Download Left Axis Deviation in Inferior Infarction

Left Axis Deviation in Inferior Infarction;
Vectorcardiographic Recognition of
Concomitant Left Anterior Hemiblock*
H . E . Kulbertus, M.D.;OOP. CoUignun, M.D.;? L. Humblet, M.D.;S
and F . Debval- Rutten, M.D.5
The vectorcardiograms of 30 patients with inferior infarction and abnormal left
axis deviation were studied. In 23 cases, the frontal plane loop was clockwise
rotated and the initial vectors were superiorly displaced. The remaining seven
tracings also showed superior orientation and clockwise rotation of the initial
forces, but the second balf of QRS was displaced further superiorly and counterclockwise inscribed. The vectorcardiographic pattern observed in those seven
cases was postulated to indicate inferior wall infarction with concomitant left
anterior hemiblock. This hypothesis was substantiated by the clinical observation of two patients in whom the separate components of the complete pattern
appeared successively. It is concluded that in inferior infarction, abnormal left
axis deviation may result either from the infarction alone, or from the concomitant presence of left anterior hemiblock which can be depicted from observation
of the frontal plane vectorcardiogram.
eft anterior hemiblock is generally considered to
be the most frequent cause of left axis deviation
in adults. 1-4 Its electrocardiographic and vectorcardiographic patterns have been thoroughly described.'-6 The mean QRS axis is shifted to the left
(higher than -30' ) and the QRS complexes show
an rS morphology in leads 11, I11 and aVF of the
standard electrocardiogram. The frontal plane loop
of the vectorcardiogram is counterclockwise rotated
with inferior orientation of the initial vectors.
Inferior wall myocardial infarction is another
condition which may lead to abnormal left axis
deviation. Therefore, whenever left axis deviation is
observed in a patient with inferior infarction, the
problem always arises whether the axis shift is due
to rupture of the electrical balance produced by the
infarction itself or might be related to a concomitant left anterior hemiblock.
The present paper is concerned with a vectorcardiographic study of 30 patients with left axis
deviation and inferior wall myocardial infarction.
Its purpose is to try to define criteria permitting
the diagnosis of left anterior hemiblock in the
presence of inferior wall myocardial infarction.
The following criteria were used for selection of the
patients. ( 1 ) All subjects in this study had presented with
clinical signs of acute myocardial infarction with transient
diagnostic rise of serum lactate dehydrogenase. (2) At the
time of the acute episode, the electrocardiogram showed the
classic criteria of inferior infarction, ie Q wave of 0.03 sec
or more with a depth 25 percent or more of a succeeding R
wave and characteristic ST segment and T wave changes in
leads 11, 111 and aVF.7-10 Patients displaying coexistent
anterior or posterior infarction were not excluded from the
series. (3)At the time of the vectorcardiographic study, the
electrocardiograms showed, in all cases, a leftward deviation
of the mean QRS axis in the frontal plane ( -30" or higher ) .
Over the past two years, 30 such cases were collected.
There were 25 men and five women, ranging in age from 35
to 86 years with an average age of 60. Their electrocardiograms showed unequivocal features of inferior infarction in
all cases. In addition, changes of coexistent anterior infarction
.From the Section of Cardiology, Department of Medical
Clinic and semiology, university of ~i~~~ school of ~ ~ d i - were observed in six patients and of posterior infarction in
cine. Liene. Belnium.
five. The interval between the acute e ~ i s o d eand time of
0 ° ~ h & g 6dk '~echYerchesdu Fonds National de la Recherche
between five months and
vectorcardiographic study
Scientifique Belge.
four
years.
tPremier Assistant.
Spatial vectorcardiograms were recorded using the Mc Fee:Collaborateur scientifiaue de 1'Universitk.
$Assistant.
Parungao axial system.11 The frontal, horizontal and left
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LEFT AXIS DEVIATION IN INFERIOR INFARCTION
FRONTAL
I
-
HORIZONTAL
FIGURE
1. Electrocardiogram and vectorcardiogram of a patient aged 35, with inferior infarction.
The mean QRS axis is located at about - 30'. The frontal plane loop is clockwise rotated and
the initial vectors are superiorly displaced. The loop is interrupted every 1 / 4 0 sec. Calibration:
500 p V in both vertical and horizontal directions.
sagittal plane loops as well as the scalar tracings X, Y and Z
presence of isolated inferior infarction, the morwere photographed by means of a Polaroid camera. A fivephology of QRS in this projection appeared to be
fold ampliscation was taken to provide better delineation of
In the six patients with coexistent anterior
the early forces. Timing of the various points of the loop was
infarction, there was a posterior displacement of the
obEained by counting dots on the photograph from the onset
20 msec vectors. On the other hand, in the five cases
of QRS.
It was readily apparent that the vectorcardiograms of the present series might be divided into
two subgroups.
In subgroup A which comprised 23 cases, (Fig
I ) , the frontal plane loop was entirely clockwise
rotated and the efferent limb was superiorly displaced. The duration of superior forces was always
greater than 25 msee. The horizontal plane loop
showed an overall counterclockwise rotation. In the
with coexistent posterior necrosis, anterior forces
with increased magnitude and duration ( > 40
msec) were noted. The left sagittal plane projection
confirmed the superior displacement of the initial
portion of the loop.
Subgroup B consisted of seven patients whose
vectorcardiograms showed obvious differences from
those described in subgroup A (Fig 2). The main
distinctive features were seen in the frontal and left
sagittal plane projections. In the frontal plane, the
beginning of the loop was also displaced superiorly
with clockwise rotation, but an abrupt shift was
FRONTAL
-
FIGURE
2. Elecu-ruu.uslrua. ru.U vectorcardiogram of a patient aged 53 with inferior infarction
and left axis deviation. In the frontal plane, the initial forces are superiorly displaced and
clockwise rotated. At about 40 msec, there is an abrupt shift of the loop. The second half of
QRS is located superior to the efferent limb and turns in a counterclockwise fashion. The loop
is interrupted every 1 / 4 0 sec. Calibration 500 p V .
CHEST, VOL. 60, NO. 4, OCTOBER 1971
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KULBERTUS ET AL
observed at about 40 msec. The intermediate vectors (50 to 60 msec) were inscribed in the left
superior quadrant above the efferent limb, and the
middle and terminal portions of QRS showed a
counterclockwise rotation. In the left sagittal plane,
the initial portion was inscribed superiorly. After
it had reached its maximally anterior extent, the
loop started to proceed posteriorly and then gradually to descend. At about 40 msec, a second inflection point was observed and the following portion
of QRS was located more superiorly and posteriorly than the rest of the loop. None of these seven
patients was found to have associated anterior infarction.
DISCUSSION
In inferior wall infarction, the presence of an
"electrically inert zone* in the diaphragmatic portion of the heart results in a rupture of the balance
of the electrical forces normally generated by cardiac depolarization. The infarction thus allows superiorly directed forces to be unopposed. This may
result in a mean QRS axis oriented superiorly and to
the left which produces an abnormal left axis
deviation. 1 2
From a vectorcardiographic viewpoint, this type
of left axis deviation appears to be quite different
from that described in left anterior hemiblock.5.6*12
The main distinctive findings are as follows: ( 1 )
The initial vectors (10 to 20 msec) are inscribed
inferiorly in left anterior hemiblock. On the contrary, they were superiorly directed in all our cases
of inferior wall infarction. (2) The frontal plane
loop is always inscribed entirely counterclockwise in
left anterior hemiblock. On the contrary, in inferior
wall myocardial infarction, the initial portion of
QRS was always inscribed clockwise in the frontal
plane, the rest of the loop being also clockwise
rotated in 23 out of the 30 cases.
Therefore, it seems that the distinction between
the two mechanisms of left axis deviation is rather
straightforward in most instances. However, there
are fewer cases where the situation appears less
clearcut.
In seven subjects of this series, the initial vectors
were oriented superiorly and inscribed clockwise in
the frontal plane, but the second half of QRS was
counterclockwise rotated and displaced further superiorly. This particular vectorcardiographic aspect associates features of inferior wall myocardial
infarction with signs of left anterior hemiblock and
one is therefore tempted to consider the two abnormalities to be concomitant. The possibility of the
coexistence of left anterior hemiblock and inferior
wall infarction has already been suggested by
L E F T SAGITTAL
XY Z
i
FIGURE3. Electrocardiogram and vectorcardiogram of a man
suffering from longstanding angina pectoris. The first electrocardiogram (30.4.1963) shows complete right bundle branch
block. Moreover, vectorial analysis of the QRS complex indicates initial forces (0.02 sec) pointing inferiorly to the right
and intermediate vectors (50 and 60 msec) located in the
upper left quadrant, higher than - 30". Those features lead
to the diagnosis of left anterior hemiblock associated with
right bundle branch block.
In the second electrocardiogram recorded after an episode
of acute myocardial infarction, a Q wave has appeared in
leads 11, I11 and aVF. In the corresponding vectorcardiogram,
the frontal plane loop shows:
a. Initial vectors directed superiorly and clockwise rotated
( inferior infarction ) .
b. An abrupt shift of the loop at about 40 msec with counterclockwise rotation of the second half of QRS and superior
displacement of V 50 msec and V 60 msec (left anterior
hemiblock).
c. A terminal appendage directed to the right and displaying
conspicuous conduction delay (right bundle branch
block). The loop is interrupted every 1/400 sec. Calibration: 500 pV.
CHEST, VOL. 60, NO. 4, OCTOBER 1971
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LEFT AXIS DEVIATION IN INFERIOR INFARCTION
Grant1 and Rosenbaum and associates* from vectorial studies of standard electrocardiograms.
The following two observations seem to corroborate this hypothesis: (1)The first example is that of
a man with left anterior hemiblock who suddenly
developed an inferior infarction (Fig 3). This
patient had suffered from unequivocal angina pectoris since 1964. The successive electrocardiographic
tracings recorded between 1964 and April 1970
were characteristic of left anterior hemiblock with
right bundle branch block. In May 1970, the patient
suddenly developed an acute episode of myocardial
infarction with definite transient rise of both creatinphosphokinase and lactic-dehydrogenase. Following this, a Q wave appeared in leads 11, I11 and
aVF of the standard electrocardiogram. The vectorcardiogram showed in addition to the right bundle
branch block, a superior orientation of the initial
vectors and a counterclockwise rotation of the QRS
loop. This pattern was very similar to that described
in group B of the present series.
(2) The second example (Fig 4 ) is that of a
patient admitted to the coronary care unit for an
episode of acute inferior wall infarction. Aberrantly
conducted ventricular beats were obtained in this
case by introduction of artificially induced atrial
premature beats. The method used in this study was
described by Cohen and co-workers.13 Atrial premature beats were produced by electrical stimuli
delivered to the right atrium by means of an R
wave coupled pulse generator (Medtronic model
5837). The control tracings showed unequivocal
changes of inferior infarction but the mean QRS
axis remained normal. In the frontal plane, the
initial portion of QRS was located superiorly and
the rotation of the loop was entirely clockwise. In
the experimentally induced beats, aberrant conduction resulted in a leftward shift of the mean QRS
axis with deep S wave in leads 11, I11 and aVF. This
modification was interpreted as caused by the
presence of left anterior hemiblock. The corresponding frontal vectorcardiogram still showed initial vectors superiorly oriented and clockwise rotated. On the other hand, the second half of QRS
was now inscribed counterclockwise and the intermediate forces were located in the upper left quadrant higher than the efferent portion of the loop.
Those two observations corroborate the hypothesis that the vectorcardiographic pattern described in
subgroup B of this series corresponds to an association of '.inferior wall infarction with left anterior
hemiblock. This conclusion is in agreement with the
results recently presented by Chahine and colleagues. 1 4
It is therefore concluded that when abnormal left
i
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FIGURE4. Electracardiogram and vectorcardiogram of a
patient aged 51 with inferior infarction. In each lead of the
electrocardiogram, the second complex follows a premature
atrial beat induced by right atrial stimulation. This results in
aberrant ventricular conduction with leftward deviation of
the mean QRS axis. In the control tracing ( 1 ), the frontal
VCG only shows the superior displacement and clockwise
rotation of the initial portion of QRS. After development of
left axis deviation (2), the afferent limb is inscribed counterclockwise and located high in the upper left quadrant. The
aspect of the frontal and left sagittal plane projections are
then very similar to what was observed in Figure 2. The loop
is intempted every 1/800 sec. Calibration: 250 pV in both
vertical and horizontal directions.
axis deviation is present in a patient with inferior
infarction, the axis shift may be due to the infarction alone, or to the coexistence of left anterior
hemiblock or both.
Observation of the frontal plane vectorcardiogram may permit the diagnosis of left anterior
hemiblock in the presence of inferior wall myocardial infarction: the initial vectors are ohented
superiorly and inscribed clockwise but the second
CHEST, VOL. 60, NO. 4, OCTOBER 1971
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366
KULBERTUS ET AL
.
half of ORS is counterclockwise r o t a t e d a n d lies
superior t o t h e efferent limb.
REFERENCES
9
10
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2 Come RA, Parkin TW, Brandenburg RO, et al: Significance of marked left axis deviation: electrocardiographicpathologic correlative study. Amer J Cardiol 15:605, 1965
3 Pryor R, Blount SC: The clinical significance of true left
axis deviation. Amer Heart J 72:391, 1966
4 Rosenbaum MB, Elizari MV, Lazzari JO: Los Hemibloqueos. Buenos .4ires, Paidos, 1968
5 Testoni F, Narbone NB, Tommaselli A: Aspetti vettocardiographici nei blocchi sinistri con electrocardiogramma
di tippo R1-SII-SIII. Mal Cardiov 9:379, 1968
6 Kulbertus H, Collignon P, Humblet L: Vectorcardiographic study of the QRS loop in patients with left
anterior focal block. Amer Heart J 79:293, 1970
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Vectorcardiography. Philadelphia, Lea and Febiger, 1953
8 World Health Organization: Hypertension and coronary
11
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14
heart disease. Classification and criteria for epidemiological studies. WHO No. 168, 1959
Massie E, Walsch TJ: Clinical Vectorcardiography. Chicago, Year Book Publishers, 1960
Toutouzas P, Hubner P, Sainani G, et al: Value of
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myocardial infarction. Brit Heart J 31:629, 1969
McFee R, Pamngao A: An orthogonal lead system for
clinical electrocardiography. Amer Heart J 62:93, 1961
Kohn PM, Harris AH: Vectorcardiographic analysis of
left axis deviation in the differentiation of diaphragmatic
and parietal block. Dis Chest 47:492, 1965
Cohen SI. Lau SH. Stein E. et al: Variations of aberrant
conduction in man: Evidence of isolated and combined
block within the specialized conduction system: an electrocardiographic and vectorcardiographic study. Circulation 38:899,1968
Chahine RA, Chapunoff E, Castellanos A Jr, et al: Diagnosis of left anterior hemiblock in the presence of inferior
wall infarction. Abstracts, 36th Annual Meeting, the American College of Chest Physicians. Chest 58:276, 1970
Reprint requests: Dr. Kulbertus, Division of Cardiology,
University of Liege School of Medicine, 4000 Liege, Belgium
Found but Not Recognized
Joseph Priestley ( 1733-1804), theologian and sciensupported combustion but prolonged the life of animals
tist, grasped the true nature of oxygen, but, ~ ~ f ~ r t m a t e -breathing it. H e named this new gas "dephlogisticated
IY, failed to comprehend the significance of his discovery.
air,mbut misunderstood the role of this gas in respiration
O n August 1, 1774, h e concentrated the sun's rays with a
and combustion.
burning-glass over mercuric oxide; and readily obtained
Gottlieb, L S: A History of Respiration.
a weas in which "a candle burned in this air with a
Springfield, C C Thomas, 1964
remarkably vigorous flame." This air, h e found, not only
CHEST, VOL. 60, NO. 4, OCTOBER 1971
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