Sources: Disturbances Of The Heart
While this terns really signifies irregularity and intermittence of
the heart, it may also be broadly used to indicate a pulse which is
abnormally slow or one which is abnormally fast, a rhythm which is
trot correct for the age, condition and activity of the patient.
Irregularity in the pulse beat as to volume, force and pressure,
except such variation in the pulse wave as caused by respiration, is
always abnormal. While an intermittent pulse is of course abnormal,
it may be caused in certain persons by a condition which does not in
the least interfere with their health and well-being.
As to whether a slow or a more or less (but not excessively) rapid
pulse in any one is abnormal depends entirely on whether that speed
is normal or abnormal for that person. As a general rule the heart
is more rapid in women than in men. It is always more rapid in
children than in adults, and generally diminishes in frequence after
the age of 60, unless there is cardiac weakness or some cardiac
muscle degeneration. The average frequence of the pulse in an adult
who is at rest is 72 beats per minute, but a frequency of 80 is not
abnormal, and a frequency of 65 in men is common; 60 is infrequent
in men but normal, while up to 90 is not abnormal, especially in
women, at the time the pulse is being counted.' It should always be
considered that in the majority of patients the pulse is slightly
increased while the physician is noting its rapidity. Anything over
90 should always be considered rapid, unless the patient is very
nervous and this rapidity is considered accidental. Anything below
60 is abnormally slow. In children under 10 or 12 years of age,
anything below 80 is unusual, and up to 100 is perfectly normal, at
least at such time as the pulse is counted and the patient is awake.
Referring to the first chapter of this book, it will be noted that
many physiologic factors must enter into the production of the
normal regularity of the pulse. The stimulus must regularly begin in
the auricle, must be perfectly transmitted through the bundle of His
to the ventricles, the ventricles must normally contract with the
normal and regular force, the valves must close normally and at the
proper time, the blood pressure in the aorta must be normally
constant to insure the perfect transmission of the blood to the
peripheral arteries and to insure the normal circulation through the
coronary arteries, and the arterioles must be normally elastic. The
nervous inhibitory control through the vagi must also be normal, and
there must be no abnormal reflexes of any part of the body to
interfere with the normal vagus control of the heart.
While the heart beats from an inherent musculonervous mechanism,
nervous interference easily upsets its normal regularity. It may be
seriously slowed by nervous shock, fear or sudden peripheral
contractions, spasm of muscles, or convulsive contractions, or it
may be stimulated to greater rapidity by nervous excitement. It may
be slowed or made rapid by reflex irritations, and it may be
seriously interfered with by cerebral lesions; pressure on the vagus
centers in the medulla oblongata will make it very slow. Various
kinds of poisons circulating in the blood, both depressants and
excitants, may affect the rapidity or the regularity of the heart.
Therefore, if it is decided that a given heart is abnormally slow or
abnormally rapid or is decidedly irregular or intermittent, the
various causes for such interference with its normal activity must
be investigated and admitted or excluded as causative factors.
Many investigations of the rhythm of children's pulses have been
made, and some of the later investigations seem to show that not
more than 40 percent are regular, the remaining 60 percent varying
from mild irregularity to extreme irregularity.
Scientifically to determine the exact character of a pulse which is
discovered by the finger on the radial artery and the stethoscope on
the heart to be irregular, tracings of one or more arteries, veins
and the heart should be taken. Two synchronous tracings are more
accurate than one, and three of more value than two in interpreting
the exact activity and regularity of the heart.