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The Anatomic Basis for High-Frequency
Components in the Electrocardiogram
By NANCY C. FLOWERS, M.D., LEO G. HORAN, M.D.,
J. R. THoMAs, M.D., AND WILLIAM J. TOLLESON, M.D.
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SUMMARY
In a correlative study between selected body-surface potential recordings and anatomic
findings, multilead sets of high-fidelity, high-speed records from 128 persons were
studied in connection with the results of our detailed postmortem dissections of their
hearts. Attention was focused on high-frequency components (notching and slurring
of the expanded QRS) as described by Langner.
We found that (1) groups with ventricular enlargement without scarring were
indistinguishable from groups with infarction on the basis of the number of highfrequency components; (2) both of these groups were clearly distinguishable from
normal subjects on this basis alone; and (3) the high-frequency component count in
the group with ventricular enlargement showed high negative correlation with age
and high positive correlation with right and left ventricular weights.
These findings suggest that the appearance of high-frequency components in the
vectorcardiogram or electrocardiogram may relate to the struggle between competing
generator sites of ventricular enlargement as well as to the classic concept of shattering
of the wave of activation on the shoals of infarction.
Additional Indexing Words:
Biventricular enlargennent
High-frequency notching
Myocardial infFarction
Radial spread of activation
Anisotropy
T HE USE of an expanded time scale or
increased frequency response to increase
electrocardiographic detail has occasionally
From the Section of Cardiology, Medical Service,
Forest Hills Veterans Administration Hospital, the
Department of Medicine, Medical College of Georgia,
Augusta, Georgia, and the Section of Cardiology,
Medical Service, Kennedy Veterans Administration
Hospital and the Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee, Memphis, Tennessee.
This study was supported by Grants HE-5586,
HE-08861, and HE-09495, from the National Institutes of Health, U. S. Public Health Service, and
research grants from the Georgia Heart Association
and the Tennessee Heart Association.
Paper was presented in part at the 41st Scientific
Sessions of the American Heart Association, Bal
Harbour, Florida, November 23, 1968.
Address for reprints: Nancy C. Flowers, M.D.,
Chief, Section of Cardiology, FHD, Veterans Administration Hospital, Augusta, Georgia 30904.
Ciecu4ation, Volume XXXIX, Apiril 1969
531
First derivative of ECG
QRS notching and slurring
been reported since the early 1930's.1 2 However, it was Langner in the early 1950's who
first appreciated that clinically pertinent,
otherwise obscure electrocardiographic information might be detected in this fashion.3 5
In 1949, Gilford,6 and in 1960, both Scher and
Young7 and Langner with Geselowitz8 looked
into the frequency spectrum of the electrocardiogram. The latter investigators recognized in 1962 the value of the first derivative
of the electrocardiogram. By the derivative's
representation of the rate of change of the
original electrocardiographic potential with
respect to time, notches in the original QRS
complex of even very small amplitudes and
durations may cause relatively wide swings
across the base line of the derivative, thus
aiding detection.9' 10 A number of investigators
have in one fashion or another attempted to
assign meaning to bites and notches out of
F5LOWERS ET AL.
532
y
s3_~~z
Vf
_
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V£6
Figure 1
High-speed, high-fidelity scalar leads (XYZ) of the axial
vectorcardiogram (VCG) and leads I, Vf and V, to V5
of the electrocardiogram (ECG) from a patient with
both biventricular enlargement and a large apical
myocardial infarction. Note the prominent notching
(n) and slurring(s) in both XYZ and V1 to V5. This is
particularly prominent in V4 and V5. Notching represents both change in slope and change in sign
(direction) while slurring represents change in slope
alone. Primary directional changes are not counted,
occurrence of notches and slurs in the highfidelity electrocardiogram? (2) If notches and
slurs do prove to be as frequent in the
records of persons without infarction, can we
find a direct dependence of the number of
notches on a variable such as ventricular mass
or age?
Methods
For the purpose of this study notches will be
defined as any departure in both slope and sign
from the primary electrocardiographic or vectorcardiographic curve after the artifacts of noise
have been excluded. Furthermore, these departures will be exclusive of the fundamental
directional changes of the QRS complex. For
example, the nadir of a Q, the peak of an R, or
nadir of an S would not be included. Slurs will
be defined as changes of slope without changes
of sign (fig. 1). Except where indicated notches
and slurs will be summed.
On 1,300 male patients admitted to Kennedy
Veterans Administration Hospital, McFee-axial
system18 vectorcardiograms in both scalar (XYZ
leads) and loop form as well as electrocardiographic leads I, Vf, and V, to V. were recorded at
the time of each admission by means of Polaroid
photography from the face of a cathode ray oscilloscope. Sweep speeds were at 500 and 200 mm/
sec. V4 was constantly recorded as a control lead.
for example, peak of R.
x
the vectorcardiographic loop1'l-'3 and Pipberger and Carter,-'2 in a well-controlled study,
set the limits of normal.
Except for Reynolds and co-workers14 in a
recent study of patients with primary myocardial disease, most of the emphasis previously
has been placed on a relationship between
coronary artery disease and the appearance
of notches and slurs of frequencies higher than
that of the basic QRS complex.' 15 17
Because most of the previous studies through
no fault of the investigators were without
benefit of anatomic correlation, we set about
to ask the following questions: (1) Can subjects with autopsy-proven myocardial infarction be distinguished as a population group
from normals or from people with other forms
of heart disease (without anatomic evidence
of myocardial scarring) on the basis of the
62
y
13
z
V4
'14
II
III
fV5
VrU2
V4
Vf
Figure 2
Scalar leads of a 69-year-old man with posteroinferior myocardial scarring. Note the relatively
smoother QRS complexes when compared with figures 1 and 4. In lower left corner direct writer recordings are shown with residual q waves of old infarction.
Circulation, Volmme XXXIX, April 1969
HIGH-FREQUENCY COMPONENTS IN THE ECG
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Surface potential from each site was recorded at
both sxveep speeds and a minimum of two such
sets for each lead was obtained. At the time of
each repeated admission, follow-up sets were
obtained. Identical leads were recorded on 36
healthy male medical students. The frequency
response of the system was 0.2 to 10,000 cycles/
sec. Notches and slurs were counted by two independent observers using the technics of Langner, Geselowitz, and Mansure. 9, 10, 15 The totals
represent the mean of the sums of notches and
slurs in XYZ and V1 to V.
At the conclusion of 4 years, 128 of the
original 1,300 patients had expired in the hospital
and autopsy permission had been obtained. Two
or more of the authors performed fresh dissections
of the hearts. The coronary tree was serially
sectioned and again opened longitudinally from
the ostium distally. The right ventricle was dis-
sected free from the interventricular septum, and
after removal of the fat was measured planimetrically and weighed. Fat was removed from
the left ventricular free wall which was then
weighed with the septum. Both the left ventricular free wall and septum were sliced
longitudinally at 0.5-cm levels from apex to
base. The results were recorded on special protocol sheets with notation of right and left
ventricular masses, right ventricular area, lesions
in the coronary arterial tree, and the exact site
and size of the lesions in the myocardium. These
lesions were also photographed in color. Thirteen
subjects were eliminated from the study because
of advanced conduction defects.
Results
In the course of study we developed a
strong impression that notching and slurring
Figure 3
Heart of patient whose ECG is illustrated in figure 2. Above left, the interventricular septum
and, above right, left ventricular free wall are seen from the left ventricular endocardial aspect.
The specimens are oriented with the valve ring at the top and the ventricular apex at the
bottom. Below, and similarly oriented, intramyocardial areas of septum (left) and free wall
(right) are exposed. Note scarring of posterior septum and beneath posterior papillary muscle
from valve rings to apex.
Circulation, Volume XXXIX, April 1969
533
FLOWERS ET AL.
534
Table 1
Principal Etiologies of Heart Disease in Subjects with
X
Y
z
x
Y
Ventricular Enlargement
z
Systemic hypertension
V4
Pulmonary
Rheuimatic
Patients
18
6
Infections
VI
Vf
g
v
T- _|
I
V2
V3
V4 l ^
0-
1 ~~mv-
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Figure 4
Scalar leads of a 47-year-old man with rheumatic
aortic insufficiency and left ventricle weighing 578 g.
Right ventricle weighed 100 g. No myocardial scarring
in spite of prominent notching (see text).
occurred at least as frequently in recordings
from subjects with large, uninfarcted hearts
as in recordings from those with myocardial
scars or fresh infarctions. Two extreme examples follow: In figure 2 note the relatively
smooth QRS complex in the scalar leads of
this subject who had postero-inferior myocardial scarring seen in figure 3. In the electrocardiogram of a 47-year-old man with longstanding aortic insufficiency of rheumatic
origin, however, notching is evident in many
leads (fig. 4). Ventricular weights were excessive, the right ventricle weighing 100 g
and the left weighing 578 g. Coronary arteries
were large and wide open without evidence of
even minimal atherosclerosis.
We set about to see if these impressions
held up under statistical analysis. The criteria
for ventricular enlargement were based upon
our own work involving over 2,000 dissections
and several autopsy studies reported by
Saphir.19 The right ventricular upper limit of
normal was assumed to be 50 g, while the left
ventricle and septum were considered enlarged if they exceeded 180 g. The all-male
groups represented in the bar graph (fig. 5)
include 36 healthy medical students of mean
age 25 years ("young normals"), and six
1
13
3
Primary or secondary myocardial disease
Unclear
persons with a mean age of 71 who had died
from other than cardiac causes in whom no
evidence of scarring or enlargement was found
("old normals"). These have been graphed
separately for reasons which will become
obvious.
In the ventricular enlargement group there
were' 46 subjects, with a mean age of 59.
Hearts were included in this group if they
(1) fulflled the weight requirements and
(2) had no gross evidence of myocardial
scarring of any size. Though not a pre-set
criterion for being included, no occlusion of
any of the coronary arteries through the third
-T
24F
201-
16
12
4
fi
NO
VENTRICULAR
ENLARGEMENT
4;
VENTRICULAR
ENLARGEMENT
8INFARCTION
Figure 5
The mean of the sums of notches in X, Y, Z, and V1
to V5 (along ordinate) of the three autopsied groups
on right and the 36 young normals, left. Standard
error is graphed. The number of subjects in each
group is noted along abscissa. The ventricular enlargement and infarction groups were indistinguishable,
but both were distinct from young tnormals: P < 0.01
atnd old normals: P < 0.05.
Circulation, Volume XXXIX, April 1969
HIGH-FREQUENCY COMPONENTS IN THE ECG
535
* normal
+ enlargement
50
*
*
*
ck > z
40
v
fi
u
v
a~~~~~~~~~~~~~~~~
.
V~~~~v
-t-- infarction
AV
^
-C 30
0
0.
v
v~~~~~~~~~~~~~~~~~~0
VV~~~cmbne
venrclr
egt
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Figure 6
Total number of notches from each subject (XYZ plus V- to V,) plotted against subject's own
combined ventricular weights. Note positive correlation in enlargement groups but less inl inf arction group illustrated by regression lines. The very high correlation (0.97) in the old normals
was not plotted due to small sample.
Table 2
Comparative Correlations WVhen Notching in XYZ and V1 to V5 were Analyzed Separately in
the Noninfarction and the Infarction Groups
Notches
Age
Bivariate (r)
RVM
LVM
Age
Multivariate (t)
LVM
RVM
r
No infarct
Infarct
-0.42
-0.11
0.42
0.14
V1-V5
0.31
0.13
-2.58
-0.31
3.01
0.56
-0.08
0.34
0.56
0.15
No infarct
Infarct
-0.48
-0.04
0.26
-0.00
XYZ
0.48
-0.01
-2.04
-0.45
1.21
-0.07
1.70
-0.23
0.55
0.06
Note: The numbers in the three bivariate analysis columns on the left are correlation coefficients as is the final column under multivariate analysis. Note that composite correlation exceeds
any partial correlation for a group. The first three columns in the multivariate section on the
right are all t values; those in italics are significant with P < 0.05 and the value in bold face is
significant with P < 0.01.
Note greater dependence on right ventricular mass for V1-V5 notching in the noninfarction
group. Left ventricular mass shows the highest correlation with notching in XYZ in the noninfarction group. Inverse age correlates well with notching in both XYZ and V1-V5 for the
noninfarction group.
Note lack of correlations in the infarction group.
branching
noted in
of the enlargediagnoses of this
group are noted in table 1 by etiology.
was
any
ment group. The cardiac
Circulation, Volume XXXIX, April 1969
In the infarction group there were 63 subjects with a mean age of 64. Hearts with
diffuse or spotty, or tiny and single scars
FLOWERS ET AL.
536
1k
T
1I
NON-INFARCTION
NO. OF NOTCHES
o 0-15
016-25
A 26-35
+ 36 & over
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0
MYOCARDIAL INFARCTION
Figure 7
Multivariate analysis of dependency of notch count on age, left, and right ventricular masses.
In the noninfarction group (above) multiple dependency is evident by the tendency of subjects
with low notch counts (open rectangles and dots) to cluster about the higher ages but lower
ventricular weights; subjects with higher notch counts (triangles and stars) hover nearer lower
ages but higher ventricular weights. Such dependency is not apparent in the more random
scatter of the infarction group (below).
were included as well as those with coalescent
large scars. All had either complete occlusion
or marked atherosclerotic narrowing of one
or more branches.
By Cochran's approximations of Student's
t-test,20 the myocardial infarction group and
the ventricular enlargement group were each
clearly distinguishable from both groups of
normal subjects with P <0.01 in the case of
the "young normals," and P < 0.05 in the case
of the "old normals." The infarction and enlargement groups, however, were indistinguishable from each other. It is obvious, then,
from the graph that the "old normals" had
more notches than the "young normals," but
the most notches were seen in the enlargement
group, with the infarction group following
very closely.
Does the number of notches depend on
age or ventricular mass? The answer is yes
under certain circumstances, as illustrated in
figure 6. Note that in the noninfarction group
there is dependency of notch frequency on
total ventricular mass as indicated by the
regression line (r = 0.35), but in the infarction
group, this dependency appears to be lacking,
with an r value of 0.09. In the enlargement
("old normal") group the dependency of
notching on weight was striking (r=0.97),
but the sample was small. When the variables
age, left ventricular mass, and right ventricular
mass were each allowed to act singly as the
Circulation, Volume XXXIX, April 1969
537
HIGH-FREQUENCY COMPONENTS IN THE ECG
Table 3
Statistical Summary of Bivariate and JMultivariate Analysis of the Combined X YZ and
Vl-V5 Data
Bivariate (r)
Notches
Age
No infarct
Infarct
-0.47
--0. 10
RV'M
0.39
0.04
AIultivariate (t)
LVMN'
0.38
0.09
Age
RVAI
LVMI
r
-2.57
-0.39
2.60
0.35
0.52
0.14
0.57
0.11
Note: High negative correlation with age and positive correlation with right and left ventricular
masses in the noninfarction groups. Correlations are much lower in the infarction group.
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independent variable and the relationship to
notches was tested, certain relationships became apparent (table 2). In the enlargement
(noninfarction) group, there was a relatively
high negative correlation with age. There was
greater dependency on right ventricular than
on left ventricular mass for notching in the
electrocardiographic leads, but this dependency was reversed in the case of the vectorcardiogram, in which case the better correlation was between notching and left ventricular
mass.
Next, we subjected these groups to multivariate analysis20 as illustrated in figure 7.
This is a scatter graph of the noninfarcted
group above, and the infarcted group below
plotted along three axes representing age,
left ventricular mass, and right ventricular
mass. The tops of the figures indicate grouping by numbers of notches. Note in the noninfarcted group that the dependency on age
and ventricular weights is graphically illustrated by the tendency of subjects with the lower
notch counts (dots and open rectangles) to
cluster toward lower ventricular weights and
higher ages, while those with higher notch
Table 4
Hypotheses as to Notch Formation in the ECG
Classical shattering of the wave of activation on the
zone of infarction
2. Departture from even radial spread of activation
throtugh the ventricutlar wall due to
a. Microinfarction
b. Ftunctional microblock
3. Accentuation of 2 by ventricular hypertrophy
(competing generator sites)
4. Relationship of anisotropy to above
1.
Circulation, Volume XXXIX, Apiil 1969
counts (triangles and stars) cluster at higher
weights but lower ages. Randomness prevails
in the scatter of subjects with infarction.
We concluded, therefore, that there was a
significant inverse dependence on age and a
direct dependence on right and left ventricular mass in the noninfarction subjects. Such
dependence was not demonstrated in the
infarction subjects. Table 3 summarizes the
statistical analysis.
Discussion
The greater dependency on right ventricular
mass for notching in the precordial leads is
thought to relate to the proximity effect of
VI and V2 especially to the enlarging right
ventricle. The vectorcardiogram, by its very
nature a more perfect vectorial averager,
favors the expression of the naturally dominant left chamber. We suspect the explanations
for left ventricular dependency for notching
in the vectorcardiogram might be so related.
What then are the casual possibilities for
notching in general (table 4)? The Purkinje
block, suggested by Oppenheimer and Rothschild in 191721 to explain interruption of the
smooth progress of the wave of activation,
still remains a tenable explanation in certain
cases. The alteration of the power spectrum
in acute infarction with ultimate resolution
with healing, as suggested by Franke and
associates,22 may well be due to functional
block in reversibly injured tissue. The work
of Langner and Geselowitz relating the number of notches to clinical coronary disease
and Reynolds' relationship of notching to
primary myocardial disease point to probable
structural interruption of the activation wave
of poorly conductive tissue.5' 14-17 But the
538
FLOWERS ET AL.
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striking occurrence of the most notches in
patients with ventricular enlargement from
many etiologies other than atherosclerotic
suggests, at the least, multiple causation.
From whatever cause, when the normally
smooth, radial spread of activation from the
endocardium outward is interrupted, and more
tangential, less efficient detours are taken,
distortion of the QRS curve results. Anisotropy
of propagation in the case of the myocardial
syncytium implies differences in conduction
along the long axis as compared to conduction
across the muscle fiber. We would like to
suggest tentatively that the anisotropic properties of the myocardium may be accentuated
and compounded by many structural or
functional changes. More practically, we may
presuppose a number of necessary deviations
in the activation pathway, but in the presence
of ventricular hypertrophy the powerful pull
of the generator in either ventricle tends to
accentuate any unevenness of the spread of
activation in the alternate ventricle.
The detection of high-frequency notching
may prove to be a screening device for heart
disease of any etiology leading to biventricular enlargement, as well as for classical
atherosclerotic heart disease.
Acknowledgment
We are grateful to Mrs. Hazel G. Wall for assistance in preparation of the manuscript and to Mrs.
Patricia Orander, Mrs. Diane Lafferty, and Mr.
Charles Eddlemon for technical assistance. The continuing cooperation of Dr. Joseph Young, Chief of
Laboratory Service at the Kennedy Veterans Administration Hospital, made possible the detailed
dissections and Mr. James A. Irby of the Medical
College of Georgia Computer Center provided helpful statistical advice.
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Types of Critics
The capacity of public somnolence to retard change illuminates the role of the critic.
In the early years of this century Abraham Flexner touched off a revolution in medical
education by placing before the public a brilliant expose of existing medical schools.
Critics who call attention to an area that requires renewal are very much a part of
the innovative process. (Of course, all critics are not heralds of the new. Some are
elegant connoisseurs of that which has arrived, and when they approve of something
it is likely to be long past its creative period. Like Hermes conducting the souls of the
dead to Hades, they usher ideas and art forms into the mausoleums of "the accepted.") JoHN W. GARDNER: Self-Renewal: The Individual and the Innovative Society. New
York, Harper & Row, Publishers, 1963 and 1964, p. 30.
Circulation, Volume XXXIX, Apfil 1969
The Anatomic Basis for High-Frequency Components in the Electrocardiogram
NANCY C. FLOWERS, LEO G. HORAN, J. R. THOMAS and WILLIAM J.
TOLLESON
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Circulation. 1969;39:531-539
doi: 10.1161/01.CIR.39.4.531
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1969 American Heart Association, Inc. All rights reserved.
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