Of predisposing causes, the majority are the same as those of which we have spoken in our general remarks on the etiology of neuralgia. A family history of a tendency to the graver neuroses is I believe universal, and, indeed, direct inheritance of angina from father to son, as in Arnold's case, has happened in many recorded instances. A very remarkable fact is the time of life at which the disease originally appears: Walshe says it is rare before the age of fifty, but excessively rare before forty. This is very interesting, as placing angina in the same category with the severe and intractable forms of facial and other neuralgias which are so highly characteristic of the period of bodily degeneration. One may even gather a suspicion, though it goes but a short way toward proof, that the essence of angina is an atrophy either of the cardiac plexus or of the nucleus of the vagus, or of that part of the spinal cord, already mentioned, which seems to be the centre of the major part of the propulsive force of the heart.
On the other hand, there is a fact, even more remarkable than the influence of age, which tells somewhat in a contrary direction. There is a most extraordinary preponderance of males among the victims of angina. Sir John Forbes found eighty males among eighty-eight patients suffering from this disease. On the first blush it would seem natural, indeed almost necessary, to explain this by supposing that, as men take a much larger amount of strong physical exercise than women, they will furnish a much larger proportion of subjects in whom an ill-nourished heart will break down under its work and be seized either with paralysis or cramp (for the two states are, after all, not opposed to each other, but only varying shades of debility.) Upon this theory one would have to believe that the origin of angina was far more peripheral than central, if we are to suppose that spasm is the ordinary condition of the heart during the anginal paroxysm. But we do not know that this is the case; indeed, there are many arguments against it; and at any rate we must suppose that in a considerable number of cases the muscular state is one of relaxation from want of power. And certainly it is infinitely more probable that paralysis or spasm of a muscular viscus should occur as a reflex consequence of neuralgia occurring in a nerve whose central nucleus was closely connected with the motor centre of the organ, than that mere paralysis of the viscus should convey a reflex impression to sensitive nerves which should express itself in the form of acute pain. It must be confessed that the matter hangs in doubt; but the evidence is, on the whole, very strong for the belief that central nervous mischief is the most important element in angina.
Another very important class of predisposing causes of angina is the mental emotions. It is notorious that the disease is one not common in humble life; it chiefly assails the more cultivated class, and especially men who are much engaged in affairs in which great mental anxiety or emotion is mingled with severe toil of intellect. Thus the professional class has always shown a sad predominance in tendency to this disease; a large number of the victims have been found among overworked clergymen, lawyers, doctors, engineers, etc. The various forms of heart-lesion which have been already mentioned must doubtless be considered highly predisposing, when there is already a neurotic susceptibility, more especially those which, like fatty degeneration of the muscular structure, greatly enfeeble the heart's action. I do not believe that these diseases will cause angina in a person who is free from the peculiar nervous susceptibility.
The immediately exciting causes are very various. The most common of all is doubtless some exertion of body, or distress of mind, which at once agitates and embarrasses the heart's action; and, where the tendency to cardiac neuralgia has once declared itself by an actual attack, very slight excesses of this kind will usually suffice to re-excite the paroxysm. Sexual excitement is particularly provocative of the attacks, in the predisposed. But much slighter causes suffice, in those cases where the irritability of the cardiac nerves has become very intense: thus a mere puff of cold air upon the face, and other similar slight peripheral impressions, by acting in a reflex manner, have frequently produced the paroxysm. I have seen an extremely severe anginal attack brought on by the slight shock of the sudden slamming of a door. And it would even appear that some peripheral excitements of a powerful kind may operate with such force as to generate angina in persons who are merely in weak health, but who cannot be supposed to be specially predisposed to angina; it is in this way, I presume, that we must explain the extraordinary occurrence, reported by Guelineau,[10] of an epidemic outbreak of angina, in which numbers of men, belonging to a ship's crew, were simultaneously affected. The men had been badly fed, and their quarters were very unhealthy; but the powerful exciting cause seemed to be the rapid change from a very hot to a very cold climate. Not only were there many cases of severe angina, but other forms of neuralgia, and severe colics, were observed in others of the crew. Among the sources of peripheral irritation which ought to be particularly considered, in relation to angina, are the diseases and injuries which produce powerful irritation of the branches of the trigeminus. Lederer's cases[11] of violent vomiting and cardiac pain, from the operation of pivoting teeth, and Remak's instances[12] of violent palpitation and cardiac distress, produced by disease of the last molar tooth, seem to show that, both through the vagus and the sympathetic, the most powerful reflex action may be produced in the heart and stomach by irritation of the fifth cranial.
Another occasional excitant of angina is an interesting link in the chain of proof that angina is au fond a neuralgia, namely, the malarial poison, which has in a good many well-observed cases distinctly induced the disease.[13] Finally, the occasional influence of excessive tobacco-smoking in producing anginal attacks, in persons not affected with any discoverable organic heart-disease, affords the strongest corroborative evidence of the essentially neurotic character of angina pectoris. M. Beau[14] has recorded many serious, and some fatal, cases from this cause. Probably in both the malarial cases and those induced by tobacco-poisoning the special neurotic tendency existed already.
Diagnosis.—The diagnosis of angina pectoris, in those severe forms with which the popular idea of the disease is chiefly connected, can hardly be a matter of much difficulty. When we see an elderly man lying in a state of deathly collapse, which has suddenly come on, with cold sweats and nearly extinguished pulse, gasping for breath, and complaining of intolerable pain in the chest and arm, and a sense of oppression more dreadful, even, than the pain, we can hardly doubt that the case is angina in its worst form. On the other hand, when a young person, especially a young female, complains even of very severe pain in the cardiac region, together with breathlessness, especially if the heart be palpitating and the face flushed, the diagnosis, though not immediately certain, already very strongly indicates the probability that the case is not one of primary cardiac neuralgia at all. These are extreme instances, however. In more doubtful cases, the following are the principal materials for decision:
| Affirmative Signs. | Negative Signs. |
| 1. Age over forty. | 1. Age under forty. |
| 2. Male sex. | 2. Female sex. |
| 3. Nervous temperament (personal and family) without marked hysteria or hypochondriasis. | 3. Temperament either not nervous at all, or markedly hysterical or hypochondriacal. |
| 4. Existence of arterial degeneration. | 4. No signs of arterial degeneration. |
| 5. Existence of valvular disease of the heart. | 5. No discernible valvular disease. |
| 6. Extension of the pain to one or both arms. | 6. Heart sounds clear and strong. |
| 7. Vivid sense of approaching dissolution. | 7. Pain fixed to one spot and increased or relieved by muscular movements of the painful parts. |
| 8. Pain running round one side, but not extending to shoulder or arm. |
It is scarcely necessary to say that no single one of the above signs is individually of positive worth for the decision, which must be made after a careful review of the comparative arguments, pro and con. The disorders with which angina is most likely to be confused are (1) Myalgia of the intercostal or pectoral muscles; (2) intercostal neuralgia; (3) acute commencing pleurisy. Either of these may very perfectly simulate the more formidable disease, as regards the two elements of acute pain and catching of the breath; but the condition of the circulation, taken together with the consideration of the above named points, will generally decide the question. Especially important is the deep persuasion of impending dissolution, when present, as a positively affirmative symptom.
It should be born in mind that, if we are summoned to a patient's assistance, and have no previous history to guide us, our diagnosis, to be useful, must be rapid; and it is always better to err on the side of angina than in other directions, and to employ remedies boldly in that sense, if there be any reasonable ground for believing the case to be of that nature. A more mature and careful diagnosis may be made when the patient has recovered from the severe symptoms of the paroxysm.