Mitral Insufficiency.
Synonyms:—Mitral regurgitation; mitral incompetency.
Definition:—A condition of the mitral valve through a lesion in the mitral leaflets, in which the valve is unable to close the orifice and prevent the return of the blood into the auricle. This may be due to shortening or thickening or other structural change of the segments of the valve which guard the auriculo-ventricular orifice. This defect may also be due to the contraction of the chordae tendineae, which support the leaflets, thus interfering with proper movement of the valve. Calcareous degeneration may also affect the bases of the segments and the tissues of which they are composed, as to materially interfere with the valvular function. A condition of stenosis is also usually present in advanced cases.
Etiology:—This condition occurs most commonly in early adult life, and more often in females than in males. Acute inflammation of the endocardium, either from rheumatism or from other cause, is apt to precede its occurrence, especially if the inflammation is of the ulcerative type, as the ulceration may destroy the chordae tendineae and thus prevent perfect valvular action. In later life the excessive use of alcohol or tobacco, and the presence of chronic blood dyscrasia or syphilis may induce the disease. The condition occurs also as a result of chronic kidney disease, especially Bright's disease, from the influence of which, upon the arterial tension, there is a prolonged increase of muscular strain in the left ventricle, the muscular structure of which may be impaired by the general toxemia and blood impoverishment. In these cases the imperfect action of the valve may be due to a dilatation of the auriculo-ventricular orifice.
Symptomatology:—In the early stages of the disease, while there is yet sufficient compensation and no other complicating disorder, there are but few symptoms upon which we can depend to make a correct diagnosis of mitral incompetency. Among the first of these is a mild form of palpitation, which is induced by a little unusual physical exercise, or by stair-climbing. Occasionally there will be some dyspnoea, which is induced by a temporary pulmonary congestion in rare cases, more especially in those who are enfeebled. There may also be a small amount of pulmonary hemorrhage, which is apt to fix the blame of the condition upon the lungs. As the condition increases all of these symptoms are increased, and there will probably be present a short, sharp cough. A few patients will have remarked that they suffer to an uncommon degree from any exposure to cold; that cold air has a very severe influence upon them. This is due to the susceptibility of the lung structures to congestion through deficient circulation in the capillaries. It is also due to the increased labor this throws upon the heart in distributing the blood through the general capillary circulation, which is more or less contracted by the influence of the cold. Walking in the cold air produces great fatigue with many of these patients in a very short time. While the exact condition can seldom be diagnosed from these symptoms, it is plainly evident that there is a slowly developing disease of the heart structures, as changes in the structure of the finger tips—clubbing—and of the features, with pallor; or a tendency to cyanosis of the lips, or of the ears, are not uncommon.
When the compensatory hypertrophy is no longer sufficient, both subjective and objective symptoms develop rapidly. Disturbances of the digestion and faults of the large glandular organs soon occur, which induce a train of symptoms, which may be attributed to other causes. There may be also increase of the palpitation, with extreme shortness of breath and ultimately the patient will be unable to lie down, because of the difficulty of breathing, and because of pain in the epigastric region, which is often present, sometimes persistently severe. If there has been no pulmonary hemorrhage previously it is more than likely to occur at this time, and with this, mild dropsical symptoms appear.
It will be seen upon examination that there is a diffused apex beat of the heart, which may be forcible in character, but is more likely to be feeble and imperfect, with a greatly enlarged area of dulness. The sound heard at the apex is quite characteristic, which may be well said to be diagnostic in character. A murmur occurs simultaneously with the apex beat, which is soft, but sufficiently loud to be readily distinguished. Later, it may be heard throughout the chest, quite distinctly, of a peculiar quality of sound, which the listener does not fail to recognize after having once heard it. In cases where the pulmonary congestion is severe and there is regurgitation, the pulmonary second sound will be exaggerated.
Diagnosis:—The diagnosis depends upon recognition of the above symptoms, and especially upon the characteristic apex sound. It is important, if possible, to determine whether the condition is due to actual disease of the valve, or to the increase of the lumen of the auriculo-ventricular orifice by dilatation. The latter condition is apt to follow prostrating disease and especially those diseases which influence the muscular structure, resulting in general relaxation, and consequent weakening of the heart muscle, with temporary dilatation. I am confident that I have observed this condition in a number of patients, where the characteristic regurgitant apex murmur was plainly heard during the weakness and by restoring the muscular condition of the patient, and increasing the strength and power of the heart, the valvular action would be sufficient, and the murmur would disappear. The characteristic murmur may also be due to anemia; this must be borne in mind in the diagnosis.
Prognosis:—Age in the patient has much to do with the probable results of this condition. Inflammatory changes of the mitral valves in children, progress rapidly, and a fatal termination is apt to occur usually before the completion of puberty. Those who have passed this stage by extreme caution and a thorough understanding of the seriousness of the condition may be carried over the period of danger until the valve is restored, or heart sounds disappear and a normal condition supervenes. It is necessary with these patients, however, that they exercise carefully until they have reached the period of physical maturity, as violent exercise may induce the return of the symptoms. In patients who are dissipated or have a severe constitutional dyscrasia, the prognosis is unfavorable, and often the progress of the disease is rapid. This is also true when the condition does not occur until late in life, and especially if the individual be somewhat broken down by previous ill health. In all cases the prognosis is more favorable, if there are no inherited tendencies, no blood taints, either inherited or acquired, and no bad habits, and especially if the previous health has been good.
