DISEASES OF THE HEART.

CHAPTER I.

ENLARGEMENT OF THE HEART.

DEFINITION and varieties of hypertrophy and dilatation-Normal dimensions and weight of heart-Enlargement by hypertrophy-Concentric hypertrophy-Symptoms and pathological effects of hypertrophy-Physical signs and diagnosis of enlargement and hypertrophy-Situation and anatomical relations of the heart in health-Alterations in degree and extent of dulness on percussion in hypertrophy-Altered situation and extent of the apex-beat, and abnormal force of impulse in hypertrophy, as determined by palpation— Mechanism of the heart's impulse-Abnormal modifications of the heart-sounds-Diminished extent and degree of the respiratory murmur and vocal resonance within the præcordia in hypertrophy, as determined by auscultation-Results of the clinical study of the heart-sounds in health-Enlargement of the præcordia and abnormal movements in hypertrophy, as determined by inspection-Increased size of the chest, as determined by mensuration-Summary of the physical signs of enlargement of the heart-Summary of the physical signs distinctive of enlargement by hypertrophy-Treatment of hypertrophy-Enlargement by dilatation-Symptoms and pathological effects of dilatationPhysical signs and diagnosis of dilatation-Summary of the physical signs distinctive of enlargement by dilatation-Treatment of dilatation.

ENLARGEMENT OF THE HEART is a term which embraces abnormal increase in the volume of this organ, in its weight, or, as is commonly the case, increase both in weight and volume. Aug mentation of the volume of the heart, and of its weight, gives rise to different forms of enlargement, which, although usually associated, may exist each independently of the other. The heart may exceed the limits of health as regards weight, in consequence of an increased thickness of its walls, the normal bulk being retained. This may and does occur, although, in the vast majority of the cases in which the weight is augmented, the volume exceeds the healthy limits. On the other hand, the bulk of the heart may be abnormally great, the cavities being enlarged, and the thickness of the walls so far diminished, that the normal weight is retained. This form of

enlargement is also of very rare occurrence, the organ generally increasing in weight when its bulk is greater than in health. Abnormal increase of the heart in weight, due to morbid thickness. of the walls of the organ, constitutes the condition called hypertrophy. Abnormal increase of the heart in volume, due to the morbid size of its cavities, constitutes the condition called dilatation. These names, hypertrophy and dilatation, thus denote different forms of enlargement of the heart, presented sometimes separately, but usually together. Each of these two forms of enlargement are subdivided by writers into several varieties, the subdivisions being based on well-marked and important distinctions. Hypertrophy differs in different cases, according to the condition of the cavities, as regards size, associated with it. It exists in some cases without any alteration of the cavities, the latter remaining normal. This variety is called pure or simple hypertrophy. The cavities may be diminished in size below the limits of health. This must be admitted as a variety of hypertrophy, although its existence is denied by some. It has been distinguished as concentric hypertrophy, or hypertrophy with contraction. The variety occurring much more frequently than the others, in fact, that which exists in the vast majority of the cases in which the heart is hypertrophied, is characterized by the coexistence of dilatation to a greater or less extent. This variety is called eccentric hypertrophy, or hypertrophy with dilatation. The other form of enlargement, viz., dilatation, differs in different cases, according to the condition, as regards thickness, of the walls of the heart. Dilatation exists in some cases, the walls retaining their normal thickness. This is called pure or simple dilatation. It is obvious, however, that, in proportion to the dilatation, the heart is hypertrophied, assuming the walls to preserve their normal thickness, inasmuch as the mass of muscular structure and the weight of the organ under these circumstances must be increased. In other cases in which the capacity of the cavities is increased, the thickness of the walls is diminished. In this variety, the weight of the heart may not exceed, and may even fall below, that of health. This is distinguished as dilatation with attenuated walls, or attenuated dilatation. The third variety of dilatation occurs with far greater frequency than either of the other

In the rare instances in which the walls are so attenuated that the weight of the heart falls below the limits of health, the condition is one of atrophy. There is, however, no practical advantage in constituting this a distinct variety of enlargement.

varieties, and is characterized by the coexistence of hypertrophy, well marked, the dilatation, however, being predominant.

These subdivisions, although based on distinctions which are real and important, are somewhat complicated and embarrassing to the student. They are consistent with the different morbid conditions of the heart, as determined by examinations after death; but they are not accompanied by diagnostic criteria, by means of which they may always be discriminated at the bedside during life. A simpler arrangement is clinically more available, and suffices for all practical purposes. We may distribute all cases of enlargement of the heart into two classes, viz., 1st. Enlargement by hypertrophy; and 2d. Enlargement by dilatation. These classes will include, respectively, cases in which the hypertrophy and the dilatation are either simple or predominant. In cases of "enlargement by hypertrophy," the cavities may or may not exceed their normal capacity. Cases in which the cavities are diminished will also fall in this class. If the hypertrophy be neither simple nor concentric, it is included in this class whenever it is proportionately greater than the coexisting dilatation. The symptoms and signs enable the diagnostician to determine, often with positiveness, the existence of hypertrophy, which is either simple, or predominant over a coexisting dilatation; but to discriminate between the cases in which the hypertrophy is simple and those in which it predominates over coexisting dilatation, is a problem in diagnosis by no means easily solved. So in cases of "enlargement by dilatation," the amount of muscular structure may or may not exceed the limits of health. The diagnostic criteria of predominant dilatation are often sufficiently positive; but it is far less easy to decide whether the dilatation be accompanied with hypertrophy or attenuation. Moreover, as regards prognosis and treatment, after the existence and degree of enlargement are ascertained, it is enough to determine which form of enlargement predominates, hypertrophy or dilatation. In treating of enlargement of the heart, I shall follow the simple classification just indicated.

As a point of departure for the study of those affections of the heart which consist of abnormal deviations in size, its normal dimensions and weight are to be considered. The healthy standards in these respects are obtained by measuring and weighing a sufficiently large number of hearts presumed to be devoid of disease. As regards measurements, the diameters and the thickness of the walls are the points which have reference to the affections to be

toient doservers present considerable varat on, which, in

me is of the length, breadth, and depth of the heart as a whole, and

15 Sanlaris or comparison, with reference to the existence of ransverse bameters, the contents of the cavities having been sal. And s. Bees to express the normal averages in dures

treated of in this chapter. The dimensions of the orifices and valves will be considered in connection with lesions in this situation. The researches of Bizot and others show that the volume of the heart varies according to sex and age. It is somewhat greater in the male than in the female, and it increases slowly, but progressively, from infancy to old age. It is to be observed that diametrical measurements after death are liable to be affected by incidental circumstances, by which they are rendered only approxima.ively correct. The degree of contraction varies according to the quantity of blood which the cavities contain at the time of death. Observations show that when death occurs from hemor

cavities are much diminished, and the volume proportionately small; while, on the other hand, if the cavities are distended with

The general remarks just made with reference to the normal volume of the heart, are also applicable to the thickness of the walls; the thickness is greater, as a rule, in males than in females, and it increases with age. It varies, also, according to the contraction of the heart at the time of death, dependent on the amount of blood contained within the cavities, and other circumstances. Hence, measurements here, as with respect to the diameters, in a collection of hearts, furnish results which are only approximations to correctness. Pursuing the same course as in expressing the normal standard of volume, it is approaching near enough to exactness to say that the wall of the left ventricle, at its thickest portion, in middle life, is not far from half an inch in the male, and in the female a fraction less. The thickest part of this ventricle is near its centre. The thickness is less near the base, and still less at the apex. The wall of the right ventricle, at its thickest portion, is a little over one-sixth of an inch, in the male, and in the female somewhat less. The thickest part of this ventricle is near the base, and the thinnest near the apex. The relative thickness of the two ventricles is, thus, in the ratio of 3 to 1. The average thickness of the right auricle is estimated to be about a twelfth of an inch, and of the left auricle somewhat greater.

The average normal dimensions of the heart as a whole, and of different parts of the organ, are important as standards of comparison by which to estimate abnormal changes. Their importance in this respect, however, is less than might, at first view, be imagined. The deviations from these standards, which are embraced within the limits of health, are to be taken into account. The range of normal variation, as regards the volume of the heart and thickness of its walls, is considerable. An addition of an inch or more to the vertical and transverse diameters may not be abnormal. So, a proportionate amount of increased thickness of the walls of the ventricles may be within healthy limits. To determine the line of demarcation between normal and abnormal deviations, is more difficult than to ascertain averages. It is not easy to fix a maximum and a minimum, beyond which the condition is always

of the Heart, Am. ed., edited by Pennock; to the work by Dr. Stokes on Diseases of the Heart and Aorta; and to Bellingham on Diseases of the Heart, Part I., Dub. ed. For results of measurements by Ranking, Gross, and others, Gross's Path. Anat., third edition, and Dunglison's Physiology, eighth edition, may be consulted; see also Traité Clinique des Maladies du Cœur, par J. Bouillaud, which contains measurements by himself and strictures on the researches of Bizot.