HEART (DISEASES OF THE) 563 congestion due to mitral obstruction. An effect of the persistent pulmonary congestion caused by mitral lesions is an over accumula- tion of blood in the cavities of the right side of the heart, and from this effect follows gen- eral dropsy. Aortic lesions interfere especial- ly with the circulation throughout the arteries of the system ; the immediate effect is to keep the left ventricle over-distended with blood. The regurgitant lesions in this situation render the supply of arterial blood to the heart itself insufficient, and more than any other involve the liability to sudden death. It is a popular impression that all organic affections of the heart involve this liability. This is far from being true; sudden death occurs in only a small proportion of cases. Valvular lesions generally occur as a sequel of acute articular rheumatism. They often take place slowly / and for a long time they are latent as regards ly symptoms of which the person affected is )nscious. Their progress, as a rule, is unat- ided by pain, and in general it is not until icy have induced a certain amount of enlarge- lent of the heart that the evils just referred begin to be apparent. Not infrequently lany years elapse before they give rise to any larked effects. When not a sequel of rheu- latism, they may arise from changes in nutri- ion incident to old age, and they are some- imes due to syphilis. The valves of the heart lay be imperfectly developed, or lesions may jsalt from disease occurring in foetal life. ?hese congenital lesions are oftener seated in 16 right than in the left side of the heart. In considerable proportion of the cases of young children affected with organic disease of the t, the primary lesions are congenital. The diagnosis of valvular lesions has been rendered ^ery complete by means of auscultation. With rery rare exceptions, they give rise to adven- titious sounds, or murmurs, the characters of which, as regards their situation, their trans- mission in different directions, and their rela- tions to the heart sounds, enable the physi- cian not only to determine the existence of lesions, but to localize them, and to distinguish between those which involve obstruction and regurgitation. Moreover, the normal heart sounds are modified in such a way as to afford information of the extent to which the valves are injured by the lesions. Auscultation, in- deed, enables the physician to determine the existence, the seat, and the character of valvu- lar lesions, long before they have occasioned any apparent morbid effects of which the pa- tient is conscious. When valvular lesions have advanced sufficiently to produce obvious symptoms referable to either obstruction or regurgitation, or to both, they will destroy life sooner or later. The duration of life varies within wide limits ; often a great amount of injury is tolerated for a long period. The le- sions are irremediable, and therefore the treat- ment does not embrace recovery as an object ; but much may be done by judicious manage- ment to relieve symptoms, to postpone seri- ous evils, and to prolong life. The more impor- tant of the measures of management relate to a proper regulation of the habits of life as regards diet, exercise, &c. While excessive muscular exercise is to be avoided, such an amount as is taken without discomfort may be highly useful by improving the general condi- tion of the system. While excesses in eating and drinking are hurtful, a deficient alimenta- tion is not less so. In brief, a great end of treatment is to render the system tolerant of the lesions as much and as long as possible, and this end is promoted by such a course of man- agement, hygienic and medicinal, as conduces to the general welfare of the economy. En- largement of the Heart. This is of two kinds, namely, enlargement due to an increase of muscular structure, and enlargement from in- creased size of the cavities. The first is repre- sented by greater weight of the heart, and is called hypertrophy ; the second is distinguished as dilatation, and is represented by augmented volume, without necessarily any increase of weight. But whenever the heart is consider- ably enlarged, the two kinds of enlargement, as a rule, are combined ; and when combined, an important distinction relates to the pre- dominance of either the hypertrophy or the dilatation. Enlargement from an increase of muscular structure, without dilatation, is called simple hypertrophy ; and enlargement solely from increased size of the cavities is called simple dilatation. Enlargement by hyper- trophy is the result of an abnormal growth of the muscular structure ; and the growth of this involuntary muscle takes place, just as voluntary muscles are made to grow, by long continued increased exercise. An immediate effect of obstructive and regurgitant valvular lesions is an undue accumulation of blood in certain of the cavities of the heart ; the organ is thereby stimulated to increased power of action, and in this consists the pathological connection between valvular lesions and hy- pertrophy. But hypertrophy has its limita- tions ; like the voluntary muscles, the muscular structure of this organ can only grow to a certain extent. It is a noteworthy fact that hypertrophic growth of the heart under the circumstances noted, so far from being an evil, is a positive advantage. The muscular strength of the organ being augmented by its muscular growth, it is enabled better to carry on the cir- culation despite the difficulties pertaining to the valvular lesions. In this point of view, hyper- trophy of the heart is conservative or compen- sating. When hypertrophy has reached its maxi- mum, the undue accumulation of blood in the cavities of the heart leads to dilatation ; the walls yield more and more to the distention. Thus, in general, hypertrophy precedes dilatation, the latter taking place after the muscular structure has increased to the extent of its ability to grow. Causes other than valvular lesions may give rise to enlargement by hypertrophy and dilata-
