Patent Ductus Arteriosus #2: Surgical PDA Ligation

1. Contemporary Role of Surgical PDA Closure

Surgical closure of a patent ductus arteriosus (PDA) is a definitive method of eliminating ductal flow without cardiopulmonary bypass. Historically, surgery was the principal invasive treatment for a persistent PDA, but its role has changed substantially with the development of reliable transcatheter occlusion techniques.

For most anatomically suitable PDAs in infants and children, transcatheter device closure is now preferred because it avoids thoracotomy and provides highly effective occlusion with a low procedural burden. The same transition is increasingly occurring in very-low-birth-weight and extremely preterm infants as transcatheter techniques become feasible at progressively smaller procedural weights. Contemporary clinical practice guidance suggests that, when procedural PDA closure is indicated in an extremely preterm infant and appropriate expertise and anatomy are present, transcatheter closure may be preferred over surgical ligation, although this remains a conditional recommendation based on limited comparative evidence.[1]

Surgical closure nevertheless remains an important treatment option when:

• transcatheter closure is anatomically unsuitable;
• vascular access or patient size precludes catheter intervention;
• device implantation has failed or produced an unacceptable residual lesion;
• the ductus is exceptionally large or has morphology unfavorable for available devices;
• concomitant thoracic or cardiac surgery makes direct closure appropriate; or
• local catheter expertise or equipment is unavailable.

The choice between medical management, transcatheter closure, and surgery is particularly complex in premature infants because the clinical significance of PDA and the optimal timing of intervention remain incompletely defined.

2. Operative Anatomy

The ductus arteriosus connects the proximal descending thoracic aorta to the pulmonary arterial circulation, typically near the origin of the left pulmonary artery. From a left thoracic operative perspective, it lies immediately beneath the aortic arch in the region between the distal arch and proximal descending aorta.

The major anatomical landmarks include:

• the left subclavian artery superiorly;
• the descending thoracic aorta posteriorly;
• the left pulmonary artery and main pulmonary artery anteriorly and medially;
• the vagus nerve passing across the arch region; and
• the left recurrent laryngeal nerve, which loops beneath the aortic arch adjacent to the ductus.

The recurrent laryngeal nerve is the most important neural structure at risk. It passes around the inferior aspect of the arch near the ligamentum arteriosum and then ascends in the tracheoesophageal groove. In neonates and particularly in premature infants, the operative field is extremely small, and the nerve may be difficult to distinguish from surrounding connective tissue.

The surgeon must also remain aware of the left pulmonary artery immediately deep to the ductus. Incomplete identification of the ductal margins can result in inadvertent encirclement or clipping of the pulmonary artery or, less commonly, the descending aorta. Therefore, accurate definition of both the aortic and pulmonary ends of the ductus is essential before any ligature or clip is applied.

3. Operative Approach

3.1 Left Thoracotomy

The traditional approach is a left posterolateral or muscle-sparing thoracotomy, usually through the third or fourth intercostal space depending on patient size and surgeon preference.

The patient is positioned in the right lateral decubitus position with the left hemithorax elevated. In neonates, complete single-lung ventilation is generally unnecessary; gentle retraction of the left lung usually provides sufficient exposure.

The pleural cavity may be entered directly. The lung is retracted anteriorly, exposing the descending aorta and posterior mediastinum. Some surgeons use an extrapleural approach, particularly in premature infants, although transpleural exposure remains common.

The operation is ordinarily performed without cardiopulmonary bypass.

3.2 Thoracoscopic Closure

Thoracoscopic clipping or ligation provides an alternative minimally invasive surgical approach. Published pediatric series demonstrate that thoracoscopic PDA closure can be performed effectively with low rates of residual shunting and major complications in appropriately selected patients.[2] However, it requires thoracoscopic expertise, adequate working space, and physiological tolerance of the operative conditions. Its relative advantage has diminished as transcatheter closure has become applicable to progressively smaller infants.

4. Surgical Exposure of the Ductus

After anterior displacement of the lung, the descending thoracic aorta is identified. The mediastinal pleura overlying the aorta may be opened longitudinally, extending superiorly toward the distal arch.

The surgeon identifies:

1. the distal aortic arch;
2. the left subclavian artery;
3. the descending aorta;
4. the ductal region;
5. the vagus nerve; and
6. the expected course of the left recurrent laryngeal nerve.

Dissection should be limited to what is required for secure ductal closure. Excessive circumferential skeletonization is unnecessary and potentially harmful, particularly in premature infants.

The ductus is typically approached from its superior and inferior surfaces. Blunt dissection is favored adjacent to the recurrent laryngeal nerve. Traction on the ductus or surrounding tissues should be minimized because the ductal wall may be thin and friable, especially in very premature neonates.

The surgeon should confirm that the structure being isolated is the ductus rather than the left pulmonary artery. Visualization of the relationship between the distal arch, descending aorta, and pulmonary artery is particularly important before clip placement.

5. Methods of Surgical Closure

Several techniques are established.

5.1 Suture Ligation

The ductus may be surrounded with one or more nonabsorbable sutures and securely ligated. Historically, silk was widely used; polypropylene or other permanent sutures may also be used according to surgeon preference.

A key technical objective is complete circumferential occlusion without tearing the ductal wall. The ligature should tighten progressively rather than abruptly. In a fragile premature infant, excessive force can produce ductal disruption and potentially catastrophic hemorrhage.

Suture ligation remains effective, although comparative observational data suggest that both suture ligation and clip application can achieve satisfactory closure in premature neonates.[3]

5.2 Clip Occlusion

A surgical clip may be placed across the ductus under direct visualization. Either a single appropriately sized clip or two clips may be used according to ductal size, device design, and institutional technique.

Clip closure can be particularly efficient because extensive circumferential dissection is often unnecessary. However, adequate visualization of both ends of the clip is critical. The surgeon must ensure that the clip does not incorporate the recurrent laryngeal nerve, pulmonary artery, or aortic wall.

5.3 Ligation and Division

The ductus may also be ligated or controlled on both sides and divided. This technique provides unequivocal anatomical interruption and was historically employed particularly for large PDAs.

Division requires more extensive mobilization and carries a greater potential consequence if either end is inadequately controlled. In contemporary isolated PDA surgery, simple ligation or clip occlusion is more commonly sufficient, while division remains useful in selected anatomy or when complete ductal mobilization is already required.

6. Confirmation of Complete Closure

Immediately after ligation or clip application, several findings should be assessed.

First, the ductus must be completely occluded. Residual flow may be evaluated by intraoperative echocardiography when clinically appropriate.

Second, adjacent vascular structures must remain unobstructed. Particular attention should be paid to the descending aorta and left pulmonary artery.

Third, hemodynamic changes should be anticipated. Interruption of a large left-to-right shunt produces an immediate reduction in pulmonary blood flow and left ventricular preload while simultaneously eliminating the low-resistance ductal runoff from the systemic circulation.

A residual PDA after surgical ligation is uncommon but can occur because of incomplete ligature placement, clip malposition, or unusual ductal morphology. Published thoracoscopic series likewise demonstrate that residual leaks, although infrequent, may require subsequent catheter intervention.[2]

7. Structures at Risk and Surgical Complications

7.1 Recurrent Laryngeal Nerve Injury

Left recurrent laryngeal nerve injury is one of the characteristic complications of PDA surgery. Vocal fold paralysis has been reported particularly in premature and low-birth-weight infants, in whom the nerve is proportionally very small and lies immediately adjacent to the operative field.[4-6]

Clinical manifestations include:

• weak or abnormal cry;
• stridor;
• aspiration;
• feeding intolerance;
• difficulty with extubation; and
• recurrent respiratory symptoms.

Some injuries recover, whereas others persist. Postoperative vocal fold assessment should be considered when symptoms suggest impaired mobility, particularly following neonatal PDA ligation.

7.2 Hemorrhage

Ductal injury can cause rapid and severe bleeding. The risk is greatest during circumferential dissection or manipulation of a friable ductal wall. Immediate proximal and distal vascular control may be challenging through a limited thoracotomy, reinforcing the principle that dissection should be deliberate and limited.

7.3 Pneumothorax and Pleural Complications

Pneumothorax, pleural effusion, and chylothorax are recognized complications. A prospective series of premature infants undergoing PDA ligation reported surgical complications including pneumothorax, recurrent laryngeal nerve palsy, and chylothorax.[7]

Thoracic duct injury is uncommon but should be considered when postoperative chylous drainage develops.

7.4 Injury to Adjacent Vessels

Misidentification or excessive clip extension can compromise the left pulmonary artery or descending aorta. This risk is reduced by visualizing the complete ductal anatomy before occlusion rather than relying solely on tactile identification.

8. Postligation Cardiovascular Physiology

Closure of a large PDA causes an abrupt change in ventricular loading conditions.

Before closure, the left ventricle ejects into both the systemic circulation and the relatively low-resistance pulmonary circuit through the PDA. Ductal closure immediately:

• removes the low-resistance runoff;
• increases effective left ventricular afterload;
• decreases pulmonary venous return and left ventricular preload; and
• reduces the volume-loaded state of the left atrium and ventricle.

Most infants tolerate this transition well. However, extremely premature infants may develop postligation cardiac syndrome (PLCS), characterized by systemic hypotension, impaired myocardial performance, increasing ventilatory requirements, and cardiorespiratory instability during the first postoperative day.

Echocardiographic studies demonstrate acute deterioration in indices of left ventricular systolic performance after surgical ligation in susceptible preterm infants.[8] Targeted neonatal echocardiography can identify myocardial dysfunction and support physiology-directed management rather than reflexive volume expansion or nonspecific escalation of vasoactive therapy.[9]

A recent multicenter retrospective comparison of infants weighing <2 kg reported PLCS after surgical closure but not after transcatheter closure in the propensity-matched cohort, although such observational comparisons remain vulnerable to residual selection bias.[10]

9. Postoperative Management

After surgical closure, management should focus on both thoracic complications and the hemodynamic consequences of abrupt ductal elimination.

Monitoring should include:

• systemic blood pressure and perfusion;
• ventilatory requirement;
• heart rate and urine output;
• serial lactate when clinically indicated;
• chest radiography if pneumothorax or pulmonary deterioration is suspected;
• echocardiography when low cardiac output, ventricular dysfunction, or residual PDA is a concern.

In premature infants with hypotension after ligation, the mechanism should be defined whenever possible. Reduced left ventricular preload, increased afterload, myocardial dysfunction, adrenal insufficiency, vasoplegia, or combinations of these processes may contribute. Therapeutic strategies therefore vary and may include carefully titrated inotropic or vasoactive support rather than indiscriminate fluid administration.

Feeding difficulty, stridor, recurrent aspiration, or unexplained inability to wean respiratory support should raise suspicion for recurrent laryngeal nerve dysfunction.

10. Surgical Closure in the Era of Transcatheter PDA Occlusion

The role of surgery should be interpreted in the context of rapidly evolving catheter technology. In a contemporary retrospective cohort of preterm infants, surgical and catheter closure were both highly effective in achieving PDA closure, although the patient populations differed substantially at baseline.[11]

The evidence is not sufficient to conclude that every premature infant requiring procedural closure should undergo catheter intervention. Institutional expertise, body size, ductal anatomy, clinical instability, access considerations, and the availability of neonatal interventional programs all influence decision-making.

Nevertheless, the overall treatment paradigm has shifted: surgical ligation is no longer the default invasive therapy for most suitable PDAs but remains a highly reliable rescue and alternative strategy when transcatheter closure cannot be performed safely or successfully.

Key Surgical Principles

• Define the anatomy before occlusion. Confirm the ductus, descending aorta, and left pulmonary artery before placing a ligature or clip.
• Protect the left recurrent laryngeal nerve. Avoid unnecessary dissection, traction, thermal injury, or inclusion of surrounding tissue.
• Minimize ductal manipulation. Premature ductal tissue may be exceptionally fragile.
• Ensure complete closure. Residual ductal flow should be excluded clinically and echocardiographically when appropriate.
• Preserve adjacent vascular patency. Exclude obstruction of the left pulmonary artery or descending aorta.
• Anticipate the loading change. Abrupt loss of the ductal shunt decreases LV preload and increases effective afterload.
• Recognize postligation cardiac syndrome early. Hypotension and respiratory deterioration after closure may reflect acute myocardial dysfunction rather than inadequate circulating volume alone.
• Select the modality according to anatomy and clinical context. Transcatheter closure is preferred for many suitable PDAs, but surgical closure remains an essential definitive option.

References

1. Mitra S, Bischoff A, Sathanandam S, Lakshminrusimha S, McNamara P. Procedural closure of the patent ductus arteriosus in preterm infants: a clinical practice guideline. J Perinatol. 2024. doi:10.1038/s41372-024-02052-9. PMID: 38997403.
2. Liêm N, Tuan TT, Linh NV. A safe technique of thoracoscopic clipping of patent ductus arteriosus in children. J Laparoendosc Adv Surg Tech A. 2012. doi:10.1089/lap.2011.0454. PMID: 22577814.
3. Mandhan P, Samarakkody U, Brown S, Kukkady A, Maoate K, Blakelock R, Beasley S. Comparison of suture ligation and clip application for the treatment of patent ductus arteriosus in preterm neonates. J Thorac Cardiovasc Surg. 2006. doi:10.1016/J.JTCVS.2006.04.040. PMID: 16935125.
4. Zbar RIS, Chen AH, Behrendt DM, Bell E, Smith RJH. Incidence of vocal fold paralysis in infants undergoing ligation of patent ductus arteriosus. Ann Thorac Surg. 1996. doi:10.1016/0003-4975(95)01152-8. PMID: 8619698.
5. Pereira K, Webb BD, Blakely M, Cox C, Lally K. Sequelae of recurrent laryngeal nerve injury after patent ductus arteriosus ligation. Int J Pediatr Otorhinolaryngol. 2006. doi:10.1016/J.IJPORL.2006.05.001. PMID: 16797086.
6. Smith ME, King J, Elsherif A, Muntz H, Park A, Kouretas P. Should all newborns who undergo patent ductus arteriosus ligation be examined for vocal fold mobility? Laryngoscope. 2009. doi:10.1002/lary.20148. PMID: 19507238.
7. Kang SL, Samsudin S, Kuruvilla M, Dhelaria A, Kent S, Kelsall W. Outcome of patent ductus arteriosus ligation in premature infants in the East of England: a prospective cohort study. Cardiol Young. 2012. doi:10.1017/S1047951112001795. PMID: 23164413.
8. El-Khuffash A, Jain A, Dragulescu A, McNamara P, Mertens L. Acute changes in myocardial systolic function in preterm infants undergoing patent ductus arteriosus ligation: a tissue Doppler and myocardial deformation study. J Am Soc Echocardiogr. 2012. doi:10.1016/j.echo.2012.07.016. PMID: 22889993.
9. Jain A, Sahni M, El-Khuffash A, Khadawardi E, Sehgal A, McNamara P. Use of targeted neonatal echocardiography to prevent postoperative cardiorespiratory instability after patent ductus arteriosus ligation. J Pediatr. 2012. doi:10.1016/j.jpeds.2011.09.027. PMID: 22050874.
10. Duboue P, Padovani P, Bouteiller X, et al. Post-ligation cardiac syndrome after surgical versus transcatheter closure of patent ductus arteriosus in low body weight premature infants: a multicenter retrospective cohort study. Eur J Pediatr. 2024. doi:10.1007/s00431-024-05481-y. PMID: 38381375.
11. Tabb C, Aggarwal S, Bajaj M, Natarajan G. Comparative effectiveness of surgical ligation and catheter closure of patent ductus arteriosus in preterm infants. Pediatr Cardiol. 2023. doi:10.1007/s00246-023-03199-6. PMID: 37316609.