JACC Vol. 24, No. I
hly 8994:24-F53 247
~~gi~gra~~~c (7) and tanta
dards have validated transt ec~~card~~gra~~~c meth- ods of ca~c~~ati~g left ventricular volumes and ejection
From the Division of Cardiology and Department of Medicine, Hartford spital, University of Connecticut, Hartford, Connecticut. This study was sented in part at the 4lst Annual Scientific Session of the American College of Cardiology, Dallas, Texas, April 1992. This study was supported by a grant
fro Foundation, Hartford, Connecticut.
1993; revised manuscript received February
1, 994.
Dr. Linda D. Gillam, Director of Echocar- diography, Cardiac Laboratory, Hartford Hospital, 80 Seymour Street, Halt- ford, Connecticut 06115.
01994 by the American College of Cardiology
are superior because the
availak im the left ventricle.
248 FISHER ET AL.
INTRACARDIAC ULTRASOUND.DERIVED LEFT V~~TR~CULA~ VOLUMES
JACC Vol. 24, No. 1 July 1 :247-53
may be obtained in smaller animal he
analogous to thos tained using transthoracic parasternal short-axis views a re therefore edgily suited to volume determinations using Simpson rule algorith
of this study, therefore, intracardiac ultrasound volumes with Simpson
I mm. The catheters
nation of the ~lt~so~nd
ts of the left ventricle were und, and their volume was acement method.
. In vivo studies were anesthetized, intubated pigs (weight 14 to were premeditated with tiletamine byd
pressure monitoring and arterial bl sampling. Ventilatory settings were adjusted in response to blood gas sampling performed at least every 30 min. Femoral vein access was USed for the intravenous delivery of fluids and medication, and continuous electrocardiographic monitoring was estab- lished to monitor heart rate and rhythm.
was always included as the first slice in the reconstructed volume.
es calculated from the intracar-
using least-squares lin
cross-sectional area measurements, images from a single heart recorded at 10 short-axis levels were analyzed in duplicate by each of two different echocardiographers. The
artifact.
method of Shrout and Fleiss (17) and by the Cronbach alpha estimate of the reliability coefikietat (18). The reliability refers to the pr~po~~o~ of the variation of an observation that is due to section to section variability in
es ragged
from
3 toe
250 FISHER ET AL. JACC Vol. 24, No. 1
INTRACARDIAC ULTRASOUND-DERIVED LEFT VENTRICULAR VOLUMES July 1994:247-53
Relation between left ve~t~cul~r volumes de!ermined by iac Mlt~sou~d and latex cast v0~l~rn~~ for ammal hearts eration alone. ~~t~s0~~d images recorded at O.S-cm intervals were used.
respectively).
In viva, ~e~lo~yna~i~ variables. There was no sign cant change in heart rate and systemic arterial and I ventricular pressures between the intracardiac ultrasound and angiographic studies.
Vo/unre determinarions. When all imaged sections were used, intracardiac ~lt~sou~d v
end-systole correlated well with phy (Y = I .04X - 3.6, r = 0.91,
end.diastolic and end-systolic values were cons rateiy, the relations we
1.04X - 3.5, r = 0.82, S
.3 ml, respectively), alth r correspondence with en ejection &action was des
4. Relation between left ventricular volumes determined by intracardiac ultrasound and latex cast volumes for hearts preserved by formalin fixation tier balloon distention. Ultrasound images recorded at O.S-cm intervals were used.
tions
wereriot
sicontrast
angiographic volume (co) ic volume (cc)s The choice
of
aof volume calculation acco tion was based on two
ventricle (23). second, the imaging orienta- racardiac ultrasound beam yields images ide- uited to Simpson rule reconstruction. Aitb~ug~ from
int of view of ease of application it might bc
to adapt single or biplane prolate ellipsoid a~goritbms to intracardiac ultrasound use because they require fewer com- ponent measurements, both the limited field of view and
fewer cross sections were
larger error
of
~a~erest~~at~o~ at this is study is ea titation and The results suggest that more complex an three~d~m~asioaal ~e~oastr~~tive tee construction are not necessary for ac nations in normal ventricles. In additiofl, astudy, the ability of disto~ed venlricular
closely to the latex cast volumes b the angiographic volumes is in
252 FISHER ET AL,
MTRACARDIAC ULTRASOUND-DERIVED LEFT VEMlZlCULAR VOLUMES
the
intrinsic
diiferenccsin
the two imaging techniques and the methods ofvohune calculation. First, even with the high resolution images obtained with high frequewcy intracardiac devices, ic techniques define the endocardial-blood in e innermost prominent trabeculae,
ad thus the volume within the muscufar
~~fQldin~s
is not
considered.
Furthermore, the contribution of the left ven- tricular outflow track to total left verecognized by the Simpson rule meth c ultrasound tech
papWry muscles and trabeculae. dye (19) and the errors inke 20). Finalty, but extrer~~~y
basis for the correction factors proposed by Kennedy et aP. (16) and used in this study. However, it might be argued that even with use of the correction factor, angio~~h~c volu
This study demonstrated a weaker c intmcardiac ultrasound and an
systolc than at end-diastok. Thi of
end-systolic
values availab
we of trabecular In
s IS
most ~rouounced at factors w also reflected in the COE&-between ultrasound and angiographic
ecause intracardiac ultrasound volumes
at end-systsle were generally smaller than
those nxasurc-d ~u~~~~~I~,the derived
ultrasound ejection fractions tended to overestimate their angiographic counterparts.However, although most of
the points were closely clus- tered,the correlation obtained was
fair (0.69), and the slope was unity. Although encouraging, these data suggest that ifthis method is to be used
for determinations of ejection fraction inthe
clinical setting, a normal range of values for this technique should be established, and the validation should be extended to include a wider range of ventricular fu. The ability of intravas- cular ultrasound to provide accurate measurements of cross- sectional areas of arteries has been previously demonstrated I21,22), but th e importance of a central coaxial catheter position has been emphasized. A coaxial position is impor- tant bxause my deviation from this alignment will result in
The error ~nbcre~t in an ccc the fact that because the
art as it is at the skia. Thus
is farther removed fro
catheter will track t
because systolic contraction tends to obscure
the tendency to underestimate end-systolic volumes is due to the fact that a catheter that is relatively immobile through- out the cardiac cycle will result in a disproportionate weight- ing of smaller apical volumes into the end-systolic volume determinations.
it& the current state of the art of the following limitations of this iermination should be noted. First, vices, the field of view provided by intracardiac ultrasound catheters is limited and prevents the recording of a full cross-sectional area in large hearts, icularly at the mitral valve level. At this time, this woul preclude total volume dete~inat~o~s in most adult human hearts and possibly those of smaller animals with grossly dyskinetic segments. However, ongoing technologic ad- vances should ameliorate this problem by providing lower frequency devices. Jt is expected that the optimal frequency
ressure-area
ique, if corn
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aughan WL, Shoukas AA, Weiss JL. Accurate volume ventricle by two- dimensional echocardiography. Circulation 1979; 204.
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Carr KW. EngPer RL, Forsythe J , Johnson AD, Gosink B.
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