Eur J Cardiothorac Surg 2007;32:573-576. doi:10.1016/j.ejcts.2007.06.026
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
Robotic-assisted closure of atrial septal defect under real-time three-dimensional echo guide: in vitro study
Yoshihiro Suematsua,*,
Bob Kiaiia,
Daniel T. Bainbridgea,
Pedro J. del Nidob,
Richard J. Novicka
a Division of Cardiac Surgery and Anesthesiology, University of Western Ontario, London, ON, Canada
b Department of Cardiac Surgery, Children's Hospital-Boston, Harvard Medical School, Boston, MA, USA
Received 28 February 2007;
received in revised form 5 June 2007;
accepted 11 June 2007.
* Corresponding author. Address: University of Tokyo Hospital, Department of Cardiothoracic Surgery, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. Tel.: +81 3 3815 5411; fax: +81 3 5684 3989. (Email: suematsu{at}tf7.so-net.ne.jp).
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Abstract
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Background: Several advances in robotic technology and imaging systems have enabled the broad application of minimally invasive techniques in cardiac surgery. We have previously demonstrated that real-time three-dimensional echocardiography (RT3DE) provided adequate imaging and anatomic detail to act as a sole guide for surgical task performance. In this study, we examined the feasibility of robotic-assisted RT3DE-guided repair of atrial septal defect (ASD) in an in vitro study. Materials and methods:
Exp. I: An RT3DE system with x4 matrix transducer (Sonos 7500, Philips Medical Systems, Andover, MA) was compared to two-dimensional echo (2DE) in the performance of common surgical tasks with the da Vinci Robotic Surgical System (Intuitive Surgical, Sunnyvale, CA). Completion times and deviation of suture from an echogenic target (mm) were measured. Exp. II: Porcine ASDs (n
= 10) were created and closed with robotic-assisted direct suturing in a water bath. During all experiments the operator was blinded to the target and operated only under ultrasonic guidance. Results: Compared to 2DE guidance, completion times improved by 70% (p
< 0.0001) and deviation of suture by the robotic system was significantly smaller (2DE: 4 ± 2 mm, 3DE: 0.2 ± 0.3 mm, p
= 0.0002) in RT3DE-guided tasks. RT3DE provided satisfactory images and sufficient anatomical detail for suturing. All surgical tasks were successfully performed with accuracy. Conclusions: These initial experiments demonstrate the feasibility of robotic-assisted direct closure of ASD under RT3DE guidance. An endoscopic port access approach may be possible with refinements in telemanipulator technology and further development of the transesophageal echo transducer.
Key Words: Robotic surgery • Real-time 3D echo • Atrial septal defect
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1. Introduction
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Intra-cardiac surgery has challenged surgeons and researchers since the pioneers of modern cardiac surgery first performed transatrial valvuloplasty [1,2] and closure of atrial septal defects (ASDs) in a beating heart. However, with the introduction of cardiopulmonary bypass (CPB), which allowed direct visualization of intracardiac structures, this approach became unpopular [3]. Nevertheless, CPB is widely recognized as having a number of adverse effects, including generation of microemboli and an inflammatory response associated with increased cytokine production and complement activation, which result in neurological dysfunction in adults and neurodevelopmental dysfunction in children [4,5].
Recently, real-time three-dimensional echocardiography (RT3DE) has been introduced to visualize the heart noninvasively without ECG or respiratory gating. This also has great potential for expanded application not only for diagnostic purposes but also for image-guided intervention. We first reported that RT3DE provides adequate imaging and anatomic detail to serve as the sole guide for the performance of surgical tasks. Real-time 3D echo-guided beating-heart ASD closure was feasible even in an animal model [6,7].
However, in our previous experiment, RT3DE-guided beating-heart surgery still required a median sternotomy because only conventional surgical endoscopic instruments were available. The advent of surgical robotic systems has enabled cardiac surgery to be performed with smaller incisions and without sternal or rib spreading. Indeed, many papers have already highlighted the lower invasiveness of the robotic system in the conduct of cardiac surgery [8,9].
The primary purpose of this study was to determine whether real-time 3D echo provides better image guidance than conventional 2D echo for surgical interventions using the da Vinci robotic system. The second purpose was to determine the feasibility of robotically assisted beating-heart ASD closure monitored by real-time 3D echo in an in vitro model.
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2. Materials and methods
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2.1 Echographic equipment
RT3DE was performed using the x4 matrix transducer on a Sonos 7500 system (Philips Medical Systems, Andover, MA). The transducer operates in a broadband 2–4 MHz range and scans a 3D volume by electronically steering the acoustic beam using a matrix of 
3000 transducer elements and associated electronics that allow scanning of a 64° x 64° pyramidal volume in real time at up to 28 frames per second. The Sonos 7500 base system volume renders the data in any viewing orientation desired, also at a 28 Hz frame rate. The orientation of the target object on the screen can be controlled with a roller ball. The image processing and rendering platform is based on a dual 2.2 GHz Pentium 4 processor PC, which supports multiple imaging modalities, including conventional B-mode 2D echo, 2D color flow Doppler imaging, biplanar 2D echo, and several real-time volume-rendering modes.
2.2 Custom tank
A custom tank was prepared for this study to evaluate surgical performance under simulated clinical image-guidance conditions. The tank consists of an acrylic reservoir covered by an opaque dome through which surgical instruments are inserted. Degassed double de-ionized H2O serves as the imaging medium inside the testing tank.
2.3 Robotic surgical system
The da Vinci surgical system 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 7 mm instruments, which possess small mechanical wrists with 7 degrees of freedom, are designed to provide the accuracy and 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 looks 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.
2.4 2DE versus RT3DE images for guiding surgical tasks
Because 2DE provides only limited spatial orientation data, its use for guiding interventional procedures has been limited to procedures in which a rigid tool can be maintained in the plane of the ultrasound image at all times [10]. To determine the potential applicability of RT3DE to guiding basic surgical tasks with the da Vinci robotic system, the following study was performed.
Titanium Clips (Weck hemoclip plus; Weck closure systems, NC) were applied with a small clip applier of the robotic system in the water-filled tank, guided by either 2DE or RT3DE performed by an experienced sonographer (n
= 10). The operator was blinded to the target and operated only under ultrasonic guidance. Task completion time and deviation of the clip from an echogenic target (mm) were measured.
2.5 Ex vivo ASD closure
The surfaces of all instruments were coated with polyvinyl acetal glue to prevent echo artifact. The operator was again blinded to the target during the experiment and operated only under ultrasonic guidance, the same as in the above tank study. The intraatrial septa from 10 slaughterhouse pig hearts were mounted in the water tank, and the septum secundum regions were excised to create an ASD (0.8–2.0 mm). All 10 defects were closed with running sutures with the da Vinci robotic surgical system (Fig. 1
). After completion of the procedure, suture placement was assessed and accuracy quantified.
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Fig. 1. Experimental setting in a custom tank. Arrow indicates mounted intra-atrial septa from pig hearts.
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2.6 Statistical analysis
Statistical analysis was performed using the Stat View (Version 5) software package (SAS Institute Inc., NC, USA). Data are expressed as means ± standard deviations. The comparison between 2DE and RT3DE images for guiding surgical tasks was analyzed by the Student's t-test.
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3. Results
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3.1 2DE versus RT3DE images for guiding surgical tasks
Compared to 2DE guidance, task completion times improved 70% (62 ± 19 s vs 18 ± 7 s, p
< 0.001) with RT3DE. The spatial orientation of the echogenic target and clipping devices was more easily observed by RT3DE. The deviation of the stapler from the echogenic target was significantly smaller with RT3DE guidance than 2DE guidance (4 ± 2 mm vs 0.2 ± 0.3 mm, p
= 0.0002).
3.2 Ex vivo ASD closure
Representative echo images of da Vinci arms and needles are shown in Fig. 2
. The best images were obtained with the ultrasonic transducer at distances of 3–5 cm from the target. The echo shadows produced on the surface of the atrial septum tissue by the instruments were found to be useful for recognizing the distance from the target even on the 2D-rendered image of the echo system. Video 1 demonstrates a representative movie of closure of ASD. The spatial orientation of the ASD, the atrial septal tissue, and the needle tip, as well as the suture, was easily recognized by RT3DE (Fig. 3
). Surgical maneuvers could be performed precisely from multiple angle views (Fig. 4
). The needles consistently penetrated the ASD tissue approximately 3–4 mm from the free edge of the tissue margin. All ASDs were successfully closed (Fig. 5
). No collateral tissue injuries were observed with this method.
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Fig. 2. Real-time three-dimensional echocardiographic (RT3DE) images, showing da Vinci arms (a) and needle (b). For better comprehension, the da Vinci arms and needle are colored light purple and green, respectively.
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Fig. 3. Real-time three-dimensional echocardiographic (RT3DE) images, showing da Vinci arm and needle from different angles (a, b). For better comprehension, the da Vinci arms and needle are colored light purple and green, respectively.
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Fig. 4. Real-time three-dimensional echocardiographic (RT3DE) images, showing needle penetrating atrial tissue (a) and thread (b). For better comprehension, needle is colored light green.
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4. Discussion
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Recently, robotically assisted surgical systems have been introduced to increase the precision of endoscopic surgery and facilitate minimally invasive cardiac surgery. Totally endoscopic, robotically assisted cardiac surgical procedures for the repair of ASD have been reported by some surgeons [11–13]. However, these robotically assisted intra-cardiac surgical procedures still require a cardiopulmonary bypass.
A variety of three-dimensional echocardiography systems has been developed during the past decade, and they provide clinicians and surgeons with new perspectives for visualizing the heart [14,15]. RT3DE, in particular, provides real-time visualization of the heart non-invasively without electrocardiographic or respiratory gating, because all planes are imaged simultaneously [16]. Accordingly, we used this new system as the sole guiding method to generate images with sufficient spatial and temporal resolution for heart surgery.
The RT3DE system used by us consists of a novel transducer and a customized image processing and rendering platform. The image of the target object on the screen can be easily manipulated and the operator can view the target from any angle without moving the imaging transducer. The accurate positioning of surgical instruments enabled by these features was confirmed by using multiple views in our tank study.
Downing et al. demonstrated beating-heart mitral valve suturing under 2D echocardiographic guidance [17]. However, with 2D imaging guidance alone, it may not be possible to perform complex surgical interventions since spatial relationships cannot be assessed instantaneously. In addition, obtaining favorable images in which both the target tissue and the surgical device can be monitored simultaneously is time-consuming, making it impractical to use this modality for real-time guidance. Other investigators have reported that despite the lower temporal and spatial resolution, as compared to conventional 2D images, operating under 3D echo guidance was superior to 2D for navigation [18]. The results of our study show that, compared with 2DE guidance, completion times significantly improved 70%, and clip deviation was significantly smaller in the RT3DE-guided tasks using the robotic system. We, therefore, consider the RT3DE to allow the ‘surgeon's view’ to be obtained in real-time and to allow the surgeon to perform surgical interventions in the same manner as endoscopic surgery.
4.1 Study limitations
Our RT3DE system provided adequate intra-operative images overall as an image-guided technology, but the spatial resolution of the RT3DE still needs optimization to advance from simulation into a clinical setting. In addition, the transducer is too large to be able to apply it directly to the heart through a small incision, since the operating field of instruments is restricted. Therefore, further technological development of the RT3DE system, such as the design of a high-frequency mini-transducer or transesophageal transducer, will probably be necessary to make minimally invasive RT3DE-guided robotic-assisted closure of ASD possible.
In summary, the in vitro results illustrated that RT3DE provides adequate imaging and anatomic detail to serve as the sole guide for the performance of surgical tasks. Also, these initial experiments demonstrate the feasibility of robotic-assisted direct closure of ASD under RT3DE guidance.
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Appendix A
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Supplementary data
Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ejcts.2007.06.026.
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References
|
|---|
- Harken DE, Ellis LB, Ware PF. The surgical treatment of mitral stenosis: valvuloplasty. N Engl J Med 1948;239:801-809.[Medline]
- Bailey CP. The surgical treatment of mitral stenosis (mitral commissurotomy). Dis Chest 1949;15:377-397.[CrossRef][Medline]
- Gibbon Jr. JH. Application of a mechanical heart and lung apparatus to cardiac surgery. Minn Med 1954:171.
- Zeitlhofer J, Asenbaum S, Spiss C, Wimmer A, Mayr N, Wolner E, Deecke L. Central nervous system function after cardiopulmonary bypass. Eur Heart J 1993;14:885-890.[Abstract/Free Full Text]
- Bellinger DC, Wypij D, Kuban KC, Rappaport LA, Hickey PR, Wernovsky G, Jonas RA, Newburger JW. Developmental and neurological status of children at 4 years of age after heart surgery with hypothermic circulatory arrest or low-flow cardiopulmonary bypass. Circulation 1999;100:526-532.[Abstract/Free Full Text]
- Suematsu Y, Marx GR, Stoll JA, DuPont PE, Cleveland RO, Howe RD, Triedman JK, Mihaljevic T, Mora BN, Savord BJ, Salgo IS, del Nido PJ. Three-dimensional echocardiography-guided beating-heart surgery without cardiopulmonary bypass: a feasibility study. J Thorac Cardiovasc Surg 2004;128:579-587.[Abstract/Free Full Text]
- Suematsu Y, Martinez JF, Wolf BK, Marx GR, Stoll JA, DuPont PE, Howe RD, Triedman JK, del Nido PJ. Three-dimensional echo-guided beating heart surgery without cardiopulmonary bypass: atrial septal defect closure in a swine model. J Thorac Cardiovasc Surg 2005;130:1348-1357.[Abstract/Free Full Text]
- Kypson AP, Chitwood WR. Robotic cardiovascular surgery. Expert Rev Med Devices 2006;3(3):335-343.[CrossRef][Medline]
- Rayman R. Robot-assisted cardiac surgery. Semin Laparosc Surg 2004;11:73-79.[Medline]
- McGahan JP, Anderson MW. Pulsed Doppler sonography as an aid in ultrasound-guided aspiration biopsy. Gastrointest Radiol 1987;12:279-284.[CrossRef][Medline]
- Dogan S, Aybek T, Khan MF, Kessler P, Mierdl S, Kleine P, Moritz A, Wimmer-Greinecker G. Computer-enhanced telemanipulation enables a variety of totally endoscopic cardiac procedures. Thorac Cardiovasc Surg 2002;50:281-286.[CrossRef][Medline]
- Torracca L, Ismeno G, Quarti A, Alfieri O. Totally endoscopic atrial septal defect closure with a robotic system: experience with seven cases. Heart Surg Forum 2002;5:125-127.[Medline]
- Bonaros N, Schachner T, Oehlinger A, Jonetzko P, Mueller S, Moes N, Kolbitsch C, Mair P, Putz G, Laufer G, Bonatti J. Experience on the way to totally endoscopic atrial septal defect repair. Heart Surg Forum 2004;7:E440-E445.[Medline]
- Takuma S, Cardinale C, Homma S. Real-time three-dimensional stress echocardiography: a review of current applications. Echocardiography 2000;17:791-794.[Medline]
- Lange A, Palka P, Burstow DJ, Godman MJ. Three-dimensional echocardiography: historical development and current applications. J Am Soc Echocardiogr 2001;14:403-412.[CrossRef][Medline]
- Sugeng L, Weinert L, Thiele K, Lang RM. Real-time three-dimensional echocardiography using a novel matrix array transducer. Echocardiography 2003;20:623-635.[CrossRef][Medline]
- Downing SW, Herzog Jr. WA, McLaughlin JS, Gilbert TP. Beating-heart mitral valve surgery: preliminary model and methodology. J Thorac Cardiovasc Surg 2002;123:1141-1146.[Abstract/Free Full Text]
- Cannon JW, Stoll JA, Salgo IS, Knowles HB, Howe RD, Dupont PE, Marx GR, del Nido PJ. Real-time three-dimensional ultrasound for guiding surgical tasks. Comput Aided Surg 2003;8:82-90.[Medline]
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Abstract
1. Introduction
