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Ann Thorac Surg 2005;80:2309-2313
© 2005 The Society of Thoracic Surgeons

Original article: Cardiovascular

Totally Endoscopic Robotic-Assisted Repair of Patent Ductus Arteriosus and Vascular Ring in Children

Yoshihiro Suematsu, MD, PhD, Bassem N. Mora, MD, Tomislav Mihaljevic, MD, Pedro J. del Nido, MD *

Department of Cardiac Surgery, Children's Hospital and Harvard Medical School, Boston, Massachusetts

Accepted for publication May 20, 2005.

* Address correspondence to Dr del Nido, Department of Cardiac Surgery, Children's Hospital-Boston, 300 Longwood Ave, Boston, MA02115 (Email: pedro.delnido{at}tch.harvard.edu).

Presented at the Poster Session of the Forty-first Annual Meeting of The Society of Thoracic Surgeons, Tampa, FL, Jan 24–26, 2005.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 References
 
BACKGROUND: This study reports on our initial experience with robotically assisted patent ductus arteriosus (PDA) closure and vascular ring division in children.

METHODS: From April 2002 to May 2004, 15 patients underwent PDA closure (n = 9) and vascular ring repair (n = 6) by a totally endoscopic approach, utilizing the Da Vinci robotic system. The mean age of the patients was 8.3 ± 4.7 years (range, 3 to 18) and the mean weight, 35.5 ± 19.0 kg (range, 14.1 to 77.0 kg). Three thoracoscopic trocars were used to accommodate the endoscopic camera and two surgical instruments with an additional small incision for lung retraction. After dissection by the surgeon seated at the master console, PDA ligation with clips or division of the atretic arch and ductal ligament was performed.

RESULTS: Total operative times were 170 ± 46 minutes (PDA) and 167 ± 48 minutes (vascular ring). One patient with vascular ring was converted to thoracotomy because of dense adhesions due to previous surgery. Precise and easy surgical maneuver was possible with the articulated surgical instruments and three-dimensional visualization in 14 patients. Intraoperative transesophageal echocardiography confirmed no persistent shunt in all PDA patients. No laryngeal nerve injury and hemorrhage were noted. All patients were extubated in the operating room. Median length of postoperative hospital stay was 1.5 days.

CONCLUSIONS: Robotically assisted PDA closure and vascular ring division is a feasible and safe procedure. Future technologic improvement, including smaller instrument size and incorporation of tactile feedback, may permit application of this technique to even younger infants and intracardiac repairs.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 References
 
Over the past decade, a number of technologic advances, such as thoracoscopic instruments and high-resolution cameras, have allowed the development of minimally invasive techniques for cardiac surgery. The introduction of robotic surgical systems represents a further step in the evolution of endoscopic instrumentation. These computer-enhanced systems offer three-dimensional visualization and significantly improved instrumentation, with motion scaling and a wrist mechanism that allows surgeons to perform complex cardiac procedures, including coronary artery bypass, mitral and aortic valve replacement, and atrial septal defect closure, through small incisions in adult patients [1]. Although these specific advantages may also benefit pediatric patients, only a few reports of robotic repairs performed in children have been made. This report describes our initial experience with robotically assisted patent ductus arteriosus (PDA) closure and vascular ring division in children.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 References
 
Patients
The institution's Clinical Review Board approved the study, and written informed consent was obtained from each patient, parent, or guardian. Between April 2002 and May 2004, 20 patients with PDA or vascular ring defects were referred to a single surgeon (P.J.dN.) in the Department of Cardiac Surgery at the Children's Hospital-Boston, Harvard Medical School. Because of the size limitation imposed by the robotic system, our exclusion criteria for robotic surgery were an age of less than 24 months and a body weight of less than 14.0 kg. Among the 20 patients, 5 patients were excluded for one of the above reasons. As a result, 15 patients were enrolled in this study; endoscopic robotically assisted PDA closure was performed in 9 patients, and vascular ring repair was performed in 6 patients. The mean ages of the patients (PDA group and vascular ring group, respectively) were 7.2 ± 3.7 years and 9.9 ± 5.8 years. The mean weights were 30.7 ± 13.8 kg and 42.1 ± 24.6 kg, and and mean body surface areas, 0.99 ± 0.29 and 1.25 ± 0.51, respectively. Concomitant cardiac anomalies consisted of a small membranous ventricular septal defect in 1 patient (PDA), a small muscular ventricular septal defect in 1 patient (PDA), and 1 patient was postoperative tetralogy of Fallot repair (vascular ring). The ventricular septal defects of the 2 PDA patients were small, and surgical correction was not indicated at the time of the PDA operation.

All patients with PDA underwent a preoperative echocardiographic examination; the mean size of the PDA defects was 2.8 ± 0.6 mm (range, 2.0 to 3.5 mm). All patients with vascular rings presented with a history of recurrent upper respiratory tract infections or dysphagia, or both. Chest magnetic resonance imaging was performed in all patients; the presence of a vascular ring comprised of a right-sided aortic arch, an aberrant left subclavian artery, and a left-sided ligamentum was confirmed in 4 patients, and a double aortic arch with atretic segment of the left arch and persistent left ligamentum was confirmed in 2 patients.

Robotic Surgical System
The Da Vinci Surgical System (Intuitive Surgical, Sunnyvale, California) consists of two primary components: the surgeon's viewing and control console and the surgical arm unit that positions and maneuvers detachable surgical EndoWrist instruments. These pencil-sized instruments, which possess small mechanical wrists with 7 degrees of motion, are designed to provide the dexterity of the surgeon's forearm and wrist at the operative site through entry ports less than 1 cm in size. One port allows access for the endoscope, and the other two ports provide access for surgical instruments. The wrists of the surgical instruments mimic the motions made by the operating surgeon, who sits at a console away from the operating table. The surgeon peers through an eyepiece that provides high-definition, full-color, magnified three-dimensional images of the surgical site provided by the endoscope, and controls the instrument arms in real time by manipulating modified joysticks [2].

Surgical Technique
After general anesthesia and single-lumen endotracheal intubation with a bronchial blocker in the left mainstem brochus, the patients were positioned in a right lateral decubitus position (15 to 20 degrees, slightly prone) to allow easier retraction of the left lung and better visualization of the surgical field. Routine monitoring included transcutaneous oxygen saturation, continuous end-tidal carbon dioxide, blood pressure, and an electrocardiogram. Figure 1 shows an intraoperative photograph. The robotic surgical cart was positioned at the cranial end of the operating table, angled 30 degrees to the patient's left side [3]. Three thoracoscopic trocars were placed in the left hemithorax to accommodate the camera and the two robotic manipulators. The left and right instrument ports were placed in the third intercostals space along the anterior axillary line and in the posterior sixth intercostal space behind the scapula, respectively. The camera port was placed in the fifth intercostal space. An additional small utility incision was placed between the left instrument and camera incisions to allow insertion of a lung retractor. No chest wall muscles were divided, and the ribs were not retracted. After thoracoscopic verification of the anatomy, the camera was attached to the robotic cart, and the robotic surgical instruments were placed through the left and right trocars.



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  		Fig 1. Intraoperative photograph (cranial direction indicated by arrow. The left instrument port (L) was placed in the third intercostal space along the anterior axillary line, whereas the camera port (C) was placed in the fifth intercostal space, just anterior to the tip of the scapula. The right instrument port was placed in the posterior fifth intercostal space behind the scapula, with an additional small incision inferiorly for lung retraction.

 
The dissection was performed with the surgeon at the master console, located at a remote position from the operating table, and using a grasper in the left robotic arm and a hook-tip cautery at a low setting in the right robotic arm. For PDA ligation, the parietal pleura overlying the duct was opened and the crossing vein was divided. The upper and lower angles of the PDA were dissected free, taking care to protect the vagus and recurrent laryngeal nerves. One or two endoscopic vascular clips were placed to interrupt the PDA. Transesophegeal echocardiography was performed in the operating room to confirm the absence of residual ductal flow. For vascular ring defects, once the dissection of the atretic segment of the left arch and ductal ligamentum was completed, clips were placed at each end of these structures using a thoracoscopic clip applier. Division of the ligamentum and complete dissection of the fibrous bands along the esophagus were performed using robotic scissors. In both procedures, the left recurrent nerve was identified using an intrathoracic stimulating probe with electromyographic monitoring before and after the procedure [4].

A single chest tube was placed through the utility thoracostomy at the completion of the procedure. The lung was reexpanded, and the chest tube was removed in the operating room in the absence of air leaking or bleeding. A chest plain X-ray film was obtained before leaving the operating theater to confirm the absence of a pneumothorax. Patients were routinely extubated in the operating room. After recovery from anesthesia, the patients were transported to the general postoperative unit. A chest film was repeated the next morning, and the patient was discharged on postoperative day 1 in the absence of complications.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 References
 
Precise and easy surgical maneuver was possible using the articulated surgical instruments and three-dimensional visualization in 14 patients. Figure 2 shows intraoperative thoracoscopic views of a robot-assisted vascular ring division. The ligamentum was exposed, dissected from the esophagus, and endoscopic clips were applied proximally and distally. Finally, the ligamentum was divided, and the tracheal and esophageal compression was relieved.



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  		Fig 2. Intraoperative thoracoscopic views of a robot-assisted vascular ring division. (A) The arrows indicate the atretic left arch and ductal ligament being freely dissected from the esophagus. (B) Endoscopic clips were applied proximally and distally (arrows indicate atretic left arch and ductal ligament dissected from esophagus). (C) Finally, the atretic arch and ductal ligament were divided.

 
The mean total operative times were 170 ± 46 minutes for PDA and 167 ± 48 minutes for vascular ring. The mean total operative blood losses were 3.3 ± 8.3 mL and 20.0 ± 40.0 mL, respectively. One procedure in a patient with a vascular ring defect was converted to a thoracotomy owing to dense adhesions from previous surgery to correct tetralogy of Fallot. No difficulties were encountered in any of the patients. An intraoperative transesophageal echocardiogram confirmed the absence of a persistent shunt in each of the PDA patients.

All patients were extubated in the operating room. The mean lengths of the postoperative hospital stays were 1.0 ± 0 days for PDA and 2.2 ± 2.0 days for vascular ring (overall, 1.5 ± 1.4 days). No permanent laryngeal nerve injuries or postoperative hemorrhage were noted. Chylothorax and wound infections were not observed. One patient required percutaneous drainage of a pneumothorax on postoperative day 1. No midterm complications, including recurrence of ductal shunting and tracheal stenosis, were observed at a mean follow-up of 20.3 ± 8.8 months (range, 7 to 32).


   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
References
 
In the past decade, technical advances, including the evolution of endoscopic instruments and high-resolution cameras, have contributed to the widespread use of video-assisted endoscopic techniques [5, 6]. The introduction of robotic surgical systems, such as the Da Vinci system, represents a further step in endoscopic instrumentation. These computer-enhanced systems offer three-dimensional visualization and significantly improved instrumentation, with motion scaling and a wrist mechanism that allow the performance of fine microsurgical tasks using an endoscopic approach [7, 8].

In 1998, Carpentier and colleagues [9] reported the first series of cardiac surgeries in adults to be performed using a prototype of the current Da Vinci system to repair mitral valve defects. These operations were performed through small thoracotomy incisions. Subsequently, the performance of endoscopic robotic coronary operations was described the following year [10, 11], and robotically assisted total endoscopic cardiac surgery to repair atrial septal defects was reported by Torracca and coworkers [12] in 2001. Despite the increasing number of reports in adults, the clinical experience of Le Bret and colleagues [13] utilizing the Zeus robotic surgical system to correct PDA and Mihaljevic and coworkers [3] utilizing the DaVinci system for a vascular ring division are the only reports in children presently available.

Previously, Burke and Hannan [14] commented that the complexity of most congenital heart operations and the large size of current robotic systems had limited the use of this technology in pediatric heart surgery. Current three-dimensional endoscopes require a 10- to 12-mm port, while surgical instruments require a 5- to 8-mm port. Even with a stationary pivot point at the chest wall, ports of this size would essentially occupy the entire intercostal space of most small children. Furthermore, to avoid instrument conflicts, the port sites must be separated by a minimum distance of 4 to 6 cm, which would span a large portion of the chest cage [15]. Therefore, we excluded patients whose body weight was less than 14 kg from the robotic procedures performed in this study.

The present study demonstrated that endoscopic PDA closure and vascular ring division with robotically assisted instrumentation was technically feasible in children. Furthermore, dissection of the aorta, subclavian artery, and ductus or ligamentum were performed easily and safely using EndoWrist instruments, including an articulated grasper, a hook-up cautery on a low energy setting, and articulated scissors, with no laryngeal nerve injuries or hemorrhage. Enhanced intracorporeal dexterity, optimized hand-eye alignment, and tremor filtering made tissue handling and dissection easy and accurate. A previous study has commented on the learning curve for robotic surgery being shorter that that for endoscopic surgery [16]. More recently, Moorthy and associates [17] showed the presence of "wristed" instrumentation, tremor abolition, and motion scaling enhanced dexterity by nearly 50% as compared with endoscopic surgery, and three-dimensional vision enhanced dexterity by a further 10% to 15% in addition to the 93% reduction in skills-based errors. Therefore, we believe that robotic surgical systems offer significant advantages over the standard thoracoscopic approach, particularly in older children where tissue dissection and instrument manipulation is required over a greater area.

We have previously employed a new port-placement planning platform developed by our colleagues to identify the optimal locations for port placement for PDA closure and vascular ring division in children [18]. As a result, the left instrument port was placed in the third interspace along the anterior axillary line, whereas the camera port was placed in the fifth intercostal space and the right instrument port in the posterior sixth intercostal space behind the scapula. This setup, in addition to proper patient positioning, provided excellent exposure, with no internal or external instrument conflicts.

The total operative time was somewhat longer than that usually required for conventional thoracoscopic procedures, with the time required for positioning of the surgical cart and placement of the robotic arms accounting for the majority of the time difference. Patient recovery in this study was excellent, however, and the length of the postoperative hospital stay was not different from that for standard thoracoscopic procedures and was shorter than that for a conventional open thoracotomy approach.

There are limitations to the application of totally endoscopic robotically assisted surgery for congenital cardiac disease. The main limitation is the relatively large size of the robotic ports, as previously described. However, currently, we have limited experience with the 5-mm new instruments and using a 5-mm single-channel scope with the daVinci system in young infants and these instruments may permit application of robotic techniques to this younger age group. Current robotically assisted surgery in children is limited to extracardiac congenital disease. Intracardiac procedures require a cardiopulmonary bypass, which in small children requires central cannulation to avoid irreversible injury to femoral or neck vessels. The resultant crowded operative field may impede visualization of relevant intracardiac structures and potentially further complicate surgical repair. Future technological improvements, including smaller instrument size, incorporation of tactile feedback, and instrument tracking may permit application of this technique in younger infants with more complicated disease rather than PDA and vascular ring, and for intracardiac repairs. Additionally, intracardiac imaging, such as real-time three-dimensional echocardiography, may further expand the application of robotics in children [19, 20].

In conclusion, our initial experience demonstrates that robotically assisted PDA closure and vascular ring division in children are feasible and safe procedures, owing to the improved visualization and dexterous manipulation afforded by the surgical robotic system. Although proper patient selection and a longer total operation time are still required, increased experience and smaller instrument sizes, may permit the application of this technique in younger infants and for intracardiac repairs.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 References
 

  1. Nifong LW, Chu VF, Bailey BM, et al. Robotic mitral valve repairexperience with the da Vinci system. Ann Thorac Surg 2003;75:438-443.[Abstract/Free Full Text]
  2. Argenziano M, Oz MC, Kohmoto T, et al. Totally endoscopic atrial septal defect repair with robotic assistance Circulation 2003;108(Suppl 1):II191-II194.
  3. Mihaljevic T, Cannon JW, del Nido PJ. Robotically assisted division of a vascular ring in children J Thorac Cardiovasc Surg 2003;125:1163-1164.[Free Full Text]
  4. Odegard KC, Kirse DJ, del Nido PJ, et al. Intraoperative recurrent laryngeal nerve monitoring during video-assisted throracoscopic surgery for patent ductus arteriosus J Cardiothorac Vasc Anesth 2000;14:562-564.[Medline]
  5. Garcia-Ruiz A, Smedira NG, Loop FD, et al. Robotic surgical instruments for dexterity enhancement in thoracoscopic coronary artery bypass graft J Laparoendosc Adv Surg Tech A 1997;7:277-283.[Medline]
  6. Kavoussi LR, Moore RG, Adams JB, Partin AW. Comparison of robotic versus human laparoscopic camera control J Urol 1995;154:2134-2136.[Medline]
  7. Suematsu Y, del Nido PJ. Robotic pediatric cardiac surgery—present and future Am J Surg 2004;188(Suppl 1):98S-103S.[Medline]
  8. Park S, Howe R, Torchiana D. Virtual fixtures for robotic cardiac surgeryIn: Niessen W, Viergever M, editors. Medical image computing and computer-assisted intervention-MICCAI 2001. Lecture notes in computer science, October 14-17, 2001, Utrecht, The Netherlands. Berlin: Springer-Verlag; 2001. pp. 1419-1420.
  9. Carpentier A, Loulmet D, Aupecle B, et al. Computer assisted open heart surgery. First case operated on with success C R Acad Sci III 1998;321:437-442.[Medline]
  10. Reichenspurner H, Damiano RJ, Mack M, et al. Use of the voice-controlled and computer-assisted surgical system ZEUS for endoscopic coronary artery bypass grafting J Thorac Cardiovasc Surg 1999;118:11-16.[Abstract/Free Full Text]
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  12. Torracca L, Ismeno G, Alfieri O. Totally endoscopic computer-enhanced atrial septal defect closure in six patients Ann Thorac Surg 2001;72:1354-1357.[Abstract/Free Full Text]
  13. Le Bret E, Papadatos S, Folliguet T, et al. Interruption of patent ductus arteriosus in childrenrobotically assisted versus videothoracoscopic surgery. J Thorac Cardiovasc Surg 2002;123:973-976.[Abstract/Free Full Text]
  14. Burke RP, Hannan RL. Reducing the trauma of congenital heart surgery Surg Clin North Am 2000;80:1593-1605.[Medline]
  15. Cannon JW, Howe RD, Dupont PE, Triedman JK, Marx GR, del Nido PJ. Application of robotics in congenital cardiac surgery Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2003;6:72-83.[Medline]
  16. Yohannes P, Rotariu P, Pinto P, Smith AD, Lee BR. Comparison of robotic versus laparoscopic skillsis there a difference in the learning curve?. Urology 2002;60:39-45.
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