This is the term applied to a slowness of the pulse. It is generally conceded that the pulse must be as low as 40 to the minute before the term bradycardia applies.
Etiology — A slow pulse is characteristic in certain families and in those who have perfect control of themselves and are not easily excited. It may be permanent, paroxysmal or temporary. When permanent, it is frequently dependent upon a structural disease of the brain in which the pneumogastric nerve is irritated, as is seen in traumatism, pachymeningitis and cerebro-spinal meningitis, hydrocephalus and epilepsy. Temporary bradycardia is often observed after typhoid fever, diphtheria, pneumonia, erysipelas, during jaundice and from intestinal toxines. The paroxysmal form appears during depression of the nervous system and disappears as that returns to a normal standard.
Pathology — In many of these cases myocardial degeneration has been found. Of these the fibroid is more frequently met with than the fatty, while sclerotic changes of the arteries of the brain are frequently associated.
Symptoms — The pulse rate is reduced, and during the recurrent attacks, so markedly, that it may be down to five. Giddiness, faintness, unconsciousness and breathlessness are often present in varying degree. Pallor, while not constant, is often observed. The arteries are rigid and tortuous and are often below normal. The area of cardiac dullness is usually increased. If hypertrophy be present, the first sound is long and low; if dilatation be present, it is short and sharp. Dyspnea is common and the Cheyne- Stokes respiration is often present during the paroxysm. The urine is scanty. Cerebral symptoms, differing in the degree of their intensity, are present during these periods of rare pulsation.
Diagnosis — This is based on the permanency of the diminution of the pulse, and the paroxysms of still greater infrequency. This should not be mistaken for those conditions in which there is temporary infrequency of the pulse.
Prognosis — This depends upon the cause; where this is amenable to treatment, the prognosis is good, but when due to some structural lesion it is unfavorable.
Treatment — The general condition of the patient must be improved, and the cause sought out and if possible removed. If dependent upon jaundice it must be corrected, as well as intestinal toxines, tobacco, alcohol, coffee, tea or uremic poisoning.
Cannabis indica — This remedy produces a very slow pulse, but the mental and nervous symptoms are present when it is indicated.
Ascelpias cornuti — The pulse is very slow and the patient is subject to violent nervous headaches, the pain being most marked between the eyes. The headache is often produced by the suppression of a perspiration. There is violent vomiting with soft, yellow, bilious stools.
Digitalis— When this remedy is indicated there is usually some form of organic heart disease. The pulse is slow but may become irregular, or intermittent, and excited by the least movement. There is a sensation as if the heart would stop beating if he moved.
Opium — The pulse is slow and full with depression on the cerebral function, as indicated by the drowsiness and stupor, the respirations are slow, stertorous and puffing.
Paris quadrifolia — This remedy produces a slow but full pulse, especially when due to spinal affections as the result of traumatism. Thinking aggravates the pain in the occiput. The eyes feel large as if the eyelids would not close over them, or as if a thread drew them back into the head.
Excerpted from: Diseases of the Heart by A. L. Blackwood, M. D.