Ligation of Patent Ductus Arteriosus in Premature Infants: Importance of Accurate Anatomic Definition

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PEDIATRICS Vol. 71 No. 3 March 1 983 373

Ligation

of Patent

Ductus

Arteriosus

in

Premature

Infants:

Importance

of Accurate

Anatomic

Definition

William H. Fleming, MD, Lynne B. Sarafian, MN, John D. Kugler, MD,

and Robert M. Nelson, Jr, MD

From the Departments of Thoracic and Cardiovascular Surgery, Pediatric Cardiology,

and Pediatric Neonatology, University of Nebraska Medical Center, Omaha

ABSTRACT. The aortic arch anatomy of the premature

infant may not be as simple to determine as the anatomy of an older child. A case of a premature infant who had

inadvertent ligation of the left pulmonary artery during attempted ligation of a patent ductus arteriosus is de-scribed. On the fourth day following the initial operation,

the patient underwent successful surgery to remove the pulmonary artery ligature and to ligate the persistent

patent ductus arteriosus. A lung scan on the seventh day following removal of the pulmonary artery ligature showed normal perfusion of both lungs. Six months later, the child’s growth, development, and chest roentgeno-gram were normal. Pediatrics 1983;71:373-375; prema-ture infant, patent ductus arteriosus, ligation of left pulmonary artery.

Surgical ligation of patent ductus arteriosus (PDA) was first described in 1939 by Gross.’ In the

ensuing years, ligation of the PDA has taken its place as an accepted therapy for premature infants who exhibit signs and symptoms of congestive heart

failure because of a left-to-right shunt through the PDA.2 increasing rate of survival for premature infants has led to a subsequent increase in the number of infants undergoing PDA ligation.3 Cri-teria for selection of surgical management, as

op-posed to medical management, vary from

institu-tion to institution.46 Although ligation of PDA can be performed safely in the premature infant,2 the aortic arch vessels must be carefully identified to avoid surgical misadventure.7

We describe a premature infant in whom the left

Received for publication March 1, 1982; accepted July 2, 1982. Reprint requests to (W.H.F.) University of Nebraska Medical Center College of Medicine, 42nd and Dewey Aye, Omaha, NE 68105.

pulmonary artery was inadvertently ligated, rather

than the PDA. The distinctive anatomy of the arch

in premature infants is reviewed and recommen-dations are made to improve identification of these

structures and ensure successful PDA ligation.

CASE REPORT

On June 16, 1980, a 30-day-old male infant weighing

1,400 g was transferred to the Neonatology Unit of the University of Nebraska Medical Center (UNMC). The infant had been born at a gestational age of 31 weeks. The patient had had findings consistent with PDA at his local hospital, and subsequently had undergone PDA

ligation at age 17 days by a thoracic surgeon. Following

this initial operation, the patient continued to require ventilator support and his murmur persisted. For this reason, the patient was referred to UNMC. Physical assessment at the time of admission revealed the

follow-ing: rectal temperature, 36.8#{176}C;pulse rate, 136 beats per

minute; and respiratory rate of 45/mm on a Sechrist

pressure ventilator delivering 25% oxygen using an

inter-mittent mandatory ventilation rate of 30 and peak inspi-ratory pressure of 30. Measurements of blood gases on

these settings were Pao2 79 mm Hg, pH 7.39, Paco2 40

mm Hg. Coarse rales were heard bilaterally. Heart sounds included an S4 gallop rhythm with a grade 3/6 systolic ejection murmur with an early diastolic component. Bounding pulses were present in all four extremities. The liver edge was palpated 2.5 cm below the right costal margin. The patient had an anterior left thoracotomy incision and left chest tube. The echocardiogram showed

enlarged left atrium and left ventricle (consistent with a

left-to-right shunt at the ventricular and/or great artery

level) and increased pulmonary artery pressure. The ECG

showed right ventricular hypertrophy. Chest

roentgeno-gram showed an enlarged heart and increased pulmonary vascular markings (Fig 1). An aortogram revealed a

per-sisting PDA and no filling of the left pulmonary artery (Fig 2).

Fourteen days after the initial ligation, at reoperation

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Fig 2. Aortogram showing no left pulmonary artery fill-ing.

Fig 4. Chest roentgenogram at time of clinic follow-up.

374 LIGATION OF PATENT DUCTUS ARTERIOSUS IN PREMATURE INFANTS

development with a weight of 5.56 kg (90th percentile). Chest roentgenogram at that time showed normal heart

size and normal pulmonary vascular markings (Fig 4).

through the previous thoracotomy, the left pulmonary

artery was found to be ligated anterior to the vagus nerve,

just distal to the PDA. The pleura was opened vertically

over the aorta in the region of the ductus and the anatomy confirmed, with the recurrent laryngeal nerve clearly seen

to come off the vagus and loop around the ductus. Using magnification, the left main pulmonary artery was

ele-vated, and the previously placed two ligatures were

di-vided and removed. The pulmonary artery immediately

ballooned out and showed pulsations out into its branches. By palpation, there was good pulsation in the

left pulmonary artery and no palpable thrombus. The

ductus was then dissected and doubly ligated with 3/0

Tevdek.

The patient had a benign postoperative course. Chest

roentgenogram 2 weeks postoperatively showed a

normal-sized heart and equal perfusion of both lungs (Fig 3). A pulmonary perfusion scan seven days

postopera-tively was read as a “normal pulmonary

ventilation/per-fusion scan.” Perfusion scan revealed that the left lung was perfused 48% v 52% for the right lung. The patient

was extubated on the eighth postoperative day. At the

6-month checkup, the patient showed normal growth and

DISCUSSION

Ligation of a patent ductus arteriosus can be

undertaken with a high degree of safety in even the

very young, premature infant. However, the

anat-omy of the premature infant is somewhat different

from that ofthe older child (Fig 5) and the literature

pays scant attention to the hazard of

misidentifi-cation of major vessels when ligation is attempted

in the premature infant. Pontius et al reviewed a group of ten infants and children who had experi-enced inadvertent ligation of the left pulmonary artery; however, none were identified as premature. In the premature infant, the ductus arteriosus is

commonly larger than the portion of aorta between the left subclavian artery and ductus, and it may appear through the unopened pleura to be the aortic arch itself. As with other surgical procedures, it is

imperative that the surgeon positively identify

ev-ery significant structure before ablation. In partic-ular, the pleura should be opened posterior to the

vagus nerve, which was not done in our reported

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RECURRENT

LARYNGEAL NERVE

ARTICLES 375

VAGUS

NERVE

PDA

PREMATURE OLDER

Fig 5. Arch anatomy of premature infant (left) and

older child (right). Abbreviations used are: Ao, aorta; LSCA, left subclavian artery; PDA, patent ductus arte-riosus.

case. The recurrent laryngeal nerve passes routinely around the ductus, although this is not absolutely reliable, as noted by Pontius et al. However, if visibility of the portion of the aorta between the

ductus arteriosus and left subclavian artery is

es-tablished and a portion of aortic arch is found between the two, there is little risk of misidentifi-cation. Unfortunately, the very large size of the ductus, equal to or exceeding that of the aorta, may be confusing to the surgeon inexperienced with premature infants. If systemic blood pressure and

esophageal stethoscope are used for monitoring, a

test occlusion of the presumed ductus with a

vas-cular forcep will permit conformation that, indeed, the correct structure has been chosen for ligation. A follow-up echocardiogram after surgery should show a return to normal of the left atrium/aorta ratio.

We are aware of three other instances, in two other states, of inadvertent ligation of the left main

pulmonary artery in premature infants during at-tempted ductus ligation over the past 8 years. Of the four instances of this complication known to us,

all the surgical procedures were performed by fully trained thoracic surgeons. None, however, had had

experience with surgical closure of the ductus in

premature infants during their residency training. Among the other three cases known to us, two were discovered at autopsy and in the third, an at-tempted reconstruction 2 weeks after surgery failed to produce flow in the left lung.

Ligation of the patent ductus in the premature

infant may be performed with a very low risk by

experienced surgeons. However, the anatomy of the

premature infant is somewhat unique and can be

treacherous and misleading, especially for those less experienced with such patients.

REFERENCES

1. Gross RE: Surgical management of the patent ductus

arte-riosus. Ann Surg 1939;1 10:321

2. Brandt B, Marvin WJ, Ehrenhaft JL, et al: Ligation of patent ductus arteriosus in premature infants. Ann Thorac

Surg 1981;32:167

3. Nelson BA, Thibeault DW, Emmanouiides GC, et a!:

Improving the results of ligation of patent ductus arteriosus

in small preterm infants. J Thorac Cardiovasc Surg

1976;71:169

4. Murphy DA, Outerbridge E, Stern L, et a!: Management of premature infants with patent ductus arteriosus. J Thorac Cardiouasc Surg 1973;67:221

5. Thibeau!t DW, Emmanouiides GC, Nelson RJ, et a!: Patent

ductus arteriosus complicating the respiratory distress syn-drome in preterm infants. J Pediatr 1975;86:120

6. Gomez R, Moreno F, Burgueros M, et at: Management of patent ductus arteriosus in preterm babies. Ann Thorac

Surg 1980;29:459

7. Pontius RG, Danielson GK, Noonan JA, et at: Illusions leading to surgical closure of the distal left pulmonary artery instead of the ductus arteriosus. J Thorac Cardiovasc Surg

1981;82:107

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1983;71;373

Pediatrics

William H. Fleming, Lynne B. Sarafian, John D. Kugler and Robert M. Nelson, Jr

Anatomic Definition