tumultuous or so peculiar as to deserve the name of a veritable delirium cordis; intermission consists in the dropping of a beat every second, third, or fourth time, or seldomer. Sometimes the intermission only applies to the pulse, the heart acting regularly, and is (mused by that particular systole not being forcible enough to propel the blood to the periphery ; occasionally we have two beats of the pulse and then an intermission, constituting what has been termed a pidsus bigeminus, or the rhythm of the intermission may be even more varied. All these forms of perverted action of the heart may accompany valvular lesions, or they may occur in hearts whose valves are sound; the walls of such hearts are, however, almost invariably more or less feeble, imper-fectly nourished, and the blood often poor and watery. They are rarely indicative of any real danger, though sufficiently troublesome and alarming to the sufferer; they arise from abnormal innervation, and are part of the penalties we pay for our present state of organization. We could enjoy nothing if we could not also suffer; and the blush of sensitiveness, the quickened pulse of affection, are paid for by the throb of anxiety, and the fatal inhibition of the heart's action due to overwhelming emotion. Most of these cases, however, own a much more ignoble origin : a flatulent distention of the stomach, a crapulous dyspepsia, the abuse of alcohol and tobacco, &c, are frequent sources of nervous heart trouble, so frequent that in some parts where young men most do congregate the tobacco-heart especially is quite a proverbial ailment. Overwork, worry, or excess of any kind is sufficient to bring on heart trouble of this character, as we can readily understand when we reflect that the heart does about one-fifth of the whole mechanical work of the bodya work equivalent to raising its own weight over 13,000 feet an hour; that it takes its rest only in short snatches as it were, its action as a whole being continuous; and that it must necessarily be the earliest sufferer from any improvidence as regards nutrition,mental emotion being in this respect quite as potential a cause of constitutional bankruptcy as the most violent muscular exertion. Fortunately, to a skilled physician there is no difficulty of determining the true nature of these cases, and they are all more or less amenable to appropriate treatment. Syncope, or fainting, is an affection somewhat similar to those just described; it essentially consists /n an emotional inhibition of the cardiac systole, so that the blood pressure within the brain falls below that necessary for the maintenance of consciousness; as the heart's action fortunately does not in these cases entirely cease, the best plan is to favour the flow of blood to the head by maintaining the sufferer with a lowered and slightly depending head until the effects of the momentary inhibition have passed off. The inflammatory affections of the heart, Carditis, Endocarditis, and Pericarditis are most important and serious affections, but their history and treatment are more suited for a work on practice of physic, in any of which full information regarding them may be found. They are mainly rheumatic and gouty in character, and they are to be regarded as varieties of these diseases ; the mere fact of their affecting the heart is of but little consequence as to their immediate result, however important it may by and by become from the valvular lesions to which they so often give rise. There are but few exceptions to this rule, and amongst them are those rare cases in which acute endarteritis blocks the coronary vessels and gives rise to fatal angina. Fatty Degeneration of the heart, which bulks so largely in the popular mind as a cause of sudden death, is an almost hypothetical lesion of most infrequent occurrence, probably never found apart from disease of the coronary arteries, impossible of diagnosis, and very rarely of itself proving suddenly fatal. (G. W. B.)