Clinical Interpretation Of Pulse Tracings


Categories: Uncategorized
Sources: Disturbances Of The Heart

A moment may be spent on clinical interpretation of pulse tracings.

It has recently been shown that the permanently irregular pulse is

due to fibrillary contraction, or really auricular fibrillation--in

other words, irregular stimuli proceeding from the auricle--and that

such an irregular pulse is not due to disturbance at the

auriculoventricular node, as believed a short time ago. These little

irregular stimuli proceeding from the auricle reach the

auriculoventricular node and are transmitted to the ventricle as

rapidly as the ventricle is able to react. Such rapid stimuli may

soon cause death; or, if for any reason, medicinal or otherwise, the

ventricle becomes indifferent to these stimuli, it may not take note

of more than a certain portion of the stimuli. It then acts slowly

enough to allow prolongation of life, and even considerable

activity. If such a heart becomes more rapid from such stimuli, 110

or more, for any length of time, the condition becomes very serious.

Digitalis in such a condition is, of course, of supreme value on

account of its ability to slow the heart. Such irregularity perhaps

most frequently occurs with valvular disease, especially mitral

stenosis and in the muscular degenerations of senility, as fibrosis.



Atropin has been used to differentiate functional heart block from

that produced by a lesion. Hart [Footnote: Hart: Am. Jour. Med. Sc.,

1915, cxlix, 62.] has used atropin in three different types of heart

block. In the first the heart block is induced by digitalis. This

was entirely removed by atropin. In the second type, where there was

normal auricular activity, but where the ventricular contractions

were decreased, atropin affected an increase in the number of

ventricular contractions, but did not completely remove the heart

block. He adopted atropin where the heart block was associated with

auricular fibrillation. The number of ventricular contractions was

increased, but not enough to indicate the complete removal of the

heart block.



Lewis [Footnote: Lewis: Brit. Med. Jour., 1909, ii, 1528.] believes

that 50 percent of cardiac arrhythmia originates in muscle

disturbance or incoordination in the auricle. These stimuli are

irregular in intensity, and the contractions caused are irregular in

degree. If the wave lengths of the pulse tracing show no regularity-

-if, in fact, hardly two adjacent wave lengths are alike--the

disturbance is auricular fibrillation. Injury to the auricle, or

pressure for any reason on the auricle, may so disturb the

transmission of stimuli and contractions that the contractions of

the ventricle are very much fewer than the stimuli proceeding from

the auricle. In other words, a form of heart block may occur.

Various stimuli coming through the pneumogastric nerves, either from

above or from the peripheral endings in the stomach or intestines,

may inhibit or slow the ventricular contractions. It seems to have

been again shown, as was earlier understood, that there are

inhibitory and accelerator ganglia in the heart itself, each subject

to various kinds of stimulation and various kinds of depression.



Both auricular fibrillation and auricular flutter are best shown by

the polygraph and the electrocardiograph. The former is more exact

as to details. Auricular flutter, which has also been called

auricular tachysystole, is more common that is supposed. It consists

of rapid coordinate auricular contractions, varying from 200 to 300

per minute. Fulton [Footnote: Fulton, F. T.: "Auricular Flutter,"

with a Report of Two Cases, Arch. Int. Med., October, 1913, p. 475.]

finds in this condition that the initial stimulus arises in some

part of the auricular musculature other than the sinus node. It is

different from paroxysmal tachycardia, in which the heart rate

rarely exceeds 180 per minute. In auricular flutter there is always

present a certain amount of heart block, not all the stimuli

reaching the ventricle. There may be a ratio of auricular

contractions to ventricular contractions, according to Fulton, of

2:1, 3:1, 4:1 and 5:1, the 2:1 ratio being most common.



Of course it is generally understood that children have a higher

pulse rate than adults; that women normally have a higher pulse rate

than men at the same age; that strenuous muscular exercise,

frequently repeated, without cardiac tire while causing the pulse to

be rapid at the time, slows the pulse during the interim of such

exercise and may gradually cause a more or less permanent slow

pulse. It should be remembered that athletes have slow pulse, and

the severity of their condition must not be interpreted by the rate

of the pulse. Even with high fever the pulse of an athlete may be

slow.



Not enough investigations have been made of the rate of the pulse

during sleep under various conditions. Klewitz [Footnote: Klewitz:

Deutsch. Arch. f. klin. Med. 1913, cxii, 38.] found that the average

pulse rate of normal individuals while awake and active was 74 per

minute, but while asleep the average fell to 59 per minute. He found

also that if a state of perfect rest could be obtained during the

waking period, the pulse rate was slowed. This is also true in cases

of compensated cardiac lesions, but it was not true in decompensated

hearts. He found that irregularities such as extrasystoles and

organic tachycardia did not disappear during sleep, whereas

functional tachycardia did.



It is well known that high blood pressure slows the pulse rate; that

low blood pressure generally increases the pulse rate, and that

arteriosclerosis, or the gradual aging of the arteries, slows the

pulse, except when the cardiac degeneration of old age makes the

heart again more irritable and more rapid. The rapid heart in

hyperthyroidism is also well understood. It is not so frequently

noted that hypersecretion of the thyroid may cause a rapid heart

without any other tangible or discoverable thyroid symptom or

symptoms of hyperthyroidism. Bile in the blood almost always slows

the pulse.





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