Bradycardia

Categories: Uncategorized
Sources: Disturbances Of The Heart

The first decision to be made is what constitutes a slow pulse or

slow heart. A pulse below 58 or 60 beats per minute should be

considered slow, and anything below 50 should be considered

abnormally slow and a condition more or less suspicious. A pulse

from 45 to 50 per minute occasionally occurs when no pathologic

excuse can be found, but such a slow rate is unusual. Before

determining that the heart is slow, it must f course be carefully

examined to determine if there are beats which are not transmitted

to the wrist; also whether a slow radial rate is not due to

intermitence or a heart block. Auricular fibrillation, while

generally causing a rapid pulse (though by no means all beats are

transmitted to the peripheral arteries), tray cause a slow pulse

because some of the contractions of the heart are not transmitted.



While any pulse rate below 50 should be considered abnormal and more

or less pathologic, still a pulse rate no lower than 60 may, be very

abnormal for the individual. For athletes and those who work hard

physically, a slow pulse is normal. Such hearts are often not even

normally stimulated by high fever, so that the pulse is unusually

slow, considering the patient's temperature, unless inflammation of

the heart has occurred.



Some chronic diseases cause a slow pulse; this is especially true of

chronic interstitial nephritis. In fact, it may be stated that any

disease or condition which increases the blood pressure generally

slows the pulse, unless the heart itself is affected. This is true

of hypertension, of arteriosclerosis, of nicotin unless the heart

has become injured, and often of caffein, unless it acts in the

individual as a nervous stimulant. Chronic lead poisoning causes a

slow pulse on account of the increased blood pressure.



A slow pulse may occur during convalescence from acute infections,

such as typhoid fever and pneumonia, and sometimes after septic

processes. While it may not be serious in these conditions, it

should always be carefully watched, as it may show a serious

myocarditis.



While weakness generally and myocarditis, at least oil exertion or

nervous excitation or after eating, cause a heart to be rapid, still

such a heart may act sluggishly when the patient is at rest, so that

he feels faint and weak and disinclined to attempt even the

slightest exertion. In such a condition calcium, iron and strychnin,

not too frequently or in too large doses, and perhaps caffein, are

indicated. Camphor is always a valuable stimulant, more or less

frequently administered, during such a period of slow heart. This

slow heart sometimes occurs after rheumatic fever; it is quite

frequent after diphtheria, and may show a disturbance of the vagi.



Although the prognosis of such slow hearts after serious illness is

generally good, a heart that is too rapid after illness is often

more readily brought to normal by proper management than a heart

which is too slow. Either condition needs proper treatment and

proper management.



It is well recognized that serious, almost major hysteria may be

present and the heart not only not be increased, but it may even be

slowed. The heart in this condition of course requires no treatment.

In cerebral disturbances, especially when there is cerebral

pressure, and more particularly if there is pressure in the fourth

ventricle, the pulse may be much slowed. It is often slowed in

connection with Cheyne-Stokes respiration. It may be very slow after

apoplexy, and when there are brain tumors. It is often much slowed

in narcotic poisoning, especially in opium, chloral and bromid

poisoning. Serious toxemia from alcohol may cause a heart to be very

slow. It is more likely, however, to cause a heart to be rapid,

unless there is actual coma.



A frequent condition causing a slowing of the heart is the presence

of bile in the blood, typically true of catarrhal jaundice. Uremic

poisoning and acidemia and coma of diabetes tray cause a pulse to be

very slow.



Not infrequently after parturition the heart quiets down from its

exertion to a rate below normal. If the urine is known to be free

from albumin and casts, and there are no signs of impending

eclampsia, the slow pulse is indicative of no serious trouble; but

the urine should be carefully examined and a possible uremia or

other cause of eclampsia carefully considered. Sometimes with

serious edema and after serious hemorrhage the heart becomes very

slow, unless some exertion is made, when it will beat more rapidly

than normal. This probably represents a diminished cardiac

nutrition.



The cardiac lesions which cause a pulse to be slow are sclerosis or

thrombosis of the coronary arteries, fatty degeneration of the

myocardium, and Stokes-Adams disease.



It is seen, therefore, that when a pulse is slower than normal, even

below 65 beats per minute, the cause should be sought. If no

functional or pathologic excuse is discovered, it must be considered

normal, for the individual, and, as stated above, even 58 or 60

beats per minute are in many instances normal for men. This is

especially true with beginning hypertension, and may be true in

young men who are athletic or who are oversmoking but are not being

poisoned by the nicotin, as shown by the fact that their hearts are

not rapid, that they are not having cardiac pains, that they do not

perspire profusely, and that they do not have muscle cramps. A pulse

of from 50 to 55 is likely to be seriously considered by an

insurance company in deciding the advisability of the risk, and

below 50 must be considered as abnormal.