The SYMPTOMS of fatty overgrowth will depend greatly on the degree of infiltration, the state of the muscle-fibres—whether normal or degenerated—and on the presence or absence of coronary atheroma. Many very fat persons enjoy excellent health and have actively beating hearts, which fail them only on severe exertion, when they get out of wind and experience cardiac distress, perhaps palpitation. The pulse is good and the heart sounds are clear. The signs of heart failure (which may be due either to excessive infiltration or secondary degeneration of the muscle, or both combined) in obese persons are generally very marked—breathlessness on slight exertion, amounting oftentimes to dyspnoea; attacks of asthma of a distressing nature coming on without cause or after a full meal; cough, with or without bronchitis; dizziness and pseudo-apoplectic attacks. Sudden death from syncope or rupture of the heart is common. Dropsical symptoms and cyanosis may supervene. The physical signs are those of heart weakness; impulse imperceptible or very diffuse; area of dulness increased, but often hard to delimit, with fat chest-walls and fatty mediastinum; sometimes a soft systolic murmur at apex; radial pulse rapid, weak, and irregular, in some instances very slow.
The DIAGNOSIS of the condition with such a series of symptoms in an excessively stout person can offer but little difficulty.
The TREATMENT in the early stage should be directed to reducing the general obesity, and such persons should be warned against taking too violent exertion or subjecting the heart to unusual strain. Moderate exercise, mental quietude, and careful dieting may do much toward postponing heart failure, which, when established, calls for the treatment which shall be described under Dilatation.
Fatty Degeneration.—An anomaly or disturbance of nutrition in which minute particles of fat accumulate in the protoplasm of the muscle-fibres, and impair the functional activity of the organ.
This is one of the most common of post-mortem conditions, and in mild grades is met with in a great variety of diseases. The fat is a product of the metabolism of the protoplasm of the muscle-fibres, and in a normal state it (or its immediate antecedents) is oxidized; but when either there is increased transformation or reduced oxidation the products accumulate in the protoplasm, and are evident as minute molecules or as distinct fine oil-droplets. The condition of cloudy swelling or parenchymatous degeneration appears in many cases to precede that of fatty degeneration, and sometimes the granules are of such a size, so abundant, and resemble fat so closely that chemical tests alone can distinguish between them.
A practical division of fatty degeneration is into—1, cases in which the process has attacked a normal heart; and 2, cases in which we find it associated with valvular disease and hypertrophic states of the muscular walls.
In the first group we have (a) The degeneration which accompanies the failing nutrition of old age, of wasting diseases, and of cachectic states. (b) The fatty change in the heart-muscle so often a sequence to, or coexisting with, the parenchymatous degeneration of fevers. (c) The extreme fatty degeneration so constantly associated with profound anæmia. (d) Certain poisons, particularly phosphorus; arsenic, lead, and antimony also act in the same way. The slow poisoning by alcohol is a very frequent cause of a gradually fatty degeneration of the heart. And (e) some local causes are important in inducing this change in the previously normal organ. Pericarditis is almost invariably associated with involvement of the superficial myocardium, either inflammatory or degenerative. Disease of the coronary arteries is a frequent and important cause of fatty metamorphosis. When due to the general conditions above mentioned, the affection is widely distributed in the organ; when the result of gradual narrowing of the vessels by atheroma, the distribution is in the regions supplied by the affected vessels.
The second group comprises those cases in which the fatty degeneration involves the muscle-substance in a condition of hypertrophy, and is an important element in inducing the disturbance of compensation upon which so many heart symptoms depend. Here the process may be more local, affecting, for example, the left ventricle chiefly, as in the hypertrophy from aortic valve disease or in association with contracted kidneys, or the right ventricle in chronic lung affections and mitral stenosis. More rarely we find the process confined chiefly to the auricles, but there may be advanced changes of this nature in the hypertrophied left auricle in mitral stenosis. The fatty degeneration of an hypertrophied heart may be induced by any of the general causes above referred to, but there are also special ones to which it is liable. The chronic congestion which accompanies a dilated heart affects the walls of the organ as well, and diminishes the vigor of the coronary circulation. In emphysema and in mitral stenosis, and other diseases which induce a dilated state of the right heart, fatty degeneration, sometimes combined with fibroid change, is, as Jenner pointed out,27 very common. This state of the right chambers also interferes with the proper oxygenation of the blood in the lungs, and so acts in a double way. Degenerative changes in the coronary arteries are specially prone to accompany valvular diseases, on which the majority of cases of hypertrophy depend, and we have here one of the most serious causes of fatty degeneration in this state. And, finally, we see this change in some hypertrophied hearts without being able to ascertain any exciting cause: a nutritive breakdown occurs, of which the fatty degeneration is the expression. Possibly in such cases the trophic nerve-influences may be at fault.
27 Medico-Chirurgical Transactions, xliii.
Defective oxidation, in whatever way brought about, seems the common factor in all forms of fatty degeneration. The process may be almost confined to the heart or be more or less general in the solid viscera and voluntary muscles. The diaphragm is sometimes much involved with the heart, even when the other muscles show no signs of the change. There certainly seems to be a special proneness to fatty degeneration in the heart-muscle which may perhaps be associated with its incessant activity. So great is the need of an abundant oxygen-supply that it early feels any deficiency, and in consequence is the first muscle to show nutritional changes.