S INUS ARRHYTHMIAis the periodic accel eration and deceleration of the heart usually associated with respiration, but oc casionally found with digitalis intoxication1 or due to other causes. This paper will dis cuss only the respiratory form of sinus ar rhythmia2 first described in 1847 by Lud wig. Though no textbook on pediatrics or cardiology fails to include a paragraph or two on sinus arrhythmia, there has been surprisingly little information collected on this subject, so that in these brief discus sions some erroneous or inadequately tested impressions have been perpetuated for 50 years.
General
holding eliminated the respiratory form of sinus arrhythmia, while increasing depth of respira tion would exaggerate any sinus arrhythmia.
0thers1215 maintained that the presence of sinus arrhythmia in patientswith rheumatic fever was a favorable indication and that a pathologic importance could be attributed to its absence. However White'6 believed that in elderly persons with arteriosclerosis or heart disease considerable sinus arrhythmia might be found as a distinctly abnormal sign. Luisada'7
has stated that in some cases of rheumatic carditis marked sinus arrhythmia is caused by the rheumatic process. Lukomski18 believed that the increasedsinusarrhythmiahe found
with acute rheumatic feverwas due to injury to the sinus node.
Landtman,'9 using Schlomka and Reindell's formulaforfrequencyindex
(RI.
HISTORICAL REVIEW
Sinus arrhythmia was first studied in the same individuals over a period of years by MacKenzie.3 He noted the relationof sinus arrhythmia to respiration, found it a benign condition,and termed it juvenilearrhythmia because of itsfrequencyin children.Authors's generally agreed that sinus arrhythmia was rarein infancy,graduallyincreasedto reach a
maximum some time between the ages of 8 and 15 years,then decreasedwith increasingage,
and was uncommon in adult life.However Jones'° found sinus arrhythmia common in adult life. Katz and Pick7 defining sinus ar rhythmia as a range (max. —¿mm. cycle length) of 0.16 seconds or more found it present in 8,302 to 100,000 records on about 50,000 pa tients. Lewis4 found that any factor that would increase the pulse rate would abolish sinus ar rhythmia, such as exercise, fever, amyl nitrate or atropine.
Several authors7'9― noted an inverse rela tionship between sinus arrhythmia and pulse rate. Katz and Pick7 also noted that breath
E Pmax.
—¿Pmm.
nP mean
P = cycle length, n = 3)
as a measure of sinus arrhythmia, described thisconditionin 200 normal individuals,in 50 patients with congenital heart disease, and in 50 patientswith acute rheumatic fever.His data (Table I) confirm some of the impressions of the previous mentioned authors. He found no sex difference in pulse rate or sinus arrhyth mia in the age groups he studied, though he did not present the data on which he based his statements.
Etiology
There has been a good deal of theorizing and considerable experimental work on the mecha nism of the respiratory form of sinus arrhythmia. While the mechanism is complex, Wiggers2° believedthatthe threemost importantfactors
were: 1) A centralmechanism—therespiratory
PEDIATRICS, September 1960
ADDRESS: (R.R., Office) 1001 South Broadway Street, Denver 17, Colorado.
402
SINUS ARRHYTHMIA
I. Data and Patterns from Groups of Individuals Followed from
I Month to 23 Years of Age
Age(yr)No.MFFrequency I (%)ndex (R.I.) (u)PulseRate (@)Congenitalheartdisease
Rheumatic heart disease Normals6—10 6—10 0—150 50 5031 22 (?) 2619 26 (?) 247.2 6.1 10.92.9 2.8 5.195 97 14021 22 291— 5 6—10 11—1550 50 5026 23 2724 97 2311.2 13.5 15.13.9 4.8 4.8105 89 7920 26 16 TABLE I
DATA FROM LANDTMAN―
centerdirectlydepressingthe vagal centerto
produce accelerationwith inspiration;2) a re flex mechanism—stretch reflexes from the lungs causing reflex vagal depression; and 3) a reflex inhibition of the inspiratory center by which the affect of 1) is diminished. Also mentioned2' as of possible importance were reflexes in the arch of the aorta and carotid sinus, which lead to slowing of the heart as the result of a rise in pressure.
The central mechanism, first proposed by Traube in 1865 and supportedby many care
ful experiments,was investigatedby Anrep
et al.22 after the reflex mechanism was abolished
by cuttingthe vagi above the lungs.With a preparation where the dog's head was perfused from an independent source, it was found that by altering the respiratory activity by changing the CO2 tension in the blood perfusing the head, the heart rate increased with respiratory activity recorded at the phrenic nerve and de creased with the cessation of activity of the phrenic. Anrep et al.2 also studied the reflex mechanism after abolishing the central mechan ism by supplying the head with blood of low CO2 tension. These experiments on the reflex mechanism showed that the lungs were “¿acon stant source of impulses directly inhibiting the vagal center.―The cardio-accelerator impulses, minimal during deflation, greatly increased with inflation; but with too frequent inflation the phenomenon of adaptationappeared,and cardio-inhibitory impulses could be evoked by severe inflation. Because Anrep and co-workers found the pulmonary reflexes operative after the ligation of the pulmonary veins and arteries of the lung, they concluded that these reflexes could take place without influenceof venous
or arterialblood pressurechanges.
Gross23 related sinus arrhythmia and respira tory ratein 30 healthymales and 30 patients
with cardiac disease. Table II summarizes his results. He concluded that there was an inverse relation between sinus arrhythmia and respira tory rate, and that in cardiac disease the sinus arrhythmia was less than in healthy individuals. The pulse rate changes, however, might have been more important than respiratoryrate changes in decreasing the sinus arrhythmia.
Starr and Friedland24 have mentioned that changes in heartfillinginduced by respiratory movements were the cause of sinus arrhythmia with the slowing occurring during that part of the respiratory cycle in which cardiac output was smallest no matter whether this occurred during inspiration or during expiration. They did not specifically state, however, whether they referred to right or left ventricular out put. (Shuler et
@ showed in unanesthetized
dogs that right ventricular output increased with inspiration and decreased with expiration, while the output of the left ventricle behaved in oppositefashion.)Also an increasein venous pressure associated with inspiration can in crease the heart rate through the Bamnbridge reflex.2°
Manzotti27 concluded that sinus arrhythmia was probablyassociatedwith changes in blood flow and blood pressure mediated by barore ceptersin the aorticarch and carotidsinus. Bard28 mentions that the slowing of the pulse followed the highest systolic pressure which occurred at the end of inspiration and probably was the resultof increasedstimulationof the pressoreceptors in the carotid sinuses and aortic arch.
Max. Cycle Length
Mm. CycleLength
@ Pulse Rate State
Range
P max. —¿P mm.
404 SINUS ARRHYTHMIA
TABLE II
I)ATA FROM Gi@os'@2'
Range, R.I.,and pulsewere measured over 10 beats.
(%)Healthy males.08
.04 .09710
5.8
11 .775
88 73resting
hyperventilation inspir. apneaCardiac
disease.046
.03
.055.9
4.3 7.178
88 79resting
hyperventilation inspir. apnea
the lungs reflexly causing acceleration of the heart by decreasingvagal tone,3) the Bain bridge reflex, and 4) changes in blood flow, cardiac output, or blood pressureassociated with respiration.
PRESENTSTUDY
I. Group Data and Individual Patterns.
Methods and Subjects
As partof the studiesof the Child Research Council,electrocardiogramshave been taken at regularintervalson a group of childrenand
young adultsover a number of years.The elec trocardiograms were taken at rest at various times during the day. The individuals have livedin Denver most of theirlives,have been in average good health, and have pursued the usual activities for their age. The records on any individual who had definite or possible rheumatic fever or any chronic disease were
excluded. Of the 199 healthy individuals
studied (96 girls and 103 boys), 43 have been followed for more than 20 years, 57 from 15 to 20 years,33 from 10 to 15 years,34 from 5 to 10 years,26 from 1 to 5 years,and 6 have been followed less than 1 year.
In this study on sinus arrhythmia 4,096 elec trocardiograms from 199 individuals were used in constructing percentiles for pulse rate, range (max. cyclelength—mm.cyclelength)and fre quency index (R.I.). Schlomka and Reindell's formula for frequency index
(R.I.
was used, but n was set equal to 1 rather than 3. About an 8-inchstripof Lead II was used for allthese measurements. All individualre cords which showed either a progressive in crease or decrease in rate were discarded as representing changes in activity rather than
respiratory arrhythmia.
Percentiles for boys and girls for the above
measurements were determined at 52 time periods between birth and 27 years.In the charts(Figs.1-5)the percentileshave been 3-point smoothed 2 times, thereby obtaining smoother curvesbut losingvaluesat 1 month, 2 months, 24 @earsand 27 @@earsand over.
To investigatethe change in sinusarrhyth mia for an individual at a particular time
with increase in pulse rate, recordings were
used of Lead II on 21 individualstaken before and after4 minutes of a given amount of ex
ercise on the bicycle ergometer (4200 ft lb/
mm/rn2).
For the 81 individuals(39 boys and 42 girls) with records available from at least 8 years of age through 17 years (with 14 to 25 years of records on each individual), values for pulse
rate, range, and frequency index were graphed
with the group percentiles as a reference. The individuals were individually rated by two ex aminers separately for pulse rate, range (into 3 groups), and P-R interval29 (into 5 groups). There were only 18 differencesin the 246
ratings and no difference was more than one
group.For the 18 differencesalternatemeasure
ments of the two examinerswere taken.
Pulse Rate
RESULTS
nP mean
220
200
180
—¿ boys
—¿ girls
•¿max. and mm. for total group
similar until the age of about 6 years (Fig. 1). After this, the decline in pulse rate in boys is slightly more rapid than the decline in girls until the age of about 17 years. After this age, there is little change in the values for the different percentiles; the girls have a pulse rate about 5 beats per minute faster than boys for each percentile. Maximum and minimum values are included in Fig ure 1 to indicate even in this relatively small group the extent of variation in healthy chil dren.
Range
Figure 2 shows the percentilesfor range
(max. cycle length —¿mm. cycle length). Defining sinus arrhythmia as present when the range is 0.16 seconds or more, sinus arrhythmia is found under a year of age in
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
AGE IN YEARS
Fic. 1. Percentile values of pulse rate for boys and girls from 3 months to 22% years. The percentiles indi
cated on the right, determined from 1,980 electrocardiograms on 96 girls and 2,116 electrocardiograms on
103 boys,have been 3-point-smoothedtwice.
both sexes. The range increases from birth to a maximum between 8 and 12 years, con siderably before the pulse slows to constant values. The girls maintain fairly steady val ues after 6 years, but for the boys the values for the 75th and 90th percentiles decrease steadilyafter the age of 11 years showing
lower ranges than corresponding percentiles for girls. After the age of 5 years, over 25% of the boys and girls show a range of 0.16 seconds or more. In Figure 2 the range is
plottedfor two boys (No. 109 and 83).
Frequency Index
83
109
406 SINUS ARRHYTHMIA
—¿ boys
girls
•¿max. for total group .64
.56
.52
siB
.44
•¿40
.36
.32
.28
.24
@ 20
C
- 16
LU
0 z .12
@ @08
.04
.00
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
AGE I N YEARS
Fic. 2. Percentile values of range (max. cycle length—mm. cycle length) for boys and girls from 3 months to 22%years. The percentilesindicated on the right have been 3-point-smoothedtwice. Individual pat
terns on two boys (No. 83 and No. 109) are presented. by a definite decrease at 12 years, which
continues until 18 years. Pulse Rate and Range
The records of the 81 individuals already described were examined to see if there was a relation between pulse rate and range. When the pulse rate was over 140, the maxi mum difference in cycle length remained below 0.10 seconds, but for other values of the pulse rate there was a wide variation in the range. Usually, however, a decrease in pulse rate was associated with an increase in range and vice versa.
The results from the tracings of two indi viduals before and after exercise are shown in Table III. The girl whose values are shown in Table lila illustrates a common pattern, though most individuals do not
show such a close relationship between pulse rate and sinus arrhythmia. In Table Ilib are the results for the only individual who showed an increase in sinus arrhythmia after exercise.
Pulse Rate, P-R Interval and Range
The ratings for range and pulse rate, and range and P-R interval were compared for each of the 81 individuals described above (Table IV).
Max. Cycle Length —¿Pulse
Rate Jim. Cycle LengthRI.Range
LU
z
>-U
z
LU
a
LU
TABLE III
(%)
a) A.M., Female, 11 yr
Before exercise 1 minute after exercise 3 minutes after exercise
5 minutes after exercise
b) R.S., Male, @27yr
Before exercise
1 minute after exercise 3 minutes after exercise
5 minutes after exercise
78 128 101
94
66
124 103
99
.40
.02
.09
.13
.10 .03
.04
.16
52.5
4.2 15.1
21.0
11.2 6.2 6.9
26.3
boys -. girls
•¿max. for total group /0
72 68 64 60
56
52 48
44
40
36 32 28
24
20
16
12
8
4
90th
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
AGE IN YEARS
/ range \
Fic. 3. Percentile values of frequency index ( X 100 for boys and girls from 3 months \mean cycle length /
Sinus Arrhythmia(Range)LowMiddieHigha)Pulse
Rate
Low
Middle High0
11 167
18
815
6
0b)P-R
Interval Low
Low middle
Middle
High middle
High2
2
12
7
56
8
7
5 65
4
7
3
2
24 22 23
SINUS ARRHYTHMIA 408
180 170
160 LU
150
LU @1)
-J
a- 130
120 110
100
LU
z
.<
Siblings
In the group of 81 individualsthere are
10 pairs of siblings of the same sex, 3 pairs of siblingsof the opposite sex,2 groups of
3 siblings of the same sex and 1 group of
TABLE IV
72
.68
—¿ gels
.64
1 60
56 .52 .48
.44
.40
.36 .32 .28 .24 .20 @
8)
.16 .@ .12
.08 @
.04
AGE IN YEARS
Fic. 4. The pulse rate and range of one girl is compared with the percentiles for these nieasurements determined from 1,980 electrocardiograms on 96 girls. Generally the pulse rate and range vary in
opposite directions.
siblings with 2 boys and 1 girl. These sib lings showed a great similarity in pulse rate, range and P-R interval. One set of siblings is shown in Figure 5 (No. 9 and 94) to illus trate this similarity. Though they show great fluctuation in range, both girls have high values. In pulse rate they tend to have below average values, and in P-R intervals both have quite low values.
Pulse Rate
DISCUSSION
90
@ 80
70
@ 60
50
0123456789 AGE IN YEARS
60 .56
.52
48
44
40
36
32 28
24
20
16
12
08
04
0
Fic.. 5. Pulse rate, range and P-R interval of two sisters are illustrated in comparison with the group data. The girls show similar percentiles for these three physiologic
measurements.
4 >
z
after 16 years, while individual No. 83 clearly does not, showing much higher values after adolescence. In the 81 individ uals with records from at least 8 years through 17 years, only one boy and one girl do not show a range of 0.16 seconds or more on at least one occasion. Of the 118 other individuals in this study followed from 1 to 18 years, 49 of the 64 boys, and 34 of the 54 girls, show a range of 0.16 seconds or more at some time.Nine of the 15 boys, and
15 of the 20 girls, who do not show this much range are under 7 years of age. This tends to confirm MacKenzie's statement3 times during the day the pulse rates we
have obtained at all ages are higher than those obtained under basal conditions.32 Range
The individual charts of range for two boys are illustrated in Figure 2 because the boys as a group show, for the higher per centiles, the decrease in range after ado lescence described by many authors.3'4'7'9'19 There is no reason, however, to suppose that individual patterns will coincide with this.Individual No. 109 follows the group
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@4:,410 SINUS ARRHYTHMIA
that all individuals at some time show sinus arrhythmia.
Frequency Index
Frequency index may be a better expres sion of sinus arrhythmia than range because
it is not as dependent on pulse rate as is
range. The values of frequency index (RI.) were higher than Landtman's valueslO be cause we took n = 1 rather than n 3, and because he found higher mean values for pulse rate than we obtained. The 75th and 90th percentiles of R.I. show higher values for girls than for boys because of the girls'
greater range and higher pulse rate.
Pulse Rate and Range
It has been
@ that after exercise
(luring the recovery phase individuals show an increase in sinus arrhythmia. Only one individual in our group of 21 (R.S., age 27) showed this increase (Table Ilib). There is not the simple relation here between range and pulse rate that Kuhneu believed to exist. R.S. with a marked pulse rate (Ic crease (from 124 to 103) showed a slight
range increase (.03 to .04 seconds) hut with a further slight pulse rate decrease (from 103 to 99) showed a marked increase in range (.04 to .16 seconds). Respiratory rate
ifl(I depth are among the other factors which are iml)Ortant in altering the sinus arrhythmia.
Pulse Rate, P-R Interval and Range
The Goodrnan@Kruskal@ index of association between two or(lered variables was computed separately for the categorized variables, range and pulse rate ( Table IVa), and range with
P-R interval (Table IV1)). The index is inter
preted not with respect to a theoretic distribu
tion, such as chi-square, but with respect to
all possible combinations of pairs of individuals
chosen (at random with replacement) from the number of in(livi(luals studied. In this study,
there are 81 individuals represented in the cross-classification table, hence there arc 81@
= 6,561 possible combinations of pairs of in
dividuals. We inspect the category value of the two variables for each of the 6,561 pairs of individuals and put the results of this inspec tion into one of three classes. In the first class,
marked SAME, we put the number of pairs in
.:@
1::;::
•¿j@
:@:.
.@:...!.
@
. .:
@
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a
b
C
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Fie. 6. a. This record shows a wandering pacemaker characterized by change in duration of the P—Hinterval and change in configuration of the P wave.
b. This record illustrates the P—Rphenomenon with the short P-H intervals pre ceded by the long cycle lengths and the long P-H intervals preceded Iw the short
cycle lengths.
which the order of the variables is the same. In the second class,marked DIFFERENT, we put the number of pairs in which the order of the variables is different. In the third class, we put the number of pairs of individualsfor whom either of the variables has the same value; that is, both individuals have the same pulse category or both have the same range category. We ignore this third class in comput ing the index. The index is the ratio of the difference between the number in the SAME class and the number in the DIFFERENT class to the total number in both classes. If the number in the DIFFERENT classisgreaterthan the num ber in the SAME class, the index will be nega tive. The index can only be taken on values from —¿1to + 1 with 0 indicatinglackof association. The computed index forrange with pulserate
is —¿.83 and for range with P-R interval is
—¿ .26. We can conclude that there is a strong
negative association between range and pulse rate, and a definite though less strong negative association between range and P-R interval. II. Effect of RespiratoryRateand Tidal Volume
on SinusArrhythmia
Methods and Subjects
To investigate the influence of the rate and depth of respiration on sinus arrhythmia, elec trocardiograms were taken on four different healthy adults from 29 to 43 years of age at various rates and depths of respiration. The tidal volumes were recorded with a McKesson Robbins Metabelor. Any tracing which showed
a progressive increase or decrease in heart rate
at any particularrespiratoryrate and tidal
volume was discarded. The sinus arrhythmia (range) was determined over the 10 cycles which gave the maximum value. Frequency index (RI.) and pulse rate were also calculated for these 10 cycles. For some of the experi ments the tidal volume used was a definite fraction of the vital capacity so that the results would be more comparable from one individual to another as vital capacities themselves varied from 4,500 to 6,000 ml.
RESULTS
Table V shows some of these results where tidal volume was approximately %, %, or 1,4 vital capacity and respiratory rate was 5 to 10 per minute. The records taken at faster respiratory rates of 20 or 40 per
minute always showed marked increase in pulse rate and a decreased range. All four
individuals showed a range of 0.16 seconds on most records. Individual No. 3 showed the maximum of 0.50 seconds. With several exceptions the four individuals show an increase in range with an increase in tidal volume, often in spite of a pulse rate in crease. When they show a decrease in range, they also show a pulse rate increase except in Case No. 4. There is a variable
change in range at the same tidal volume when the respiratoryrate is changed from 5 to 10. Usually pulse rates are slightly faster and range slightly slower with this increase in respiratory rate.
DISCUSSION
These results generally confirm the state ments of Lewis4 and Katz and Pick7 that greater tidal volumes cause an increase in sinus arrhythmia. This is true only as long as the work entailed by the deep respiration does not cause a pronounced increase in pulse rate. Changes in CO2 content associ ated with a rapid respiratory rate also might he responsible for the decrease in range found with rapid respiration.While it is
generally true that increased tidal volume is associated with increased range, the ex ceptions recall Anrep's statement22 that “¿the conditions affecting the respiratory arrhyth mia are so numerous that it becomes diffi cult to control them on the whole animal.―
Methods
III. Effect of Breath-holdingon SinusArrhythmia
Tracings of Lead II of the electrocardiogram were taken from 15 individuals with inspira tion and expiration manually recorded on the record, and breath-holding maintained for vari ous periods. With one additional individual breath-holding was voluntarily maintained for a variety of times varying from 1 to 60 seconds.
RESULTS
The tracings showed that with inspiration increasein heart rate always occurred and
Respiratory RateT.V.4PulseMax. Cycle Length Mm. CycleLength RangeFrequency Index (R.I.)(%)1.29-yearmale575068.1821.0V.C.*=4,SOOml5 5 10 10 101,500 2,250 750 1,500 2,25075 75 76 78 76.28 .29 .15 .16 .1728.5 36.6 19.8 20.8 21.22.29-year male51,00062.3031.6V.C. =6,000 ml5 5 10 10 102,000 3,100 1,000 2,000 3,00067 76 67 71 79.45 .35 .37 .31 .1650.5 44.5 41.1 36.8 20.63.33-year male575067.3134.2V.C.=4,SOOml5 5 10 10 101,500 2,300 725 1,500 2,2@5071 62 69 72 71.22 .50 .26 .27 .4426.3 50.7 30.0 32.9 51.74.48-year male575070.2124.2V.C.=4,SOOml5 6 10 10 101,500 2,250 700 1,500 2,25075 75 72 67 79.28 .24 .14 .29 .1734.4 29.9 17.4 32.0 22.2
412 SINUS ARRHYTHMIA
TABLE V
* V.C.—vital capacity; T.V.—tidal volume.
beats, after which there was slowing whether expiration took place or whether the breath was held. The slowing of the pulse rate occurred with expiration only by coincidence. With expiration after breath holding for 10 to 20 seconds the pulse showed either increase or decrease. After the period of slowing with continued breath holding, there was an increase in heart rate in only one case. On the tracings from one individual who held his breath for a varying period of time at a constant tidal volume of 2,000 ml the amount of slowing was the same whether expiration took place promptly after full inspiration or whether the breath was held for varying times.
DISCUSSION
Manzotti27 states that sinus arrhythmia does not stop immediately at the beginning
being delayed one respiratorycycle.With
our tracings we were unable to duplicate his resultsin the majorityof cases.We found in
only one case an increase in heart rate with continued breath-holding, which occurred after about 8 to 10 seconds. This might be brought about by the central mechanism, with the increased CO2 level stimulating the respiratory center and causing a reflex in hibition of the vagal center.
SUMMARY
Though there are many comments on res piratory sinus arrhythmia in articles and textbooks, there have been surprisingly few data collected.We have presented data from 4,096 electrocardiograms of 199 healthy individuals on pulse rate, range (max. difference in cycle length), and fre quency index
(
range
\mean cycle length
pulse rate and a definite though less strong negative association between range and P-R interval. Siblings show marked similari tiesin their group positionfor pulse rate,
sinusarrhythmia (range),and P-R interval.
The influence of variation in tidal volume and respiratory rate on sinus arrhythmia (range) was investigated. The results show that there is usually an increase in range
with increase in tidal volume but a variable response to respiratory rate changes. Rapid respiratory rates decrease sinus arrhythmia (range) probably by the increase in pulse rate from the greater work involved, though changes in CO2 tension of the blood might also be important.
From studying the effect of breath-hold ing on sinus arrhythmia we find that slow ing usually occurs 3 to 6 heart beats after the increase in rate which is associated with inspiration, and occurs with expiration only by coincidence. The amount of slowing is not related to the time of expiration.
Acknowledgment
The authors wish to express their great ap preciation for the many helpful suggestions and criticisms of Dr. Edith Boyd, Dr. John Githens, Dr. Robert McCammon and Dr. Alfred Wash burn; and for the statistical assistance of Mrs. Pearl Van Natta.
REFERENCES
1. Bellet, S.: Clinical Disorders of the Heart Beat. Philadelphia, Lea, 1953.
2. Anrep, G. V., Pascual, W., and Rossler, R.: Respiratory variation of the heart rate. I. The reflex mechanism of the respira tory arrhythmia. Proc. Roy. Soc. London, ser. B., 119:191, 1936.
3. MacKenzie, J.: The Study of the Pulse. Edinburgh, Young J. Pentland, 1902. 4. Lewis, T.: Clinical Disorders of the Heart
Beat, 5th Ed. London, Shaw and Sons, 1920.
5. Krumbhaar, E. B., and Jenks, H. H.: Elec trocardiographic studies in normal in fants and children. Heart, 6:189, 1916. 6. Burnett, C. T., and Taylor, E. L.: Electro
cardiograms on 167 average healthy in
fants and children. Am. Heart J., 11:
185, 1936.
7. Katz, L. N., and Pick, A.: Clinical Electro Pulse rates for this group, though not as
low as those taken under basal conditions,32 show generally lower values with a greater variation than those often reported.30'31 The girls have higher pulse rates than the boys as a group after the age of 6 years.
Sinus arrhythmia defined as a range of 0.16 seconds or more is present under a year of age in both sexes. The range in creases to a maximum between 8 and 12 years and only the 75th and 90th percentiles for boys show a definite decrease after this. Of 81 individuals from whom we have rec ords from the ages of at least 8 years through 17 years, only one boy and one girl do not at some time show a range of 0.16 seconds or more.
The values for the frequency index (de fined in text) we obtained were higher than those of Landtman.19 The girls show higher values than the boys after the age of 12 years for the 75th and 90th percentiles be cause of their higher range and higher pulse rate.
414 SINUS ARRHYTHMIA cardiography. Part I. The Arrhythmias.
Philadelphia, Lea, 1956.
8. Schlomka, C.: Untersuchungen uber die
physiologische Uragelmassigkeit des Herzschlages. Ztschr. Kreislaufforsch., 29:510, 1937. Quoted by Landtman.19 9. Nadas, A.: Pediatric Cardiology. Philadel
phia, Saunders, 1957.
10. Jones, E. W.: Sinus arrhythmia and sino
atrial block. Practitioner, 81:355, 1958. 11.Kuhne,K.:Die respirtorischeArrytmiebei
Herzkrankungen im Kindesalter. Mon atsschr. Kinderh., 66:7, 1936. Quoted by Landtman.19
12. MacKenzie, J.: Diseases of the Heart, 4th Ed. Humphrey Milford, Oxford Univ. Press, Edinburgh, 1925.
13. Levine,S. A.: ClinicalHeart Disease.
Philadelphia, Saunders, 1936.
14. Wenckebach, K. F., and Winterberg, H.: Die unregelmassige Herztatigkeit. Liep zig, 1927. Quoted by Landtman.19 15. Scherf, D., and Boyd, L. J.: Clinical Elec
trocardiography. Philadelphia, Lippin cott, 1946.
16. White, P. D.: Heart Disease, 4th Ed. New York, Macmillan 1951.
17. Luisada, A. A.: The Heart Beat. New York,
Hoeber, 1953.
18. Lukomski, P.: Elektrokardiographische Beabachtungen bei akutem Rheumatis mus. Deutsches Arch. klin. Med., 174: 268, 1932. Quoted by Landtman.19 19. Landtman, B.: Heart arrhythmias in chil
dren. Acta paediat., 34:Suppl. 1, 1947. 20. Wiggers, C. J.: Physiology in Health and
Disease. Philadelphia, Lea, 1949. 21. Fulton, J. F.: A Textbook of Physiology.
Philadelphia, Saunders, 1955.
22. Anrep, C. V., Pascual, W., and Rossler, R.: Respiratory variations of the heart rate. II. The central mechanism of the re spiratory arrhythmia and the inter-rela tions between the central and the reflex
mechanisms. Proc. Roy. Soc. London, ser. B., 119:218, 1936.
23. Gross, D.: The correlation between sinus arrhythmia and the respiratory rate. Ex
per. Med. & Surg., 11:141, 1953. 24. Starr, I., and Friedland, C. K.: On the
cause of the respiratory variation of the ballistocardiogram, with a note on sinus arrhythmia. J. Clin. Invest., 25:53, 1946. 25. Shuler, R. H., Ensor, C., Cunning, R. E., Moss, W. C., and Johnson, V.: The dif ferential effects of respiration on the left and rightventricles.Am. J. Physiol.,
137:620, 1942.
26. Bainbridge, F. A.: The effect of venous fill ing upon the rate of the heart. J. Phy siol., 50:65, 1915.
27. Manzotti, M.: The effect of some respira
tory manoeuvers on the heart rate. J.
Physiol., 144:541, 1958.
28. Bard, P.: Medical Physiology. St. Louis, Mosby, 1956.
29. McCammon, R. W.: Unpublished data. 30. Ziegler, R. F.: Electrocardiographic Studies
in Normal Infants and Children. Spring field, Thomas, 1951.
31. Sodi-Pallares, D., Portillo, B., Cisneros, F., Dc La Cruz, M. V., and Acosta, A. R.: Electrocardiography in infants and chil dren. Pediat. Clin. North America, No vember, 1958, p. 872.
32. Iliff, A., and Lee, V. A.: Pulse rate, respira tory rate, and body temperature of chil dren between 2 months and 18 years of age. Child Develop., 23:237, 1952. 33. Nordenfelt, 0.: Studien über respiratori
sche Arrhytmie besonders des Kindesal ters. Arch. Kreislaufforsch., 13:97, 1943. Quoted by Landtman.19
34. Schlomka, C., and Reindell, H.: Unter suchungen über die physiologische Unragelmassigkeit des Hergschlages. Ztschr. Kreislau.fforsch., 28:473, 1936. Quoted by Landtman.19
35. Coodman, L. A., and Kruskal, W. H.: Measures of association for gross classifi
cations. J. Am. Statistical A., 49:723,
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Richard Reeve and Kee DeBoer
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SINUS ARRHYTHMIA: I. Data and Patterns from Groups of Individuals Followed
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