___
Prediction of the Severity of Aortic Stenosis by Doppler Aortic Valve
Area Determination: Prospective Doppler-Catheterization Correlation
in 100 Patients
JAE K. OH, MD. FACC.
FACC,
GUY
A. JAMIL
S. REEDER.
TAJIK.
CHAHLES
P. TALIEHCIO.
MD, FACC.
KENT
MD. FACC,
R. BAILEY.
DAVID
R. HOLMES.
PHD, JAMES
B. SEWARD,
JR., MD,
MD, FACC,
MD, FACC
Rorkewrr. Miarrmm
Noninvasive evaluation of aortic stenosis lacked quantilalive hemrdynamic informalion before the application of
Doppler echocardiography. In 15¶080.
Hatlc et al. (II repwted
that the pressure @-adient across a stenotic aortic valve
could be estimated from oeak Doorder sonic Row velocitv
with use of the modified Bemoiii equafion. Subsequent
validation studies 12-6) demonstrated an excellent towel.+
don between pressure gradients by Doppler and by cardiac
catbelerization. Peak Doppler Row velocity or prewre
gradient alone. houever. is not always sufficient to determine the severity Gf aortic stenosis. because Row vrlocily
and pressure gradient vary with car&w output lor a siren
sonic valve area. Recently. several studier 17-10)examining
small numbers of patients have shown that sonic wdvc area
cuuid be ~eiirbly &naled from two-dimensioeel sad Doppkr echwudiography with we of the continuity equalion.
We performed a prospective otudy 10 compare Dopplerderived aoilic valve area with cnlheterilation-derived sonic
valve area in a large group of patimts with amtic stenosis.
We also sought to deiermise oihtr Doppler variables that
might be useful in predicting the rsverity of antic slmo~is.
S~wdyp&kale. ia+dimensional and Doppler u.hocardioemnh) was performed in I20 palientr undergoing clinically b&ted
~cardrx catheterizauun for aortic slcnosis
from July 1981 to September 1986. Twelve patients had
aasociatcdwsreaonic regqiiladon and were excluded from
funher analysisbecauseof Ihe limitation of cardiac catheteri&on in determining aoctic valve area in this wp.
Eight
addibonal palienls were excluded becausefour had unsalisfacrory echocaFdiographicexaminatiansandfour did MH have
cardiac ou,put meaauement during catheterization.
The remaining II pndents were 55 men and 45 wwt!zB
with a mean age of 71 years @an& 53 to 95). The presmling
symptoms were chest pain in 38, dyspnea or congestive
hean failure lor both) in 65 and syncopc or presyncope in IS;
9 padenls were asymptomatic. Eishly-eight patients had
sinw rhythm,
had aerial fibrillation and
paced
rhylhm. Filly-three patients had left ventricular hypcrlrophy
on clectmcardiognm:
13 patients had tell bundle branch
block. Sixty palienis had aortic regurgitation detected by
Doppler ultrasound (trivial 10 mild in 50. moderate in IO).
Two-dimercrinal and Doppler echncardiogrsphy. A Hewlett-Packard 77020A cardiac ukrasound imaging unit WBS
used for two-dimensional and Doppler rtudics urilieiy a 2.5
MHz phased-array duplex transducer. A nonimaging transd&was
used fir c&inunus wnve Doppler examination.
Echwardographic
sludy !a
performed within I2 h of
cardiac cathelerizalion ii all pnlicms by oue of Ihc exaitiners (J.K.O. or C.P.T.,. DoPpkr study preceded cathelerizaLion in YO oalicnls and was oerformed aller catheterization
with the &servers ueawrc of rhe cathelerizaliun data in th:
remaining 20 palicnts (admill:d ln the hospibd an the day at
cslhererization instend of the night before).
T/w /c$ wnrric,drrr n,,rJlo~r ,r,,c, diumdrr was measured
lrom a systolic freeze-frrsmc @amsamal long-axis view) with
built-in calipers placed where the unleriorand porlerioraonic
cusps met the ventricular seplum and the anterior mitral
leaflet. respectively. The mensuremcnts were repealed three
times lor each valienl and an nverw value was nbbdned. The
area of the leit ventricular oulfl& &act was calculated as
(diameter + 21’ Y w, assuming a circular shape. The left
venlricular outflow tract vrloci~y war deterndn~d fmm the
apical view by positioning lhe Duppler sample volume 0.5 lo
1.0 cm pmximal to Be aortic anulus. The sample volume WE
carefully moved up and down in the letI venwicubr oulknv
tru area to recwd a siable and sunsiwn audio 2nd speclnl
signal. avoiding the accclemfed velocity that occ.urb just
proximal Lo the stenotic aortic valve. Peak aoriic valve Row
&cily
was obtained by a nonimaging. coutinuous wave
Doppler probe syslemaically placed in various msilions:
apical. right and IeB paraslcmai, subcoslal and su&emal
windows. Speclral velucily prnfiles were recorded ofi strip
charts at xxeds of JO and IO0 mmIs (Fie. I).
II
I hada
the modified Bcmoulli’s eq&ion (pr:s&gradienl
s-4 x
velocity’). Mean anriic pressure gradient and lime-velocity
integral of the sonic valve and Lhe left venlricular ourflow
trzt were ohmined by integrating the respective systolic
Dappler vchxily spectra nn the Microsonic dighiring tablet
connecrcd Lo an IBM PC-XT computer. In pzlients with
sinus or paced rhythm. a single representative Doppler
veloch) spectrum from thr outllow tact and the nortic valve
was digitized, but in patiems with atriai fibrillation. velwiiies from IO consecutive bears were analyzed 10 obtain an
average vJue. Eclopic and posteclapic heats were excluded
from analysis.
plgwt 1. Strip chsn recording of kn vsmriwhr ou,now ,rkw
,L”OT, velocity ,@a,and peak awtk vslw (AV, llow vdaity
Omttom~al n speed oi JO mmk. Each crdibratian n!nrk a! the top
represents0.2 ml, and kn venlricular wlkw lre,ct veIncity is 0.9
IrJs. Each eslibmion mark at Ihs bmom represents 1.0 nds and
peak aordc 6ow vehxify is 4.5 m/s. The peak v&city cormspands
to a maximal inslanbmenusgraditnl of 81 mm Hg I= 4 x 4.J’). The
diaslolic Da~ler ~peclrum above the baseline indicates amtic
rcgugilalion. From the let? vcntrieulnr outRow tract and aonk
valve velaeilien, B velmily ratio ol 0.2 (= 0.9 + 4.5) can be
calculaled.
Aorfic wh
wtw IAVA) was calculated from twodimensional and Doppler dala with the conlinuity equation
as Lllows:
where AV = aortic valve. AVA = aartic valve area. LVOT
= left venlricular outflow tract and TVI = lime-velocity
integral. Because Row across the left vemricular ouGknv
lract and the a&c valve share the same ejection period.
aonic valve area was also calculated from a simplified
continuity equation lhal uad peak velocity ratio instead of
lime-velocity integral (9):
where V = peak Ruw velocity.
C&be
ulbeteriudcm.
Jmracardiac prersurea were recorded with fluid-filled ca,he,err (7F ur SFI connected 1”
strain-gauge pressure lransducers (Guuld P23MI. The ryclolic presswe gradient across the aorGc valve WBE meawed
by either pullback technique imm Ihe kn vmiclc
10 a~
ascending aorta (32 palientsl or dual ca,he,er technique wi,h
oimulmneous pressure mearurements in ,he ascending aorta
and lef, venlricle wilh the lransseptal lechnique !6R
palienla). The pretsure Brad& was calculaled by rupenmposing pressure recordings when they were ohlained by
pullback. When mearure,wn, was by dual ca,he,ers. s,muItaneoully recorded pres*ure Iracings were annlyzed. Cardiac o~,pu, wa6 determined by irdcqanine
pen
dyedilution ,?chnique (dye was in&ad
ims ,he len vemricle
and sampled from tho femoral arkryl. Values from lhree
determinalians were averaged unless there WI il chne
agreemenl between ,he Bfrl two measuremcms.
Coroaary ungioproph~. periurmed in all In0 p&n,%
showed sig&ican, s,encnir fluminal narruuing a7ffL) in 59
patients (single vessel diseax in 24. IWO vessel disease in 14.
lhiee vessel disease in IS and lef, main cxonary awry
disease in 3).
DU%d,km af swerl,~. The xevcrbv of sonic s,enour was
defined by ca,he,e&ion-derived
a&
valve mea ai follows: mild, >I .O cm’: moderate. >,I75 ,u
cm’: severe.
SO.75 cm’. On the basis of this defminoon. sonic s1enos,s
was mild in 17 palients. moderate m 20 d,,d were in 63.
SMWk,d
aaafysk. Doppler and cnthekrimtion
dm
were analyzed by independent obwvers. The rc~ul!~ were
I.O
?xprerrrd ar mea” + SD The cwrel&m
between ulbekrizdicm and Do~ler aoItic VBIYZ gmdient and arex wa>
rakula,ed by Gmpk linex rcgressmn. In addition. the he51
line going through Ihe origin ;.a~ ublsincd. and ,be regrcscmn equation aar exprerxd by use of ca,hc,crirz,ion dma
a$ mdependen, vanabler. For each value of Darrdcr-dewed
aorlic pesk vcloci,ie% mean gradients and &k
velocity
r&x
sens,,,v~,y and specificity for were aor,ic uewi\
were calculated ,O determine Doppler variables useful in
prediciing the severity oiaonic ~,eousis.
RWIHS
Mean asd range of rwo-dimensional and Doppler cchocardiogmphic d&a and cardiac calhetcrizalion dala are
show in .Table I.
Peak wtie San rebxig. Tnis variable rmgcd from 2. I IO
6.4 ml\ lmcan 4.0) (carre$ponding ,o maxhnal ins&nlaneous
gradirn,s uf 17 10 Ifd mm Hg [mean 671). Figure 2 rhows
peak aorltc Row velonly plolted against cathstenzaliondrrived aunic valve area in the IW patknlr. Apeal veloaty
of ~4.5 m/s wr highly specifk for severe nortic sten&s (2S
uf 311.93Sil hu, with low senailivity 128 ~163.44%. A higher
velocily curafflruch 8s 5.0 mlsJfur,herdecreaaed wxmvily
wifhau, wbr,&al
improvement in specificity for %:vere
aurtic L:enosi\ IFig. 3). A, lower peak sonic veloci,ie$ there
was a .wide mnge of overlapin ,he severby ofaortic s,erms,s
lcnlhc,er,raliun-derived sonic valve area range 0.30 10 1.81
cm’!. H.+lf of ,he 70 patiemr wi,h a peak aolic Row velocity
ra 5 is were fuund ,o have severe arlic sknasi<.
F,g,,re
+Cerrclation between
Doppler-derived and catl.ctcrizationFigure 2. Peak Doppler wtic flow velocity campared with aortic
wtve area (AVA) by catbetcrizaGon lcathl in Ml patiems with
Mat aertk v&c grsdknt. The Doppler-derived mean
eortic valve nradient in this stud” rewed from 8 to to8 mm
Hg (mean 4lj. At catheterize&
the&m
gradient ranged
from 8 to 90 mm Hg (mean 43). There was a good correlation
tr = 0.R y = O.R9x + 2.3; standard error of estimation
[SEE] IO) between the Doppler- and catheterization.derived
mean gradients (Fig. 4). A Doppler-derived mean gradient
~50 mm Hg was highly specific (30 of 32. 94%) for severe
aorticstenosis hut less sensitive (3Oof63,48%)(Fig.
51. At
a h&r
mean grsdienl culoif. sensitivity decreased even
further without significant improvement in specificity (Fig.
3). At a Doppler-derived mean gradient of GO mm Hg, the
scvcrity of sonic stenosis could not be reliably predicted
from the mean gradient alone. These findings were
to
those of catheterization-derived mean gradients. When the
catheterization-derived mean gradient was plotted against
the catheterization-derived aortic valve area, a similar result
war obtained (Fig. 6) (spccifieity 97% and sewitivity 4%).
Time-vehxiiy Integral ~tla md peak vrlmity ratio. The
continuity equation states tht+t the left vearicular outrlw
tract and eortic valve flow time-velocity integral ratio is
inversely proportional to the ratio between left ventricular
outflow tract and wtic valve area. With the same systolic
similar
BIgwe 3. Plot of stndtivity against I - w&Acity for severe am-tic
wmsis of Dopplerderived antic peak flow velocities OetW. mean
&ients @ntert and vetccity ratios (rtght). Representative Dop
P,C, derived values are shown with ,he,r data pint indicatedby a,,
-*I.
(Cathbderivrd meangradientsoerors the slenoticaortir. valve in 100
patients. Mean slandard ermr ol srtimation @EEt (evimation of
catheteriza!ien mean gradient from DcPpkr mean gradicst) wi19 10
mm HE.
ejection time shared by left ventricular auttlaw tract and
aortic valve Row and their relatively similar shape of
curves. the ratio between left ventricular oatflow tract and
aortic valve peak velwity correlated well with their timevelwity intcwal ratio Cr = 0.94). The Desk veloeitv ratio was
a025
I (92%) of 63 patientr with’ severe aor& stenosis
bet was also ~0.25 in 12 (32%) of 31 who had an aortic valve
area >O.lS cm2 (Fig. 7). As the ratio decreased, it became
more specific hut lesrc sennitive for severe aortic stenosis.
Wke!! & t&o ygs C,,
, 15
had lr”PrP
.“._,
__ to*%,
,““.“, nfdn
_. .” IwfiF”,.
I_.._“,” ._”
_._._
aonic stenosis. At the ratio of >0.25. specitlcity decreased
markedly without much change in sensitivity for severe
aortic stenosis @ii. 3).
Aetik valve em. Dopplerderived nortic valve area correlated well with catketerilation-derived
a&c valve e.rea
when either the time-velocily integral ratio (r = 0.83. y =
0.76~ + 0.16; SEE 0.19) (Fig. 8) or the peak velocity pdtio (r
= 0.80. y - 0.67x + 0.22: SEE 0.20, was used. Diierences
between Doppler and catheterization meawrements were
greater when sonic valve area war > I .O em*: catketwiz~
velocity
in
rents. Dc.pplardert”ed nlem sonic“al”egmJtcnl
mmmwared
with aortic valve area (AVA) by rathetorizeion tcathl in IM
patients. Numbers of patients in sash quadrant are ~bown in
paremhexs.
“r
I
MCC
,““c
““I
Pm%
II. ‘+I 0
1217.11
0
ID
PPL‘X<
m
=
do &
rp&
m
P
>m
9.7
9n
don-derived amtic vAve area was higher lhitn Dopplerderived wrtic valve ared in all padenr~ cxcepr ow.
In IO patients with a moderate degree of aurtlc rcgurgilzlion. the correlation was less satisfactory (r = 0.71). Calheterizatkmderived aorlic valve area was \m;dkr than Dop
pier-derived aorlic valve area in II of these 10 patients.
Rife*
with hw cardiac OuQut. Thiny-eight paWna
had a cardiac output c4.0 literslmin. and 29 of lhcm had
w-we aordc stenosis. Peak Doppler aurtic Row vcloe~~y
84.5 m/s and Doppler-derived mean gradient FO mm Hg
were able to delect only IO (34%) of these 29 patients. In
contrast, peak flow velocity and mean gradient > 3.0 nu’sand
20 mm Hg, respectively. were quite sensitive 191%) and
speciiic (WA) for sevcrc aortic stenosis in this subset uf
patients. The peak velocity ruio of G.25 WBE highly wnsilive (92%) for severe aoriic stenosis in patients with low
cardiac outpat, as in the enure sludy population.
Fifteen patients With severe sonic stenorir bad a left
ventrisular ejection fraction <40% on tw+dimensmnal
echocardiography or MI ventriculography, or bath. Of the
Figwe ‘1. Plot of peak velocily (V) ratio between Ikli venlricular
o”,ncnvtraEl ,L”wr, .&aonic “alYe &xY,againsl aotiic YBlW area
(AVA) bycathelerizalionIca,h) in IMpalienl~. Numberrofpatlenlr
in each qundrant are shown m parentheses.
a,
*I
;LL&
OS
01
rn/
‘HE
SLVLRITY
or
wi
AORTIC
ET *L.
YrENOS1S
,221
Figure 8. Correlr!ion between catheleridationGW- dewed BOOK
YlllYC .,rc.,
‘W”lC VdlYC,,rea Wlh “V “fk,, “Enlriculvr ““tn”H iKEI and ~c,,;c
wlw lime vrkwly intwal wl:o in IW palienlr. Mean iundxd
cnur or c*,,ma*on SEC) WBT0.19 cm’.
,\“:,I rndlhpp,w
cchwardlupanphyEcho,
!k”“d
Fi~mt6.
Cdlbcterilation ICW- denvcd medn aomc uIve grxlenl
UP, cmnpwd Wllh sonic “.I”L ,Awz,,*“A, hg c;,thelrr,r;llL”n I”
IOD patients Numberi of par&r in each quadrant are chnan an
parentheses.
0
TION
0,
II
15. 173’/i) had a peak Duppkrnonic ilow velocity of <4.j
ml5 and d Doppler-denred mwn gradient of 60 mm Hg.
Discussion
Orer the la\, 3 deader. cardiac cathctcnration llias been
the dnagnortic procedure of choice for dewmining the
wwzrw of nortic stenosis. Recent rludies (i-IO). howcwr.
have demonstrated Ihat Doppler echocardiography can reliably determine aortic prcswre gradiem and zonic villve
area. Our study arseand the predictive value of variou?
Doppler d&a in determining the wwity
of aonic stenosb
and correlated Doppler-derived and calheleriraiian-derived
wartic wlve areas in IIXI di;l: pzli:n!c.
Fwdktive vrlw of pew sortie lkw vrlwily nmJ
derived mean gmdknt I” do(trmiaing tho severity of antic
rtenosia. The pressure gradient IS only a partial drterm~nanl
of the reverby ufaonic s,eno~s. For a constant aonzc z,lvc
area. the aortic valve gradient may vary considerably.
depending an cardiac wlput. Therefore, it il not rurpririns
that aortic Row velocily or preosure gradient alone did not
establish Ihe wverily of sonic sLamsis in many pl~ents.
There ~8% a wide range in the ~cvcrity of aorlic stenosis
(sonic valve area ranging from 0 30 to I.Sl cm’) at peak Row
vckxnies of ~4.5 mis or mean gradients of ~50 mm Hg. In
fdct. the lowest pest velocily (2.
found in a patient
with a left venlricular ejeclion fracrion of 24% and seveic
40rbc stenosis. wilh a Doppler-derived aonic valve arca of
06u cm’ Ikit vennicular outflow tract diarncrer and peak
velocity of 1.8 cm and 0.5 mis. rerpeclivcly~. Aonic valve
area ra\ 0.58 cm2 at catheterization (mean gradient 8 mm
Hg. cardiac uutput I.8 literslmin).
Thus. calculation of valve wea is an CSSenlial Part Of
evaluating the degree ofaonic stenosis. Our data emphasize
that valve area calculation is critical in patient5 with peak
aorlic Row v&city of <4.5 m/r or a Doppler-deriv~d mean
gradient of <SO mm Hg.
I m/s)
was
Dapplcr-derived vcmosca,heterizationdcrivd sarllr valve
arca. The condnuhy equation for aortic valve area CalculC
lion was dcrivcd from a hydraulic orifice formula that
describes Row axoss a fired orifice as a product of orifice
area and flow velocity. In previous studies (7-10) based on
small numbers of patients. the Doppler-derived nortic valve
arcir had a good correla!ion with catheterizationderived
ooflic valve ares. Our prospeclive study of IW patmnts has
canfirmed the ear&r preliminary obrrrvationr in this rcgwd.
Aortic v&c arca ohlaincd by peak velocity ratio was
inlerchangcabk with that obtained by the lime-vclocily
inlceml ratio method. This is one of the advanta~csof usiop.
thcicfl ventricular oultlow trac, rather than oihcr orifice;
(right venlticular oulflow or milral or tricuspid inflow) in the
cardiac chnmbcrs to cstimmc Ihe amount
Row across the
aortic valve. Other advanlagcs (7.10) are as follows: I) Flow
acrossthe left ventricular outflow tract is alwavs the sameBS
that acrosr the aonic valve; therrfore. flow m&surement is
no1affected bv sonic valve raur&ttion.
21Left vcn~ricular
outAow tracLdiametcr at the~l&l of the aorlic anulus is
rclmively constant compared .uilh that a[ other sites.
I.& venlricular outllor tract sod a&k valve flow wlocily
nlio. Although left venwiculsr outflow tract arca and Row
velwity vary widely among individual patients, they wve
as au internal reference for a given patient in the assessment
of aonic ucnosis. Changes in hemodynemic status a&xl the
velocities itcross the left venlricular outflow tract and rhe
aortic valve proportionately. so that their velocily ratio
remains essentially unchanged. In fact, the ratio alone op.
pears 10be a very sensitive index in [he detection of scvcrc
aortic stenosis. The ratio was rO.ZJ in 58 (92%) of 63
patiems with scwc aortic recnosisand was not a&led by
the status u; vmJirc outouI. This rmio was called the
“dimenrioolr ,PDoppler in&x” by Otto el al. (7). However.
their cutoB ratio was higher (0.3) because they defined
severe aomc ?lcnosis as a&c valve area of 41.0 cm’. The
rmio sts:~ld bc helpful in following the pmgression of sonic
stenosis or evalo&
the therapeutic eficacy of aortic
balloon valvuloplasty or dccalcilcation procedure because
the left venrricular outflow watt arca should remain conant
for a given patient.
Whsl if the scvcri$ of wrlic akmxls is dlwrdaol In
Doppler and catbcl&tion
cvahmtioo? Usually. patient3
whh sonic SLenosisare categorized into severity groups on
the basis of clinical and laboratory evaluations. When patients were ~eparmcd into mild, moderate and severe aortic
stenosistroops on the basis of Doppler- and celhetcrizalionderived aanic valve areas, 27 pslienls had discordant sevcrity wth Ihc Iwo methods (Fig. 9). This is in parl relaled lo
our arbilrary definition of the severity of sonic stenosis.
Allhouph aortic valve area of ~0.75 cm2 WBSd&cd as
s?Verc aortic stenosisin chir study, other instilutions (7) may
osc 8 dilTcrent cutoff for severe sonic stenosis. By the
crileria of Olto et al. (71. only eight of our patients had
of
discordant severity of sonic stenosis. Becausea laboratory
value is a guideline for patient management rather than an
absolute indication for thempeutic or palliative intervention,
the discordance should not impose a mi\ior clinical decision
vroblem. escwiallv when the hemodvnamic data are inter&cd in c&m&n
with other cl&l
data.
When amtic valve area of0.73 cm2 was used to separate
patients iota two
one with scverc and the othci with
mild to moderate aortic stenosis. 20 patients bad discordant
sevcrily in the
and catheterizalion evaluation (Pi&
9). Their mean aortic gmdieol and aortic valve was by
Doppler lechnique and catheterization and Ihc milnagemcnt
decisions are listed in Table 2. The average absolute ditkrcnce in mean gradient and aortic valve area by the two
melhodsin~hesctOpalientswas8mm Hg(rangcOto 19)aod
0.2) cm2 (raogc 0.06 to 0.473,respeclively. It was similar to
the mean SEE in [he entire study population (10 mm I& and
0.20 cm’. respeclively).
Of
pdtieots categorized as having severe aortic stcoosis by Doppler technique but not severe by catheterization.
4 underwent oortic valve rcdacementormcchanicaldcbridemat within a month, In &mpmison, nonriurgir~l managemeat was selected for lhrcc of nine patients categorized as
having scvcre aonic stenosis by c~thelcrizati& and not
severe by Doppler technique. Themfore, our data suggest
that. like catheteriza&-m. Doppler echocardiography can
guide clinicians to therapeutic decisiora for patients with
aortic stenosis.
Limltallw.
Estimation of aortic valve area by Doppler
echocardiography has wersl well recognized limitalions
(7-10). such as difficolty in measuring the IeR ventricular
outflow lracl diameter due to hcovy calciiicalion of tic sonic
value and inabilily to obtain a reliable DBIROW
tract velocity
becauseof subsonic obstroclion from basal septal hypcrtrophy. However. we were able to obtain a sslisfactory Doppler
rludy in 91% of patients. The accwdte Doppler ossessmcnt
of the severity of aorric stenosis rcquirez the examiner to
obtain the best possible Doppler signals available fmm the
left ventricular outflow tract and the aortic valve. Adequate
training in Doppler technique and perseverance (the prow
groups,
Dappler
II
dure usually taker 30 miz %i a skil’ed examiner) in obtaining
the best Doppler signal5 from mukiple positions are re-
when;he s&erily of aortic slewsis is IO be assessed. If IL:
quality of Ihe echocardicgraphic Doppler study is salisfactwy (which it should be in 97% of palientrl and resuI1~
cuncu: with other clinical findings. cardiac catheterizalion
will usually yteid lillle addirional infarmarion regarding padent mansgemenr decision?. However. preoperative cardiac
calheterizatian is indicated for evaluadon of coronary die
ease or lor re~olul~on or conflicting clinical and Doppler
data.