562 HEART (DISEASES OF THE) in affections proceeding from disturbance of the circulation and nutrition in different organs of the body, more especially the brain. (See BRAIN, DISEASES OF THE.) The phenomena thus produced are treated of by medical writers under the head of embolism, and the study of these phenomena within the last quarter of a century has enlarged in no small degree the boundaries of pathological knowledge. The local effects of endocarditis are also of much importance as laying the foundation for pro- gressive changes, especially in the valves of the heart, constituting what are called valvu- lar lesions. The inflammation in endocarditis is generally limited to the left side of the heart, that is, to the endocardial membrane lining the left ventricle and the left auricle. Like peri- carditis, this is very rarely a primary disease ; and in the great majority of cases it occurs in connection with acute articular rheumatism. It is evidently due to the same internal agency which in rheumatism causes the inflammation within the joints, this agent being a morbid principle in the blood, supposed to be lactic acid. Endocarditis occurs in a much larger proportion of cases of acute articular rheuma- tism than pericarditis. These two diseases are associated whenever rheumatic pericarditis oc- curs ; in other words, the latter affection rarely if ever occurs in rheumatism without the co- existence of endocarditis. The development of endocarditis is attended with little or no pain or other subjective symptoms referable to the heart ; and hence the knowledge of its exist- ence followed the application of auscultation to the study of diseases of the chest. The diag- nosis rests wholly upon physical evidence ob- tained by auscultation. The roughening of the endocardial membrane within the left ventricle causes, as already stated, an adventitious sound or murmur, and the production of this murmur while a patient is under observation constitutes the proof of the presence of the affection. The diagnostic murmur accompanies the first sound of the heart, and is referable to the mitral valve. The immediate danger from endocar- ditis is slight; indeed, there is no immediate danger to life except from the formation within the heart of a clot (thrombosis) of sufficient size to arrest the circulation either within the heart or the large vessels. The liability to em- bolism has been already referred to, but this is seldom if ever directly fatal. The affection, however, is by no means one of small impor- tance, the danger being that valvular lesions may be the result. These lesions, progressively increasing, may at a period more or less re- mote, often after the lapse of many years, oc- casion death. As regards treatment, endo- carditis calls for no active measures. It is im- portant that undue action of the heart be pre- vented as far as possible by enjoining mental and physical quietude, and relieved, if it ex- ist, by soothing remedies. The alkaline treat- ment in cases of rheumatism is preventive to a certain extent of this affection, as it is of peri- carditis. It is probable also that the judicious use of alkaline remedies moderates the inten- sity of the endocardial inflammation, and thereby diminishes its local effects. Carditis, or Myocarditis. Inflammation of the substance of the heart, irrespective of the pericardium and the endocardium, is extremely rare. Sup- purative inflammation, however, sometimes oc- curs, giving rise to an abscess in the walls of the organ or in the septum between the ven- tricles. The pus contained in the abscess may be discharged into the pericardial sac, causing pericarditis, or into the ventricular cavity, causing purulent infection of the blood Cpya3- mia). Induration produced by a morbid in- crease of the tissue which unites together the muscular fibres, is another effect of inflainnm- tion seated in the walls of the organ. There are no means of determining during life the existence of carditis or myocarditis. II. OE- GANIC DISEASES. Th e organic diseases or struc- tural lesions to which the heart is liable relate, first, to the valves and orifices, and second, to the walls of the organ. Valvular Lesions. In the great majority of cases these are seated in the left side of the heart, being either mitral or aortic, or in both the situations indicated by these terms. The changes embraced under the name valvular lesions are various, arising from morbid thickening or attenuation, calcification (formerly called ossification), rupture of valves, &c. The various changes, however, produce their evil results chiefly in two ways, namely, by affecting the valves so as to render them more or less incompetent to perform their func- tions, and diminishing the size of the mitral or aortic orifice so as to produce more or less ob- struction to the passage of blood. The lesions which render the valves incompetent permit the blood to flow backward or regurgitate, and hence they are sometimes distinguished as re- gurgitant lesions. On the other hand, those which diminish the size of the orifices prevent the free passage of the blood in its direct or onward course, and hence they are termed obstructive lesions. Not infrequently the lesions are such as to involve both regurgitation and obstruction at the same orifice. The lesions may be situated at either the mitral or the aortic orifice, or at both orifices ; and in some instances one or both of the corresponding orifices in the right side of the heart, the tri- cuspid and the pulmonie, are the seat of analo- gous lesions. Obstruction of the flow of blood through the orifices within the heart, and re- gurgitation, lead to enlargement of the organ and to various morbid effects in other organs. The effects of mitral lesions relate especially to the lungs. Owing to the congestion of the lungs induced by obstruction and regurgitation at the mitral orifice, the changes in the blood effected by respiration are impeded, whence the sense of want of breath which in certain cases of disease of the heart is the source of great distress. Haemorrhage into the air tubes and into the air cells sometimes results from the
