SIGNS OF HEART WEAKNESS
It should be remembered that a normal heart may slow to about 60 during sleep, and all nervous acceleration of the pulse may be differentiated during sleep by the fact that if the heart does not markedly slow, there is cardiac weakness or some general disturbance. There is also cardiac weakness if there is a tendency to yawn or to take long breaths after slight exertions or during exertion, or if there is a feeling of suffocation and the person suddenly wants the windows open, or cannot work, even for a few minutes, in a closed room. If these disturbances are purely functional, exercise not only may be endured, but will relieve some nervous heart disturbances, while it will aggravate a real heart disability. If the heart tends to increase in rapidity on lying down, or the person cannot breathe well or feels suffocated with one ordinary pillow, the heart shows more or less weakness. Extrasystoles are due to abnormal irritability of the heart muscle, and may or may not be noted by the patient. If they are noted, and he complains of the condition, the prognosis is better than though he does not note them.
It has long been known that asthma, emphysema, whooping cough, and prolonged bronchitis with hard coughing will dilate the heart. It has not been recognized until recently, as shown by Guthrie, [Footnote: Guthrie, J. B.: Cough Dilatation Time a Measure of Heart Function, The Journal. A. M. A., Jan. 3, 1914, p. 30.] that even one attack of more or less hard coughing will temporarily enlarge the heart. From these slight occurrences, however, the heart quickly returns to its normal size; but if the coughing is frequently repeated, the dilatation is more prolonged. This emphasizes the necessity of supporting the heart in serious pulmonary conditions, and also the necessity of modifying the intensity of the cough by necessary drugs.
In deciding that a heart is enlarged by noting the apex beat, percussion dulness, and by fluoroscopy, it should be remembered that the apex beat may be several centimeters to the left from the actual normal point, and yet the heart not be enlarged.
The necessity of protecting the heart in acute infections, and the seriousness to the heart of infections are emphasized by the present knowledge that tonsillitis, acute or chronic, and mouth and nose infections of all kinds can injure the heart muscle. In probably nearly every case of diphtheria, unless of the mildest type, there is some myocardial involvement, even if not more than 25 percent of such cases show clinical symptoms of such heart injury. Tuberculosis of different parts of the body also, sooner or later, injures the heart; and the effect of syphilis on the heart is now well recognized.