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arotid-Subclavian Artery Index: Newchocardiographic Index to Detect Coarctation ineonates and Infants

li Dodge-Khatami, MD, PhD, Stephanie Ott, MD, Stefano Di Bernardo, MD, andelix Berger, MDivision of Cardiovascular Surgery and Congenital Cardiology, University Children’s Hospital, Zürich, Switzerland, and Clinic for
ongenital Heart Diseases, Deutsches Herzzentrum, Berlin, Germany
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Background. In neonates and young infants (less than 3onths), coarctation may be missed or underestimated

y echocardiography, especially with a patent ductusrteriosus or severe concurrent illness. A reliable nonin-asive screening tool for coarctation would be useful forhese patients.

Methods. From 1997 to 2003, echocardiographic evalu-tion was performed in 63 consecutive patients withoarctation (47 neonates and 16 infants) as well as in 23ontrols (16 neonates and 7 infants). End-systolic mea-urements were obtained from 12 different sites of theortic arch.Results. In patients, the diameters of the ascending and

escending aorta were comparable to controls, but theimensions of the transverse arch were significantlymaller. The distances between the origins of the greatessels were longer in patients with coarctation than in
ontrols. The ratio of the aortic arch diameter at the left
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2005 by The Society of Thoracic Surgeonsublished by Elsevier Inc

ubclavian artery, to the distance between the left carotidrtery and the left subclavian artery, which we propose ashe carotid-subclavian artery index, was significantlymaller in patients with coarctation. A cut-off point at 1.5howed a sensitivity of 97.7% and 94.7%, and a specificityf 92.3% and 100%, for neonates and young infants,espectively. The positive predictive value to have coarc-ation was 97.7% and 100%, for neonates and infants,espectively.

Conclusions. The carotid-subclavian artery index is aimply obtainable noninvasive screening parameter,howing high sensitivity and specificity for coarctation,nd may be useful in unstable patients or in those with aatent ductus arteriosus in which coarctation may beverlooked.

(Ann Thorac Surg 2005;80:1652–8)
© 2005 by The Society of Thoracic Surgeons
oarctation of the aorta is a very common congenitalheart malformation that occurs in approximately

% of all congenital heart diseases [1]. It is frequentlyssociated with other abnormalities such as tubular hy-oplasia of the aortic arch (63%), left ventricular outflowbstruction (40%), bicuspid aortic valve (40%), ventricu-

ar septal defect (28%), and atrial septal defect (12%). It isefined as a narrowing of the aorta immediately distal to

he origin of the subclavian artery. In most cases, a ridgerotrudes into the lumen of the vessel from the posteriornd lateral walls. In older children, clinical manifesta-ions range from mild clinical symptoms such as hyper-ension in the upper extremity, a systolic murmur, oriminished femoral pulses, and echocardiographic diag-osis is straightforward [2]. In newborns or young in-

ants, the presentation is often more severe, in the formf shock or severe congestive heart failure. A concomi-ant large patent ductus arteriosus (PDA) may render the

ccepted for publication April 25, 2005.

ddress correspondence to Dr Dodge-Khatami, Division of Congenitalardiovascular Surgery, Children’s University Hospital Zürich, Stein-

iagnosis difficult, thus delaying surgical interventionntil after the ductus closes [3]. In these situations, anasily measurable, yet sensitive and specific parameterould be useful, to reliably screen for and diagnose

oarctation in all neonates and young infants. Impor-antly, the timing of diagnosis should be established beforelosure of a patent ductus arteriosus to avoid deteriorationf cardiac function and global systemic perfusion.This study aims at finding a noninvasive echocardiog-

aphy parameter to predict coarctation, independent oflinical status or other confounding factors relating to theatient.

aterial and Methods

pproval for this study was given by our Institutionaleview Board, and informed parent consent was obtainedystematically. Between January 1997 and February 2003,reoperative echocardiographic studies and demographicsf 63 consecutive neonates and young infants with coarcta-ion who underwent corrective cardiac surgery at our hos-ital were recorded. Young infants were included until ange of 3 months. Echocardiographic investigations were
erformed by two cardiologists (S.D.B. and F.B.) with the
0003-4975/05/$30.00doi:10.1016/j.athoracsur.2005.04.041

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ame ultrasonography equipment, and recorded on videoor retrospective analysis. Measurements of the aortic archere obtained by two-dimensional echocardiography at the

nd of systole from the suprasternal notch view, afteralibrating the system using the two-dimensional centime-er scale. Morphologic parameters and distances (d1 to d12)ere measured by three independent observers (S.O,.D.B, and F.B.) as described in Figure 1, and noted sepa-ately. During the same time frame, 23 controls (16 neonatesnd 7 infants) were admitted to the hospital because ofnfectious diseases or respiratory distress syndrome, butith a structurally normal heart, and underwent the sameetailed echocardiographic measurements. For this groupf patients, the measurement of d8 was left out, and d12 wasefined as the narrowest diameter of the isthmus of theorta.

tatistical Methodsasked interobserver variability pertaining to echocar-

iographic measurements was not significant. Measure-ents were recorded in millimeters and represent abso-

ute values. All data are presented as mean values andtandard deviations in parentheses. Windows Excel Ver-ion 97 and the Statview 5.01 statistical program weresed for calculations and statistical analysis. Mean valuesnd standard deviations of demographic and echocardi-graphy data of both groups were compared with thenpaired Student t test. Statistical significance was de-ned as a p value of less than 0.05.

esults

f the 47 neonates and 16 infants undergoing surgical

ig 1. Scheme of a normal aortic arch (left) and of coarctation of thescending aorta diameter (measured at the level of the right pulmonahiocephalic trunk); d3 � proximal transverse arch diameter (at the ohe origin of the left subclavian artery); d5 � descending aorta diamerachiocephalic trunk and the origin of the left carotid artery; d7 � deft subclavian artery; d8 � distance between the origin of the left surigin of the brachiocephalic trunk; d10 � diameter of the origin of trtery; and d12 � narrowest diameter of the coarctation.

epair for coarctation, there was no surgical mortality. t

wo neonates with severe aortic arch hypoplasia re-uired early redo surgery for residual coarctation (3.2%),nd subsequently fared well. There was no morbidity inhe infant group. The data are hereafter regrouped andresented for the 63 neonates and 23 infants.The demographic and echocardiographic data of the 63

eonates are summarized in Table 1. Associated cardiacefects in the group with coarctation (n � 47) were as

ollows: patent ductus arteriosus in 20 patients (42%), ven-ricular septal defect in 20 patients (42%), bicuspid aorticalve with or without aortic valve stenosis in 20 patients42%), and atrial septal defect or foramen ovale in 14atients (30%). Two patients had chromosomal abnormali-

ies, 1 with Down syndrome, and 1 with Turner syndrome.During the same period, echocardiographic measure-ents from 23 infants were obtained; 16 of these under-ent surgery for repair of coarctation, and 7 belong to the

ontrol group. The demographic and echocardiographicata of these infants are summarized in Table 2. Associ-ted cardiac defects in the group with coarctation wereicuspid aortic valve with or without aortic valve stenosis

n 12 patients (75%), ventricular septal defect in 10atients (63%), and patent ductus arteriosus in 3 patients

19%). None of the controls had associated cardiac de-ects or a PDA.

reat Vessel and Aortic Arch Dimensionshe diameters of the ascending and descending aortaere not significantly different in patients with coarcta-

ion, neither for neonates nor for infants, as comparedith controls. The dimensions of the transverse archere significantly smaller in the coarctation group, espe-

ially in neonates. The distances between the origins of

(right). The following measurements were obtained: d1 � proximalery); d2 � distal ascending aorta diameter (at the origin of the bra-of the left carotid artery); d4 � distal transverse arch diameter (atistal to the isthmic region); d6 � distance between the origin of thece between the origin of the left carotid artery and the origin of thean artery and the coarctation of the aorta; d9 � diameter of thet carotid artery; d11 � diameter of the origin of the left subclavian

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han in controls, both in neonates and infants: the meanistance from the brachiocephalic trunk to the carotidrtery (d6) in neonate patients with coarctation was 2.8m, compared with 1.5 mm in controls (p � 0.0013). In

nfants, the distance in patients with coarctation was 3.9m, compared with 2 mm in controls. The mean distance

rom the left carotid artery (LCA) to the left subclavianrtery (LSA [d7]) in the neonate group with coarctationas 7.32 mm, compared with 2.37 mm in neonate controls

p � 0.0001). In infants, the mean distance from the LCAo the LSA (d7) was 7.27 mm in those with coarctation,ompared with 2.67 mm in controls (p � 0.0001) (Fig 2).he diameters of the great vessels were larger in theoarctation group for neonates and infants; however,ignificant increases were found in d10 only. Upon sub-roup analysis of patients with associated intracardiachunts or a PDA, there was no significant difference inreat vessel or arch dimensions, as compared with pa-ients without associated defects.

To have a comparative parameter, we calculated theatios d1 to d7, d3 to d7, and d4 to d7. These indices were

able 1. Demographic Data and Variables in Neonates:oarctation and Controls

eonates

CoarctationPatientsn � 47

Controlsn � 16 p Value

emographic dataAge (days) 12 (10) 16 (12) 0.15Weight (kg) 3.0 (0.6) 3.2 (0.9) 0.37Length (cm) 50 (7) 50 (4) 0.90Body surface (m2) 0.20 (0.02) 0.20 (0.04) 0.52

urther measurementsShortening fractionof LV (%)

34 (9) 36 (7)

Gradient maximumat COA (mm Hg)

31 (18)

Flow velocitymaximum at COA(cm/s)

267 (80) 130 (28)

ortic dimensiond1 (mm) 6.8 (1.5) 7.5 (1.3) 0.0965d2 (mm) 5.6 (1.1) 7.1 (1.2) � 0.0001d3 (mm) 4.3 (1.0) 6.2 (1.3) � 0.0001d4 (mm) 3.4 (0.8) 5.9 (1.4) � 0.0001d5 (mm) 6.2 (1.4) 5.9 (1.1) 0.3227d6 (mm) 2.8 (1.5) 1.5 (0.4) 0.0013d7 (mm) 7.3 (3.0) 2.4 (0.8) � 0.0001d8 (mm) 3.6 (1.6)d9 (mm) 4.1 (0.9) 3.8 (1.1) 0.2494d10 (mm) 2.8 (0.6) 2.4 (0.5) 0.0174d11 (mm) 2.2 (1.2) 2.2 (0.4) 0.9052d12 (mm) 2.1 (0.9) 5.0 (1.1) � 0.0001

ean values are given, followed by standard deviation in parentheses.

OA � coarctation; LV � left ventricle.

roportionally significantly smaller in coarctation pa- M

ients, when compared with either control neonates orontrol infants (Table 3).

We used these ratios, d1/d7, d3/d7, and d4/d7, to findredictive accuracy of two-dimensional echocardiogra-hy in the diagnosis of coarctation for neonates, as well

able 2. Demographic Data and Variables in Infants:oarctation and Controls

nfants



emographic dataAge (days) 75 (34) 55 (12) 0.1318Weight (kg) 4.43 (1.38) 4.45 (0.64) 0.9642Length (cm) 56 (6) 55 (3) 0.6168Body surface (m2) 0.23 (0.07) 0.24 (0.02) 0.6967

urther measurementsShortening fractionof LV (%)

34 (6) 38 (5)

Gradient maximumat COA (mm Hg)

48 (26)

Flow velocitymaximum at COA(cm/s)

319 (116) 121 (12)

ortic dimensiond1 (mm) 7.8 (1.1) 8.2 (2.2) 0.5576d2 (mm) 6.8 (1.1) 7.4 (1.8) 0.2868d3 (mm) 5.5 (1.4) 6.6 (0.8) 0.0639d4 (mm) 4.5 (0.9) 6.3 (0.9) 0.0003d5 (mm) 7.3 (1.9) 6.5 (0.8) 0.3054d6 (mm) 3.9 (1.8) 2.0 (0.6) 0.0133d7 (mm) 7.3 (2.4) 2.7 (0.8) � 0.0001d8 (mm) 5.6 (2.5)d9 (mm) 4.7 (1.2) 4.4 (0.5) 0.4945d10 (mm) 3.3 (0.8) 2.4 (0.2) 0.0090d11 (mm) 2.5 (0.5) 2.4 (0.2) 0.6439d12 (mm) 2.3 (0.8) 5.6 (0.9) � 0.0001


OA � coarctation; LV � left ventricle.

able 3. Ratios of Aortic Arch Dimensions to Great Vesselistances: Coarctation and Controls



eonates 47 16Index d1/d7 1.13 (0.83) 3.56 (1.55) � 0.0001Index d3/d7 0.98 (0.87) 3.38 (1.43) � 0.0001Index d4/d7 0.76 (0.86) 2.95 (1.24) � 0.0001

nfants 16 7Index d1/d7 1.17 (0.43) 3.17 (0.83) � 0.0001Index d3/d7 1.04 (0.43) 2.94 (0.88) � 0.0001Index d4/d7 0.81 (0.29) 2.66 (0.78) � 0.0001


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s for infants. To facilitate the recognition of coarctation,e defined the index d4/d7 as the carotid-subclavian

rtery index. This ratio was significantly smaller in theoarctation group in neonates and infants, comparedith their respective controls. If the cut-off point for the

arotid-subclavian artery index is fixed at 1.5, there is aensitivity of 97.7% and a specificity of 92.3% for aeonate to have coarctation, with a positive predictivealue of 97.7%, and a negative predictive value of 92.3%.ith a similar cut-off for the carotid-subclavian artery

ndex in infants, our data show a sensitivity of 94.7% andspecificity of 100%. The positive predictive value is

00%, and the negative predictive value 90.9% (Table 4).egarding neonates only, an index d4/d7 below 2 gives aery specific and sensitive result, but when infants arencluded, a d4/d7 index below 1.5 gives the most accurateesults taking both age groups into consideration.

omment

ince the early 1980s, the method of diagnosis for coarc-ation has changed from using clinical data, with orithout preoperative catheter confirmation, to relying

lmost exclusively on echocardiography [4]. Echocardi-graphy can allow noninvasive assessment of the aortic

able 4. Sensitivity, Specificity, Positive and Negative Predict

Sensitivity % Specificity %

eonatesIndex d1/d7 � 1.0 59.09 100.0Index d1/d7 � 1.5 88.63 100.0Index d1/d7 � 2.0 97.72 92.30Index d1/d7 � 2.5 100.0 69.23Index d3/d7 � 1.0 84.09 100.0Index d3/d7 � 1.5 50.00 92.30Index d3/d7 � 2.0 97.72 84.61Index d3/d7 � 2.5 97.72 61.53Index d4/d7 � 1.0 97.72 100.0Index d4/d7 � 1.5 97.72 92.30Index d4/d7 � 2.0 97.72 97.72Index d4/d7 � 2.5 100.0 53.84

nfantsIndex d1/d7 � 1.0 52.63 100.0Index d1/d7 � 1.5 89.47 100.0Index d1/d7 � 2.0 84.21 90.00Index d1/d7 � 2.5 94.73 90.00Index d3/d7 � 1.0 63.15 100.0Index d3/d7 � 1.5 84.21 100.0Index d3/d7 � 2.0 89.47 90.00Index d3/d7 � 2.5 100.0 80.00Index d4/d7 � 1.0 89.47 100.0Index d4/d7 � 1.5 94.72 100.0Index d4/d7 � 2.0 100.0 80.00Index d4/d7 � 2.5 100.0 50.00

rch, identification of the narrowing at the aortic isthmus, s

ow measurement, and determination of the instantradient over the coarctation [5–7]. However, a signifi-ant number of patients with coarctation are not properlyiagnosed during the neonatal period [5, 6]. That may beue to patent ductus arteriosus without flow accelerationt the isthmus of the aorta, to poor image quality, or to aocation further downstream in the descending aorta.urthermore, clinical judgment may be impaired in situ-tions with diminished contractility of the left ventriclend poor cardiac output, or other reasons such as infec-ion or breathing artifacts [8]. Another potential problems, that even with the use of Doppler flow assessment inhe descending aorta, the anatomic severity of coarcta-ion cannot always be assessed [2, 9–11]. Other authorsave tried to find a reliable echocardiographic parameter

o predict aortic coarctation in the newborn using mor-hologic measurements, including aortic arch diameterst different sites, calculations and comparison of diame-er ratios, or measurements of distances between thereat vessels of the aortic arch [12, 13]. That has to dateot given satisfying results to clearly identify a coarcta-

ion in difficult situations, and too many diagnoses haveone unrecognized.The study by Morrow and coworkers [12] enforces our

esults, reporting significant alterations in the dimen-

alues According to Cut-Off

ositive Predictive Value % Negative Predictive Value %

100.0 41.93100.0 72.2297.72 92.3091.66 100.0

100.0 65.0095.65 35.2995.55 91.6689.58 88.88

100.0 92.8597.72 92.3097.72 90.0088.00 100.0

100.0 52.63100.0 83.3394.11 75.0094.73 90.00

100.0 58.82100.0 76.9294.44 81.8190.47 100.0

100.0 83.33100.0 90.9090.47 100.079.16 100.0

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hy. They found no differences between patients andontrols concerning the descending aorta and left sub-lavian artery diameters, but demonstrated that theength of the transverse arch between the LCA and LSAas significantly increased in patients with coarctation

12]. Our results support his findings and add a usefulnd reproducible index, with the use of a noninvasiveiagnostic tool. Nihoyannopoulos and associates [14]ssessed the predictive accuracy of two-dimensionalchocardiography in defining aortic arch obstruction.sing viewing of the aortic arch only, the overall sensi-

ivity of the method was only 88%. They found two-imensional echocardiography to be more specific thanensitive for the prediction of aortic arch obstruction,oting that with a low origin of the LSA, particularttention should be paid to the visualization of thesthmus [14].

Contrary to our findings, Aluquin and coworkers [13]ound the distal ascending root diameter and descendingorta to be significantly larger in patients with coarcta-ion. Our data show that the proximal and distal diame-ers of the ascending aorta are smaller in patients withoarctation, and that the diameter of the descendingorta is larger in coarctation patients, either due toncreased resistance before the stenosis or to post-tenotic dilatation from turbulent flow. Nevertheless, ourata concur with theirs regarding the transverse arch,hich was notably longer in the coarctation group, as

ompared with controls.Excluding older invasive angiographic studies, newer

oninvasive modalities to accurately assess and diagnoseoarctation in the younger population exist, and are botheliable and reproducible [2, 15]. These include axial,

ultiplanar computed tomography scan and magneticesonance imaging, which are more expensive, cumber-ome, and could require anesthesia and intubation in theewborn and infant population.Because of the significant decrease in diameter of the

istal transverse aortic arch just before the LSA (d4) in

ig 2. Echocardographic images of two different aortic arches with aery and significant narrowing of the transverse arch. Calculation of tion. (AAO � ascending aorta; LCA � left carotid artery; LSA � lehiocephalic trunk.)

atients with coarctation, and the significant prolonga- i

ion of the distance from the origin of the LCA to therigin of the LSA (d7), we found it useful to use these twoariables as part of the carotid-subclavian artery index.herefore, we propose the carotid-subclavian artery in-ex, where the diameter of the transverse arch at therigin of the LSA (d4), is put in ratio to the distance fromhe origin of the LCA to the origin of the LSA (d7), as acreening tool for coarctation. In neonates and youngnfants with coarctation, the carotid-subclavian arteryndex yields a sensitivity of 97.7% for neonates and 94.7%or infants, using a cut-off point below 1.5. The longer theistance (d7) and the smaller the diameter of the aorticrch at the origin of the LSA (d4), the smaller thearotid-subclavian artery index, and the higher the pre-ictability of coarctation. These findings remain validegardless of the presence or absence of an associatedntracardiac shunt or PDA.

tudy Limitationshe results of our study are to be taken into the perspec-

ive of a retrospective design and its limitations. Tochieve validity, the carotid-subclavian artery indexhould be prospectively assessed in patients with onlyild hypoplasia of the aortic arch, with or without

oarctation. Also, the numbers are relatively small, re-ucing the power of the finding. To establish the useful-ess of the carotid-subclavian artery index as a screening

ool for coarctation, a prospective study with a greateropulation of newborns and infants is needed, both withnd without coarctation.In conclusion, the carotid-subclavian artery index issimple screening parameter, readily obtained, and

tandardized from two-dimensional echocardiographyisualization of the aortic arch. It shows high sensitiv-ty and specificity for coarctation in our population ofewborns and infants with a cut-off point below 1.5,

ndependently of concomitant intracardiac or extracar-iac shunts. In difficult subsets of patients with a largeDA and severe concurrent illness with hemodynamic

distance between the left carotid artery and the left subclavian ar-rotid-subclavian index is highly specific for the presence of coarcta-clavian artery; TAA � transverse aortic arch; Tr. brach. � bra-

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ndex may lead to earlier diagnosis and subsequenturgical correction, before ductal closure and dimin-shed cardiac output with reduced systemic perfusionccurs.

eferences

1. Jenkins NP, Ward C. Coarctation of the aorta: natural historyand outcome after surgical treatment. Q J Med 1999;92:365–71.

2. Lim DS, Ralston MA. Echocardiographic indices of Dopplerflow patterns compared with MRI or angiographic measure-ments to detect significant coarctation of the aorta. Echocar-diography 2002;19:55–60.

3. Rothman A. Coarctation of the aorta, an update. Curr ProblPediatr 1998;28:37–60.

4. Grech V. Diagnostic and surgical trends, and epidemiologyof coarctation of the aorta in a population-based study. IntJ Cardiol 1999;68:197–202.

5. Strattford MA, Griffiths SP, Gersony WM. Coarctation of theaorta, a study in delayed detection. Pediatrics 1982;69:159–63.

6. Thoele DG, Master AJ, Paul MH. Recognition of the coarc-tation of the aorta: a continuing challenge for the primarycare physician. Am J Dis Child 1987;141:1201–4.

7. Robinson PJ, Wyse RKH, Deanfield JE, et al. Continues wavedoppler velocimetry as an diagnosis of critical left heart
obstruction in neonates. Br Heart J 1984;52:552–6.
ricular dysfunction, pulmonary edema, and pulmonary

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8. Rinelli G, Marino B, Santoro G, et al. Pitfalls in echocardio-graphic-based repair of aortic coarctation. Am J Cardiol1997;80:1382–3.

9. Stern HC, Locher D, Wallnofer K, et al. Noninvasive assess-ment of coarctation of the aorta: comparative measurementsby two-dimensional echocardiography, magnetic resonance,and angiography. Pediatr Cardiol 1991;12:1–5.

0. Muhler EG, Neuerburg JM, Ruben A, et al. Evaluation ofaortic coarctation after surgical repair: role of magneticresonance imaging and Doppler ultrasound. Br Heart J1993;70:285–90.

1. Seifert BL, DesRochers K, Ta M, et al. Accuracy of Dopplermethods for estimating peak-to-peak instantaneous gradi-ents across coarctation of the aorta: an in vitro study. J AmSoc Echocardiogr 1999;12:744–53.

2. Morrow WH, Huhta JC, Murphy DJ, et al. Quantitativemorphology of the aortic arch in neonatal coarctation. J AmColl Cardiol 1986;8:616–20.

3. Aluquin VPR, Shutte D, Nihill MR, et al. Normal aortic archgrowth and comparison with isolated coarctation of theaorta. Am J Cardiol 2003;91:502–5.

4. Nihoyannopoulos P, Karas S, Sapsford RN, et al. Accuracy oftwo-dimensional echocardiography in the diagnosis of aorticarch obstruction. J Am Coll Cardiol 1987;10:1072–7.

5. Lee EY, Siegel MJ, Hildebolt CF, Gutierrez FR, Bhalla S,Fallah JH. MDCT evaluation of thoracic aortic anomalies inpediatric patients and young adults: comparison of axial,multiplanar, and 3D images. AJR Am J Roentgenol 2004;182:
777–84.
NVITED COMMENTARY

his article [1] describes a novel and potentially impor-ant new echocardiographic index for the diagnosis ofoarctation of the aorta in neonates and infants. Theuthors have proposed the index because of the frequentifficulty in confidently establishing the diagnosis ofoarctation, particularly in the smallest and youngestatients. Three anatomic features create this difficulty:

he coexistence of a large ductus arteriosus, the presencef hypoplasia of the aortic arch, and the lack of “co-lanarity” of the aortic arch, ductus, and descendingorta. Previous investigators [2, 3] have suggested thatpecific dimensional thresholds for the aortic isthmus of.5 mm [2] or 3 mm [3] allow the diagnosis of coarctation.owever the specificity and sensitivity of such a measure

re far from perfect, and the application of either stan-ard to very small infants will certainly lead to overdiag-osis of coarctation. The addition of Doppler assessmentsas variously been believed to be of limited value [4] or ofignificant help if combined with size criteria [3]. Inresent day practice, despite the several proposed diag-ostic tests for coarctation, it is still quite common tollow the ductus to close under observation to allow aoarctation to “declare itself” if present. Such a declara-ion will take the form of the acute development of aorticbstruction with potential consequences of distal hypo-erfusion and metabolic acidosis, renal injury, left ven-

ypertension. In effect, the patient is forced to prove heas a disease by becoming ill.The validation of the carotid-subclavian artery indexould allow the relegation of observed ductal closure to

he slagheap of history where it rightly belongs. Theeasurements required to calculate the index are readily

btained from standard suprasternal views of the distalrch. Accurately aligned Doppler windows are not re-uired, and there is no necessity for co-planarity of theortic arch, ductus, and descending aorta. There is alsoo requirement for detecting a “coarctation shelf” asescribed by other authors [5]. Another advantage ofsing the index is the fact that it is a ratio, and thus itould not be confounded by extremely small patient

ize.However several caveats are worth mentioning in

egard to the new measure, which has not yet been testedn other centers. Despite the excellent sensitivity andpecificity of this index, it is important that it not bepplied in isolation. There is the occasional neonate, withransverse aortic arch hypoplasia and a large patentuctus arteriosus, who does not develop coarctation of

he aorta, and an aggressive strategy of surgical interven-ion in these patients based on an as-yet unconfirmedchocardiographic index that could result in unnecessaryrocedures and exposure to potential late complications,
uch as recurrent arch obstruction and distortion. Beyond
0003-4975/05/$30.00doi:10.1016/j.athoracsur.2005.07.011

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