Echocardiographic visualization of coronary artery anatomy in the adult

in the Adult PAMELA

S. DOUGLAS,

MD.

NATHAN1F.L

REICHEK.

F%ilndul~hb.

P~w~.~~lvamn

FACL.

MD.

JOHN

FIOLKOSKI.

BARBARA

BERKO.

MD.

FACC

ndar, 5 palienB with corana~, 2 patienlr with congnibd and I padent with cPrdi”rnyo~tbic diseaw. The mea,, .+ge *as 47 * IS yews (range 17 to 79). Moditleattonr of standard prartarnal and apical views p+rmitted high quaIity imwsof

portionnoicach

ofthe major

epicardial wstls

.xkq”atr for a.~~zment of luminal diameter. Tbc ktl main ccwwty artery wax seen in 30 (86%) of the 35 ,ubj& and its bibrentioa was veen in 15. The kft ante&r d-diagrwomwy artery wassee” in 30 r”bje& (mean kogtb 3.9 c 2.3 em. maximal length 7% the left eirc”milex artery in It II.1 t 1.0, maximal 3.ai Bnd the right carartery in 32 (5.6 1 2.6, maximal 12). Prmtmal and mid pwtionr “4 the left anterior dcscrnding artery were wn in 23 and It s”bjc.zts. ~qe~dwly. The avrrage prmtmal knglh visualized HBC 4.2 cm. and th?

k&m

Coronary artery werecorrectly identified in faur uf tive rubjw’s (two in thp kfl anterior dewnding one iR the

The noninvasive delineation “f cor”nary ancry anatomy is of great importance yet has proved frustraling. To dale.

congenifal tomographic

imaging of P curwng

moderate

ti”n

the cardiac

SUCC~SPhas been achieved

with

crowsectional

hesfl discare

during

II 1.121. Problems cycle,

echocardiographlc imaging of the left mam coronary artery in adults (I-6). coronary aneurysms in children with muco-

difficulle;nclading

cutnne”“~

vented adcquatc vis”ab~a~m”

lymph node syndrome

and proximal

coronary

“nawny

Il
diseaseI 17-10) shddren

with

and limdations

with

and penetration

and display.

the introduaian

“1 cammercially digital

our re\“la\

or

availabie an-

mmging wdh

m !hc adult.

The

preseor

echocardiographic

in an iniliid

proccwng

modification

standard image planes. has enabled viudlizatlon crowsectional

have Pre-

anery segmeotr.

cme loop recall (13). combined

rnalomy

m the

rechnrcal

of all hut Ihe m”st proximal

nular phaqzd array rmnsducerc. md

rewlution

of image processing

dilated coronary Recendy.

rubopnmat

mherent

vessel that changes poricombined

of

ofcoronary

Wdy

describe\

the

merhads

employed

and

rcries of 35 patients.

mitral

slcmx~s.

bacterial

crldocarditis

and nortic

anoris

in

includmc 23 men and I! women with an average age of47 c 18 ycan (range 17 to 7% Ten normal subjects and 5 txalienlr

each. No Ggificanl cardtuc disease or isolated milral valve prolap% was found in the remaining elph! subjects. Cardiac diagnosis war confirmed by history. physical examination and full M-mode. two-dimensional and

from a total of j3 inpatients and outpalicnt? haring.rkne.

of coronary

one pattenl

DDpplcrechocardiographic B thallium clinically

indicated

coronary

anery

two

pulmonary

and

echocardiograms.

disease

in five.

stenosis.

The

venlricular idiopathtc

diagnosis septal

defect

cardiomyopathy.

WBP in

exemisc

study.

Cardiac

tell was required

calhcteriralion

to confirm

or

the absence

direaw in subjects >45 years old: angia?raDhy identified the location and severitv of lesions in the five with coronary disease. artery

formed with an Advanced Tcchndnpy Laborarory Ultnmark S echocardiograph equipped wth a dynamic& focuaed 3.5 and 5.0 MHz annular array fran~ducer. dwfai image processing, frame wabbei and tine loop rewew. Routine echocardiographic views wz:e altered w lhar each vessel could be imaged parallel to 115long axis. The mwl useful techniques for retarding image5 of each coronary artery are dercnbed as follows: Left muin eoronnry mm-y. This artery wa* imaged from a pxaternal shun-axis wew at the level of Iha aomc ~001 with the transducrr in the third or founh lefl mtercorldl rpace.

_^^

^

_

Results High quality images of portions of each of the four epicardial coronary vessels adequate for assessment of Iummel diameter were oblained in all subjects. The left main coronary artery was seen in 30 (86%) of the 35 subjxls and its bifurcation in 15 (Ftg. IA). The left anterior descending coronary artcry was seen in 30 subjects (Fig. IB and C and Fig. 2) (mean length 3.9 f 2.3 cm. maximal length 7.5). the left circumflex afiery in I I (I .I t 1.0 cm, maximal 3.0) (Fig. 3). and the right coronary artery in 32 (mean 5.6 + 2.6 cm, maximal 12) (Fig. 41. Table I shows the average length visualized and luminal diameter of segmental portions of the left anterior descending. leit circumflex and right coronary arteries. Septal or diagonal branches were seen in (31%~ of the 35 subjects, a marginal branch in the coronary sinus in all and ~malkr veins in 3. Coronary artery disease. Of the five patients with corenary artery disease, catheterizalion-documented lesions were correctly identified in four (two in the left anterior descending. one in the left main and one in the right coronary artery) (Fig. 5). In the fifth patient, the proximal coronary arteries were obscured by calcifications in the sonic valve. Calcification of the coronary artery lesions. however. did not limit rewlolution of the artery.

I,

Figure 3. The pr0xim.dM

cireumRcxcoronaryancry Wrmns~ is shown using n modified apical four chxmbrr view in R JO year old “0mI.l man. I.” _ ten “e”,“c,c.

transducer was rotates approximately 10” counterclockwise and an&d slightly superiorly. From the apical four chamber view. the transducer was rotated slightly clockwise to move the imaging plane posteriorly and infewxly to include the left atrioventricular groove. Ri,rhr romnrrq w&-y. The ostium of the right coronary anery war imaged from both the parastemal short-axis and subcostal wevs. The proxtmal and mid right coronary artery was imaged from the pamrtcrnal short-axis view at the level of the aortic valve by sliding the transducer away from the sternum and angling it superiorly and rotating clockwise. From the short-axis rubcostal position. the transducer war angled toward the pulmonary oultlow tract. The mid and distal ngh! coronary artery was imaged from the apical four chamber view. The trtmsduca was angied slightly posteriorly and rotated approximately IO” clockwise. Image analysis. Keal time image were stared m tine lOop, permitlmg frame by frame reviea: optimal delineation was usually obtained in late diartole. Imaging and recordir.a time averaged IO to 20 mm per patient. Slop frame images wcrc analyzed by two independent observers who were unaware of other pwicnt data. The length and luminal diameter of each coronary snery segment visualized was digitized manually Far this purpose. the left anterior descend&! artery ww arbitrarily divided into proximal (tint 5 cm) and mid I5 to IO cm) portions. and the right coronary a~lcry into proximal llirst 5 cm). dirtal (beyond the acute mar& awl mid lhetween proximal and disrslj portions.

II

Discussion Problem in eehoesrdlographie imaging of the romnrry arteries. This study demonstrates that high quality images of both proximal and distal coronary arteries and measurement of luminal diameter may be obtained noninvasively using cross-sectional echocerdioaraohv. Satisfactory examinations of part of the left t&t, i&ianterior d&ding. and right coronary arteries were obtained in 86 to 91% of patients; the &cumtlex artery was seen in only one third. In previous reports (I-f& successful visualization of the left miin corona, artery war achieved in 58 to 99% of patients. Imaging of just lhe origins of the left anterior descending and circumflex arteries has been more difficult, being reported in JJ and 34X of patients, respctivcly (3.4). Few data are available regarding visualizatibn of the right coronary artery. Some of the difficulties encountered in obtainingadequnte coronary artery images are those inherent in any echacsrdiographic study andinclude obesity. unfavorable chest wall configuration, chronic obstructive llng disease and advancing age. Tbesc problems are augmented by several features unique to wrooary artery imaging. The small diameter of the coronary arteries approaches the beam width of cowcntional equipment. This is especially true when using apical views because the coronary arteries are relatively distant fmm the tmnsducer. and beam widlh increases with depth.

Flswe 4.Three imases of the right comnaw artery tRCAt. A. The origin of the right coronaryarteryis shownusinga subcostalview I a 76 yearold normal woman. 8, Tbs mid and distal right coronary arteryarevisualizedwing a modifiedapicalfour chamberview in a 14 year old man with aortic regurgitation.C, The right comwy artery and adjacentvein IV) are displayedusing a mcditied apical low ebamberview in a 37 year old normrl Inan. The win is seen draininginto the c~mnary sinus(CSI. Ao = aortic root: LV = left ventricle.

Further, such views require high pnerration to yield adequate resolution. Because echocardiographic imaging is iomographic by n&we and epicardial vessels follow the curving surface of the heart, description of a long p&cm ofa single vewel can only be accomplished through we of multiple views. each with a slightly diiTerent transducer angularion. each displaying a dierent but adjacent segment oithr artcry (Fig. 2C and D). Further, the ~ccsds move continuously in and out of the imaging plane in concert with normal cardiac motion, and may only be visible briefly during the cardiac

I and

bnaging of .zoawy artery d&we. The difficulties are especially ibnwrtant in the diagnosis of cornnary artery discare. Positive identification of significanl luminalnarxwing requiresvisualizationofthe normal anery both proximal and distal ,o a suspected lesion. An apparent obslmction may simply be due &I motion artifact or to curving of the vessel Out of the imaging plane. As 8” alternative, hi& intensity coronary artery echoes have been proposed as B finding diagnostic of coronary atherosclerosis. Acknowledged limilations of this technique include a requirement for mod’fied gray wale processing U4,lS). possible overreading nf a left anterior descending ancry plaque as left main

relateo

coronary artery disease and confusion of epicardial fat (2) or cholesterol cry~Js 16) with calcium, .~dvantages 01 present method. Because of the limitations ofpreviou~ly available scanning equipment, development of techniques for transducer placement sod angulation ,o obtain views of vessels otbcr than the left main coronary artery has oo! been necessary. Our results demonstrate that mod. ifications of rtandard apical, parastemal and subcoslal echo. cardiographic views can yield images of subsranttal portions of the epicardial coronary vasculature. The more extensive vwalix3tion of coronary anatomy is a necessary prcrequicite to any possible clmical appkca~on ofwronary imaging. including positive identification of coronary lesions. Our

t

sucee~\ is in part to the uw of all ocouwc windows. allowing visualizitioo in a greater percentafe of pmient9. More important. several fenlures of the echocordioprophx equipment minimize difficulties previowly mherent in coronary imaging. The annular array tramducer ored m the present study provider high penelrarmn wilboul lobb of resolution, enabling production of clearer imaCes of smaller. deeper structures. itb technology ineorporate;both harizonlal and vertical focusing of digitally encoded images. providing multiple depth focusing of thinner (approximalely I mm) tomographic zliceu. The tine low allows caoture. frame by frame review and recording aoh repeated’playback of H single cardiac cycle during which the coronary vessel may be visible only briefly. Limitations of method. Our study has some important limitdionn. Although ~‘e successfully aht?ined coronary images in all subjects, views were sometame limited and complete examination of the emire epicardial vasculature was not possible. Because only segments of the vcs(cI( can be visible in any single view. asrercmcnr of long sections of an artery req&erpiecing together socce&~ views of adjacent segments. Even in the “best case.” circumflex artery imaging was suboptimal. Coronary imaging will always be affected by patienl factors known 10 influence overall routine echocardiographic image quality; in addition, highly echogenic structures in the ~XLOIIICroot (such as a prosthesis or calcified valve) can limit rewtution of the coronary ostia. Although WC have demonstrated the feasibility of the technique in the elderly and in those with heart disease, its sensitivity, specificity and predictive value for recognition ofcoronary atherosclerosis remain to be defined. For example. although we were able to identify intraluminal echoes in some patients. images remain somewhat indistinct and are not yet of sufficient quality to permit quantitative evaluation of the severity of coronary rtenorer. Our results need to be confirmed by others and by prospective studies evaluating the clinical utility of the methods presented.