aperture for the transit of the blood. Fig. 14 represents a section of the aorta close to the ossified semilunar valves, and also the great diminution of the valvular orifice. Diseases of the Mitral Valve.-Sometimes this valve become so thickened, and its aperture so much constricted, as not to permit the blood of the left auricle to pass freely into the left ventricle. This condition of the mitral valve often accompanies a diseased state of the aortic valves. In twenty-nine cases of valvular disease, examined by Forgeot, in nine the aortic valves were alone affected, in ten the mitral, and in the remaining ten both aortic and mitral. When the mitral valve is alone diseased, and its aperture contracted, there must not only be a diminution in the stream of blood which enters the left ventricle, but when this valve does not close accurately, there must also be, on the ventricle contracting, a regurgitating stream of blood from the ventricle into the auricle. A change will therefore necessarily take place in the second sound. In proportion as the vital stream into the left ventricle is lessened, so must the circulation through the whole arterial system be diminished, and the left auricle and pulmonary veins will become congested and dilated from the regurgitated blood. A young countryman suffered from great difficulty of breath- case. ing and occasional hæmopto. The "saw sound" was very remarkable; and for some months previous to his death, he was himself in the habit of hearing a noise when in bed, like the From M. barking of a dog, as if at a neighbouring farm-house. After death, water was found in the left chest, large portions of the lung apoplectic, and the left auriculo-ventricular orifice contracted, its diameter not being larger than the trunk of the common carotid artery. Fig. 15 represents a section of the left auricle, showing the diseased mitral valve and the contracted auriculo-ventricular orifice. Forgeot. Fig. 15. Diseases of the Tricuspid Valve.-The diseases of the valves of the pulmonic are much less frequent than those of the systemic heart. "Of twenty-nine cases of valvular disease, the tricuspid was found changed only in one case, and in none was the semilunar valves of the pulmonary artery detached." It appears, indeed, that the acute or inflammatory affections attack chiefly the left heart, while the right is more the seat of chronic ailments. In a former part of this work I pointed out at some length the difference in the structure and functions of the two hearts, especially of their auriculo-ventricular valves; that valve in the systemic heart completely preventing any regurgitation of the blood into the auricle on the contraction of the ventricle, whilst the valve of the pulmonic heart is so constructed, that when the ventricle is distended, and its walls forced to yield beyond a certain limit, the valvular aperture is then widened, and a free communication established between the auricle and the ventricle. Hence when that portion of the endocardium, the duplicature of which forms the tricuspid valve, becomes thickened, and the parietes of the right ventricle are so much thickened that they cannot sufficiently yield to permit the blood to regurgitate into the auricle, the valve then becomes unable to perform the function of a "safety-valve," for which purpose it See page 110. is assigned; and various irregularities arise in the venous Symptoms. circulation. An interruption to the circulation in the left heart being Symptoms. characterized by changes in the arterial circulation, a derangement in the venous system is equally characteristic of a disturbance in the circulation of the right heart. The congested state of the pulmonary vessels causes a difficulty and oppression in respiration, and the turgescence of the veins of the head renders the intellectual powers sluggish and inert; the portal system also becomes turgid, -a condition which is frequently relieved by the hæmorrhoidal flux. the impulse, The changes in the currents of the blood caused by a diseased Changes in tricuspid valve, produce changes in the heart's impulse, the congested state of the right ventricle which accompanies the valvular disease increasing the force of the ventricular contractions, which increased action must influence the circulation in the pulmonary artery; and therefore we find that it is only in diseases of the systemic heart that changes take place in the arterial pulse. and in the When the passage of the blood from the right auricle to the ventricle, or when the regurgitation of the blood is impeded, the sounds. second sound of the heart is changed, assuming different characters according to the condition of the tricuspid valve, and likewise of the surrounding parts. In such complicated cases various alterations must necessarily take place in the currents of the blood, and consequently in the sounds of the heart, such as we cannot suppose could be discriminated by the human ear. With this impression, we are compelled to doubt the accuracy of many of those signs that have been pointed out as appertaining to particular alterations in the heart's Difficulties of the diagnosis. apparatus; and I am inclined to suspect that some of those physical signs, described with so much pedantic accuracy, have not always been the result of actual observation, but the offspring of fertile imaginations,-an opinion corroborated by the numerous errors in diagnosis made by those who place their chief reliance upon physical signs. When we contemplate the great number of the organic diseases of the heart, their various stages, their duration, the numerous tissues, the different portion of each tissue which may be affected, and their combinations with the diseases of other organs, we need not indeed be surprised at the difficulty in distinguishing the organic diseases of the heart from one another. The difficulty is still further increased when we consider that there is scarcely one symptom of those organic diseases, physiological or anatomical, which is not to be met with in the functional diseases of the central organ. Nevertheless, an accurate knowledge of the physiological and anatomical symptoms, along with the history of the disease, will in many instances enable a correct opinion to be formed of its nature and general character-an opinion of far more importance as regards the treatment that should be adopted, than any remedial means suggested merely from a knowledge of some minute changes which may have taken place in the structure of the organ. How much more rational would a system of treatment be in a case of gouty affection of the heart, founded on the principle of treating gout generally, than based upon the knowledge of a disease of any particular portion of the serous membrane of the heart. These remarks strictly apply to the diseases of the endocardium, as there are but few symptoms which can be said properly to belong to each of them. The only step which can with confidence be taken to distinguish a disease of the lining See page 484. membrane of the heart, is to determine whether it be the endocardium of the pulmonic or of the systemic heart. Chap. viii. Treatment. As regards the treatment of the organic diseases of the endocardium, I have little to add to what has been already said when considering "The Treatment of the Diseases of the Heart in general," and also to the observations that have been made on the treatment of the inflammatory affections of the endocardium. As it is extremely probable that more or less inflammation may, during the progress of the organic changes of the endocardium, occasionally supervene, the presence of such inflammation should always be taken into consideration when any system of treatment is adopted; and my impression is, that the benefit so often derived from the preparations of iodine, colchicum, and iron, in this class of ailments, is produced by the influence of these medicinal substances on the arthritic and rheumatic inflammations which accompany the changes in the structure of the valves, and also in promoting the absorption of the lymph that has been effused on their surface and on the subserous cellular tissue. Besides the use of such remedies as may subdue any inflammatory condition of the endocardium, all those means should be employed which diminish the vigour and irritability of the heart, compatible with the functions of life. For this purpose neurotics cautiously administered may be had recourse to; but serious consequences follow when that class of medicines are given in too large doses doses sufficient to diminish so much the power of the heart, that when from the mechanical obstruction to the circulation caused by diseased valves, the heart is unable to circulate the blood. It is under these circumstances that fatal effects have arisen from the injudicious use of digitalis, hydrocyanic acid, and chloroform. The During one of the paroxysms of syncope, so frequent in those suffering from diseases of the lining membrane of the heart, the heart having then become congested and unable to propel the blood, the abstraction of a small quantity of blood from a vein, as the external jugular, may be employed; which, along with the application of stimuli to the sneiderian membrane and cutaneous surface, will assist the heart to carry on the circulation. vital element must, however, be in such cases taken away with much caution; for, as I observed when considering the effects of neurotics, if more blood happens to be removed than is consistent with the continuance of the action of the heart, life may be instantly extinguished. Analogous to the effects of blood-letting, is dry-cupping on the Page 517. |