Heart 1997;77:173-175

CASE STUDY

Pulmonary atresia, "intact ventricular septum",and aortopulmonary collateral arteries

Reinout J Mildner, Laszlo Kiraly, Narayanswami Sreeram

AbstractIn muscular pulmonary atresia, majoraortopulmonary collateral arteries arecharacteristic of pulmonary atresia withventricular septal defect and are rarelyseen in pulmonary atresia with intactventricular septum. Two unusual cases ofmuscular pulmonary atresia arereported, one with an intact septum andone with a perimembranous ventricularseptal defect, closed in utero by aneurys-mal tricuspid tissue. In both cases thepulmonary blood supply came entirelyfrom aortopulmonary collaterals. In case1 a collateral artery connected the leftsubclavian artery and hypoplastic pul-monary arteries, and several aortopul-monary collaterals arose from thedescending aorta, without overlapbetween these two circulations. In case 2the pulmonary trunk and arterial ductwere absent and the pulmonary bloodsupply came entirely from collateralarteries. The right ventricle was of nor-mal size and tripartite with a closed peri-membranous ventricular septal defect,discovered only at postmortem examina-tion. These observations suggest rightventricular outflow tract obstructionearly in fetal development, with involu-tion of the pulmonary trunk and sixtharch derivatives, and persistence ofprim-itive aortopulmonary connections. Themorphology in case 1 is at odds with thetheoretical division of pulmonary atresiawith intact septum and pulmonary atresiawith ventricular septal defect into twoseparate pathological entities that occurat different stages in fetal development.

(Heart 1997;77:173-175)

sent in PA/IVS. We describe two unusualcases: one of PA/IVS and the other ofPA/VSDin which the pulmonary blood supply camepredominantly from MAPCAs.

Case 1A nine month old boy presented with cyanosisfrom the age of one week. Until assessment, hehad lived in India. At physical examination agrade JI/VI systolic murmur was heard at theleft sternal edge. The diagnosis of PA/IVS wasmade by echocardiography. However, thecommunication between the systemic and pul-monary circulations was not identified.Cardiac catheterisation confirmed PA withIVS and suprasystemic right ventricular pres-sure. The tricuspid valve was hypoplastic(8 mm diameter) with a small right ventricle,consisting of an inlet portion only. A diminu-tive pulmonary trunk was present and a rightventriculo-coronary artery connection wasdemonstrated. An aortopulmonary collateralartery arose from the left subclavian artery tosupply confluent but hypoplastic pulmonaryarteries. Four further MAPCAs arose from thedescending aorta, supplying both lungs (figlA-C). The aortic arch was right sided andthe atrial appendages were juxtaposed. Bymeans of bilateral thoracotomies and a mediansternotomy, the right and left sided collateralswere anastomosed to the respective pulmonaryarteries, and a 5 mm central aortopulmonaryshunt was created. One hour after surgery hedeveloped evidence of myocardial ischaemiaand systemic acidosis. Despite appropriateresuscitation, he died. Postmortem examina-tion confirmed the anatomical diagnosis ofmuscular pulmonary atresia with intact ven-tricular septum.

Heart Unit,BirminghamChildren's HospitalR J MildnerL KiralyN SreeramCorrespondence to:Dr RJ Mildner, Heart linkECMO Unit, GlenfieldHospital, Groby Road,Leicester LE3 9QP.Accepted for publication27 September 1996

Keywords: pulmonary atresia; intact septum; collateralarteries

Pulmonary atresia with intact ventricular sep-tum (PA/IVS) is a rare cardiac malformation.'The blood supply to the lungs in this disorder isusually dependent on the arterial duct. Incontrast to pulmonary atresia with ventricularseptal defect (PA/VSD) major aortopulmonarycollateral arteries (MAPCAs) are rarely pre-

Case 2A one day old term, female neonate presentedwith cyanosis. A continuous murmur, gradeII/VI, was heard at the left sternal edge. Onechocardiography, the right ventricle was wellformed (tricuspid valve 11 mm diameter), butthe pulmonary trunk or arteries could not beidentified and the ventricular septum appearedintact. An arterial duct was not seen. At emer-gency cardiac catheterisation the provisionaldiagnosis of PA/IVS was made. The tricuspid

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Mildner, Kiraly, Sreeram

Figure 1 (A) Leftsubclavian arteriogram(patient 1) showingcollateral artery supplyingconfluent but hypoplasticnative pulmonary arteries.LP, left pulmonary artery;RPA, right pulmonaryartery. (B) Descendingaortogram (patient 1)showing collateral arteries(CO) supplying bothlungs. (C) Compositediagram showing theparenchymal distributionof native pulmonaryarteries and collateralarteries in patient 1. Aorta(unshaded), pulmonarytrunk and arteries (lightshade); collateral arteries(dark shade). Desc Ao,descending aorta; MPA,main pulmonary artery.

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valve was only mildly regurgitant; the rightventricle was well developed and tripartite (fig2A) with suprasystemic right ventricular pres-sure. The pulmonary trunk was absent, thenative pulmonary arteries were severelyhypoplastic but confluent (fig 2B), and thearterial duct was absent. Several collateralarteries from the brachiocephalic trunk sup-plied the upper part of the right lung (fig 2B).The lower lobe of the right lung was suppliedfrom a collateral artery arising from the leftsubclavian artery. Further direct MAPCAsarose from the descending aorta supplying theleft lung (fig 2B). Coronary artery distributionwas normal. In view of the severe hypoplasiaof the native pulmonary arteries and the smallsize of individual collateral arteries, it was

decided not to undertake surgical palliation.

Figure 2 (A) Right ventriculogram (patient 2) showingtripartite right ventricle (rv) with mild tricuspidregurgitation. ot, outflow tract. (B) Aortogram in patient,showing collateral arteries (CO) supplying left lung andlower lobe of right lung. Arrow indicates confluent,hypoplastic pulmonary arteries. (C) Brachiocephalicarteriogram in patient 2, showing two collateral arteries(arrows) supplying the upper segments of the right lung.

The patient died suddenly at home aged onemonth. At postmortem examination muscularpulmonary atresia was confirmed, with absentpulmonary trunk. However, there was a smallperimembranous VSD which was closed bytricuspid valve tissue and had not been notedon angiography. This led to the revised diag-nosis of PANVSD.

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Pulmonary atresia, "intact ventricular septum". and aortopulmonary collateral arteries

DiscussionPulmonary blood supply via MAPCAs is com-monly associated with PAIVSD and occasion-ally with tetralogy of Fallot. Only very rarelyhas it been described in other types of pul-monary atresia, including PA/IVS.1De Ruiter et al 2 suggested that in early

embryonic development transient systemic topulmonary collateral arteries may arise duringtwo extended periods. During maldevelop-ment of the pulmonary outflow tract thesetransient connections may persist as systemic-pulmonary collateral arteries. The timing andthe extent of pulmonary outflow tract malde-velopment may determine the origin and dis-tribution of the collateral arteries. In additionthese workers postulate that when pulmonaryobstruction occurs at a much later stage offetal development or postnatally, bronchialarteries may develop into systemic-pulmonarycollateral arteries. Thiene et al3 found that inPA/VSD, early right ventricular outflow tractobstruction leads to involution of the pul-monary trunk and sixth aortic arch derivativeswith persistence of primitive aortopulmonaryconnections.Our two cases show several features usually

associated with PA/VSD. Both patients hadmuscular pulmonary atresia with an absent ordiminutive pulmonary trunk that is more com-monly seen in PA/VSD.4 In addition a normalarterial duct was absent in both, with the pul-monary blood supply coming entirely fromMAPCAs. In case 1 the anatomical findingscan be explained if it is assumed that a VSDwhich was present during early fetal life hadsubsequently closed. But without evidence forsuch a feature, the combination of PA/IVSwith pulmonary blood supply by MAPCAs isat odds with the division of pulmonary atresiawith intact septum and pulmonary atresia with

VSD into two separate pathological entities.'In case 2 the presence of a VSD closed byaneurysmal tricuspid tissue explains the find-ing of a well developed, tripartite right ventri-cle. This observation is supported by Orie eta16 who found that most isolated VSDs diag-nosed antenatally close in utero. Therefore incases of apparent PA/IVS with MAPCAs thepossibility of in utero closure of a VSD shouldbe considered.

Kutsche and Van Mierop and Santos et a1 5 7reported that in PA/IVS the arterial duct isusually well developed and has a specific mor-phology suggesting anterograde flow until latefetal gestation. Case 1 was unusual in thisrespect because there was no characteristicarterial duct. However, we have no data on thehistology of the collateral arteries arising fromthe subclavian arteries in either case to estab-lish whether these are in fact true collaterals orarterial ducts.

1 Freedom RM, Burrows PE, Smallhom JF. Pulmonary atre-sia and intact ventricular septum. In: Freedom RM,Benson LN, Smallhom JF, eds. Neonatal heart disease.London: Springer-Verlag, 1992:285-307.

2 De Ruiter MC, Gittenberger-de Groot AC, Poelmann RE,Van leperen L, Mentink MMT. Development of thepharyngeal arch system related to the pulmonary andbronchial vessels in the avian embryo. With a concept onsystemic-pulmonary collateral artery formation.Circulation 1994;87:1306-19.

3 Thiene G, Frescura C, Bortolotti U, Del Maschio A,Valente M. The systemic pulmonary circulation in pul-monary atresia with ventricular septal defect: concept offourth and sixth aortic arches. Am Heart .7 1981;101:339-44.

4 Elzenga NJ, Gittenberger-de Groot AC. The ductus arte-riosus and stenosis of the pulmonary arteries in pul-monary atresia. IntJ Cardiol 1986;11: 195-208.

5 Kutsche LM, Van Mierop LHS. Pulmonary atresia withand without ventricular septal defect: a different etiologyand pathogenesis for the atresia in the 2 types? Am 7Cardiol 1983;51:932-5.

6 Orie J, Flotta D, Sherman FS. To be or not to be a VSD.Am 7 Cardiol 1994;74: 1284-5.

7 Santos MP, Moll JN, Drumond C, Arujo WB, Romao N,Reis NB. Development of the ductus arteriosus in rightventricular outflow tract obstruction. Circulation 1980;62:818-22.

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