Bradycardia, or persistent slow pulse, is much rarer than the persistent rapid pulse discussed at the beginning of the chapter on tachycardia. Cases are, indeed, sufficiently rare to be medical curiosities. Prof. Clifford Allbutt has called attention to the fact that the status of bradycardia or brachycardia, as Osler (following Riegel because of the analogue tachycardia) prefers to call it, is very different from that of tachycardia. In the latter, especially, in the specific sense of the term, the symptoms occur paroxysmically, endure for a definite length of time and then there is a return to the normal pulse rate. For this, or at least for the condition known as essential tachycardia, there is no well-defined cause and no definite pathological lesion. Bradycardia or brachycardia, however, is usually present as the result of some known physiologic or pathologic condition; it endures as long as the cause continues to act and then ceases, usually not to return unless the same cause gives rise to it again.{343}

There are some cases, however, of slow pulse that cannot be traced to any definite lesion and in which the pulse is much slower at certain times than at others, though without its being possible to trace any definite immediate cause. These cases seem to be physiological analogues of tachycardia. In tachycardia there is an irritation of the accelerator nerves to the heart, in brachycardia of the inhibitory nerves.

Depressed Mental States.—Occasionally the reason for this can be found, though it is rather vague. In depressed mental states, for instance, a pulse between fifty and sixty is common. In people who suffer from periodic fits of depression it is not unusual to find that in the early morning the pulse is not more than fifty-five. I have seen patients who were worrying about their hearts present records of early morning pulse before they got up that were always below sixty. This is probably in a certain number of people quite normal. I remember a series of observations made on the attendants in the Charite Hospital in Berlin in which it was clear that the normal German morning temperature at seven a.m. was below 97 F., while the pulses were always below sixty. A reassurance of this kind is helpful to patients who have acquired the bad habit of taking their own pulse and have been disturbed by finding it so much below what they consider normal.

Illustrative Case.—A number of cases of persistent slow pulse seem to be congenital or produced by some definite pathological lesion, yet do not prove serious for the patient. Some years ago I described one of these cases in a paper read before the Section on Medicine of the New York Academy of Medicine [Footnote 29] and I have had the opportunity to follow it for about fifteen years. Though the patient's pulse is usually below forty and even after a rapid walk does not rise above fifty, she is in reasonably good health and during those years has buried two husbands. When I saw her she was compelled to go up and down stairs frequently and yet did not experience much difficulty. While patients suffering from palpitation would find it impossible, because of the discomfort produced, to make the journeys up and down stairs that she did, she felt only about as much respiratory discomfort as would come to a woman of her size. Her respirations were somewhat hurried—22 to 24 to the minute—but her general health was very good. Her urine was normal, her liver not enlarged, her ordinary organic functions were not disturbed and there was no sign of arterial degeneration.

[Footnote 29: The Medical News, November 10, 1900.]

With the pulse rate as low as this one might expect to find the patient phlegmatic, slow of movement and not readily moved to emotion. On the contrary, she has always been rather nervous and high-strung and inclined to be excitable. Her cardiac condition was first noted just after the first grip epidemic in this country, though her attention was not called to it during the course of the grip. It seems probable that the heart condition was acquired as a consequence of some irritative lesion affecting the inhibitory nerves to the heart that developed at that time. After her heart condition had been discovered she was for a time a skirt dancer and frequently danced for the amusement of her friends. She was always lively and active and after her first husband's death, when it became necessary for her to earn her own living, she was on the stage for a time and danced without any embarrassment of either {344} heart or respiration. As a consequence of running down in weight and general health, owing to conditions since her husband's death, she noticed that dancing proved exhausting to her and she gave it up.

In general, she considered herself quite as capable as any of her friends for the ordinary duties and amusements of life. When I first saw her her digestion had been somewhat disturbed by worries and unsuitable nutrition taken at irregular intervals and this, I think, accounted much more than her heart for her complaint of tiredness on exertion. Later, after her second marriage, when she was in better circumstances, all her symptoms disappeared and even her heart rate rose so that it was seldom below forty, and after exertion always went to fifty. What was needed in her case more than anything was a change of environment, the satisfaction of mind that comes with freedom from worries and the cares of making her own living, and the improvement in digestion due to regular meals of good, simple, nutritious food.

Compatibility with Health and Activity.—The above case is interesting as illustrating mental influence upon such a serious condition as bradycardia. Most people who suffer from it are likely to be over-depressed and this reacts to disturb digestion and also further to disturb the heart itself. What these patients need above all, then, is reassurance with regard to their condition. There are some striking examples in history and in medical literature of bradycardia or persistent slow pulse in persons who are able to accomplish a large amount of work and whose general health and capacity for accomplishment were not at all disturbed by this physical condition. Above all, they were not depressed and did not lack initiative. Napoleon I, whose pulse is said normally to have been about forty, rising during the excitement of battle to fifty, is a typical example. Medical literature records a number of patients with congenital slow pulse without any discernible heart lesion who lived long and successful lives. One of these was a very successful English athlete. The prognosis of these cases is not as bad as it might seem to be and the mental state of the patient is more important than anything else in the treatment.{345}