PEDIATRICS Vol. 104 No. 2 August 1999, pp. 227-230

Video-Assisted Thoracoscopic Surgery for Patent Ductus Arteriosus in Low Birth Weight Neonates and Infants

Redmond P. Burke, MD^*, Jeffrey P. Jacobs, MD, Wen Cheng, MD^§, Alfredo Trento, MD^§, and Gregory P. Fontana, MD^§

From the ^* Division of Cardiovascular Surgery, Miami Children's Hospital, Miami, Florida;  Division of Thoracic and Cardiovascular Surgery, All Children's Hospital, University of South Florida College of Medicine, St Petersburg, Florida; and ^§ Division of Cardiovascular Surgery, Cedars Sinai Hospital, Los Angeles, California.

	ABSTRACT

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Background.  Video-assisted thoracoscopic surgery (VATS) has been assuming an expanded role in the management of cardiothoracic disease. As instrumentation and experience increase, VATS is being applied to treat smaller patients. We report our experience with 34 low birth weight infants undergoing VATS interruption of patent ductus arteriosus (PDA).

Methods.  VATS allows PDA interruption without the muscle cutting or rib spreading of a standard thoracotomy. Four small, 3-mm incisions are made along the line of a potential thoracotomy incision. Ports placed through these incisions admit endoscopic instruments, a camera, and a vascular clip applier.

Results.  Median age at surgery was 15.5 days (range: 1-44 days). Median weight at surgery was 930 g (range: 575-2500 g). Twenty patients weighed <1 kg, and 13 weighed <750 g. All patients had congestive heart failure and had either failed indomethacin therapy or had contraindications to indomethacin. Median surgical time was 60 minutes (range: 31-171 minutes). Echocardiography documented elimination of ductal flow in all patients. Operative mortality was zero. Four patients (4/34 = 12%) required conversion to open thoracotomy: 1 because of difficult exposure, 1 because of pulmonary dysfunction and anasarca, 1 because of a large 1-cm duct, and 1 because of coagulopathy and poor pulmonary compliance. Two patients died before discharge: 1 patient (surgical weight: 605 g) died on postoperative day 2 because of intracranial hemorrhage, and 1 patient (surgical weight: 1725 g) died on postoperative day 88 because of multiple system organ failure. Follow-up has demonstrated no PDA murmur in any patient, but echocardiography revealed trace ductal flow in 2 patients.

Conclusions.  VATS offers a minimally traumatic, safe, and effective technique for PDA interruption in low birth weight neonates and infants.  Key words:  patent ductus arteriosus, video-assisted thoracoscopic surgery.

A patent ductus arteriosus (PDA) was first successfully ligated surgically on August 26, 1938, by Dr Robert E Gross.¹ The management of PDA has evolved considerably since this surgical milestone.

Before 1991, the standard operative approach to the PDA was through a posterolateral thoracotomy. Over the past several years, video-assisted thoracoscopic surgery (VATS) has been assuming an expanded role in the management of cardiothoracic disease. In 1991, video-assisted approaches to PDA ligation were developed concurrently in Paris by Laborde^2,3 and in Boston by Burke.⁴ These VATS PDA techniques are safe, effective, and minimally traumatic. They allow PDA interruption without the muscle cutting or rib spreading of a standard thoracotomy.

As instrumentation and experience increase, VATS PDA ligation is being applied to treat smaller patients. Concerns about postoperative pain syndromes, compromised respiratory mechanics, and chest wall deformity associated with standard posterolateral thoracotomy have led us to pursue the use of VATS PDA ligation in smaller children. Therefore, we report our experience with VATS PDA ligation in 34 low birth weight infants.

	METHODS

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Patients

A total of 34 consecutive low birth weight infants who underwent VATS PDA ligation are included in this report. (Low birth weight is defined as 2500 g.) All patients had congestive heart failure. These patients represent 20% of our total VATS PDA experience of 174 patients between April 6, 1993 and October 1, 1996. A VATS database (a component of the CardioAccess Cardiothoracic Database, CardioAccess Inc, St Petersburg, FL, and Miami, FL) has been maintained prospectively on all patients and has been used for data collection.

Informed consent was obtained in all cases and included consent for both VATS PDA ligation and potential conversion to open thoracotomy.

Surgical Techniques

Under general anesthesia, with single lumen endotracheal intubation, patients were placed in the right lateral decubitus position. Routine monitoring included transcutaneous oxygen saturation, continuous end tidal carbon dioxide, blood pressure, and electrocardiogram. Four small 3-mm thoracostomy incisions were made in the posterolateral chest wall to admit a grasping forceps, cotton swabs for lung retraction, a 2.7-mm endoscope, and an L-shaped cautery. No chest wall muscles were cut, and the ribs were not retracted. Exposure was achieved by retracting the inflated left upper lobe inferomedially. The parietal pleura overlying the duct was opened. The upper and lower angles of the PDA were dissected free (Fig 1), taking care to protect the vagus and recurrent laryngeal nerves, which were easily visualized. A mechanical arm held the videoscope in position, providing a stable camera image and reducing obstruction in the operative field. Endoscopic vascular clips were placed to interrupt the PDA (Fig 2). Rapid conversion to thoracotomy was possible to control bleeding, although this was never necessary. A thoracostomy tube was placed through one of the ports while the others were closed. The lung was reexpanded, and the thoracostomy tube was removed in the operating room.

View larger version (112K): [in this window] [in a new window]   Fig. 1.   Endoscopic view of PDA. One indicates aortic isthmus (descending thoracic aorta between the left subclavian artery and the PDA). Two indicates PDA. Three indicates descending thoracic aorta inferior to the PDA. The tip of a cotton swab is seen resting on the descending thoracic aorta.

View larger version (109K): [in this window] [in a new window]   Fig. 2.   An endoscopic vascular clip is placed to interrupt the PDA. The arrow points to the clip on the PDA.

Although VATS PDA ligation has been performed in the operating theater, the procedure certainly could be performed either in the open warmer of the neonatal intensive care unit or in an attached minioperating room depending on institutional preferences.

	RESULTS

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Patient Characteristics

VATS PDA ligation was performed in 34 low birth weight infants (median age: 15.5 days; range: 1-44 days; median weight: 930 g; range: 575-2500 g [Fig 3]) between April 6, 1993 and October 1, 1996. Twenty patients weighed <1 kg, and 13 weighed <750 g. All patients had congestive heart failure, and all had either failed indomethacin therapy or had contraindications to indomethacin.

View larger version (34K): [in this window] [in a new window]   Fig. 3.   Range of patient weight at time of surgery.

Preoperative Evaluation

All patients underwent preoperative echocardiography confirming the diagnosis of PDA.

Operative Course

Surgical time is defined as the interval from skin incision to placement of the surgical dressing. Surgical time ranged from 31 to 171 minutes (median: 60 minutes). (This VATS PDA surgical time compares with a surgical time ranging from 20 minutes to 1 hour [median: 35 minutes] in a similar group of low birth weight infants undergoing PDA ligation by thoracotomy.) The lowest intraoperative core temperature ranged from 34.8°C to 36.7°C.

Operative mortality was zero. Four patients (4/34 = 12%) required conversion to open thoracotomy: 1 because of difficult exposure, 1 because of pulmonary dysfunction and anasarca, 1 because of a large 1-cm duct, and 1 because of coagulopathy and poor pulmonary compliance.

Intraoperative esophageal stethoscope examination documented the elimination of the ductal murmur in all patients.

Postoperative Course

Echocardiography confirmed elimination of ductal flow in all patients.

Two patients died before discharge; 1 patient (surgical weight: 605 g) died on postoperative day 2 because of intracranial hemorrhage and 1 patient (surgical weight: 1725 g) died on postoperative day 88 because of multiple system organ failure.

The hospital stay in the remaining 32 patients ranged from 1 to 186 days (median: 56 days).

Postoperative complications occurred in 2 patients; 1 patient (surgical weight: 575 g) developed necrotizing enterocolitis requiring a laporatomy and ileostomy on postoperative day 16 and 1 patient developed vocal cord paresis, which is now asymptomatic. No patients developed chylothorax.

Follow-up

Length of follow-up ranged from 2 days to 323 days. No patient has shown a PDA murmur in follow-up. Echocardiography has shown trace residual ductal flow in two patients. All incisions healed well without significant scarring or complications.

	DISCUSSION

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Surgical ligation has been shown to be a safe and effective procedure for treating a small premature infant with a PDA causing large left-to-right shunting.⁵ Multiinstitutional collaborative research has demonstrated that effective treatment for hemodynamically significant PDA in small premature infants involves initial anticongestive treatment followed by indomethacin; an operation is used when indomethacin therapy is ineffective.⁶

In addition to therapeutic PDA ligation for hemodynamically significant lesions, a potential role exists for prophylactic PDA ligation in very low birth weight neonates weighing 1000 g. Prophylactic surgical closure of the PDA in this subgroup of patients can reduce the complications of prematurity including the risk of necrotizing enterocolitis.⁷

Therefore, surgical closure of the PDA is beneficial therapeutically in low birth weight infants and potentially beneficial as prophylaxis in very low birth weight neonates. VATS PDA ligation offers the important advantage of decreased chest wall trauma in these small patients. Proper chest wall and spine mechanics depend on a delicate balance of neural function, ligamentous support, and muscular forces. By avoiding muscle division and rib spreading, the video-assisted operation minimizes the risk of nerve injury (associated with postthoracotomy pain syndromes⁸) and rupture of intercostal ligaments (associated with scoliosis^9,10). In adults, video-assisted pulmonary wedge resection compared with an open thoracotomy technique has been associated with improved early postoperative chest wall compliance and respiratory function.¹¹ Postthoracotomy scoliosis and shoulder muscle dysfunction may be more pronounced in the pediatric population in which rapid growth could exaggerate thoracotomy-induced imbalances in chest wall mechanics.

Perioperative thermal regulation is challenging in premature neonates. Decrease in convective heat loss during surgery represents an additional advantage of VATS PDA interruption. By avoiding a thoracotomy and wide opening of the pleural cavity, body heat is retained. The lowest intraoperative core temperature seen during VATS PDA interruption in this series was 34.8°C.

Contraindications to VATS PDA interruption include dense left pleural adhesions, a calcified PDA, coagulopathy, and severe pulmonary dysfunction. These patients require open surgical PDA ligation. Conversion from VATS PDA to open thoracotomy is rapid and safe. Four patients in this series required conversion to open thoracotomy; we consider this an exercise of good surgical judgment rather than a complication.

Several studies have documented complication rates after open PDA interruption. Residual flow after ligation has been seen in 5% to 23% of patients.^12,13 Left pulmonary artery ligation has been reported in 10 cases over 27 years of literature in review.¹⁴ Recurrent laryngeal nerve injury has been seen in 1.1% to 4.2% of patients.^12,15 VATS PDA ligation in infants 2500 g has complication rates similar to those of open techniques (residual flow: 2/34 = 5.9%; recurrent laryngeal nerve injury: 1/34 = 2.9%).

The ideal treatment for PDA is unknown. Transcatheter procedures require ionizing radiation and placement of an intravascular foreign body; furthermore, they have a significant incidence of residual flow. The vascular trauma produced by the transcatheter approach precludes its use in the low birth weight patient.

A very small thoracotomy incision for PDA interruption in low birth weight patients is not comparable with the VATS approach. The trauma of the thoracotomy extends beyond the length of the incision and is more related to the inevitable need to cut the intercostal muscles and rigorously retract the ribs. Using conventional instruments, light sources and loupe magnification, as thoracotomy incisions decrease in size, surgical precision suffers, instruments crowd the operative field, and visualization is compromised markedly. The VATS approach is designed specifically to maintain surgical precision through extremely small incisions.

A significant learning curve for endoscopic surgery exists.¹⁶ It is imperative that these new procedures be thoroughly planned and practiced in a laboratory setting or simulator before applying them to children. VATS PDA ligation in low birth weight infants requires the use of smaller instruments, trocars, and cameras compared with VATS PDA ligation in larger patients; however, the procedure itself is somewhat less demanding because of the decreased connective tissue overlying the PDA in low birth weight infants.

This multiinstitutional prospective study of VATS PDA ligation in infants 2500 g demonstrates that the endoscopic technique is safe and effective. VATS PDA ligation avoids potential long-term morbidity related to chest wall trauma, fluoroscopic radiation, percutaneous vascular access, and intravascular foreign bodies.

	FOOTNOTES

Received for publication Apr 1, 1998; accepted Feb 22, 1999.

Reprint requests and correspondence to Redmond P. Burke, MD, Division of Cardiovascular Surgery, Miami Children's Hospital, 3200 SW 60 Court, Suite 102, Miami, FL 33155-4069. E-mail: redmond{at}aol.com

	ABBREVIATIONS

PDA, patent ductus arteriosus; VATS, video-assisted thoracoscopic surgery.

	REFERENCES

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