Reconstruction of hypoplastic aortic arch and coarctation in a 720-gram premature infant

Reconstruction

of Hypoplastic Aortic Arch and Coarctation 720-Gram Premature Infant

in a

By Frank L. Hanley, Bryan J. Drucker, Kevin Turley, and Norman H. Silverman San Francisco, California l The case of a 720-g infant born at 29 weeks of gestation who underwent successful surgical correction of a hypoplastic aortic arch and aortic coarctation is presented. The infant was initially brought to surgery with an echocardiographic diagnosis of patent ductus arteriosus with left to right shunt unresponsive to indomethacin therapy. The correct diagnosis of hypoplastic aortic arch and severe coarctation with ductal dependent blood flow to the lower body was made intraoperatively. This case illustrates the danger of limited diagnostic testing in premature infants assumed to have isolated patent ductus arteriosus, and also that these small infants can undergo successful surgical repair of complex aortic arch lesions. Copyright o 1993 by W. 8. Saunders Company INDEX WORDS: Aortic coarctation;

hypoplastic aortic arch.

P

ATENT DUCTUS arteriosus (PDA) is a common finding among premature infants and is strongly correlated with low birth weight.’ The incidence of ductal patency is roughly 9% for neonates weighing more than 1,500 g, 20% for neonates weighing between 1,000 and 1,500 g, and 40% for neonates weighing less than 1,000 g.2 The diagnosis is often made on clinical grounds and confirmed by twodimensional echocardiography and Doppler flow studies. These studies are often limited in scope because of both clinical instability and diminutive size of the patient, as well as a clinical focus on the ductus. These factors increase the possibility that associated lesions, which occur in 10% to 15% of neonates with PDA,3 will be overlooked. Surgical intervention is common in neonates with PDA and it remains the standard form of therapy if indomethacin is either unsuccessful or contraindicated. Intraoperative recognition of associated critical lesions is therefore of paramount importance. We present the case of a 720-g premature infant who was diagnosed clinically with PDA. Echocardiography confirmed the diagnosis; however, associated severe aortic coarctation and tubular hypoplasia of the distal aortic arch were overlooked. The correct diagnosis was made intraoperatively, and successful surgical reconstruction was performed. CASE REPORT A 775-g twin boy was born at 29 weeks gestational age by cesarean section. He was noted to be flaccid and cyanotic at birth but improved with immediate endotracheal intubation and mechan-

Journal of Pediatric

Surgery,

Vol 28. No 5 (May), 1993: pp 731-734

ical ventilation. A PDA was suspected by physical examination and was confirmed by echocardiography at 2 days of age. Failure of ductal closure with indomethacin was documentedby echocardiography at 4 days of age and on the following day because of persistent signs and symptoms of a PDA he underwent left thoracotomy with the intention of ductal ligation. During dissection of the PDA, evaluation of the aortic isthmus showed it to be hypoplastic, estimated at 1 mm diameter. A pulse oximeterwas placed on the foot and temporary ductal closure with forceps resulted in loss of pulsation in the foot. The diagnosis of a “ductal dependent” hypoplastic aortic arch/coarctation was made. The ductus was left patent, prostoglandin El (PGEl) was started, and the patient was returned to the intensive care nursery after routine closure of the thoracotomy incision. Arch repair was not performed at this operation because of a lack of an indwelling arterial catheter, large-bore intravenous line, proper operating room setup, and blood bank preparation. Due to differences of opinion among various consulting physicians regarding the likelihood of performing a successful arch reconstruction in this small infant, the initial management plan was to administer PGEI and total parenteral nutrition in an attempt to allow the infant to grow before performing surgery. However, the infant showed no signs of growth over the ensuing 2 weeks and developed renal insufficiency and gastrointestinal bleeding. During this period repeat echocardiographic and Doppler flow studies were performed, which clearly showed the severe aortic isthmus hypoplasia (diameter, I .4 mm), periductal coarctation, and a markedly abnormal Doppler signal in the descending aorta (Figs 1A and lB), as well as a small muscular ventricular septal defect. At 18 days of life the infant, weighing 720 g, underwent reconstruction of the distal aortic arch and isthmus and ductal ligation. The operative findings were severe distal arch and isthmus tubular hypoplasia (1.0 to 1.4 mm diameter) over a l.O-cm length from the left carotid artery to the ductus, a normal aortic arch (4.0 mm diameter) proximal to the carotid artery, large PDA (5 mm diameter) and descending thoracic aorta (5 mm diameter), and a discrete preductal coarct shelf with a pin-hole opening. Details of the operative approach are described in Fig 2. The postoperative course was uncomplicated, with resolution of the renal and gastrointestinal problems. The hemodynamics were markedly improved and the patient was removed from the ventilator 4 weeks after surgery. Postoperative echocardiographic and Doppler studies suggested no isthmus narrowing and a normal descending aortic flow signal (Figs 1C and 1D). Five months after surgery the infant was thriving (weight, 3.4 kg) and the systolic blood pressure differential between the right arm and leg was less than 10 mm Hg. The muscular ventricular septal defect persists.

From

fhe Division of Cardiothoracic

Surgery, Department

qf

Surgery, and the Department of Pediatrics. University of California, San Francisco, CA. Address reprint requests to Frank L. Ha&y, MD, Department of Cardiovascular Surgery The Children’s Hospital, 300 Longwood Ave, Boston, MA 02115. Copyright o 1993 by W B. Saunders Company 0022-3468/93/2805-0023$03.00/O

731

HANLEY ET AL

Fig 1. (A) Echocardiographic study of distal arch and isthmus with color flow study of coarctation. Diameter of distal arch and isthmus ranged from 1.0 to 1.4 mm. (g) Doppler flow signal in descending aorta showing attenuated flow. (C) Coronal view from suprasternal notch of distal arch and isthmus after reconstruction. Note echo-dense Gore-Tex graft (arrows) and isthmus patency. (D) Doppler flow signal in descending aorta after reconstruction shows normal contour. AAo, ascending aorta; CoA, coarctation; DAo, descending aorta; InA, innominate artery; LCA, left carotid artery; LSCA. left subclavian artery.

ARCH REPAIR IN PREMATURE INFANT

LSCA

In.A, CoA / h

/

PDA

Tlmm

DISCUSSION

This report makes two major points. First, evaluation of premature infants by echocardiography to confirm a clinically suspected PDA should not be so limited in scope that other important “ductal dependent” cardiac lesions are overlooked. In this patient’s case, had the indomethacin been successful, or had the PDA been ligated at the initial surgery, severe instability or death would have likely followed. In addition, although the diagnosis was made at the initial operation, as is the case in many institutions, the operative set-up for an infant PDA ligation is not adequate for more complex surgery. This makes it very difficult, if not impossible, to surgically correct

Fig 2. Exposure was through the fourth intercostal space via a left posterolateral thoracotomy incision. (A) The extremely narrowed aortic isthmus as well as the arch, ductus, and descending aorta were dissected. The hypoplastic segment and coarct area were isolated as shown. (B) The ductus was ligated and a longitudinal incision made as shown. A segment of 4-mm PTFE (Gore-Tex) tube was tailored to the length of the incision, opened longitudinally and its edges minimally rounded. (The width of the opened tube was not narrowed. Width = k = 12.7 mm). (C)The PTFE tube was sewn into place using running suture. At the level of the distal arch and isthmus the PTFE tube accounted for 80% of the circumference of the reconstructed aorta. AAo. ascending aorta; CoA. coarctation; DAo, descending aorta; InA, innominate artery; LCA, left carotid artery; LSCA, left subclavian artery; PDA, patent ductus arteriosus; PTFE, polytetrafluoroethylene (Gore-Tax).

more complex lesions at the initial exploration even if they are recognized. Appropriate preoperative diagnosis would allow for proper preparation with adequate indwelling arterial and venous catheters, proper surgical instruments, availability of a full-service operating room and table, and adequate blood bank preparation. The second point is quite straightforward, namely that successful surgical correction of complex aortic arch problems is possible in small premature infants. In spite of the fact that there is a large experience with complex neonatal cardiac surgery at the institution where this case was managed, the recommendation by the surgical team that operative repair be

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performed was initially met with resistance by many of the primary care and consulting physicians. The reason for this position was that the operative mortality was thought to be prohibitive because of the infant’s size. The ease with which this operation was carried out, and the uncomplicated postoperative recovery and subsequent course of this patient, suggest that this position is not warranted.

HANLEY ET AL

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RS, Kumar

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