While mitral regurgitation is the most frequent, it is also the most hopeful of all the valvular lesions, and is also the most tractable when comulications begin to appear. James K. Crook (N. Y. Med. Jour., June 19, '97).
Pathology. — The diseased valve pre sents the changes already described un der the head of CHRONIC ENDOCARDITIS. The edges of the valve-segments and of the chorda; tendinem to which they are attached are frequently more or less ad herent one to another. In advanced stages the valvular orifice may be trans formed into a rigid, calcified ring. The mechanical effects of mitral regurgita tion are as follow:— During systole blood escapes backward through the valve into the left auricle, which cavity, therefore, receives blood both from normal sources and from this new abnormal one. Consequently the left auricle becomes dilated, and, as a consequence of the new demands made upon it, hypertrophied, so that its walls may be three or four times the normal thickness. Moreover, the left ventricle receives with each diastole, not only its normal quantity of blood, but an abnor mally great amount from the dilated and hypertrophied left auricle; so that it also becomes dilated and hypertrophied. As the valve-lesions become aggravated, or the strength of the left auricle dimin ishes, the flow of blood from the pul monary veins into the left auricle be comes impeded and the whole pulmo nary circuit congested, thus putting a strain upon the right ventricle. It is the hypertrophied right ventricle which is the main factor in preserving a normal flow of blood in case of mitral regurgita tion. At last the right ventricle fails,— dilates; the tricuspid valve becomes rela tively incompetent; the right auricle is embarrassed, and finally the systemic circulation becomes congested.
Patients with mitral regurgitation be fore the advent of the subjective symp toms may be seen to be slightly cya notic, and young subjects are apt to have clubbing of the ends of the fingers. As compensation fails, the lungs become congested and oedematous and undergo brown atrophy; the liver, spleen, and kidneys present the lesions of passive congestion, the lower extremities begin to be cedematous, and finally generally dropsy and orthopncea appear.
Prognosis.—Mitral regurgitation may exist for years without subjective discom fort, particularly if the patient escapes any great nervous or physical stress in life. Moreover, when compensation is impaired, judicious treatment will re peatedly restore the patient to a state of comfort. Finally, of course, the em barrassment cannot be alleviated and death ensues; but death is apt to be gradual rather than sudden.
Treatment. — With regard to treat ment, much which is applicable to this subject has already been detailed in the article upon DILATATION OF THE HEART, and other considerations will be discussed at the end of the section on VALVULAR DISEASES.
Mitral Stenosis.
Mitral stenosis is a change in the mitral valves which impedes the normal flow of blood from the left auricle into the left ventricle.
Symptoms.—Many individuals present this lesion without being conscious of ill health. They may experience a certain amount of shortness of breath upon ex ertion, but do not suspect the existence of cardiac mischief. Some patients are . of a tolerably fresh complexion and do not suggest the idea of cardiac difficulty, but rather of chlorosis; such patients, so far as the writer's experience goes, are rather slight and undersized. The great majority of sufferers are women. Some cases are supposed to be congenital, but this must be exceptional. As compen sation fails, we have the usual train of cardiac symptoms, with the difference that pulmonary engorgement, bronchitis, passive congestion of the lungs, orthop ncea and hmnoptysis are more common with this than with other valvular lesions because of the direct way in which it impedes the pulmonary circuit.
Diagnosis.—As already stated, the dis ease may be unsuspected until a phys ical examination is made. Upon in spection of the chest, we may observe the apex-beat, displaced slightly to the left. The lower part of the sternum and the apex region may be somewhat promi nent in children, and an impulse may be seen with the systole in the fourth and fifth left space, due to the hypertrophied right ventricle.