Thoracoscopic Ligation of the Patent Ductus Arteriosus



Fig. 7.1.
The modification of the 3-mm retractor (Karl Storz GmbH and Company, Germany). (a) The 3-mm Storz fan retractor. (b) The retractor is placed on the plastic towel drape (Towel Drape, Medical Concepts Development, St. Paul, Minn) in the expanded open position. (c) The plastic is allowed to stick to the arms of the retractor. (d) The plastic is folded around the arms of the retractor. (e) The excess plastic is trimmed. (f) The retractor is opened and closed to ensure proper function and plastic adherence. Reprinted from Lukish J. Video-assisted thoracoscopic ligation of a patent ductus arteriosus in a very low-birth-weight infant using a novel retractor. J Pediatr Surg 2009; 44: 1047–50. Published by Elsevier Inc.



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Fig. 7.2.
Incision and instrument placement for VATS PDA ligation in VLBW infants. (a) Midaxillary line, fifth intercostal space, site for retractor, no port used. (b) The posterior axillary line, fifth intercostal space, and site for port placement, camera, and insufflation. (c) The posterior site for dissector and clip applier, no port used (original artwork courtesy of Gary Wind, MD, FACS). Reprinted from Lukish J. Video-assisted thoracoscopic ligation of a patent ductus arteriosus in a very low-birth-weight infant using a novel retractor. J Pediatr Surg 2009; 44: 1047–50. Published by Elsevier Inc.


Following test occlusion, the clip applier (Weck Horizon, Teleflex Medical, Limerick, PA) is inserted through the posterior 5-mm working port, and two medium metal clips are applied near the PDA junction with the aorta (Fig. 7.3). The area is inspected for optimal clip placement and hemostasis, and the thoracic cavity is examined once again to rule out any evidence of lung injury. The incisions are then closed in the standard fashion. Prior to closure of the last incision, positive inspiratory pressure is applied to fully inflate the lung to facilitate evacuation of the pneumothorax. The authors do not routinely place thoracostomy tubes in the absence of suspected lung injury.

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Fig. 7.3.
Intraoperative thoracoscopic photo of exposure achieved using the modified retractor. Clip is in place with ligation of PDA. Note that the lung can be assessed through the plastic drape.




Postoperative Management


Postoperatively, a chest radiograph should be performed to rule out pneumothorax, and an echocardiogram should be confirmed to confirm occlusion of flow [2124]. Close hemodynamic monitoring is crucial in the postoperative period, due to the abrupt hemodynamic changes associated with surgical ligation. Following ligation, there is an increase in diastolic arterial pressure and associated increase in MAP compared to preoperative levels [16]. However, there is commonly a transient decrease in systolic arterial pressure, likely associated with delayed left ventricular adaptation to the abrupt increase in afterload [16]. Postoperative MAP frequently fails to rise to normal levels in the immediate postoperative period. Some studies suggest a transient decrease in postoperative cerebral perfusion, further highlighting the need to maintain adequate MAPs [16]. Some studies also suggest increased oxygenation index following ligation [16]. The risk of post-ligation cardiorespiratory decompensation likely depends on the size of the defect, the time of closure, and the gestational age of the infant. Careful titration of fluids and vasopressors must be employed to maintain adequate perfusion while avoiding pulmonary fluid overload.


Complications


The rate of intraoperative mortality is exceedingly low, with the overall rate reported to be <1 %. There are no intraoperative deaths reported in recent literature of thoracoscopic PDA repair, and two reported during open repair. Intraoperative hemorrhage is also uncommon, with rates estimated between 0.5 and 1 % and even lower in recent series [1719, 2224]. Injury to surrounding structures, such as the pulmonary artery and descending aorta, is exceedingly rare, usually resulting in death [2527].

More common complications include injury to the recurrent laryngeal nerve, which are reported to range between 0.5 and 6 %, with no significant difference noted between VATS and open approaches [1719, 21, 23]. Over half of these are transient injuries with return of function [18, 19]. Rates of pneumothorax are between 0.5 and 6 %, and rates of chylothorax are estimated between 0.5 and 3 %, with no difference between minimally invasive and open repair [1719, 21, 23]. Reported incidence of residual flow in the duct ranges between 0.5 % and 6 % [1719, 21, 23], with a trend toward higher incidence in open repair that reaches statistical significance in some studies [17]. In contemporary series, conversion from thoracoscopic to open repair is between 0.5 and 4 %, with the most common cause reported to be poor exposure due to inability to retract the lung safely. Missed concurrent abnormalities are reported in less than 1 % of cases, with the most common abnormality being coarctation of the aorta [21, 23].

In the Johns Hopkins University series of 25 T-PDA ligations in very low-birth-weight infants, there have been no intraoperative deaths, 1 conversion to open procedure, 1 recurrent laryngeal nerve injury, and no other immediate morbidity.

Postoperative mortality approaches 15 % in some series, with the greatest risk factors being prematurity and low birth weight [14, 18, 23]. Sepsis is the leading cause of in-hospital death, frequently with associated necrotizing enterocolitis. Other causes are chronic respiratory disease and multisystem organ failure [14, 18, 23]. In our series we have had 3 deaths postoperatively all from sepsis related to NEC.


Conclusions


Thoracoscopic PDA ligation offers many of the advantages of a minimally invasive surgical approach that have been previously reported as well as a potential reduction in post thoracotomy scoliosis by avoiding rib spreading, muscular division, and minimization of the risk of nerve injury or rupture of intercostal ligaments. T-PDA ligation is effective and can be safely performed in very low-birth-weight infants. Exposure and magnification of important anatomic landmarks are superior compared to open techniques. This factor results in shorter operative time. In addition to the enhanced cosmesis, this minimally invasive approach may reduce postoperative pain, pulmonary morbidity, and the future incidence of chest wall and spine deformities in children.

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Oct 25, 2017 | Posted by in PEDIATRICS | Comments Off on Thoracoscopic Ligation of the Patent Ductus Arteriosus
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