Download Echocardiographic Diagnosis of Idiopathic

Echocardiographic Diagnosis of Idiopathic
Hypertrophic Cardiomyopathy
without Outflow Obstruction
By A S. ABBASI, M.B., M.R.C.P.E., R. N. MACALPIN, M.D.,
L. M. EBER, M.D.,
AND
M. L. PEARCE, M.D.
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SUMMARY
The echocardiographic findings of eight patients with hypertrophic cardiomyopathy
without outflow obstruction (HMC) and of 15 normal (Norm) individuals are
presented.
The characteristic features in HMC were: (1) interventricular septal width much
greater than normal (HMC= 2.5 + 0.3 cm, Norm = 1.0 + 0.2 cm, P <0.005); (2)
normal or only slightly increased posterior left ventricular wall thickness; (3) the
ratio of interventricular septal to posterior wall thickness .2.0; (4) ejection fraction
greater than normal (HMC = 0.76 0.08, Norm = 0.68 0.06, P < 0.025); (5)
reduced velocity of the early diastolic closing motion of the anterior mitral leaflet
(HMC = 60 23 mm/sec, Norm = 124 29 mm/sec, P < 0.005); (6) absence of
abnormal systolic movement of the anterior mitral valve, as seen in hypertrophic obstructive cardiomyopathy. The diagnosis of hypertrophic cardiomyopathy can be
made with echocardiography, even when outflow tract obstruction of the left ventricle
is absent.
Additional Indexing Words:
Interventricular septal hypertrophy
Idiopathic hypertrophic obtsructive cardiomy opathy
HYPERTROPHIC cardiomyopathy is
difficult to diagnose clinically. Cardiac
catheterization, angiocardiography, and coronary arteriography are often necessary for the
correct diagnosis of chest pain, dyspnea, an
unexplained heart murmur, or an abnormal
electrocardiogram with which these patients
may present. When obstruction to the left
ventricular outflow is present in this condition,
systolic approximation of the mitral valve to
the interventricular septum can be demonstrated as a characteristic deformity by
echocardiography. 12 However, in nonobstructive hypertrophic cardiomyopathy,3-5 there is
no gradient across the left ventricular outflow
tract and an abnormal systolic movement of
the mitral valve is not seen on echocardiography, even after amyl nitrite or isoproterenol
provocation.6 The diagnosis in cases without
outflow obstruction is based on angiocardiographic demonstration of left ventricular wall
and interventricular septal hypertrophy, diminished end-systolic volume, and papillary
muscle hypertrophy.7-8 In some cases the
hypertrophy may be restricted to the ventricular septum.9-10 The ventricular septal hypertrophy is difficult to assess with isolated left
ventricular angiograms and simultaneous left
and right ventriculography has been advocated for this diagnosis." These procedures have
From the Department of Medicine, University of
California School of Medicine, Los Angeles, California.
Supported in part by U. S. Public Health Service
Grants HE-5056 and HE-05844.
Address for reprints: A. S. Abbasi, M.D., Department of Medicine, UCLA Center for the Health
Sciences, Los Angeles, California 90024.
Received February 17, 1972; revision accepted for
publication June 30, 1972.
Circulation, Volume XLVI, November 1972
Mitral valve motion
897
ABBASI ET AL.
898
the obvious drawbacks of potential risk,
expense, and patient inconvenience.
Recent advances in ultrasound technics have
made it possible to estimate left ventricular
volume, left ventricular wall thickness, and
width of the interventricular septum noninvasively. 12-15
We are reporting the ultrasound findings of
eight patients with hypertrophic cardiomyopathy without left ventricular outflow obstruction.
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Methods
Eight patients were studied; three were men
and five were women. The ages of the patients
ranged from 26 to 64 years with a mean age of 44
years. Four patients presented with chest pain as
their leading symptom. Five patients had dyspnea
on exertion; two were referred because of an
abnormal electrocardiogram, suggesting old myocardial infarction in one and left ventricular
hypertrophy in the other.
Five patients had cardiac catheterization,
angiocardiography, and coronary arteriography.
None of these five patients had a gradient between the left ventricle and the brachial artery at
rest, and only one had a gradient of 20 mm Hg
during isoproterenol infusion. The diagnosis of
hypertrophic cardiomyopathy in these patients
was based on the angiocardiographic features
described by Simon7 and Cohen.8 Three patients
who did not have cardiac catheterization had
clinical evidence suggesting hypertrophic cardiomyopathy.3, 5 The clinical features included
evidence of left ventricular hypertrophy with
normal blood pressure, rapid carotid upstroke,
prominent fourth heart sound, and absence of
ejection click. A short systolic murmur grade 12/6 was also present at the apex or lower left
sternal border. Echocardiograms were also taken
of 15 healthy volunteers.
Echocardiographic Measurements
Echocardiograms were performed using a
commercially available ultrasonoscope* utilizing a
2.25 MHz, 0.5 cm-diameter transducer with a 10
cm focust and a repetition rate of 1,000 impulses
per sec. The calibration dots on the oscilloscope
were set so that adjacent dots were separated
horizontally by 0.5 sec, and represented 1 cm
tissue depth vertically. The technic of recording
the echogram was that described by Feigenbaum
et al.13 and Popp and Harrison.14 In brief, the left
ventricular cavity size was determined by placing
the transducer at the fourth or fifth left intercostal
space, close to the sternum. The transducer was
then rotated slightly superiorly and medially to
localize the characteristic motion of the anterior
mitral leaflet, and a record of its motion was
made. From this position, the transducer was
*Ekoline 20, Smith-Kline Instruments.
tAerotech Laboratories.
Table 1
Echocardiographic Measurements of Eight Patients with Hypertrophic Cardiomyopathy and 15 Normal Subjects
BSA
(in)
Pt
1
2
3
4
et
6
7
8
Mean
Sd
(cm)
Ss
(cm)
1.58
1.88
3.8
4.0
2.2
2.4
5a7.5
1.51
1.65
1.66
4.4
5.0
3.0
89.2
130.9
2.05
4.5
5.0
1.68
1.79
4.8
5.2
3.a
3.0
2.2
3.0
3.0
EDV
(ml)
67.1
95.4
130.9
101.8
147.2
(ml)
EF
IVS
(cm)
LVPW
(cm)
11.2
14.4
28.2
44.8
28.2
11.2
28.0
28.0
24.3
0.81
0.79
3.0
2.2
1.5
0.68
0.66
0.70
2. 5
2.5
ESV
0.91
0.72
0.81
2.7
2.0
2.5
2.6
2.5
-0.3
1.1
1.2
1.0
1.2
0.8
1.0
(mm/see)
2.0
2.0
54
70
2.2
2.5
2.3
32
110
2.5
50
64
1.0
2.5
2.5
60
42
1.1
-0.21
2.33
-0.24
SD
1.73
-0.17
Normal:
Mean
SD
.
1.85
125.4
40.1
0.68
1.0
0.9
1.17
0.16
-29.0
-14.0
-0.06
-0.2
-0.2
NS
NS
<0.025
<0.00t5
-0.14
<0.00
`
=
P
-
102.5
.
311.5
0.76
'-=0.08
MVDS
IVS/LVPW
NS
60
--23
124
-29
<0.00I5
Abbreviations: BSA = body surface area; Sd = end-diastolic short axis; Ss = end-systolic short axis; EDV =
end-diastolic volume; ESV = end-systolic volume; EF = ejection fraction; IVS = interventricular septum: LVPW
left ventricular posterior wall; MVDS = mitral valve diastolic slope; SD = standard deviation; NS = not significant.
Circulation, Volume XLVI, November 1972
DIAGNOSIS OF CARDIOMYOPATHY
899
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rotated slightly laterally and inferiorly to record
the posterior left ventricular wall echo just behind
the mitral echo. In order to delineate the
ventricular septal echo, the depth compensation
was adjusted so that maximum gain was placed
close to 0 cm on the oscilloscope. In this way, the
entire width of the septum was clearly seen
separated from the anterior heart wall. All the
patients had echocardiograms taken before and
after inhalation of amyl nitrite.
The left ventricular minor diameter was
measured echocardiographically between the enidocardial echo of the posterior left ventricular
wall and the endocardial border of the left septal
surface. The minor diameter at end~diastole (Sd)
was measured at the time of the R wave of the
simultaneously recorded electrocardiogram, and
that at end-systole (Ss) was taken at the poinlt
where the endocardial surface of the septum and
the posterior wall were nearest to each other. The
ventricular volumes were estimated by: EDV =
1.047(Sd)3; ESV =1.047 (Ss)3, where EDV is
end-diastolic volume and ESV is end-systolic
volume.14 The ejection fraction (EF) was
calculated
-ES
EF-ED EDV
as:
The estimation
of the ventricular volume from the echocardiographic short axis of the left venitricle has been
validated recently.'2-16 The reproducibility of the
measurements among observers, and at different
times in the same patient, has been documented
by Pombo et al.17 The measurement of posterior
left ventricular wall thickness and ventricular
septal width was made at end-diastole. The early
diastolic slope of the mitral valve was estimated
as described by Edler.'s
Results
Table I shows echocardiographic features
of the patients with nonobstructive hyper-
ECG
I.V. Septum
-'
3[
Endocardium
Epicardium
Figure 1
Echocardiogram of a normal individual. The interventricular septal (I.V.Septum) width (0.8
cm), the short axis at end-diastole (Sd) and at end-systole (S,), the endocardium, and the epicardium are shown. Note the normal posterior left ventricular wall thickness (0.8 cm) between
endocardium and epicardium.
Circulation, Volume XLVI, November 1972
ABBASI ET AL.
900
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trophic cardiomyopathy (HMC) and of 15
normal individuals. In patients with HMC,
both end-diastolic and end-systolic volumes
were relatively smaller than normal, but the
difference was not statistically significant. The
ejection fraction was significantly greater in
HMC than in normal subjects (P < 0.025). The
most striking difference was seen in the interventricular septal (IVS) width, which in 1MC
was two and a half times greater than the
normal (with no overlap of values between
HMC and normals). There was no significant
difference between posterior left ventricular
wall thickness in the two groups. The early
diastolic slope of the anterior leaflet of the
mitral valve in HMC was significantly less
than in the normal group (P<0.005); only
one patient with HMC had a valve slope in
the normal range. An abnormal systolic
movement was not seen in any patient, even
after amyl nitrite inhalation.
Figure 1 shows an echocardiogram of a
normal individual. The IVS (0.8 cm), the
short axis at end-diastole (Sd) and at endsystole (Ss), the endocardium and epicardialpericardial junction of the posterior left
ventricular wall, and its thickness (0.8 cm),
are well seen.
Figure 2 shows a record of a patient with
HMC. Of note are the wide ventricular
septum (2.5 cm), the relatively small left
ventricular cavity size, and normal posterior
left ventricular wall thickness (0.8 cm). Also
of interest is the strong echo from the left side
of the ventricular septum, suggesting a
thickened endocardium.
ECO
i
^
I-le.V. Septum
Endocard ium
'
----
r
Epica-di§um
a.
11A- S
Figure 2
Echocardiogram of a patient with hypertrophic cardiomyopathy without outflow obstruction.
Note the wide I.V.Septum (2.5 cm) and normal posterior left ventricular thickness (0.8 cm).
Abbreviations same as in figtre 1.
Circulaion, Volume XLVI, November 1972
DIAGNOSIS OF CARDIOMYOPATHY
901
Figure 3 shows the mitral valve motion of a
patient with HMC without obstruction. Note
the absence of aniterior systolic movement of
the mitral valve. This echocardiogram was
taken after inhalation of amyl nitrite. In
conitrast to this, figure 4 shows the motion of
the mitral valve of a patient with hypertrophic
obstructive cardiomyopathy. The systolic anterior movement of the mitral valve toward
the ventricular septum is quite well seen.
Discussion
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Autopsy studies of patients with hypertrophic cardiomyopathy with or without outflow obstructioni have shown two types of
myocardial hypertrophy. The most common
variety is an asymmetric hyperthrophyj 19 22
mainly involving the interveentricular septum
_~ W --
1
-
_k
qb.q-. %~
and, to some extent, the free anterolateral wall
of the left ventricle. The posterior left
ventricular wall may be entirely normal. A
much less common variety is that of diffuse
hypertrophy21 22 involving the left ventricle in
more or less symmetric fashion. Our cases
appear to be of the asymmetric type, as the
posterior left ventricular wall was within
normal limits, except in one case. The
ventricular septum, however, was consider-
ably thicker than normal.
Menges23 in his three autopsy cases of
hypertrophic cardiomyopathy reported ventricular septal thicknesses of 2.8, 2.0, and 3.1
cm. In his series of normal cases, the thickness
of the ventricular septum was 1.0-1.5 cm
(average 1.3 cm). The values for ventricular
septal width in the present study agree well
-41-
p-
1
.)Q
ECG
I.V. Septum
-AML
PM L
L. V. post. wall
Figure 3
The mitral valve of a patient wcith hbi ertrohic cardiomzyopathy teith1ou1t obstruction, after
inhalatiotn of amiji niitrite. Bothl thlc anterior (AML) and posterior (PML) valtve lcaflets are
seeni. Note the absence of sylstolic antetior motion of the mitral valve.
Circulation, Volunet XLVI, Novem;ber 1972
ABBASI ET AL.
902
o_
ECG
-IV. Septum
AML
SAM
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LV. post. wall
Figure 4
The anterior mlitral leaflet (AML) of a patient with hypertrophic cardiomyopathy with outflow
obstruction. Note the prominent systolic anterior movement of the nmitral valve (SAM).
with those found by Menges. In the three
cases of hypertrophic cardiomyopathy that
Menges analyzed, the ratio of thickness of
ventricular septum to that of free anterolateral
wall ranged between 1.55 and 1.76. In 20
normal hearts, this ratio averaged 0.45 and
in 50 hypertrophied hearts (other than
hypertrophic cardiomyopathy) it averaged
0.98, exceeding 1.25 in only one instance. Thus, it seems that cardiac hypertrophy associated with hypertension and
aortic stenosis is symmetric, affecting uniformly the left ventricular wall and the
ventricular septum. However, in hypertrophic
cardiomyopathy, the ventricular septum is
disproportionately more hypertrophied.
Since the posterior left ventricular wall is
least affected by hypertrophy in hypertrophic
cardiomyopathy, the ratio of the ventricular
septum to the posterior left ventricular wall
becomes even more significant. In our series of
hypertrophic cardiomyopathy, this ratio was
-2.0 in every case.
The septal width, as measured by echocardiography, may overestimate the actual width
of the septum because the ultrasound beam
may not be directed at a right angle to the
septal surfaces. However, the technic we
employed was highly standardized and reproducible, and the empiric difference between
the hypertrophic cardiomyopathy and normal
is highly significant (P <0.005).
The echocardiographic ventricular volumes
in our normal series and in hypertrophic
cardiomyopathy without outflow obstruction
are in agreement with the angiocardiographic
volumes in normal individuals and in hypertrophic cardiomyopathy with or without outflow obstruction reported by Conn and
Circulation, Volumte XLVI, November 1972
DIAGNOSIS OF CARDIOMYOPATHY
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associates,24 particularly when corrected for
body surface area.
The rate of early diastolic closing motion of
the anterior mitral leaflet was significantly
reduced in all but one of the patients with
hypertrophic cardiomyopathy. However, this
has also been noted in patients with aortic
stenosis,l and may reflect slow left ventricular
filling due to reduced left ventricular distensibility in these patients.1 25
The hallmark of hypertrophic cardiomyopathy is an abnormally thick ventricular septum
with a ratio of septum to posterior left ventricular wall thickness > 2.0. Unlike hypertrophic obstructive cardiomyopathy, there is
no abnormal systolic movement of the mitral
valve in hypertrophic cardiomyopathy without
left ventricular outflow tract obstruction.
Acknowledgment
We wish to acknowledge the assistance of Mrs.
Nancy Ellis, the senior echocardiography technician at
UCLA.
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Circulation, Volume XLVI, November 1972
903
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Circulation, Volume XLVI, November 1972
Echocardiographic Diagnosis of Idiopathic Hypertrophic Cardiomyopathy
without Outflow Obstruction
A S. ABBASI, R. N. MACALPIN, L. M. EBER and M. L. PEARCE
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Circulation. 1972;46:897-904
doi: 10.1161/01.CIR.46.5.897
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