Download Left Ventricular Volume

Evaluation of the Ability of Echocardiography
to Measure Acute Alterations in
Left Ventricular Volume
By D. R. REDWOOD, M.D., W. L. HENRY, M.D.,
AND
S. E. EPSTEIN, M.D.
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SUMMARY
Measurement of acute serial changes in left ventricular volume is often desirable. Although left
ventricular volumes estimated echocardiographically correlate well with results of angiographic methods,
the sensitivity with which echocardiography can detect acute alterations in volume is unknown. Accordingly, the effect on transverse left ventricular dimension of interventions known to alter left ventricular
volume (tilting and administration of nitroglycerin and phenylephrine) was studied in six normal subjects.
Tilting significantly reduced end-diastolic dimension (from 48 ± 1.7 to 41.8 ± 1.5 mm, P < .01) and endsystolic dimension (from 32.2 ± 0.6 to 27.5 ± 0.8 mm, P < .001). Nitroglycerin also reduced end-diastolic
dimension (from 44.8 ± 2.3 to 39.8 ± 2.1 mm, P < .02) and end-systolic dimension (from 30.2 ± 1.3 to
26.5 ± 1.2, P < .005). In contrast, phenylephrine increased end-diastolic dimension (from 42.3 ± 2.6 to
45.6 ± 2.6 mm, P < .025) but did not significantly alter end-systolic dimension (from 28.9 ± 2.0 to
31.8 ± 2.9 mm). Mean rate of circumferential fiber shortening (mean Vcf) was not altered significantly by
tilting or by phenylephrine, but was increased by nitroglycerin (from 1.3 ± 0.1 to 1.7 ± 0.1 circ/sec,
P < .005). In addition, a study of eight patients with chronic rheumatic mitral valve disease showed that
there was a positive correlation between the percentage change in R-R intervals and the percentage change
in transverse diastolic dimension (y = .22 x 110, r = 0.68). These results indicate that the anticipated
changes in left ventricular volume are readily detected by echocardiography. Thus, this noninvasive
technique may be uniquely valuable in situations in which it is desired to make serial measurements of left
-
ventricular volume.
Additional Indexing Words:
Tilting
Nitroglycerin
Phenylephrine
estimated by the echo technique varies as the cube of
the transverse dimension.'
The present investigation was undertaken to determine the ability of echocardiography to detect acute
volume changes in normal hearts by use of maneuvers
and pharmacologic agents known to alter left ventricular volume. In addition, the changes in ventricular volume were correlated with alterations in cycle length in a series of patients with atrial fibrillation.
ECHOCARDIOGRAPHY has been proposed as an
alternative means to cardiac catheterization
in assessing left ventricular performance, and has the
distinct advantage of being a noninvasive method,
therefore lending itself more readily to serial
measurements. Recent studies to determine whether
echocardiography can be utilized to measure endsystolic and end-diastolic left ventricular volumes
have shown a good correlation between the volumes
estimated by echocardiography and volumes estimated by left ventricular angiography.'-3 However,
the sensitivity with which the echocardiographic
method is able to detect acute changes in left ventricular volume has not been studied. It should be
emphasized that any decrease in echo sensitivity may
lead to large errors in calculated volume, since volume
Methods
Normal Subjects
Six normal subjects, aged 19 to 23 years gave informed
consent and were studied in the fasting and unsedated state.
Under local anesthesia, a #20 Teflon catheter was inserted
by the Seldinger technique into the brachial artery. Arterial
pressure and electrocardiogram were monitored continuously. Echocardiograms were recorded using an
Aerotech Gamma transducer (2.25 MHz, 0.5 in diameter, 10
cm focus) connected to an Ekoline 20 ultrasound unit. The
signal was fed via a custom built video amplifier to a
Honeywell 1856 Line Scan recorder and recorded continuously on light sensitive paper (Kodak Rapid Access type)
at a paper speed of 50 mm/sec. The transverse dimension
was defined as the distance between the left ventricular surface of the interventricular septum and the endocardial sur-
From the Cardiology Branch, National Heart and Lung Institute,
Bethesda, Maryland.
Address for reprints: David R. Redwood, M.D., Cardiology
Branch, National Heart and Lung Institute, Building 10, Room 7B15, Bethesda, Maryland 20014.
Received March 29, 1974; revision accepted for publication July
5, 1974.
Circulation, Volume 50, November 1974
Atrial fibrillation
901
902
REDWOOD, HENRY, EPSTEIN
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face of the posterior left ventricular free wall, measured just
below the tip of the anterior leaflet of the mitral valve. The
end-diastolic dimension was taken as the maximum distance
in diastole between the septal and posterior left ventricular
endocardial surfaces and the end-systolic dimension as the
minimum distance in systole between these two surfaces.
The mean rate of circumferential fiber shortening (mean
Vcf) was defined as the extent of shortening of the minor internal circumference (the diameter of which was the
transverse dimension of the left ventricle) between enddiastole and end-systole divided by the time required for
shortening. To eliminate the effect of respiratory excursion,
the measurements taken from several consecutive cardiac
cycles were averaged. In order to obtain consistent and
reproducible recordings, the T-scan method previously
described was utilized.4 Only those recordings in which clear
echoes of both endocardial borders could be defined were
used for analysis. To avoid interpretive bias, all recordings
were coded and analyzed by one of us without prior
knowledge of the intervention used.
Echocardiographic measurements of acute changes in left
ventricular volumes were obtained in the following manner:
1) Tilt. Subjects were initially studied supine and then
tilted to the 80° head-up position. Repeat echo recordings
were taken following stabilization of changes in heart rate
and arterial pressure and the subject was then returned to
the supine position.
2) Nitroglycerin. In order to obtain adequate
hemodynamic effect from sublingual nitroglycerin, the subjects were studied in the 300 head-up position. Echocardiograms were recorded before and after nitroglycerin,
given sublingually in repeated 0.4 mg doses sufficient to induce a fall in mean arterial pressure of between 10 and 20
mm Hg.
3) Phenylephrine. Phenylephrine was given intravenously
inl a dose of from 0.2 to 1 mg/min in order to induce a rise in
mean arterial pressure of from 20 to 30 mm Hg. Echocardiograms were recorded before and following the infusion.
chronic rheumatic mitral valve disease. Echocardiograms
were obtained using the techniques outlined above. Only
those recordings in which clear echoes of both the septum
and the posterior left ventricular free wall could be obtained
were analyzed. In each patient, the percentage change in
successive R-R intervals was plotted against the percentage
change in the transverse diastolic dimension.
Results
Tilt
Change from the supine to the 800 head-up position induced an average rise in mean arterial pressure
of 12 mm Hg and an average increase in heart rate of
12 beats/min. End-diastolic transverse dimension
decreased significantly (from 48 ± 1.7 to 41.8 ± 1.5
mm, P < .01), as did end-systolic transverse dimension (from 32.2 ± 0.6 to 27.5 ± 0.8 mm, P < .001)
(fig. 1). There was no change in mean Vcf with tilting
(1.5 ± 0.1 vs 1.5 ± 0.1 circ/sec).
Nitroglycerin
Nitroglycerin induced an average decrease in mean
arterial pressure of 11 mm Hg and an increase in heart
rate of 18 beats/min. End-diastolic transverse dimension decreased from 44.8 ± 2.3 to 39.8 ± 2.1 mm
(P < .02). End-systolic transverse dimension decreased from 30.2 ± 1.3 to 26.5 ± 1.2 (P < .005) (fig.
1). At the same time, mean Vcf increased significantly
from 1.3 ± 0.1 to 1.7 ± 0.1 circ/sec (P < .005).
Phenylephrine
Phenylephrine resulted in an average rise in mean
arterial pressure of 25 mm Hg and a decrease in heart
rate of 27 beats/min. End-diastolic dimension increased significantly from 42.3 ± 2.6 to 45.6 ± 2.6
mm (P < .025) (fig. 1). End-systolic dimension in-
Patients
Eight patients with atrial fibrillation were studied. All had
TILT
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Effect of tilt, nitroglycerin and phenylephrine on left ventricular transverse
dimension. In each panel data points to
the left are control measurements of
transverse dimension at end-diastole (open
circles) and end-systole (closed circles).
Data points to the right represent
measurements taken following each of the
interventions.
Circuilatiotn, Volurne .50, November 1974
ULTRASOUND DETERMINATION OF LV VOLUME
creased in four of six patients and was unchanged in
two. As a group the change did not reach statistical
significance (28.9 ± 2.0 vs 31.8 ± 2.9) (fig. 1).
Similarly, no significant changes were noted in mean
Vcf (1.5 + 0.2 vs 1.2 + 0.1 circ/sec).
Atrial Fibrillation
There was a positive correlation between the percentage change in R-R intervals and the percentage
change in transverse diastolic dimension (y = 0.22 x
- 110, r = 0.68) (fig. 2).
Discussion
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An estimate of left ventricular volume can be made
from determination of the transverse dimension of the
left ventricle as recorded echocardiographically.
Usually, the transverse dimension has been cubed,
with or without use of additional correction factors, to
obtain volume.' In general, a good correlation has
been shown between echocardiographic and
angiographic estimates of volume except in patients
with abnormally contracting segments of the left ventricular wall.'-3, 5 In the present study, by using
transverse dimensional changes in serial studies on a
single patient, possible errors inherent in volume estimation were avoided. Because of technical
limitations imposed by current echocardiographic
techniques, changes in left ventricular transverse
dimension can be estimated accurately only if the
changes in dimension are greater than the resolution
of the echo technique. Such limitations are due
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PERCENTAGE CHANGE IN TRANSVERSE
DIASTOLIC DIMENSION
Figure 2
Relation between percentage change in R-R interval and transverse
diastolic dimension in patients with mitral valvular disease and
atrial fibrillation.
Circulation, Volume 50, November
1974
903
largely to the resonance of the quartz crystal used to
generate the echo signal and also in part to the resolution of the recording apparatus. It is therefore possible
that while commonly employed interventions may induce alterations in left ventricular volume, these
changes may be within the limits of measurement
error and thus not detectable echocardiographically.
The present study was undertaken to test the potential
feasibility of employing echocardiography to measure
acute serial changes in transverse dimension. The
results indicate that the method is sufficiently sensitive
to detect alterations in left ventricular volume
produced by such relatively non-extreme interventions as head-up tilt, nitroglycerin administration, and
phenylephrine infusion.
Although it was not possible to determine the sensitivity of this technique in any quantitative manner,
it is interesting to compare the changes in dimension
found in this study with the changes in wall dimension
determined by previous studies using cineradiography
of ventricular epicardial tantalum clips.6-8 Williams et
al.7 in their study of the effects of nitroglycerin in six
supine patients, found that left ventricular enddiastolic length (interclip distance) decreased an
average of 6.2%, while left ventricular end-systolic
length decreased an an average of 5.9%. In addition,
Burggraf and Parker,9 in a recent echocardiographic
study of the dimensional changes induced by
nitroglycerin in normal subjects, found that left ventricular end-diastolic dimension decreased an average
of 4% and end-systolic dimension an average of 6.4%.
The changes observed in the present study were of
greater magnitude - 11.7% and 12.7%, respectively
- but these differences could well be explained by
the use of the 300 head-up tilt in the present study,
thus allowing for a greater venous pooling effect of
nitroglycerin. In addition, arterial pressure fell to a
more pronounced extent with a resulting greater increase in reflex tachycardia, alterations that have been
shown to reduce ventricular dimensions. Similarly,
methoxamine was shown by Harrison et al.8 to increase left ventricular end-diastolic interclip distance
by 3.3% and end-systolic distance by 4.7%. Average
changes induced in the present study were 9.1% and
10.5%, respectively. Again, these differences most
probably can be attributed to the greater hemodynamic effect that was induced in our study. Whatever
the explanation concerning quantitative differences
observed between this and previous studies, it is clear
that the echo technique is capable of detecting acute
changes in left ventricular dimension in normal subjects. In addition, anticipated change in end-diastolic
volume also was detectable by echocardiography in
patients with atrial fibrillation and chronic rheumatic
mitral valve disease.
904
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Mean rate of circumferential fiber shortening has
been shown to correlate well with other indices of
myocardial contractility10 and a good correlation also
has been demonstrated between mean Vcf estimated
angiographically and that estimated echocardiographically. 11 However, as in the case with the ventricular volume measurements, no studies have determined the sensitivity of this index in detecting acute
changes in contractility. In the present investigation
we were able to detect anticipated changes in mean
Vcf following administration of nitroglycerin, but no
significant changes were found following tilting or
phenylephrine infusion, both of which would have
been expected to alter contractility, although in opposite directions.
In summary, the inherent resolution properties of
ultrasound limit the accuracy with which small
changes in transverse left ventricular dimension and
mean Vcf can be measured. Thus, volume would have
to change by at least 8-10 ml or by about 5% of enddiastolic volume before any anticipated change could
be detected in transverse dimension. Nonetheless, the
results of the present study suggest that echocardiography is a sufficiently sensitive technique that it
can detect acute dimensional changes in the left ventricle induced by various maneuvers in both normal
subjects and patients. Since adequate echocardiograms can be obtained in the majority of patients,
this noninvasive technique should therefore have
wide application in monitoring effects of interventions
and therapy.
REDWOOD, HENRY, EPSTEIN
References
1. POMBO JF, TROY BL, RUSSELL RO: Left ventricular volumes
and ejection fraction by echocardiography. Circulation 43:
480, 1971
2. FORTUIN NJ, HOOD WP JR, SHERMAN ME, CRAICE E:
Determination of left ventricular volumes by ultrasound.
Circulation 44: 575, 1971
3. MURRAY JA, JOHNSTON W, REID JM: Echocardiographic
determination of left ventricle performance. Ann Intern
Med 72: 777, 1970
4. HENRY WL, CLARK CE, EPSTEIN SE: Asymmetric septal
hypertrophy. Circulation 47: 225, 1973
5. RATSHIN RA, BoYD CN JR, RACKLEY CE, MORASKI RE, RUSSELL
RO JR: Quantitative echocardiography: Correlations with
ventricular volumes by angiocardiography in patients with
coronary artery disease with and without wall motion abnormalities. (abstr) Circulation 48 (suppl IV): IV-48, 1973
6. HARRISON DC, GOLDBLATT A, BRAUNWS ALD E: Studies on
cardiac dimensions in intact unanesthetized man. Circulation 30: 448, 1963
7. WILLIAMS JF JR, GLICK G, BRAUNWALD E: Studies on cardiac
dimensions in intact unanesthetized man. Circulation 32:
767, 1965
8. HARRISON DC, GLICK G, GOLDBLATT A, BRAUNWTALD E: Studies
on cardiac dimensions in intact unanesthetized man. Cir-
culation 29: 186, 1964
9. BURlCRAF GW, PARKER JO: Left ventricular volume changes
after amyl nitrite and nitroglycerin in man as measured by
ultrasound. Circulation 49: 136, 1974
10. KARLIN\ER JS, GAULT JH, ECKBERG D, MULLINS CB, Ross J JR:
Mean velocity of fiber shortening. Circulation 44: 323, 1971
11. COOPER RH, O ROURKE RA, KARLINER JS, PETERSON KL,
LEOPOLD GR: Comparison of ultrasound and
cineangiographic measurements of the mean rate of circumferential fiber shortening in man. Circulation 46: 914,
1972
Circulation, Volume 50, November 1974
Evaluation of the Ability of Echocardiography to Measure Acute Alterations in Left
Ventricular Volume
D. R. REDWOOD, W. L. HENRY and S. E. EPSTEIN
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Circulation. 1974;50:901-904
doi: 10.1161/01.CIR.50.5.901
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