Download Alternate Patterns of Premature Ventricular Excitation

Alternate Patterns of Premature Ventricular
Excitation During Induced Atrial Bigeminy
By STAFFORD
COHEN, M.D., SUN H. LAU, M.D.,
BENJAMIN J. SCHERLAG, PH.D., AND ANTHONY N. DAMATO, M.D.
I.
SUMMARY
Alternate patterns of
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premature ventricular excitation have been observed during
induced atrial bigeminy in 18 subjects, including five normal volunteers. Each study
was performed in the cardiac catheterization suite where a transvenous catheter
electrode was positioned in the right atrium. Coupled or paired stimuli were delivered
to the atrium by an isolated battery-powered source at an adjusted interval whiclh
resulted in alternate patterns of ventricular excitation from alternate premature beats
("alternating premature ventricular excitation").
In most instances "alternating premature ventricular excitation" occurred when
parameters of preceding cycle length, premature coupling interval, and atrioventricular
conduction time were constant.
In man also some observations were made of His bundle excitation during premature
atrial stimulation, and in the intact dog heart some observations were made of alternating premature ventricular excitation during His bundle stimulation.
A tenable explanation for alternating premature ventricular excitation is advanced
which rests on three postulates: (1) A long cycle length is followed by a long
refractory period. (2) The refractory period of each branch of the specialized
conduction system is dependent on its preceding cycle length or recovery period; and
(3) the diastolic recovery period of a blocked segment of the specialized conduction
system is shorter than the recovery period when blockade does not occur.
Additional Indexing Words:
Aberrant ventricular conduction
Left bundle-branch block
Specialized conduction system
His bundle stimulation (dog)
Right bundle-branch block
Incomplete bundle-branch block
His bundle electrogram
Methods
Observations were made on 18 subjects,
including five normal volunteers by methods of
investigation which have been previously
described in detail.1 2 In brief, each study was
performed in the cardiac catheterization suite
with the subject in the nonsedated postabsorptive state and supine position. A bipolar
or tripolar catheter electrode was introduced into
an antecubital vein, utilizing sterile percutaneous
technic and local anesthesia. The catheter was
positioned against the lateral wall high in the
right atrium under fluoroscopic and electrocardiographic control. Coupled or paired stimuli were
delivered to the atrium by an isolated batterypower source (Medtronics R-wave, coupled pulse
generator) at an adjusted milliamperage which
would assure atrial capture. The atrial coupling
interval, or the interval between paired pulses,
A N UNUSUAL form of alternating ventricIlular conduction has been observed in 18
patients during right atrial pacing studies. The
purpose of this report is to describe the
phenomenon and to propose an electrophysiological mechanism of alternating patterns of
premature ventricular excitation during induced atrial bigeminy.
From the Cardiopulmonary Laboratory, U. S.
Public Health Service Hospital, Staten Island, New
York.
This work was supported in part by the Federal
Health Program Service, U. S. Public Health Service
Project Py 69-1, National Institutes of Health Grants
HE-11829 and HE-12536 and NASA Contract T22416.
Circulation, Volume XXXIX, June 1969
819
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COHEN ET AL.
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Figure 1
Method of producinig alternating ventricular excitation: (A) Coupled atrial premature beats
(Rl-S coupling interval, 318 mnsec) results in normal ventricular excitation (R). (B) All
premature beats with a shorter coupling interval (276 msec) result in incomplete right bundlebranch block pattern of ventricular excitation. An S wave has appeared in lead I and an rsR'
in lead V>. (C) Further reduction of the coupling interval (250 msec) results in an alternating
pattern of ventricular excitation with alternlate coupled atrial premature beats in which
ventricular excitation alternates between complete right bundle-branch block and incomplete
right bundle-branch block. (D) All premature beats with a further decrease in coupling
interval (233 msec) now result in a complete right bundle-branch block pattern.
was gradually decreased until an alternating pattern of ventricular excitation occurred from alternate premature atrial beats (fig. 1). The atrial
coupled or paired pace interval was maintained
above 300 msec to avoid the atrial vulnerable
period.3
In the remainder of this report, an alternating
pattern of ventricular excitation from alternate
coupled or paired atrial premature beats will be
referred to as "alternating premature ventricular
excitation."
Direct brachial artery pressure was recorded
during alternating premature ventricular excitation in one patient.
Supplementary observations are presented
which relate to the mechanism of alternating
premature ventricular excitation. These data
include His bundle electrograms which were
recorded in man during the induction of atrial
premature beats. The details of the method have
been described elsewhere.4 In addition, alternating premature ventricular excitation was produced in the intact hearts of four mongrel dogs by
electrical stimulation of the His bundle through
two Teflon-coated stainless steel wires which had
been inserted by needle placement directly into
the area of the His bundle. The sinus node was
crushed after it was ascertained that the pattern
of ventricular excitation appeared constant when
activated by the normal sinus mechanism or by
His bundle stimulation.5 Atrioventricular nodal
rhythm usually followed the crushing of the sinus
node. A His bundle stimulus was coupled to each
spontaneous control beat at an adjusted interval
which produced alternating premature ventricular
excitation (fig. 2).
All electrocardiograms were displayed on a
multichannel oscilloscopic photographic recorder
(Electronics for Medicine or Sanborn 4560
series) and records taken at paper speeds of 25 to
100 mm/sec. His bundle recordings were taken at
200 mm/sec.
Nomenclature
Incomplete right bundle-branch block pattern
is defined as a right bundle-branch block pattern
of 0.08 to 0.11-sec duration.6
Incomplete left bundle-branch block pattern is
defined by criteria which include absence of q
waves (with or without slurring of the R wave)
in leads "facing" the left ventricle (leads I, aVL,
V5, and V6), small or absent R waves in lead
Circulation, Volume XXXIX, June 1969
821
PREMATURE VENTRICULAR EXCITATION
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Figure 2
Alternating ventricular excitation from His bundle stimulation: Coupled His bundle premature
beats in the intact dog heart result in alternating conduction. Preceding diastolic interval
(R2-R1), coupling interval (R1-S), and atrioventricular conduction time (S-R2) are constant.
V1, and qrs duration of 0.08 to 0.11 sec.7 8
Left axis deviation was determined by the
criterion of a mean frontal axis of -30° or beyond.
Results
The results are presented in table 1. There
were 22 instances of alternating ventricular
excitation in the 18 patients. In order of
frequency, the alternating patterns were as
follows: Right bundle-branch block alternating with control excitation, 10 examples (figs.
3 and 4); left axis deviation alternating with
right bundle-branch block with left axis
deviation, four examples (fig. 5); right
bundle-branch block alternating with right
bundle-branch block with left axis deviation,
two examples (fig. 6); right bundle-branch
block alternating with incomplete right
bundle-branch block, two examples (fig. 1);
right bundle-branch block alternating with
left bundle-branch block, two examples (fig.
Circulation, Volume XXXIX, June 1969
7); incomplete left bundle-branch block
alternating with control excitation, one
example; and right bundle-branch block with
left axis deviation alternating with control
excitation, one example.
In four patients, it was possible to record
two distinct types of alternating ventricular
excitation at different coupling intervals.
Alternating premature ventricular excitation
occurred in 14 of 18 cases when the preceding
cycle length, premature coupling interval, and
conduction time were constant (figs. 2, 3, 5,
and 8).
Alternating durations of the cycle (R2-R1)
immediately preceding the cycle which
terminated in the premature atrial beat (R1R2) occurred in four of 18 cases (figs. 4 and
6). In each case, the shorter preceding cycle
length was always associated with one form of
premature ventricular excitation, and the
822
COHEN ET AL.
Table 1
Sumnmary of Results
Pt.
ECG
diagnosis
Age
(yr)
Alternating patterns
J.G.* 43 N
R.H.* 31 N
B.A.
V.C.
B.B.*
P.I.*
R.N.
F.S.
F.F.*
J.S.
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A.D.
J.A.
H.L.
G.R.
G.G.
G.A.
F.H.
T.F.
58
48
35
30
51
62
32
54
70
51
36
19
50
51
70
55
RBBB
RBBB
RBBB LAD
Inf. MI
RBBB
LAD
RBBB
N
LAD
N
ILBBB
RBBB
S1S2S3
LAD
RBBB LAD
N
RBBB
RBBB
NSST& T RBBB LAD
LAD
RBBB
LVH
RBBB
RBBB
Inf. MI
RBBB
N
LAD
R/S V1 > 1 RBBB
RBBB LAD
LAD
LAD
N
RBBB
LAD Inf. MI RBBB
C
C
RBBB
C
C
RBBB LAD
C
C
LAD
C
IRBBB
C
C
C
IRBBB
LBBB
RBBB LAD
C
RBBB
RBBB LAD
LBBB
C
*
Normal volunteers.
Abbreviations: N = normal; LAD left axis deviation; Inf. MI = inferior myocardial infarction; NS
ST & T = nonspecific ST & T-wave abnormality;
LVH = left ventricular hypertrophy; R/S V1 > 1 =
R/S ratio in lead V1 is greater than 1; RBBB right
bundle-branch block; RBBB LAD
right bundlebranch block and left axis deviation; C
control
QRS; LAD = left axis deviation; IRBBB = incomplete right bundle-branch block.
=
=
=
=
longer preceding cycle length was always
associated with the alternate form of
premature ventricular excitation.
The peak arterial pressures generated by
alternate pathways which were not necessarily
reflected in measurements of atrioventricular
conduction time, preceding cycle length, and
premature coupling interval.
When a premature atrial beat results in a
pattern of aberrant ventricular conduction,
there is either a primary delay in excitation
through a branch of the specialized conduction system or functional block of a branch of
the speciahzed conduction system. In the
event of a functional block of conduction, the
ventricular myocardium supplied by the
blocked branch is ultimately activated by an]
indirect route. The blocked branch has a
shorter diastolic recovery period than the
unblocked branches by virtue of its late
activation. It follows that the next coupled
atrial premature beat should find the
previously blocked segment less refractory
than alternate pathways. This "unblocking"
permits either normal or less delayed
conduction. Thereafter the recovery time of
the segment wvould once again be relatively
longer because of a longer diastolic recovery
period and the coupled atrial premature beat
which follows the "uniblocking" mav once
again find the branch in an increased
refractory state which does not permit normal
passage. This view is presented in schematic
form in figures 3, 5, 6, and 7. The alternating
patterns of ventricular excitation indicate that
the right bundle branch, anterior division
of the left bundle branch, and common left
bundle branch may have blocked or delayed
conduction and that the refractory period of
each branch of ventricular excitation varied
with the pattern type in the one case in which
it was recorded (fig. 4).
Selected records of His bundle electrograms
are presented which demonstrate aberrant
ventricular conduction with retrograde His
bundle excitation (fig. 9), and alternating
ventricular excitation with unchanged atrium
to His bundle and prolonged intraventricular
conduction times during aberrant beats (fig.
8).
Discussion
This report demonstrates that alternate
coupled or paired atrial premature beats may
excite the ventricles through alternate pathways. Katz and Pick9 illustrate a case of atrial
bigeminy which is similar to the type of
c"alternating premature ventricular excitation"
described herein. However, these authors
ascribed alternating pathbways of excitation to
slight differences in atrial coupling intervals.
Altered ventricular excitation following an
atrial premature beat depends upon the
duration of the preceding cycle length, the
coupling interval, and the atrioventricular
conduction time.' Each of these factors is of
Circulation, Volume XXXIX, June 1969
PRE\IATURE VENTRICULAR EXCITATION
R1 R2
R1
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R1R2
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<
RECOVERY
RBB
Figure 3
Right btunidle-branch block alternating with normal control excitation: Coupled premature atrial
beats resuilt in alternating patterns of ventricular excitation. The coupling inter val (R1-S),
preceding cycle length (R2-R,), and A-V conduction timie (S-R2) intervals are constant. A
schematic representation of the recovery period of the right bundle branch is presented at
the bottom of the figure. See text for explanation of why there is longer diastolic recovery
period of the right buindle branch following a normally conducted premature beat and why
right buindle-branich block patterns of aber-rant conduction follow the longer recovery period.
a
importance in the production of alternating
premature ventricular excitation because one
or both of the alternating patterns is in the
form of aberrant ventricular conduction.
The refractory period of the conduction
system is directly related to the preceding
diastolic interval."', 11 It can be inferred from
the duration of phase 3 of the myocardial
action potential that there is a very sensitive
relationship between diastolic cycle length
and refractory period in man wlhich may
change fromn beat to beat in the presence of a
changing heart rate.'2 In four of the 18 cases,
there was an alternation of the duration of the
cycle length (2R,11) which preceded alternate fixed-coupled atrial premature beats. The
longer preceding cycle lengths resulted in
greater prolongation of the refractory period
of the specialized con(lldction system, and the
shorter preceding cycle lengths resulted in less
lrtulailt&n;
Volionu
XXXIX,
June
1969
prolongation of the refractory period. Therefore, the atrial premature beats which
followed the longer preceding cycle lengths
had a greater chance of abnormally exciting
the ventricle than those which followed the
shorter preceding cycle lengths. In the
majority of cases (14 of 18) electrophysiological parameters, such as preceding cycle
length, atrioventricular conduction time, and
premature coupling interval, were constant for
each pattern of premature ventricular excitation. It is unlikely that the specialized
conduction system would both permit and
prevent conduction under the same electrophysiological circumstances. Analysis of the
records revealed that alternating premature
ventricular excitation resulted from electrophysiological changes within the branches of
the specialized conduction system is dependent upon its rate of excitation (figures 3, 5, 6,
and 7).
824
COHEN ET AL.
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R2
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OCONTINUOUS STRIP
Pt RH
Figure 4
Alternating ventricular excitation with simultaneous atrial pulse: Coupled atrial premature
beats result in alternating excitation of normal and right bundle-branch block patterns. Atrioventricular conduction time (S-R2) is constant for all premature beats. Coupling interval (Rl-S)
vary 10 msec. The diastolic interval (R2-R1) which follows normally conducted premature
beats is consistently longer than the diastolic interval which follows premature beats of right
bundle-branch block configuration. The peak systolic pressure in the brachial artery generated
by normally conducted premature beats is consistently greater than that generated by the
premature beats of the right bundle-branch block pattern.
R
la R2-R
R1 2 R2
RR
R
14
R2
R
R
R
MSEC 598
S2-R2M1SEC
1~~~~1
212
_
sec _
sec
RECOVERY
RBB
ANT DIVLBB
-
-
Figure 5
Alternating left axis deviation with right bundle-branch block with left axis deviation: Paired
atrial pacing results in alternating ventricular excitation. Preceding diasolic interval (R2-R1),
premature atrial stimulation interval (R1-R2), and atrioventricular conduction time (S2-R2) are
all constant. Pairs 1, 3, and 5 terminate in left axis deviation. Pairs 2, 4, and 6 terminate in
right bundle-branch block with left axis deviation. The recovery periods of the right bundle
branch and anterior division of the left bundle branch (which results in left axis deviation
when blocked) are schematically represented at the bottom of the figure.
Circulation, Volume XXXIX, June 1969
PREMATURE VENTRICULAR EXCITATION
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RBBANTLBB _M
825
-a
Figure 6
Alternating right bundle-branch block and right bundle-branch block with left axis deviation:
Couipled atrial premature beats result in an alternating pattern of excitation consisting of
alternlating right bundle-branch block and right bundle-branch block with left axis deviation.
The cotupling intervals (RH-S) and A-V conduction times (S-R2) are identical for all premature
beats. The diastolic interval (R2-RH) is 60 msec longer in those cycle lengths preceding right
btundle-branch block with left axis deviation. The diastolic recovery period of the right bundle
branch and anterior division of the left bundle branch (which restults in left axis deviation
-i h1ent blocked) is schienmaticallyl represented at the bottonm of the figulre.
Consecutive supraventricular impulses may
stimulate repetitive ventricular beats (fig. 10)
or ventricular tachycardia. This event is
believed to occur because the branch of the
specialized conduction system which was
initially refractory to antegrade conduction
remains refractory to subsequent stimuli from
above as a result of intermediary late
(retrograde) activation."' 12 Repetitive functional block can thus occur, provided that the
atrial input frequencies fall within required
limits. An example is shown of retrograde
activation of the His bundle in man after an
aberrant beat of right bundle-branch block
configuration (fig. 9). In all likelihood
retrograde activation of the His bundle
occurred through late activation of the right
bundle branch. This observation would
support the thesis that following the right
Curculaion, Volume XXXIX, June 1969
bundle-branch block pattern of aberrant
ventricular conduction, the right bundle
branch has a shorter recovery period than that
following normal conduction.
It is possible for retrograde conduction of a
main bundle branch to occur without His
bundle activation. Thus, retrograde His
bundle activation does not follow all instances
of aberrant conduction and is not apparent in
figure 8. The fact that alternating ventricular
excitation can be produced in dogs by His
bundle stimulation precludes implicating
pathways other than those of the specialized
conduction system (fig. 2).
Several examples of alternating incomplete
and complete bundle-branch block were noted
(fig. 1). This type of alternation can be
explained by the fact that the refractory
period of the specialized conduction system is
826
COHEN ET AL.
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MSECI 200
.
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-
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.
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RECOVERY
RBBLBB-
-
--
Figure 7
Alternating right bundle-branch block and left bundle-branch block: Coupled atrial premature
beats result in alternating right bundle-branch block and left bundle-branch block patterns
of excitation. Coupling interval (R1-S) and conduction time (S-R2) are constant. Diastolic
intervals (RR-Hj) vary but do not appear to influence the alternating pattern. The recovery
periods of the riglit and left bundle branches are schematically represented at the bottom of the
figure.
R2-RlMSEC
985
985
X~~~~~~~~~~~~
R1-S MSEC 28!
285
VI
285
-
4
r--k $-Y""- -,? 4
P -HBMSEC9 6
HB-R2MSEC 1
h..
t-
-
-
--.. .,&- W.Ai
t'
I
I SEC
.
r-11
A
..
96
158
ISEC
960
Figure 8
Alternating right bundle-branch block and normal conduction with His bundle recording:
Coupled premature atrial stimuli result in alternating ventricular excitation; the preceding
cycle length (R2j-R1) and coupling interval (R2-S) are constant. A His bundle electrogram
(HBE) reveals that A-V conduction time (P-HB) is also constant. Intraventricular conduction
time (HB-R2) is longer for premature beats of right bundle-branch block configuration (190
nisec) than premature beats of normal configuration (158 msec).
Circulation, Volume XXXIX, June 1969
PREMATURE VENTRICULAR EXCITATION
827
HB
HBE
s
.
HB
HB
p^vjeft%l
(....Ol
0
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.4
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Pt AD
Figure 9
Retrograde His bundle excitation following right bundle-branch block: A normal beat is
followed by a premature atrial stimulus (S) which results in a right bundle-branch block pattern
of ventricular excitation. Antegrade His bundle electrograms (HBE) are designated by the
white arrows. A retrograde His bundle activation designated by a black arrow follows
aberrant ventricular conduction. Retrograde His bundle activation is of opposite polarity than
antegrade His bundle activation.
shortest at the His bundle and progressively
increases as distal points are measured.13
Previous communications" 2 have noted the
ease of transforming an incomplete right
bundle-branch block pattern of aberrant
ventricular conduction to a complete right
bundle-branch block pattern of aberrant
ventricular conduction by shortening the
premature coupling interval. Incomplete right
bundle-branch block is believed to result from
distal block or delay of impulse passage and
complete right bundle-branch block from
proximal block of impulse passage.14 Because
of the distal location of block in incomplete
right bundle-branch block, it is unlikely that
antidromic excitation can occur with retrograde activation of the right bundle branch.
The premature atrial coupling interval can be
adjusted from one which will always result in
incomplete right bundle-branch block to one
which will result in unsustained complete
Circulation, Volume XXXIX, June 1969
right bundle-branch block (fig. 1). In all
likelihood, complete right bundle-branch
block cannot be sustained because proximal
block permits antidromic stimulation from the
left side with retrograde activation of the right
bundle branch. The result is shortening of
diastolic recovery time and refractory period
which permits the next coupled premature
beat to traverse the proximal portion of the
right bundle branch. The end result is
alternating ventricular excitation of incomplete right bundle-branch block and complete
right bundle-branch block patterns.
There is ample evidence that varied sites of
direct ventricular stimulation result in varied
patterns of ventricular excitation and stroke
volume.'5' 16 It appears from the case in whieh
a direct brachial pulse was obtained that each
of the alternate patterns of aberrant ventricular conduction resulted in a different
contractile force and peak systolic pressure
828
COHEN ET AL.
L E AD
I'2,v{8:4?!f4
I
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LEAD a
0
PF
biIq
6
s
LEAD V,
t-Il SEC-
Pt
jP
Figure 10
Consecutive premature atrial impulses with consecutive aberrant ventricular excitation: The
second and third labelled atrial stimuli (S) result in a right bundle-branch block pattern of
venticular excitation indicated by arrows..
(fig. 4). Longer diastolic intervals followed
the aberrant ventricular conduction pattern
associated with the higher peak systolic
pressures. This may have resulted from greater
stimulation of the carotid sinus than that
which occurred with the aberrant ventricular
conduction pattern associated with lower peak
systolic pressures.
References
1. COHEN, S. I., LAU, S. H., HAFT, J. I., AND
DAMIATO, A. N.: Experimental production of
aberrant ventricular conduction in man.
Circulation 36: 673, 1967.
2. COHEN, S. I., LAU, S. H., STEIN, E., YOUNG, M.
W., AND DAMATO, A. N.: Variations of
aberrant ventricular conduction in man:
Evidence of isolated and combined block
within the specialized conduction system: An
electrocardiographic and vectorcardiographic
study. Circulation 38: 899, 1968.
3. HAFT, J. I., LAU, S. H., STEIN, E., KoSOWSKY, B.
D., AND DAMATO, A. N.: Atrial fibrillation
produced by atrial stimulation. Circulation 37:
70, 1968.
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PREMIATURE VENTRICULAR EXCITATION
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4. LAU, S., ET AL.: Recording of His bundle
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11. MOE, G., MENDEZ, C., AND HAN, J.: Aberrant A-V
Circulation, Volume XXXIX, June 1969
829
impulse propagation in the dog heart: A study
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12. FISCH, C., EDMvUNDS, R. E., AND GREENSPAN, K.:
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1960, p. 160.
14. MOORE, E. N., HOFFMIAN, B. F., PATTERSON, D.
F., AND STULCKEY, J. H.: Electrocardiographic
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Alternate Patterns of Premature Ventricular Excitation During Induced Atrial
Bigeminy
STAFFORD I. COHEN, SUN H. LAU, BENJAMIN J. SCHERLAG and ANTHONY
N. DAMATO
Circulation. 1969;39:819-829
doi: 10.1161/01.CIR.39.6.819
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1969 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539
The online version of this article, along with updated information and services, is
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