Definition:—An expansion of the chambers of the heart from actual stretching of the walls, resulting in the enlargement of the entire organ. It will be seen that the distinction between dilatation and hypertrophy is a clear one, as in the latter case the enlargement is due to an actual increase in the amount of structural tissue of the organ. At the same time, it is possible the two conditions may exist together, and a diagnosis calculated to distinguish how far either condition is involved in the enlargement may be impossible. In simple dilatation, the walls do not materially decrease in thickness, but the cavities of the heart are enlarged. In hypertrophic dilatation, as has been defined, the cavities enlarge and the walls increase in thickness. In atrophic dilatation the cavities are enlarged and the walls of the heart become thin until in some cases they seem hardly able to exercise the necessary pressure upon the contained volume of blood.
The amount of dilatation may be uniform or it may involve one of the auricles or one of the ventricles only, or there may be dilatation of all the cavities, but considerable variation as to the amount of dilatation.
Etiology:—Anything that obstructs the circulation persistently will induce dilatation. The commonest cause probably is aortic constriction which directly increases the intra-ventricular pressure and dilates the walls of the left ventricle. The increase of pressure, of course, is neutralized by the compensatory hypertrophy, but the nutrition of the muscular structure of the walls is materially interfered with. The condition is also brought about by excessive muscular exercise, as by athletics, bicycling and mountain climbing and among school children by jumping the rope. The author has observed it among bicyclists who were inordinate cigarette smokers.
The dilatation occurs in many cases where disease has weakened the walls of the heart, which may occur from various forms of exanthematous disease where endocarditis has resulted, or from rheumatism, as also from pericarditis, or myocarditis. The degenerative changes in the structure of the heart result in dilatation. Chronic gastritis or other chronic disorder of the gastro-intestinal tract, if not corrected by appropriate treatment, may be followed by dilatation.
Symptomatology:—The disease may appear with considerable suddenness after extreme muscular exercise, or heart symptoms may appear as a result, after some days or weeks perhaps, have elapsed, when an examination will show dilatation. If the symptoms have not prevented farther exercise, the dilatation may be progressive. Usually the dilatation is insidious and gradual, extending over a considerable period of time. The common symptoms are distress over the heart or in the chest, palpitation readily induced by increased effort, rapidly increasing difficulty in breathing, cold extremities and cold skin. The heart beats with increasing rapidity, and the apex beat is notably feeble. Over the tricuspid valves there is distinct murmur in systole. Venous pulsation in the neck is one of the apparent evidences of this condition. The pulse is feeble, rapid and irregular.
Diagnosis:—When there has been previous inflammation, it is difficult to distinguish between the organic murmurs and those which this condition has induced. With hypertrophy there is increased energy in the heart's action, with dilatation there is feebleness; with hypertrophy there is a slow, full round, regular pulse that resists compression; with dilatation there is a small rapid, soft, feeble pulse, easily compressible; with simple hypertrophy there is cerebral fulness, excitability of the circulation of the brain with throbbing carotids; with dilatation there may be no unusual fulness of the cerebral circulation, or anemia may exist with apparent pulsation in the veins of the neck.
Prognosis:—If the conditions are diagnosed early and all the factors are taken in hand at once, the patient's life may be prolonged many years. The author has under observation a case which was induced by prolonged violent dancing, developing within a short time more than twenty-six years ago. With a full appreciation of the character and danger of the condition a course of life was laid out for the young man which he has carried out with no violation during the entire time. There was no apparent increase in the dilatation for perhaps fifteen years, but during the past ten years the evidences have become slowly more marked and the valvular sounds much more distinct, the dilatation seems to be uniform. The prognosis as to recovery is not good.
Treatment:—In simple cases the use of pure heart tonics which exercise their influence, devoid of any stimulation, are to be selected. The patient must avoid excitement of whatever character, must eat plain, easily digested and highly nutritious food, must control all inclination to anger, and must avoid anxiety and worry. He must be placed in the most favorable environment possible. Agents calculated to produce an improved tone of the nervous system and to encourage the digestion and appropriation of nutrition are all essential.
The Eclectic Practice of Medicine with especial reference to The Treatment of Disease, 1910, was written by Finley Ellingwood, M.D.