BrHeart3r 1982; 48: 180-3

Unusual vascular ring in infant with pulmonary atresiaand ventricular septal defectROXANE McKAY, JAROSLAV STARK, MARC DE LEVAL

From the Thoracic Unit, The Hospitalfor Sick Children, Great Ormnd Street, London

SUMMARY A 3-day-old infant investigated for cyanotic heart disease was found to have partialDiGeorge syndrome and pulmonary atresia with ventricular septal defect. The only source ofpulmonary blood flow was a right-sided persistent ductus arteriosus which originated from an

aberrant right subclavian artery. Such a vascular ring has not been described previously. Surgicaltreatment included a left-sided prosthetic shunt in infancy followed by resection of the ligamentumarteriosum and right subclavian artery during the second year of life.

A left aortic arch with aberrant right subclavian arteryand right ductus arteriosus is a rare form of completevascular ring. Only cases in which there was also a

retro-oesophageal and right descending thoracicaorta, with the ductus arising from the dorsal aorticroot, have been recorded in the English publica-tions. I 2 The patient presented here is unique in thatthe descending aorta was on the left and the persistentductus arteriosus originated from the aberrant subcla-vian artery itself. The association of this anomaly withpulmonary atresia, ventricular septal defect, and par-

tial DiGeorge syndrome created special problems insurgical management.

Case report

A male infant, 3*2 kg, was transferred at 3 days of agefor investigation of increasing cyanosis. Pregnancyand delivery had been uncomplicated, and he firstbecame "dusky" with tachypnoea seven hours afterbirth. On physical examination, the baby had oddfacies, with pointed ears, widely spaced eyes, anddown-turned mouth. Moderate central cyanosis, a

soft systolic murmur along the left sternal edge, and a

single second heart sound were noted. No murmurwas heard along the right sternal edge. Relevantlaboratory investigations included an arterial Po2 of32 mmHg in room air, a serum calcium of 158 nmol/1, and the absence of thymic shadow on chest x-rayfilm.

Cardiac catheterisation showed pulmonary atresiawith a ventricular septal defect, left aortic arch, andan aberrant right subclavian artery. The sole bloodsupply to the lungs came from a right-sided persistent

ductus arteriosus arising from the aberrant subclavianartery (Fig. la). With patency of the ductus main-tained by an infusion of prostaglandin El at 0.1 ,ug/kgper min, a modified Blalock-Taussig shunt3 was con-structed the following day, using a 6 mm Gore-Texconduit between the left subclavian and left pulmo-nary arteries. Postoperative recovery washaemodynamically satisfactory but complicated bymultiple episodes of twitching, necrotising entero-colitis, and monilia infection. Investigation of thepatient's hypocalcaemia subsequently disclosed lowlevels of parathormone on three occasions (70-140ng/l; normal= 130-380 ng/l). Thymic dependent lym-phocytes, however, were present and appeared tohave normal function. A diagnosis of partial DiGeorgesyndrome4 was made, and the child was eventuallydismissed from hospital at 3 months of age. Mild con-gestive heart failure was controlled by digoxin, andserum calcium levels maintained by dihydrotachys-terol. The latter was discontinued after one year with-out recurrence of hypocalcaemia.A poor feeder throughout infancy, the baby suf-

fered progressive dysphagia and was unable to takesolid food at 14 months of age. Reinvestigation of hiscardiovascular status at that time showed that the duc-tus arteriosus had closed and the shunt was patent(Fig. lb). Systemic arterial saturation was 74%. Onbarium swallow, the oesophagus was compressed lat-erally and posteriorly, consistent with a vascular ringformed by the left aortic arch, aberrant right subcla-vian artery, and the right ligamentum arteriosum(Fig. 2). The patient subsequently underwent divi-sion of the ligamentum arteriosum and aberrant rightsubclavian artery through a right thoracotomy with

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f.........................'/t>8.W..e}..Fig. 1 Aortogram at 3 days ofage (a) and selective injection into the origin ofthe left subelavian artery 14 monthslater (b). The catheter shows the position of the ascending aorta in thefirst investigation, with contrast opacifyingthe distal arch, the aberrant right subclavian artery, and the descending aorta. Confluent pulmonary arteries aresupplied by a right-sided persistent ductus arteriosus which is stenosed at its mid-portion (arrow).

Fig. 2. Barium swallow in oblique (a) and lateral (b) projections showing compression of the oesophagus by thevascular ring.

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complete relief of his feeding problems. At 3Y2 years

of age, he now awaits correction of his pulmonaryatresia and ventricular septal defect.

Discussion

Anomalies of the aortic arch are encountered notinfrequently in palliative surgery for cyanotic congen-

ital heart disease. Among 841 patients explored with a

view to systemic-pulmonary anastamosis, Bahnsonand Blalock observed 40 vascular rings, including 36instances of retro-oesophageal subclavian artery.5 Theaberrant subclavian artery on either side can be usedto perform a satisfactory Blalock-Taussig anas-tomosis, and the resulting complete vascular ring hasnot caused symptoms of tracheal or oesophageal com-pression.67 When the anomaly is a double aortic arch,using the smaller arch for the shunt achieves simul-taneous palliation of cyanosis and division of the vas-

cular ring.89 In our patient, however, the pulmonaryblood supply depended upon the integrity of the vas-cular ring, and the presence of a right-sided ductusprecluded a Blalock-Taussig shunt on the side oppo-site to the aortic arch. With knowledge of the archanatomy from preoperative angiography, it was poss-ible to plan the initial prosthetic shunt on the side ofthe aortic arch, and this permitted subsequent inter-ruption of the vascular ring when it became symp-tomatic.

Embryologically, this anomaly can be explained bypersistence of the right sixth arch as the ductusarteriosus and the right eighth dorsal aortic root as theaberrant subclavian artery, with regression of the leftsixth arch and the right fourth arch.'0 Factors thatdetermine the side of the descending aorta areunknown but, it is of interest in this case, where theaorta remained on the left, that the retro-oesophagealportion of the subclavian artery was considerablylarger than normal (Fig. la). Since the patient alsohad pulmonary atresia, it seems unlikely that the largesegment resulted from preferential blood flow duringdevelopment. Developmental anomalies of the thirdand fourth pharyngeal pouches are often associatedwith those of aortic arch derivatives, but this isthought to represent a response to a common

teratogenic factor rather than a causal relation. I

The likelihood of compression symptoms occurringfrom this vascular anomaly is difficult to estimate.Among 14 patients reported with left aortic arch,right descending aorta, and right ligamentumarteriosum half suffered respiratory distress or feed-ing problems in infancy.'2 13 Associated cardiacanomalies were common, but none required palliativesurgery, and the vascular ring was treated on its ownmerits.2 14 In each case, the ligamentum or ductusarteriosus was divided through a right thoracotomy

McKay, Stark, de Leval

rather than through the left-sided exposure used formost vascular rings.

Congenital heart disease as a presentation of theDiGeorge syndrome is well recognised and should besuspected in any infant with craniofacial stigmata andanomalies of the aortic arch."1 15 The twitchingepisodes caused by hypocalcaemia in this patient wereof little consequence; but sudden death during cardiaccatheterisation or after correction of acidosis with alk-ali has been attributed to arrhythmias secondary toexacerbated hypocalcaemia.4 In the partial DiGeorgesyndrome, patients may have considerable cell-mediated immunity and, despite profound hypocal-caemia in infancy, achieve remission permanentlyduring early childhood. Since survival of suchpatients has now been seen into the third decade,'6aggressive treatment of the cardiovascular anomaliesappears to be justified.

References1 Edwards JE. Retro-esophageal segment of the left aortic

arch, right ligamentum arteriosum and right descendingaorta causing a congenital vascular ring about the tracheaand esophagus. Proceedings of the Staff Meetings of theMayo Clinic 1948; 23: 108-16.

2 Park SC, Siewers RD, Neches WH, Lenox CC, Zuber-buhler JR. Left aortic arch with right descending aortaand right ligamentum arteriosum. A rare form of vascu-lar ring. Jf Thorac Cardiovasc Surg 1976; 71: 779-84.

3 deLeval MR, McKay R, Jones M, Stark J, MacartneyFJ. Modified Blalock-Taussig shunt: use of the subcla-vian artery orifice as flow regulator in prostheticsystemic-pulmonary artery shunts. J Thorac CardiovascSurg 1981; 81: 112-9.

4 Conley ME, Beckwith JB, Mancer JFK, Tenckhoff L.The spectrum of DiGeorge syndrome. J Pediatr 1979;94: 883-90.

5 Bahnson HT, Blalock A. Aortic vascular rings encoun-tered in the surgical treatment of congenital pulmonicstenosis. Ann Surg 1950; 131: 356-62.

6 Blalock A. Surgical procedures employed and anatomicalvariations encountered in the treatment of congenitalpulmonic stenosis. Surg Gynecol Obstet 1948; 87: 385-409.

7 Arciniegas E, Hakimi M, Hertzler JH, Farooki ZQ,Green EW. Surgical management of congenital vascularrings. J Thorac Cardiovasc Surg 1979; 77: 721-7.

8 Binet JP, Carpentier J, Pottemain M, Langlois J. Doubleaortic arch associated with tetralogy of Fallot in infants.Report of two cases. J Thorac Cardiovasc Surg 1966; 51:116-8.

9 Waterston DJ, Pohl V, Kallfelz HC, Kreutzberg B.Shuntoperationen bei Fallotscher Tetralogie mit doppel-tem Aortenbogen. Dtsch Med Wochenschr 1971; 96:1191-5.

10 Stewart JR, Kincaid OW, Edwards JE. Left aortic arch:aberrant right subclavian artery and right ductusarteriosus (subgroup 11B2). in: An atlas of vascular ringsand related malformations of the aortic arch system. Spring-field, Illinois: Charles C Thomas, 1964: 70.

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11 Freedom RM, Rosen FS, Nadas AS. Congenital car-diovascular disease and anomalies of the third and fourthpharyngeal pouch. Circulation 1972; 46: 165-72.

12 Ergin MA, Jayaram N, LaCorte M. Left aortic arch andright descending aorta: diagnostic and therapeutic impli-cations of a rare type of vascular ring. Ann Thorac Surg1981; 31: 82-5.

13 Berman W Jr, Yabek SM, Dillon T, Neal JF, Aki B,Burstein J. Vascular ring due to left aortic arch and rightdescending aorta. Circulation 1981; 63: 458-60.

14 Baumstark AE, Gordon DH, Hailer JO, Martin EC. Theleft aortic arch and right descending aorta. Br J Radiol1977; 50: 788-92.

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15 Moerman P, Goddeeris P, Lauwerijns J, Van DerHauwaert LG. Cardiovascular malformations inDiGeorge syndrome (congenital absence or hypoplasia ofthe thymus). Br Heart J 1980; 44: 452-9.

16 Miller MJ, Frame B. Partial DiGeorge syndrome orbranchial dysembryogenesis? (letter). Am J Dis Child1976; 130: 1376-7.

Requests for reprints to Dr Roxane McKay, MilberCottage, Manor Road, Seer Green, Beaconsfield,Buckinghamshire HP9 2QU.

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