Download Muscular Subaortic Stenosis: The Temporal

Muscular Subaortic Stenosis: The Temporal Relationship
Between Systolic Anterior Motion of the Anterior
Mitral Leaflet and the Pressure Gradient
CHARLES POLLICK, M.B., CHRISTOPHER D. MORGAN, M.D., BRIAN W. GILBERT, M.D.,
HARRY RAKOWSKI, M.D., AND E. DOUGLAS WIGLE, M.D.
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SUMMARY Recent studies indicate that in patients with muscular subaortic stenosis at rest, left ventricular outflow tract obstruction is associated with severe systolic anterior motion (SAM) of the anterior mitral
leaflet and prolonged SAM-septal contact. We correlated the temporal relationships between echocardiographic and hemodynamic events in 18 patients with muscular subaortic stenosis (gradient of 73 ± 18 mm
Hg [mean ± SD]).
After the ECG R wave, aortic ejection began at 72 ± 12 msec and the onset of SAM 23 msec later, at 95 +
22 msec. The onset of the pressure gradient at 162 ± 22 msec after the R wave was almost simultaneous with
the onset of SAM-septal contact at 168 ± 28 msec. SAM-septal contact was maintained for 195 msec and
ceased at 363 41 msec after the R wave. Peak posterior left ventricular wall movement occurred at 387 +
48 msec, 219 msec after peak SAM (the onset of SAM-septal contact). The excursion and mean rate of
development of SAM from onset to septal contact (14 ± 2 mm and' 208 ± 55 mm/sec, respectively) were
almost three times the excursion and mean rate of inward movement of the posterior wall in the s'ame period
of systole (5 ± 1 mm and 75 ± -16 mmlsec, respectively).
In terms of the systolic ejection period, SAM'began at 6.0 6%, and the onset of the pressure gradient
and SAM-septal contact were almost simultaneous, at 23 ± 5% and 25 ± 7%, throughout this period. The
end of SAM-septal contact occurred at 76 10% of the systolic ejection period and peak posterior left
12%.
ventricular wall movement occurred at 82
We conclude that the onset of SAM is a very early systolic event. The onset of the pressure gradient occurs
just before or with the onset of SAM-septal contact, suggesting a cause-and-effect relationship. Posterior
wall hyperkinesis plays no part in the genesis of SAM in these patients, judging by the differing rate and
extent of excursion of SAM and the posterior wall and the fact- that peak left ventricular wall movement
occurs 219 msec after peak SAM (onset of SAM-septal contact). Tethering of the anterior mitral leaflet by
the papillary muscles is not the cause of SAM, since SAM-septal contact ceases at 76 ± 10% of the systolic
ejection period, whereas a tethering effect should last until end-systole. SAM is most likely caused by a
Venturi effect related to rapid early' systolic ejection.
IN THE 20 years since Bjork et al. I observed an abnormal movement of the anterior leaflet of the mitral valve
in patients with muscular subaortic stenosis (MSS),
angiographic2'4 and echocardiographic '6 demonstrations of systolic anterior motion (SAM) of the anterior
mitral leaflet have confirmed this observation.
Much controversy hast surrounded the significance
and mechanism of SAM-in patients with MSS. SAM
was originally thought to produce left ventricular outflow tract obstruction in these patients;'4 others have
considered SAM to be the result of "cavity obliteration"7 and hyperkinetic posterior wall movement7-9
and, as such, did not believe that it caused outflow
tract obstruction.'0' II Several investigators2' 3, 12 have
suggested that SAM is produced by papillary muscle
contraction pulling the anterior mitral leaflet toward
the septum. In 1970, Wigle et al.13 suggested that rapid
ejection in the early phase of systole could draw the
anterior mitral leaflet into the left ventricular outflow
tract by a Venturi effect, causing outflow obstruction
and mitral regurgitation.
More recent studies'4' 1 indicate that all patients
with MSS and evidence of left ventricular outflow
tract obstruction at rest have prolonged systolic contact between the anterior leaflet of the mitral valve
and the interventricular septum (prolonged SAM-septal contact). Thus, in 27 out of 27 cases of MSS with
outflow tract obstruction at rest, SAM-septal contact
always exceeded 30%, and averaged 54 of echocardiographic systole. 'I We have classified this type of
SAM as being severe by M-mode echocardiographic criteria,'5 and this is equivalent to SAM involving
the lower one-third to one-half of the anterior mitral
leaflet on two-dimensional (2-D) echocardiographic
examination. 16
We studied the temporal relationships between these
M-mode echocardiographic and hemodynamic events
in patients with MSS at rest. In addition, to determine
if SAM and posterior wall hyperkinesis in MSS are
related, we compared the timing of peak SAM (onset
of SAM-septal contact) when it first occurs with the
timing of peak posterior wall movement, the excursion
of SAM from onset to septal contact with the excursion
of the posterior wall in the same phase of systole, and
the mean rate of development of SAM from onset to
septal contact with the mean rate of posterior-wall inward movement in the same phase of systole.
From the Division of Cardiology, Department of Medicine, Toronto
General Hospital and the University of Toronto, Toronto, Ontario,
Canada.
Presented in part at the 52nd Scientific Sessions of the American
Heart Association. Anaheim, California, November 1979.
Address for correspondence: Charles Pollick, M.B., Toronto General
Hospital, 12-217 Eaton Building, 101 College Street, Toronto, Ontario
M5G 1L7, Canada.
Received April 21, 1980; revision accepted April 22, 1982.
Circulation 66, No. 5, 1982.
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CIRCULATION
1088
Finally, to determine whether SAM and the resultant SAM-septal contact is a result of traction of the
papillary muscles on the anterior mitral leaflet or a
Venturi effect, we observed the time of offset of SAM.
If papillary muscle traction is the cause of SAM and,
hence, SAM-septal contact, then SAM-septal contact
should last as long as papillary muscle contraction,
i.e., to end-systole.- If the Venturi effect is the cause of
SAM and SAM-septal contact, then one would expect
SAM-septal contact to cease before end-systole because of a reduced ejection velocity, or because of a
decrease in left ventricular pressure (if SAM-septal
contact was being maintained by hemodynamic
factors).
Methods
Patients
We studied 18 patients with MSS (11 male and
female, average 39 years). The diagnosis was
based on established clinical, hemodynamic and echocardiographic criteria.'7
seven
VOL 66, No 5, NOVEMBER 1982
Echocardiographic Methods
All patients underwent standard M-mode echocardiographic studies using a Smith-Kline Ekoline 20 ultrasonoscope interfaced with a Cambridge or an Irex
recorder. A 2.25-MHz transducer 1.5 cm in diameter
was used. All patients had echocardiographic evidence
of asymmetric hypertrophy of the heart with septalposterior wall ratios greater than 1.5. SAM of the
anterior mitral leaflet was considered present when
both anterior and posterior mitral leaflet echoes and the
posterior left ventricular wall were observed.
Timing of Studies
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Group I
In patients 1-6 (group 1) (three with latent obstruction and three with resting obstruction), hemodynamic
and echocardiographic studies were performed together so that hemodynamic and echocardiographic events
could be timed simultaneously (table 1). The measurements for three to five beats were averaged in each
patient.
Hemodynamic Methods
Patients underwent both retrograde and transseptal
left-heart catheterization using the percutaneous Seldinger technique from the right groin. Simultaneous
left ventricular inflow and aortic root pressures were
recorded using a transseptal catheter advanced through
the mitral valve orifice into the left ventricular inflow
tract and a retrograde catheter in the aortic root. In each
case, care was taken to ensure that the recorded intraventricular pressure gradient indicated true outflow
tract obstruction, and not catheter entrapment. 18 19 Fluid-filled catheters connected to a Statham 23Db transducer were used and pressures were recorded on an
Electronics for Medicine recorder. Fifteen patients had
a gradient at rest. In three patients with latent obstruction, the timing studies were carried out in the presence
of a provoked gradient during isoproterenol stimulation. The mean gradient for all 18 patients was 73
18 mm Hg (mean ± SD).
Group 2
In patients 7-18 (group 2), the hemodynamic and
echocardiographic studies were performed separately,
usually a few days apart.
All patients had resting obstruction, characterized
by a stable left ventricular outflow tract gradient at rest
(table 2). We specifically excluded patients with labile
obstruction, in whom the gradient varies markedly at
rest. Such cases are rare in our experience. Because of
the stability of the obstruction in these 12 patients, the
pressure gradients during the hemodynamic and echocardiographic studies were probably similar. To minimize differences in physiologic states at these different
times of investigation, we selected cardiac cycles from
both studies with identical heart rates (i.e., cycle
lengths to within 10 msec of each other).
Patient 3 also had a separate echocardiographic
study performed several days beforehand. We chose
TABLE 1. Sequence and Timing ofEchocardiographic and Hemodynamic Events in Group I- Simultaneous Studies
Patient
2
1
3
4
5
6
Mean ± SD
83
71
59
69
100
73 ± 16
56
Onset of aortic ejection
77
113
109
69
128
69
94±26
Onset of SAM
142
170
187
186
194
211
Onset of pressure gradient
182 ± 23
170
160
225
187
188
211
190± 24
Onset SAM-septal contact
325
237
290
Peak LV pressure
290
295
293
288 ±28
382
409
368
400
367
End SAM-septal contact
391
386± 17
445
PLVW
movement
N/A
389
439
470
N/A
Peak
436 ± 34
427
446
427
422
442
420
431 ± 11
End of pressure gradient
445
477
478
452
445
454
458± 15
Dicrotic notch
710
930
790
685
821
760
RR interval
62
80
86
71
59
60
70± 11
Gradient (mm Hg)
All values (except gradient) are in msec.
Abbreviations: SAM = systolic anterior motion; LV - left ventricle; PLVW posterior left ventricular wall; N/A
not assessable.
MUSCULAR SUBAORTIC STENOSIS/Pollick et al.
1089
TABLE 2. Sequence and Timing of Echocardiographic and Hemodynamic Events in Group 2 - Nonsimultaneous Studies
Patient
Mean + SD
17
18
16
14
15
12
13
11
10
8
9
7
71 ± 10
88
65
77
76
57
67
62
62
79
69
85
67
Onset of aortic ejection
96±21
58
117
110
109
91
89
102
82
85
79 138
89
Onset of SAM
151 152±14
141
153
153
137
145
154
133
178 149
149
179
Onset of pressure gradient
185 157±23
153
164
182
153
144
134
164
119 184
179 128
Onset SAM-septal contact
280± 35
268
282
297 229 267 246 307 330 338 263
235 298
Peak LV pressure
322 351 ±44
341
396 413 328 308 268 399 393 329 377
335
End SAM-septal contact
331 371 ±40
384
396 459 349 328 313 387 393 351 400
358
Peak PLVW movement
408 ± 34
381
424
439
444
447
339
380
369
426
396
426
425
End of pressure gradient
454±31
410
425 467 486 472 471
485 430 415 421
492 469
Dicrotic notch
840 840 730 1070
800 880 1020 760 960 960 800 760
RR interval
75 ±20
104
70
91
102
80
98
70
65
58
71
44
48
Gradient (mm Hg)
All values (except gradient) are in msec.
Abbreviations: SAM = systolic anterior motion; LV = left ventricular; PLVW = posterior LV wall.
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10 cardiac cycles from both-echocardiographic studies
with identical heart rate and compared the timing of the
onset of SAM-septal contact after the R wave. During
cardiac catheterization this was 181 ± 2 msec. In the
study several days beforehand it was 178 ± 2 msec
(NS). Thus, this patient, whom we believe to be representative of the whole group, showed no difference in
the timing of this echocardiographic event taken several days apart. Finally, to ensure that both echocardiographic and hemodynamic studies were comparable,
patients who were taking ,3 blockers discontinued them
at least 48 hours before both studies.
In group 2, we could usually find only one cycle per
patient for correlation between the hemodynamic and
echocardiographic events, because of the requirement
of selecting cardiac cycles with identical lengths.
When we could find more than one cycle of identical
length in the echocardiographic and hemodynamic
studies in any one patient, the timing of events correlated to within 10 msec of the other cycles measured in
that patient.
mm Hg
Timing of Events
Hemodynamic Events
From the simultaneous left ventricular inflow and
central aortic pressure tracings, five events were timed
from the peak of ECG R wave (fig. 1): (1) Onset of
aortic ejection. (2) Onset of the pressure gradient. This
was defined by the point where left ventricular and
aortic pressures diverged. This divergence occurred at
the peak of the aortic percussion wave, beyond which
the left ventricular pressure rose and the aortic pressure
fell (fig. 1). In some patients (fig. 2), an early, smaller
gradient, the "impulse gradient,"20 was recorded between the left ventricle and aorta, in the period of early
systole from the onset of aortic ejection to the peak of
the percussion wave. However, in these patients, the
main divergence of left ventricular and aortic pressures
still occurred at the peak of the percussion wave. Thus,
the peak of the percussion wave was taken as the onset
of the pressure gradient in all patients. (3) Peak left
ventricular pressure. (4) End of the pressure gradient.
(5) Dicrotic notch.
L
160120-
80400-
FIGURE 1. Simultaneous left ventricular (LV) and aortic
pressure tracing from a patient with muscular subaortic stenosis indicating the hemodynamic events that were timed in this
study from the R wave (see text). (1) Onset of aortic ejection. (2)
Onset of the pressure gradient. (3) Peak LV pressure. (4) End of
the pressure gradient. (5) Dicrotic notch.
Echocardiographic Events
Four echocardiographic events were timed from the
peak of the R wave (fig. 3): onset of SAM, the onset of
SAM-septal contact (peak SAM), the end of SAMseptal contact, and peak point of posterior left ventricular wall systolic movement.
To permit interpatient correlation all time intervals
CIRC1JLATION
1 090
mm Hg
160-180.
12080-
^
-- 02 s
-
---
40-~
PW
W--W
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FIGURE 2. Simultaneous hemodynamic and echocardiographic recordings in a patient with muscular subaortic sten7osis at rest (case 3, gradient 86 mm Hg). The arrow indicates the
onset of systolic anterior motion-septal contact and the onset of
the pressutre gradient (definied as the peak of the aortic percussion wave), whitch are simultaneous. IVS - interventricular
mitral valve; PW
posterior wall; AO
septum; MV
central aortic pressure; LV = left ventricular pressure.
=
=
were corrected for heart rate by dividing by the square
root of cycle length. Both hemodynamic and echocardiographic studies were usually recorded at paper
speeds of 50-100 mm/sec.
VOL 66, No 5, NOVEMBER 1982
groups. Thus, the data for all 18 patients have been
grouped together (table 3, fig. 4) and the mean data are
considered below.
Onset of Aortic Ejection and SAM
The onset of aortic ejection occurred at 72 ± 12
msec after the R wave, followed 23 msec later by the
onset of SAM, at 95 ± 22 msec (table 3, fig. 4). In
terms of the systolic ejection period, the onset of SAM
was a very early systolic event, occurring at just 6 ±
6% of this period (table 3).
Onset of the Pressure Gradient and
SAM-Septal Contact
The onset of the pressure gradient was almost simultaneous with the onset of SAM-septal contact. Thus,
the onset of the pressure gradient occurred at 162 ± 22
msec, and the onset of SAM-septal contact occurred at
168 ± 28 msec after the peak of the R wave (table 3,
fig. 4). In terms of the systolic ejection period, the
onset of the pressure gradient occurred at 23 ± 5% and
the onset of SAM-septal contact at 25 ± 7% of this
period (table 3).
In eight patients, the time of onset of the pressure
gradient and the time of onset of SAM-septal contact
were within 10 msec of each other (including four of
the patients examined with simultaneous hemodynamic and echocardiographic studies) (table 1, fig. 2); in
seven patients, the onset of the pressure gradient began
just before the onset of SAM-septal contact, by 31 ± 9
msec (range 18-45 msec); in the remaining three patients, the onset of the pressure gradient began just
after the onset of SAM-septal contact, by a mean of 30
± 25 msec (range 11-59 msec).
Paired analysis revealed that there was no significant difference between the time of onset of SAM-
Extent and Rate of Excursion
of Sam and the Posterior Wall
The anterior excursion of SAM was measured from
the onset of SAM (fig. 3A) to SAM-septal contact (fig.
3B). The anterior excursion of the posterior left ventricular wall in the same period of systole (onset of
SAM to SAM-septal contact) was also determined.
The excursion of SAM and the posterior wall was
divided by the time period: onset of SAM to SAMseptal contact, to obtain the mean rate of development
of SAM and the mean rate of posterior wall inward
movement in this phase of systole.
Statistical analysis was performed using the paired t
test. Data are expressed as mean ± SD.
Results
Timing of Events
The sequence and timing of events after the peak of
the R wave corrected for heart rAte. are shown for
individual patients in groups I and 2 in tables I and 2.
The sequence and relationship between hemodynamic
and echocardiographic events was the same in both
IVS
0 v.
-
.
t.-7:..
tA -A .
;
0
J
-X
D
PLVW
FIGURE 3. M-mode echocardiogram from a patient with muscular subaortic stenosis during provocation with isoproterenol
(gradient 80 mm Hg), indicating the echocardiographic events
that were timedfrom the R wave. (A) Onset of .systolic anterior
motioni (SAM). (B) Onset (4 SAM-septal contact. (C) End of
SAM-septal contact. (D) Maximum point ojfposterior leJt yentricular wall (PLVW) systolic movement. IVS = interventricular septum; aml - anterior mitrail leaflet; pml
posterior
mitral leaflet.
=
*wi4.r
1091
MUSCULAR SUBAORTIC STENOSIS/Pollick et al.
R WAVE (ECG)
MAXIMUM
POSTERIOR
LV WALL
start
SAM
l
AlONASAM-SEPTAL
._. . .
VS
3
;;2 _$ 5.
-t..
PRESSURF
*FvW
- .---
GRADIENT
0
.I
T
-s-t
=
-1c
'VS'
drcrotic
start
EJECTION
-
iw
ecg
notch
I
100
I--
200
TiME
-
300
msec
400
--
I-
500
0~~
FIGcURE 4. The sequence of events, with the echocardiographic events on top and the hemodynamic events underneath.
Time intervals displayed are mean for all 18 patients. SAM
systolic anterior motion; LV = left ventricular.
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septal contact and the time of onset of the pressure
gradient.
SAM and the Posterior Left Ventricular
Wall Movement
All patients showed a marked temporal disparity
between the onset of peak SAM (SAM-septal contact)
and the point of peak posterior left ventricular wall
movement. The onset of SAM-septal contact occurred
at 168 ± 28 msec and the peak point of posterior left
ventricular wall movement at 387 ± 48 msec after the
peak of the R wave. In terms of the systolic ejection
period, the onset of SAM-septal contact occurred at 25
+ 7% through this period, while peak posterior left
ventricular wall movement occurred near the end of
this period (at 82 ± 12%).
Paired analysis revealed a significant difference between the timing of the onset of SAM-septal contact
and the peak point of posterior left ventricular wall
movement (p < 0.001).
Offset of SAM-Septal Contact
The offset of SAM-septal contact occurred before
TABLE 3. Sequence and Timing of Events for All 18 Patients
% of
systolic
ejection
period
Msec
Onset of aortic ejection
72 + 12
0
Onset of SAM
95 ± 22
6±6
Onset of pressure gradient
162 ± 22
23 + 5
Onset of SAM-septal contact
168 + 28
25 + 7
Peak LV pressure
283 ± 32
55 ± 8
End SAM-septal contact
363 ±41
76 ± 10
Peak PLVW movement
387 ± 48
82 ± 12
End of pressure gradient
416 ± 30
90 ± 5
Dicrotic notch
455 ± 26
100
±
Values are mean
sD.
Abbreviations: SAM - systolic anterior motion; LV - left
ventricular; PLVW = posterior LV wall.
~
~~~~~~~
s,
2
FIGURE 5. Dual M-mode echocardiogram of a patient with
muscular subaortic stenosis at rest. The upper panel is at the
-level of the mitral valve (MV) and the lower panel is simultaneous with the upper panel but taken at the minor axis. Two
vertical lines are drawn between the onset of systolic anterior
motion (SAM) and SAM-septal contact. The excursion of SAM is
17 mm, compared with 4 mm in the posterior wall (in both
panels), and mean rate is 142 mmlsec vs 33 mmlsec. IVS =
interventricular septum (the entire septum is not shown); PW posterior wall.
the end of the systolic ejection period in all patients.
The end of SAM-septal contact occurred at 363 + 41
msec, and the dicrotic notch 455 ± 26 msec after the
peak of the R wave. The end of SAM-septal contact
occurred at 76 ± 10% and, by definition, the dicrotic
notch at 100% of the systolic ejection period.
Extent and Rate of Excursion
of SAM and the Posterior Wall
The excursion of SAM from onset of SAM to SAMseptal contact was 14 ± 2 mm, compared with a posterior left ventricular wall excursion in the same period
of systole of 5 ± 1 mm (p < 0.01) (fig. 5).
The mean rate of development of SAM was 208 ±
55 mm/sec and the mean rate of posterior left ventricular wall inward movement in this same period of systole was 75 ± 16 mm/sec (p < 0.01) (fig. 5).
Discussion
Patients with MSS and a true resting left ventricular
outflow tract pressure gradient have severe SAM, defined as SAM with septal contact for 30% or more of
echocardiographic systole.'5
We examined the temporal relationship between severe SAM and the pressure gradient in patients with
MSS. As a group, the onset of SAM-septal contact was
almost simultaneous with the onset of the pressure
gradient. Thus, the onset of the pressure gradient occurred at 162 ± 22 msec and the onset of SAM-septal
contact at 168 ± 28 msec after the peak of the R wave
(table 3, figs. 2 and 4). In terms of the systolic ejection
period, the onset of the pressure gradient occurred at
23 ± 5% and the onset of the SAM-septal contact
occurred at 25 ± 7% of this period (table 3). The
accuracy of these measurements may be affected by the
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CIRCULATION
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potential measuring error of 10 msec associated with a
paper speed of 50 mm/sec and by a delay in the pressure recordings that occurs with a fluid-filled system
which, in a previous study, was 8 ± 2 msec.2' However, we believe that such considerations would not
change the striking temporal relationship between
these two events, and paired analysis revealed no significant difference between the time of onset of SAMseptal contact and the time of onset of the pressure
gradient, suggesting a cause-and-effect relationship
between these two events. Thus, we suggest that the
left ventricular outflow tract pressure gradient in patients with MSS develops as a result of the substantial
reduction in left ventricular outflow tract size that occurs just before or with the onset of SAM-septal
contact.
In a concomitant study of left anterior oblique left
ventricular cineangiograms in patients with MSS at
rest,22 the radiolucent line in the outflow tract that
indicates angiographic SAM-septal contact occurred at
37.5% of the time period from end-diastole to endsystole. This is almost identical to the time of onset of
echocardiographic SAM-septal contact which, in the
present study, occurred at 36.9% of the period from
the peak of the R wave to the dicrotic notch. The present study and the cineangiographic studies confirm
previous work23' 24 that the pressure gradient begins
early in systole, and therefore in a ventricle that still
has to eject most of its stroke volume. In one angiographic study,22 34% of left ventricular emptying occurred before the radiolucent line of angiographic
SAM-septal contact, while 66% of left ventricular emptying occurred in the presence of the radiolucent line.
Based on the present study and the cineangiographic
study, we believe that SAM-septal contact produces
obstruction to left ventricular outflow, causing approximately 66% of left ventricular emptying to occur
in the presence of a systolic overload. These findings
are similar to those of Ross et al.,24 who found that
70% of forward flow occurred in the presence of the
pressure gradient. The significance of this hemodynamic burden in patients with MSS at rest is reflected
by the prolonged left ventricular ejection time,25 26 and
the compensatory posterior wall hypertrophy.27 Both
of these features of obstruction to left ventricular outflow return toward normal after surgical relief of the
MSS. 26, 27
Our results are in accord with those of Glasgow et
al.,28 who recently performed echocardiographic and
Doppler flow studies in 12 patients with MSS. They
demonstrated a sharp decrease in aortic flow at the
onset of SAM-septal contact and that 47 ± 17% of the
total left ventricular diameter shortening occurred after
the onset of SAM-septal contact. Retrograde flow was
detected into the left atrium (mitral regurgitation).
Murgo et al.29 questioned the importance of the pressure gradient in hypertrophic cardiomyopathy. They
reported no difference in the ratio of forward flow time/
systolic ejection period between three groups of patients with and without pressure gradients. By using
this ratio, however, the direct relationship between the
VOL 66, No 5, NOVEMBER 1982
pressure gradient and systolic ejection period is
masked.26 30 31 Indeed, the data indicate that prolongation of the ejection period is associated with a prolongation in forward flow time and angiographic left
ventricular emptying in the group with "resting gradients." Differences between the groups may have
been minimized by including two patients with resting
gradients less than 20 mm Hg in whom the ejection
period was probably normal. In addition, the lack of a
significant difference between the groups may partially
reflect a beta error due to the relatively small sample
size.
This study indicates that severe SAM is unlikely to
be the result of a direct pushing action of the posterior
left ventricular wall. First, there is a marked temporal
disparity between the initial development of peak
SAM (onset of SAM-septal contact), which occurs at
25 ± 7% of the systolic ejection period, and peak
posterior wall movement, which occurs at 82 ± 12%
of the systolic ejection period (p < 0.001). Second,
the mean rate of development of SAM (208 + 55 mm/
sec) is almost three times the mean rate of inward
posterior wall movement (75 ± 16 mm/sec) (p <
0.01). Third, the extent of excursion of SAM from its
onset to SAM-septal contact was 14 ± 2 mm, whereas
posterior wall excursion in this same period was only 5
± 1 mm (p < 0.01). These gross discrepancies between the timing, rate and extent of movement of SAM
vs the posterior left ventricular wall refute the suggestion that posterior wall hyperkinesis is the cause of
SAM in patients with hemodynamically proved MSS.
Some reports2, 3, 12 have suggested that SAM is
caused by a tethering action of the papillary muscles
drawing the anterior mitral leaflet into the outflow tract
and against the septum. If this were the case, SAMseptal contact should be maintained as long as the
papillary muscles are contracting, i.e., until end-systole. The present study, however, indicates that the
offset of SAM-septal contact occurs at 76% of the
systolic ejection period. This fact casts serious doubt
that papillary muscle traction on the anterior mitral
leaflet causes SAM. Furthermore, the concept that papillary muscle traction causes SAM has been seriously
questioned by two-dimensional echocardiographic
studies, 16, 32 which demonstrate that the distal one-third
to one-half of the anterior mitral leaflet bends at a right
angle to both the proximal part of the leaflet and to the
long axis of the papillary muscles.
In 1970, Wigle et al. 13 suggested that rapid ejection
in the early nonobstructive phase of systole could draw
the anterior mitral leaflet into the left ventricular outflow tract by a Venturi effect, producing obstruction to
ventricular outflow and mitral regurgitation in patients
with MSS. The left ventricular outflow tract is narrowed at the onset of systole'X'6 and rapid early ejection occurs in these patients.3 The combination of
these features in patients with MSS at rest would promote a Venturi effect on the anterior mitral leaflet. We
suggest that by this Venturi effect, the anterior mitral
leaflet is sucked rapidly toward the septum; it is kept
sustained against the septum either by continued Ven-
MUSCULAR SUBAORTIC STENOSISIPollick et al.
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turi-induced suction or by the left ventricular systolic
pressure. In late systole, the anterior mitral leaflet falls
away from the septum because ventricular ejection
velocity decreases or ventricular pressure decreases or
both.
Our results are seemingly at variance with those of
Chahine et al. 10, 11 who could find no relationship between SAM and the pressure gradient. However, with
the hemodynamic techniques they used, they could not
distinguish between true left ventricular outflow obstruction and cavity obliteration with catheter entrapment. Also, SAM was only described as being absent
or present, without specifying the degree.
In a recent study'5 of 74 patients with hypertrophic
cardiomyopathy, we found that all 27 patient who had
MSS at rest had early and prolonged SAM-septal contact (severe SAM) by M-mode echocardiography. In
this same study, patients with latent MSS or hypertrophic nonobstructive cardiomyopathy had either no
SAM or, at most, mild-to-moderate SAM (without
prolonged SAM-septal contact).
One must recognize that SAM may occur in normal
persons and in many conditions other than hypertrophic cardiomyopathy. 15 In most of these situations, the
SAM is mild or, at most, moderate, and two-dimensional echocardiographic examination of such patients
reveals that SAM has a chordal or leaflet tip origin,34'35
whereas severe SAM is produced by the lower onethird to one-half of the body of the anterior mitral
leaflet. 16, 35 In a few situations other than hypertrophic
cardiomyopathy, severe SAM has also been demonstrated, with concomitant left ventricular outflow tract
obstruction. 15, 35
In summary, we suggest that SAM with early and
prolonged septal contact in these patients is created by
a Venturi mechanism and that septal contact is maintained by either continued Venturi-induced suction or
by the left ventricular systolic pressue, resulting in
both the left ventricular outflow tract obstruction and
the mitral regurgitation that accompanies it.36
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
References
1. Bjork VO, Hultquist G, Lodin H: Subaortic stenosis produced by
an abnormally placed anterior mitral leaflet. J Thorac Cardiovasc
Surg 41: 659, 1961
2. Dinsmore RE, Sanders CA, Harthorne JW: Mitral valve regurgitation in idiopathic hypertrophic subaortic stenosis. N Engl J Med
275: 1225, 1966
3. Simon Al, Ross J Jr, Gault JH: Angiographic anatomy of the left
ventricle and mitral valve in idiopathic hypertrophic subaortic stenosis. Circulation 36: 852, 1967
4. Adelman AG, McLoughlin MJ, Marquis Y, Auger P, Wigle ED:
Left ventricular cineangiographic observations in muscular subaortic stenosis. Am J Cardiol 24: 689, 1969
5. Shah PM, Gramiak R, Kramer DH: Ultrasound localization of left
ventricular outflow obstruction in hypertrophic obstructive cardiomyopathy. Circulation 40: 3, 1969
6. Popp RL, Harrison DC: Ultrasound in the diagnosis and evaluation
of therapy of idiopathic hypertrophic subaortic stenosis. Circulation 40: 905, 1969
7. Criley JM, Lennon PA, Abbasi AS, Blaufuss AH: Hypertrophic
cardiomyopathy. In Clinical Cardiovascular Physiology, edited by
Levine HJ. New York, Grune & Stratton, 1976, p 771
8. Gehrke J: Reliability of systolic anterior motion (SAM) of the
mitral valve (MV) and asymmetric septal hypertrophy (ASE) in
23.
24.
25.
26.
27.
28.
29.
1093
hypertrophic cardiomyopathy (HCM). (abstr) Am J Cardiol 39:
270, 1977
Silverman KJ, Hutchins GM, Weiss JL, Moore GW: Catenoid
shape of the interventricular septum in idiopathic hypertrophic
subaortic stenosis. Am J Cardiol 49: 27, 1982
Chahine RA, Raizner AE, Ishimori T, Montero AC: Echocardiographic, hemodynamic and angiographic correlations in hypertrophic cardiomyopathy. Br Heart J 39: 945, 1977
Chahine RA, Raizner AE, Nelson J, Winters WL, Miller RR,
Luchi RJ: Mid systolic closure of aortic valve in hypertrophic
cardiomyopathy, echocardiographic and angiographic correlation.
Am J Cardiol 43: 17, 1979
King JF, Reis RL, Bolton MR, DeMaria A, Zelis R, Mason DT:
Superior to inferior septal hypertrophy in IHSS: the fundamental
determinant of obstruction. (abstr) Circulation 48 (suppl IV): IV-6,
1973
Wigle ED, Adelman AG, Silver MD: Pathophysiological considerations in muscular subaortic stenosis. In Hypertrophic Obstructive
Cardiomyopathy. CIBA Foundation Study Group no. 37, edited by
Wolstenholme GEW, O'Connor M. London, J & A Churchill,
1971, p 63
Gilbert BW, Adelman AG, Buda AJ, Mackenzie GW, Corrigal
DM, Wigle ED: Echocardiographic classification of hypertrophic
cardiomyopathy. (abstr) Am J Cardiol 41: 371, 1978
Gilbert BW, Pollick C, Adelman AG, Wigle ED: Hypertrophic
cardiomyopathy: the subclassification by M-mode echocardiography. Am J Cardiol 45: 861, 1980
Rakowski H, Gilbert BW, Drobac M, Vaughan-Neil EF, Pollick
C, Wigle ED: Anatomic variations in subgroups of hypertrophic
cardiomyopathy as assessed by wide angle two dimensional echocardiography. (abstr) Am J Cardiol 43: 348, 1979
Wigle ED, Felderhof CH, Silver MD, Adelman AG: Hypertrophic
obstructive cardiomyopathy (Muscular or hypertrophic subaortic
stenosis). In Myocardial Diseases, edited by Fowler NO. New
York, Grune & Stratton, 1973, p 297
Wigle ED, Auger P, Marquis Y: Muscular subaortic stenosis: the
initial left ventricular inflow tract pressure as evidence of outflow
tract obstruction. Can Med Assoc J 95: 793, 1966
Wigle ED, Marquis Y, Auger P: Muscular subaortic stenosis: initial left ventricular inflow tract pressure in the assessment of intraventricular pressure differences in man. Circulation 35: 1100, 1967
Murgo JP, Altobelli SA, Dorethy JF, Logsdon JR, McGranahan
GM: Normal ventricular ejection dynamics in man during rest and
exercise. Circulation 52 (suppl III): III-92, 1975
Rubenstein JJ, Pohost GM, Dinsmore RE, Harthorne JW: The
echocardiographic determination of mitral valve opening and closure. Correlation with hemodynamic studies in man. Circulation
51: 98, 1975
Morgan CD, Pollick C, Wigle ED: Cineangiographic timing of left
ventricular outflow obstruction and systolic emptying in muscular
subaortic stenosis. (abstr) Circulation 60 (suppl II): II-262, 1979
Pierce GE, Morrow AG, Braunwald E: Idiopathic hypertrophic
subaortic stenosis. III. Intraoperative studies of the mechanism of
obstruction and its hemodynamic consequences. Circulation 30
(suppl IV): IV-152, 1964
Ross J Jr, Braunwald E, Gault JH, Mason DT, Morrow AG: The
mechanism of the intraventricular pressure gradient in idiopathic
hypertrophic subaortic stenosis. Circulation 34: 558, 1966
Wigle ED: The arterial pressure pulse in muscular subaortic stenosis. Br Heart J 25: 97, 1963
Wigle ED, Auger P, Marquis Y: Muscular subaortic stenosis: the
direct relation between the intraventricular pressure difference and
the left ventricular ejection time. Circulation 36: 36, 1967
Henry WL, Clark CE, Roberts WC, Morrow AG, Epstein SE:
Differences in distribution of myocardial abnormalities in patients
with obstructive and nonobstructive asymmetric septal hypertrophy
(ASH): echocardiographic and gross anatomic findings. Circulation 50: 447, 1974
Glasgow GA, Gardin JM, Burm CS, Childs WJ, Henry WL: Echocardiographic and Doppler flow observations in idiopathic hypertrophic subaortic stenosis. (abstr) Circulation 62 (suppl III): 111-99,
1980
Murgo JP, Alter BR, Dorethy JF, Altobelli SA, McGranahan GM:
Dynamics of left ventricular ejection in obstructive and nonob-
1094
CIRCULATION
structive hypertrophic cardiomyopathy. J Clin Invest 66: 1369,
1980
30. Stefadouros MA, Canedo MI, Karayannis E, Abdulla A, Frank
MJ: Internally recorded systolic time intervals in hypertrophic subaortic stenosis. Am J Cardiol 40: 700, 1977
31. Nesje OA, Enge I: External carotid pulse recordings in hypertrophic obstructive cardiomyopathy. Acta Med Scand 202: 197,
1977
32. Henry WL, Clark CE, Griffith JM, Epstein SE: Mechanism of left
ventricular outflow obstruction in patients with obstructive asymmetric septal hypertrophy (idiopathic hypertrophic subaortic steno-
VOL 66, No
5,
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sis). Am J Cardiol 35: 33, 1975
33. Hermandez RR, Greenfield JC Jr, McCall BW: Pressure-flow studies in hypertrophic subaortic stenosis. J Clin Invest 43: 401, 1964
34. Boughner DR, Rakowski H, Wigle ED: Mitral valve systolic anterior motion in the absence of hypertrophic cardiomyopathy. (abstr)
Circulation 58 (suppl II): 11-235, 1978
35. Rakowski H, Gilbert BW, Drobac M, Pollick C, Boughner D,
Wigle ED: Obstructive versus non-obstructive SAM: a crucial distinction. (abstr) Am J Cardiol 45: 491, 1980
36. Wigle ED, Adelman AG, Auger P, Marquis Y: Mitral regurgitation
in muscular subaortic stenosis. Am J Cardiol 24: 698, 1969
Angiocardiography of Multiple Ventricular
Septal Defects in Infancy
KENNETH E. FELLOWS, M.D., G. RICHARD WESTERMAN, M.D.
,
AND
JOHN F. KEANE, M.D.
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SUMMARY Biplane cineventriculography in 364 infants 1 year of age or younger demonstrated multiple
ventricular septal defects (VSDs) in 56 (15%). Among 111 infants with VSDs (with or without patent ductus
arteriosus), 18 (16%) had multiple VSDs, whereas 14 of 39 infants (36%) with VSD and coarctation of the
aorta had multiple VSDs. The incidence of multiple VSDs in infants with tetralogy of Fallot was 7% (eight of
117), in infants with d-transposition of the great arteries 19% (eight of 43), and in infants with common
atrioventricular canal 15% (eight of 54). Perioperative axially angled cineangiocardiography correctly
predicted the presence of multiple VSDs in 13 of 15 infants (86%) who underwent operation.
THE MORTALITY RATE for surgery of congenital
heart disease when associated with multiple ventricular septal defects (MVSDs) is 14-17%,' 2 compared
with 4% when a single VSD is present.3 With the trend
in many medical centers toward surgical correction of
congenital heart defects during infancy," 4,5 precise
preoperative diagnosis in babies is becoming increasingly important. Our previous experience, in which the
presence of MVSDs was identified preoperatively in
only 55% of patients operated upon,' indicates that
preoperative diagnosis must be improved.
This study was undertaken to determine the incidence of MVSDs in infants with ventricular septal
defect (VSD), VSD and coarctation (VSD/CoAo), tetralogy of Fallot (T/F), d-transposition (d-TGA) and
common atrioventricular canal (CAVC) using
cineangiocardiography. A second objective was to
evaluate whether the use of axially angled views improved preoperative diagnosis. Additionally, the incidence of spontaneous closure of one or more of these
defects was examined among those with VSD and
VSD/CoAo by clinical observation and subsequent
cardiac catheterization, and among those with d-TGA
by repeat cineangiography.
Materials and Methods
Between January 1, 1975, and December 31, 1980,
364 babies 1 year of age or younger with the diagnosis
of VSD (111 infants), VSD/CoAo (39 infants), T/F
(1 17 infants), d-TGA (43 infants) and CAVC (54 infants) underwent cardiac catheterization and biplane
cineangiocardiography at Children's Hospital Medical
Center, Boston. The catheterization data and angiocardiograms from these studies were analyzed to determine the prevalence of MVSDs (i.e., more than one
VSD in the same patient) (table 1).
Cineangiocardiography was performed using either
left ventricular or biventricular injections with biplane,
image-intensified cine filming at 64 frames/sec. Injected volumes of contrast varied between 1 and 2 ml/kg
body weight. Axially angled views in either the long
axial oblique (200 cranial and 700 left oblique) or hepatoclavicular (400 cranial/40° left oblique) projections
were used in most cases between 1975 and 1978, and
in all studies after 1978. Infants whose cineangiograms
demonstrated more than one VSD constituted the study
group;* questionable cases were excluded.
Between January 1, 1978, and April 30, 1981, 15
infants were found to have MVSDs at the time of
From the Departments of Radiology, Cardiac Surgery and Pediatric
Cardiology, Harvard Medical School and Children's Hospital Medical
Center, Boston, Massachusetts.
Presented at the 54th Scientific Sessions of the American Heart Association, November 1981, Dallas, Texas.
Address for correspondence: Kenneth E. Fellows, M.D., Department
of Radiology, Children's Hospital Medical Center, 300 Longwood
Avenue, Boston, Massachusetts 02115.
Received February 18, 1982; revision accepted April 26, 1982.
Circulation 66, No. 5, 1982.
*A VSD is identified angiographically by a stream of contrast across
the interventricular septum; all infants included in this study demonstrated streaming at more than one level in the septum. Although excluded when recognized, it is possible that a few patients in this study
had a single defect, as viewed from the left ventricular side of the
septum,6 which produced two or more streams because of right ventricular trabeculation and musculature. This was not thought to be a limitation of the study because the surgical approach, which usually is through
the tricuspid valve and right ventricle, would cause these defects to
appear to be "multiple" also.
Muscular subaortic stenosis: the temporal relationship between systolic anterior motion
of the anterior mitral leaflet and the pressure gradient.
C Pollick, C D Morgan, B W Gilbert, H Rakowski and E D Wigle
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Circulation. 1982;66:1087-1094
doi: 10.1161/01.CIR.66.5.1087
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1982 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539
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