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The Orthogonal Vectorcardiogram in 100 Normal Children
(Frank System)
With Some Comparative Data Recorded by the Cube System
By PAUL G. HUGENHOLTZ, M.D., AND JEROME LIEBMAN, AI.D.
With the technical assistanice of Mrs. E. Donaldson
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I NTEREST in exact delineation of the direction and magnitude of successive timed
vectors of the myocardial depolarization process has been increasing in recent years. The
usefulness of specific instantaneous vectors
has, for example, been demonstrated in the
assessment of the degree of left ventricular
hypertrophy in children with aortic stenosis'
and in the exact identification of areas of infaretion in the adult heart.2 3 The analysis
of instantaneous vectors in various cardiac
disorders associated with hypertrophy of
either of the ventricles, as well as parts
thereof, appears to be particularly promising,
since it has been shown that different areas
of the myocardium will contribute their electromotive force to the over-all QRS activity
at different times during the cardiac cycle.
Presently many electrocardiographic concepts,
such as systolic and diastolic overloading, still
await correlation with exact hemodynamic
data to confirm their usefulness in congenital
heart disease. Subdivision of the sum of electromotive forces at different instants appears
to be one of the ways by which correlation of
various hemodynamic disorders can be attempted. Thus, the need for detailed control
data, particularly in children, is apparent.
In a previous publication,4 data have been
presented regarding the magnitude of various
areas of the planar projections of the spatial
QRS loop in 135 children. The present analy-
sis used the determination of the direction
and magnitude of successive vectors at intervals of 10 milliseconds.5 These have been
recorded in a group of 100 children, aged 7
months to 16 years, by means of the Frank
lead system.6 For comparison a second group
of 47 normal children, of the 135 previously
reported, in whom the eube system had been
used, was reanalyzed in the manner described
above. The results have also been compared
to those recorded in older age groups studied
in a similar fashion7-9 in order to investigate
changes in spatial direction of depolarization
forces with advan-cing age.
On a theoretical basis the Frank lead system is a good one because of its orthogonal
representation of electrical forces. Practically, it has beeni shown to possess greater
reproducibility, constancy of lead axis and
accuracy of recording.10 11 It has the added
advantage of simple and easy application.
Although this reference system has been designed for adults, it was thought that this
study might establish its value in younger age
groups.
Methods and Material
The seven electrodes of the Frank lead systenm
were applied in the usual fashion6 to 100 normal
children aged from 7 months to 16 years (fig.
1). All were patients hospitalized at the Children's
Hospital Medical Center mostly for various surgical conditions and nearly all were ambulatory.
All had normal chest films and by physical
examination were shown to have no cardiac abnormalities. Electrocardiograms were taken shortly
before or right after the recording of the vectorcardiogram and were normal. All studies were done
in the recumbent position.
The position of the electrodes was identical
to that previously indicatedG except for the
selection of the fourth intercostal space for the
From the Sharon Cardiovascular Unit, Children 's
Hospital Medical Center, and the Department of
Pediatrics, Harvard Medical School, Boston, Massachusetts.
Supported in part by grants from the National
Heart Institute (H-2515-C3) and (HF-8886-C2 Dr.
Hugenholtz), U. S. Public Health Service.
Circulation, Volume XXVI, November 1962
891
I()-)
8I9ItENIIIOILTZ, IiEBMAN
raphl%.:; Tllus, eountereloekwise rotatioin of this
25
NUM BER
OF
NUOF 2ER
C'F
loop wNas preserved.
50 r
20
4G0-
PATIENTS
PAT ENT S
3C
-
20r-
6-9
4-6
3
9-12
0 05
I...
i2-15
0 06
0 O'?
0 06
0 09
,,,
AGE IN YEARS
OURATiON OF Q RS
IN
SECONDS
Figure 1
)istribution accorcinig to aye (01d1 dturation of the
QRS 7OO1). A partial suptperibnpositionz of both
carn.es is seen', indicating a longer QRS cdtrationl
in the oldler age groups. Sixteen of the 22 patients
iith a QRS dutration, of 0.06 second?W or less wiere
4 jers old, or youfnger. while of tie 7$ with
a
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QR9 S
of
0.07
seconi?
or
Wore.->*
71
wcr)e oldo -r th(an
years of oge.
pjlacemient of the horizontal plaine leads. Sealar
represeentation was n-ot obtained. The recording
apparatus consisted of a Sanborn Vector Amnplifier modified to accept the input of a Frank
corrected lead svstem, and a Sanhorn Model 185
Visoseope to which a Dumiont 35-rimm. oscillograph
record camera type 296 was attached. The vector
loop was interrupted every 0.0025 secoond, the
resultant line being in the formn of a teardrop
with the blunt edge leading.
AMultiple photographs were taken of each of
the three planiar projectioins. Inrereased amplification was used whenl necessary. Care was taken
to avoid superimilposition of P and T loops and
to obtain exact recordings of the isoelectric point.
Wlhen necessarv the teAchnii of "hE-point shift
was used. The filmiis weere read on a Docuamant
Model R roll film reader fromii whiech all ineasuremi-ents -were mlade. One 1-illivolt of standardization
the oscilloscope equaled 10.5 inches on the projector. On1ly the QRTS loops w-ere st-udied in detail.
The directioii of instantaneous 0.01, 0.02, 0.03,
0.04, 0.05, 0.06, 0.07, and 0.08-second vectors
well as the maximilum QRS vectoris and the half
area QRS vectors7 was recorded. Ani average
of mtiultiple determinations was obtained and plotted on a polar coordinate scale, using the notation
proposed by Helmi.12 The -e( tot agnitude was
measured in a simlilar fashion. The T loop was
analyzed for the direction and m-agnitude of the
mwaximnunm vector only. P vectors were not studied.
Details of these technies have been previously
on
as
discussed.2
3
The sagittal plane was viewed fromii the patient's
left shoulder in accordance with the recommendamade by the (Conmamittee on Vectoreardiogtionins
Results
The restults obtainied with the Franik syste:n
for the horizontal plalne projection are expressed graphically in the scattergraxns i
figure 2A-F. Tables 1 and 2 contain the mnean
value of the 100 determiinationis miiade for eael
of the vectors in each of the three planes
studied with their standard deviations. There
were onily 80 nieasuremeni-ts of the 0.07-secondi
vector and 26 of the 0.08-secolnd vector. In
the fronital planie the spread in the 0.01-second
vector was such that no significant ealculations could be miiade. The 0.02-second vector
was divided according to direction of rotation
as showil in tables 1 and 2. The 0.03-seconid
vector was grouped together buit separatioin
depending on the direction of rotation was
again utilized ini the calculationi of the 0.04second vector. The absence of Gaussian distributioni precluded calculationi of the 0.06, 0.07,
and 0.08-second vectors in the frontal plane.
In these categories magnitudes were also not
calculated.
Conisiderable variation was foun:d for the
mnaximnuni QRS vector, both in the lhorizontal
(S.D. 1)2.9 ) anid the sagittal plane (S.D.
39.2 ) projectioins. Calculation of the halfarea vector reduced this spread considerably.
(S.D. 32.6 , S.D. 28.1° respectively.) in the
frointal planie muaxiulmn and half-area vector
wvere niearly idenitical (fig. 3).
Results of the cube systemii are given in table 3. Gaussian distributioin did not occur in
any systematic fashion in either the initial or
final QRS vector (fig. 4). The 0.01-secon{d
vector showed wide spread in the sagittal
(S.D. 49.9°) but close grouping in the horizontal plane (S.D. 22.7 ). On the other hand,
the 0.02-seconid vector was found to vary
greatly in the horizontctl planie (S.D. 83 ")
while the samie vector fell in a narrow ran(ge
on the sagittal projection (S.D. 6.20). The
0.03-second and maxin-uma QRS vectors, both
im the miidrange of the enitire QRS duration ,
sllowe(l a ssurprisingTly smlall degree of variaCirculation, Volume XXVI, November 1952
V
VECTORCARDIOGRAM IN NORMAL CHILDREN
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894
HUGENHOLTZ, LIEBMAN
Table 2
Magnitude of Successive Instantauaeous QRS Vectors ijo 100 Normal Children with a Comparison of Other
Series (in Millivolts)
Present
series
0.01
0.02
0.03
0.04
0.05
Horizontal plane
100 Adults
72 Adults
Pipberger8
Bristow7
Sagittal plane
Present
series
100 Adults
72 Adults
PipbergerS
Bristow7
Present
series
0.31
(0.16)
0.08
0.32
0.09
0.20
0.05
(0.06)
(0.15)
(0.06)
(0.11)
(0.04)
0.65
(0.24)
0.26
0.64
0.12
(0.26)
0.25
(0.10)
0.46
(0.13)
(0.31)
(0.37)
0.98
(0.39)
0.51
(0.24)
0.43
(0.19)
1.29
0.46
(0.50)
(0.30)
0.98
(0.33)
0.86
(0.33)
0.90
(0.40)
0.93
(0.37)
0.62
0.74
NC
0.60
(0.30)
NC
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0.06
0.23
(0.18)
0.07
0.08*
(0.08)
0.09*
(0.09)
NC
0.08
0.03 t
(NC) +
0.05t
NC
(NC)
Half Area
T
1.02
(0.37)
(0.32)
(0.29)
0.25
(0.17)
Maximum
Frontal plane
100 Adults 72 Adults
Pipberger8 Bristow7
NC
1.23
1.15
1.58
1.19
1.12
1.24
1.49
1.31
1.67
(0.37)
(0.34)
(0.37)
(0.40)
(0.41)
(0.36)
(0.47)
1.18
(0.37)
(0.45)
0.99
1.04
(0.41)
(0.43)
(0.50)
0.34
0.35
0.51
0.30
0.35
0.44
0.44
0.36
0.47
(0.14)
(0.15)
(0.14)
(0.16)
(0.14)
(0.12)
(0.17)
(0.13)
(0.14)
*Only 75 determinations.
tOnly 26 determinations.
fNot calculated.
tion (S.D. less than 10.70 in both). This occurred in each of the three projections. Considerable spread existed again in the final
vectors, and precluded calculation of statistical parameters.
Discussion
Frank System. Direction of Vectors. General Considerations
Sineo the corrective network incorporated
in the Frank system is based upon studies
with the adult torso,6 the question may be
raised whether this system should be used in
children at all. From a theoretical point of
view, this problem is probably handled best
by the design of a new series of resistances.
However, such an approach could never compensate for the wide variations in size found
between the infant and the older child. Furtherinore, despite over-all growth over the
years, the relative proportions of the heart
and the chest-cage alter but little. Thus, if
any changes occur beyond the age of 1 year,
they should affect magnitude rather than direction of the QRS vectors.
Little scatter was found in each of the selected vectors, and the standard deviationis of
the 100 determinations show remarkable similarity, indicating a very consistent performance of the recording system. Furthermore,
the magnitude of this statistical measure
equals that of other large groups of measurements made in adults (table 1). Thus, from
a practical point of view, it also appears that
the Frank lead system can be applied to
children.
Circulation, Volume XXVI, November 1962
VECTORCARDIOGRAM IN NORMAL CHILDREN
HORIZONTAL
A 0.01
D)
E o05
0 04 SECOND
SECOND
C 0.03
F 006
SECOND
SECOND
2 70-
2 70'
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~~Aw
o
\I/
,
PLANE VECTORS
S 0.02 SECOND
SECOND
895
go'
-
0~~~~~~~
90-
910.
Figure 2
Scattergrams of successive instantaneous spatial QRS vectors, from 0.01 second to 0.06
second, in 100 normcal children as projected on the horizontal plane. A relatively narrow
and constant spread is seen throughout with the exception of the 0.04-second vector.
The open circles indicate recordings with a QRS duration of 0.05 second or shorter.
The closed circles refer to a QRS duration of 0.06 second or more. No significant difference
wvas found between both categories.
Among the various age groups there was
little difference in the orientation of the various vectors, an observation also made in the
previous series4 (fig. 1). It must be pointed
out, however, that in the 0.03, 0.04, and 0.05second scattergrams, the values from the individuals with a short QRS duration were the
most leftward, posterior, and superior within
the given group (fig. 2B, C, D). Although
they added to the wider spread observed in
the 0.03 to 0.05-second range, no separate
Gaussian distribution could be found.
The horizontal plane projections of each of
the selected vectors fell sufficiently apart from
each other to have statistical significance (p
< 0.01) (fig. 3A). The standard deviations
of each of the instantaneous vectors fell in a
narrow range and were of the same magnitude as those found in the projection of these
Circulation, Volume XXVI, November 1962
vectors on the other planes. Only the stand-
ard deviation for the 0.04-second horizontal
plane vector was a distinctly larger figure
(33.50). This is illustrated in figure 2D. This
isolated finding, not found to the same degree
in the corresponding sagittal plane projection
(S.D. 26.30), is probably best explained by
the inconstant performance of the A and C
electrodes,6 which would show the greatest
influence of the proximity effects of the left
ventricular depolarization process. Varying
the placement of this electrode was found to
affect the resultant direction of the vector
greatly. Despite great care to place the electrode in the fourth intercostal space, relative
changes in the cardiac position in many children may have unduly affected this particular
measurement. This appears the more likely
since no such wide spread was found in the
8HUGENHOLiTZ, I.IEBMAN
896
2 7O0
T70O
360
360°
0.
o.
i8d°-
122 8)
9RO
HOR IZO NTA L
90.
PLAN E
SAGITTAL PLANE
FRONTAL PLANE
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Figure 3
Diagram of mean2 values of successive instantaneous QRS vectors as projected on the
horizontal (A, left). sagittal (B, center), and frontal (C, right) planes. Extreme variation in initial and final rectors precluded their calkulation in the fron2tal plane projection
(table 1).
Table 3
Direction of Selected QRS Vectors in 47 Normal Child;ren (in Degrees), (Cube System)
Horizontal plane
Sagittal plane
Range
Time in
seconds
Mean
Range
S.D.
Mean
0.01
0.02
0.03
0.04
0.05
0.06*
132
42
10
329
275
22.7
83.0
12.0
NCt
NTC
Nc
181
113
95
43
265-109
160- 93
104- 68
346
168
174- 43
107- 1
26-320
21-201
336-208
360-201
320
90-279
81-270
Maximum 11
97-348
7.5
96
109- 82
97-299
Frontal plane
S.D.
S.D.
Mean
Range
49.9
6.2
NC
WVide scatter
NC
6.7
NC
NC
NC
65
10.7
10.0
81
NC
49-141
34- 81
147-296
2.0
Wide scatter
Wide scatter
NC
56 C-CXVI
78- 34
62 CW
8- 78
NC
NC
NC
9.7
9.5
*Only 31 cases had a QRS duration of 0.06 second or longer.
tNot calculated.
IThere wvere 37 patients wvhose frontal plane loops rotated cloe ,kwise and 10 counterclockwise.
sagittal plane projection with whieh the horizontal plane shares only the y-axis. Therefore, investigators utilizing this particular
vector should appreciate that the largest scatter in this series oceurred in the direction of
the 0.04-second veetor. On the other hand,
data obtained on adults show isolated variations of the standard deviation up to 40.40
in some series.9 Thus, factors, not necessarily
limited to the pediatric age group, may still
affect the results of these "corrected" systems, which otherwise are outstanding by
their consistent performance.
The sagittal plane projection shows an even
more ideal distribution curve for each of the
vectors studied, with a slightly smaller resulting standard deviation. Again slgnificant dif-
ferences existed between the mean values of
each selected vector (p < 0.01) (fig. 3B).
The frontal plane (fig. 3C) projection behaves in many respects quite differently from
observations reported in adults.,5 In addition
to the higher incidence of the number of
clockwise rotating loops (85 per cent of all
patients at the time the 0.05-second vector
was inscribed), there was a considerable degree of crossing-over and figure-of-eight configuration with very narrow loops. This indicates that the spatial loop is in a nearly 450
angle to both the horizontal and sagittal
planes, thus resulting in a widely open projection upon these planes, whereas it is nearly
perpendicular to the frontal plane. Thus only
slight ehange in spatial orientation may reCirculation,
Volume XXVI, November 1962
897
VECTORCARDIOGRAMI IN NORMIAL CHILDREN
sult in considerable variability in direction
of rotation.
This method of measurement is particularly
vulnerable in this manner of analysis, since
small variations in initial and final vectors
may result in complete alteration of direction
of inscription of the planar loop from clockwise to counterclockwise and consequently in
variations of vector projection up to maximally 180°. Consequently only the 0.02 and
0.03-second vectors have been caleulated, since
they were found to be the only ones to fall
in a statistically significant distribution.
HORIZONTAL
174C
5 °~45
%
0.01 SEC. VECTOR
S.D. 22.70
Maximum QRS Vector and Half-Area QBS Vector
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Despite the relatively constant distribution
curves found for the instantaneous QRS vectors, as projected on the horizontal and sagittal planes, consistently higher spread was
observed for the maximum QRS vectors, a
measurement not necessarily falling at the
same instant of ventricular depolarization.
Similar observations have been made in
adults by Pipberger5 and Forkuer and coworkers.5 Bristow7 therefore has preferred to
calculate the half-area QRS vector, which he
found to have a smaller range, suggesting that
it was a more meaningful parameter. Our
results seem to bear this out. As in the instantaneous 0.04-second horizontal plane projection, the largest spread occurred in the
horizontal plane half-area QRS vector (S.D.
32.60). Explanations would be similar to
those given for the wide range of the 0.04second vector. By contrast, the half-area QRS
vector of the frontal plane (S.D. 18.80) and
sagittal plane (S.D. 28.10) appeared to be
within the range observed throughout this
series.
Comparison with Other Series
Although no comparable data have been
published in this age group, comparison with
similar types of measurements in young
adults, and even older individuals,9 seemed
to be of interest. As shown in table 1 very
little differenee exists in the direction of early
vectors as projected on the horizontal and
sagittal planes in these varying age groups.
However, by 0.03 second a progressively
Circulation, Volume XXVI, NoVemler 4962
107
0.02 SEC. VECTOR
S.D. 830
0.03 SEC. VECTOR
S.D. 120
Figure 4
D)iagra'mmatic representation of variations in
ranges and standard deviations of initial spatial
Q RS vectors projected on the horizontal plane
as they are recorded by the cube system.
faster posterior and inferior orientation is
evident in our normals, probably best explained by the fact, that the average QRS
duration is shorter, thus increasing the velocity of inscription. Also, the over-all rainge of
the standard deviations is quite similar in the
reported studies, supporting the theory that
among corrected lead systems this type of
data may be exchangeable. This observation
confirms those of Forkner and co-workers5
and suggests, for younc adults at least, that
898
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advancing age alters the Frank vectoreardiogram relatively little. Even in the group of
93 men in their sixth decade of life, Mori et
al.9 found measurements with the SVEC III
system which, at least for the horizontal and
sagittal plane projections, correspond closely
to our patients as far as the initial and terminal forces are concerned. However, the
0.03-second vector and those following did
show significant differences. It also should be
pointed out that in the latter study the final
forces were expressed as 10 to 40 millisecond
terminial forces which, therefore, do not necessarily correspond to the 50 to 80-millisecond
vectors of our individuals. Furthermore, in
all these studies the frontal plane projections
are more open, and more complete analysis
has been possible. This indicates that, with
advancing age, a slight but definite alteration
in the spatial loop oecurs in an orientatioin
more parallel to the frontal plane.
Magnitudes. Comparison- wivth Other Series
As expected, considerable differences were
found in the magnitudes of the early and
terminal vectors, when they were compared to
the data of Pipberger8 and AMori et al.9 (table
2). This may indicate that in this respect the
Frank system may not necessarily represent
the electromotive force correctly in varying
age groups. On the other hand, the remarkable agreement for the maximum QRS-vector
nagnitude as well as the maximum T-vector
magnitude between our data and those of
Pipbergerg and Bristow7 in young to middle
aged adults suggests that comparison is vTalid
and that the differences found for the early
QRS-vector magnitudes are real. Further
conclusions nmust await publication of additional data.
Cube System. Direction of Vectors
The results of the 47 individuals studied
are given in table 3. They indicate that considerable differences in the appearance of the
planar QRS loops existed between both systems. In no instance could the round, open
loops, registered by the Frank system, be
found in the recordings made by the cube
system. Rather narrow, elongated, and at
HUGENHOLTZ, LIEBMAN
times ellipsoid curves were the rule. Comparison of the individual measurements of
instantaneous vectors, furthermore, showed
considerable differences both in mean values
and in their standard deviations. The most
marked discrepancies occurred in the direetions of initial and terminal forces, and it
was in these groups that non-Gaussian distribution most frequently existed.
For example, the 0.01-second vector as projected on the horizontal plane showed a range
of 1740 to 450, with anl S.D. of 22.70, and the
0.02-second vector had a range of 107' to 1°,
with an S.D. of 83° (fig. 4). By contrast,
these same instantaneous vectors projected on
the sagittal plane gave an eveen wider range
for the 0.01 (265° to 109°) S.D. 49.90 and a
much narrower range, of 20 to 850 with an
S.D. of only 6.2° for the 0.02-second vector.
Such differences for the same instantaneous
vector strongly suggest that a non-orthogonal
r ecording svstem is responsible. Since for the
0.03-seconid vector extremely narrow ranges
were found for both the horizontal and the
sagittal plane projections, it appeared that
when a given instantaneous vector projected
largely alonig the transverse, or x axis, a much
more condensed distribution was obtained
than when it projected largely along the anteroposterior, or z axis. These findings seem to
confirm the predictions made by Pipberger
anid others,14 who on theoretical grounds, have
indicated that one of the greatest weaknesses
of uncorrected lead systems, such as the cube
technic, is the inconstancy of effective lead
axes when thev are compared to anatomic
lead axes.
This same fact may explain why the overall configuration of the planar loops obtained
with the Lube system displays such flattened,
narrow, and ellipsoid configurations. Sinee
the z, or anteroposterior., axis is jointly represented in the sagittal plane and horizontal
plane, inaccurate representationi of forces,
largely paralleling the z axis, would result in
wide variations of initial and terminal forces
in both these planar projections.
Furthermore, it would also explain the unCirculation, Volume XXVI, November 1962
899
VECTORCARDIOGRAM IN NORMAL CHILDREN
LSAGITTAL
my
LSAGITTAL
SAGITTAL ON HORIZONTAL
_______
I
.y
z
0.01 SEC. VECTOR
-------
yonx
z
SAGITFTAL ON HORIZONTAL
181'
__
001
!
Z
SEC.
VECTOR
y onxK
R
ROTATE -90°
107°
ROTATE 90'
0.02 SEC. VECTOR
2
161'
71M O
0-02 SEC. VECTOR
MAX. VECTOR
I
1-
113'
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72°
HALF AREA VECTOR
32
MAX. VECTOR
FIG.
A2
FIG. B
rigure 5
Superimposition of mutually perpendicular planes
(Frank system). Nearly complete superimposition
of the planar projections of the spatial 0.01,
0.02 second, maximum and half-area QRS vector
occurs, when the superior-inferior (y) axis of
the left sagittal plane (A) is rotated 90Q around
the anteroposterior (z) axis, common to both
planes, so that y falls on the x (transverse)
axis of the horizontal plane (B). Shaded areas
cover dotted areas nearly completely. Since these
forces were of equal magnitude orthogonal representation is present.
usually small variations found for the 0.03second and maximum QRS vectors which,
since their direction is nearly parallel to the
x and y axes, will hardly be influenced by
that small component of the parallelogram of
forces, which would project on the z axis, perpendicular to each of the former.
Comparison of Cube with Frank System
In a truly orthogonal system a spatial vector of a given magnitude pointing anteriorly
at 1800 in its left sagittal projection, should,
by definition, be directed at 90° in its horizontal projection, if it is to remain of identical magnitude. This may be illustrated
simply by rotating the left sagittal plane
Circulation, Volume XXVI, November 1962
----.
84FIG. A
FIG. B
rigue
6
Superimposition of mutually perpendicular planes
(cube system). Superimposition of planar projections of QRS vectors of equal magnitude recorded with the cube system fails to confirm orthogonal representation of spatial forces. Marked
discrepancies are seen when left sagittal (shaded
area) projections are compared to horizontal
(dotted area) plane projections showing nonorthogona,l representation of spatial forces.
clockwise around its anteroposterior, or z,
axis in such a fashion that its inferosuperior,
or y axis, becomes superimposed on the transverse, or x, axis of the horizontal plane. Such
analysis of the planar projection of timed vectors of equal magnitude was carried out both
for the data obtained by the Frank and by
the cube system. If the cube system were to
possess orthogonal characteristics, such as the
Frank system has been reported to have, this
analysis should result in similar results. The
findings are illustrated in figures 5A,B and
6A,B.
The 0.01-second mean vector, recorded by
the Frank system, as projected on the sagittal
plane at 1970, completely coincides with the
900
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0.01-second mean vector as projected oni the
horizointal plane at 107°. The 0.02-second
meanl vector shows a differeniee of only 90 between the two planar projections, whereas the
maximumn QRS vector again shows complete
superimposition of the means. The half-area
vector also shows only a 30 differenee (fig. 5A
and B). Thus, after rotation nearly conmplete
superinmposition of the vector projections on
these two inutually perpendicular planes occurs, fulfilling one of the tenets of true orthogonal representation of spatial forces. These
findings would correspond to the observations
on the azimuth made by Mori et al.9 with the
SVEC III system.
A similar analysis of early vectors and the
maximum vector, as recorded by the cube lead
system, shows that for the 0.01-second meaii
vector a difference of 410 was found and for
the 0.02-second vector a difference of 19Q
(fig. 6A and B). On the other hand for the
0.03-second vector and the maximunm QRS
vector a better correspondence existed. These
findings re-emphasize the poinlt, that in the
cube system approximnate orthogonial representation does occnr only for those forces
whose main direction is parallel to the x and
y axis, whereas in the Frank system equal
representation of forces occurs along all axes.
Although the cube systeni has been widely
used in the past decade analysis of the kind
described has not been published. It appears
nowthatthe direction of instantaneousvectors
registered by the cube system niust be considered unreliable because of its considerable
variation in projectioii along the z or anteroposterior axis, at least as far as initial and
terminal forces are concerned. By contrast,
the Frank systenm, by virtue of its corrective
network, appears useful for the analysis of
just this kind of data. The artifacts hampering the latter systenm would seemn to lie only
in the relatively wide spread in direction and
magnitude of the 0.04-second vector in the
horizontal plane and the maximnumn QRS vectors in the sagittal and horizontal plane projections. In the frontal plane wide spread of
early and late forces occurs in both recording
HUGENHOLTZ, LIEBMAN
systems equallv. This is, however, less of a
drawback tbani it appears to h)e, since the
clinlical usefulniess of early aiild late frontal
plane vectors, in the agfe groups studied in
this analvsis is limited.
Conclusions
Data recorded by the Frank corrected network in 100 normal children aged 7 months
to 16 years have been given on the direction
and miagnitude of successive instantaneous
spatial QRS vectors as projected on the horizontal, sagittal, and frontal planes.
Gaussian distribution with remarkably
similar, and consistent, ranges was observed
for nearly all parameters. Exceptions were
the 0.04-second vector and maximumi QRS
vector. Reasons for this discrepanlcy have
been discussed. Surprisingly good agreement,
with comparable rarnges, was found with series published on younig adults studied by
the Franik anid SVEC-III methods. This indicates little change in the spatial loop with
advancing age, except for a miore rapid leftward and posterior progression of successive
spatial vectors due to the shorter QRS duratioIn in the younger age groups.
Comparison with a smnaller aroup of children of sinmilar age in which the cube systein
of electrode placenment was used showed
marked variation of initial and terminal
forces in the latter systemn. Furthermore,
when conipared to the Frank data, discrepancies in direction of imiean vectors existed for
each parameter studied.
Data have been presented to support the
thesis that variable representation of electromotive forces along the anteroposterior or z
axis, is responsible for the inconstant performaanee of the cube systein. This lack of
performaince was niot present in the Frank
system.
It is felt that, with a few specific exceptions, the Frank svsteme will give specific,
statistically significant measurements of instantaneous vectors, and it is suggested that
it be used in vectoreardiographic studies of
hemaodyiianaie disorders of the pediatric age
group.
Circulation, Volume XXVI, November 1962
VECTORCARDIOGRAM INT NORMAL CHILDRENT
Acknowledgment
The authors would like to thank Alexanider S.
Nadas, M.D., for critically reviewi-ng the manuscript.
7.
References
8.
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The very first step towards success in any occupation is to become interested in it.
-SIR WILLIAM OSLER. Aphorisms From His Bedside Teachings and Writings Edited
by Williaim Bennett Bean, I.D. New York, Henry Schunian, Inc., 1950, p. 31.
(Circulation, Volume XXVI, Novnember
1962
901
The Orthogonal Vectorcardiogram in 100 Normal Children (Frank System): With
Some Comparative Data Recorded by the Cube System
PAUL G. HUGENHOLTZ, JEROME LIEBMAN and E. Donaldson
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Circulation. 1962;26:891-901
doi: 10.1161/01.CIR.26.5.891
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1962 American Heart Association, Inc. All rights reserved.
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