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Ann Thorac Surg 2006;82:624-628
© 2006 The Society of Thoracic Surgeons
a Department of Surgery, London Health Science Center, The University of Western Ontario, London, Ontario, Canada
b Department of Epidemiology and Biostatistics, London Health Science Center, The University of Western Ontario, London, Ontario, Canada
c Department of Anesthesia and Perioperative Care, London Health Science Center, The University of Western Ontario, London, Ontario, Canada
d Department of Medicine, London Health Science Center, The University of Western Ontario, London, Ontario, Canada
e Department of Cardiothoracic Surgery, Cleveland Clinic Florida, Weston, Florida
Accepted for publication March 7, 2006.
* Address correspondence to Dr Kiaii, London Health Science Center, University Campus, 339 Windermere Road, London, Ontario, Canada N6A-5A5 (Email: bob.kiaii{at}lhsc.on.ca).
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Abstract |
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METHODS: One hundred and fifty consecutive patients with single vessel coronary artery disease were prospectively studied. The left internal thoracic artery was harvested using three different approaches, with 50 patients consecutively assigned to each group. The off-pump coronary artery bypass (OPCAB) group underwent median sternotomy with direct visualization. The automated endoscopic system for optimal positioning (AESOP) group employed the AESOP 3000 system (Computer Motion Inc, Goleta, CA) for robotic-assisted visualization with endoscopic manual left internal thoracic artery harvesting. The Zeus group used the Zeus robotic telesurgical system (Computer Motion Inc) and internal thoracic artery harvesting was performed remotely from a surgical console. Postanastomotic left internal thoracic artery flows and day one postoperative angiography were used to assess internal thoracic artery quality and patency.
RESULTS: Average left internal thoracic artery harvest times were 23 ± 2.5, 63.3 ± 20.3, and 66.1 ± 17.9 minutes in the OPCAB, AESOP, and Zeus groups, respectively (p < 0.001, OPCAB vs AESOP and Zeus). Intraoperative graft flows averaged 28.1 ± 11.9, 33.7 ± 19.3, and 36.9 ± 24.6 mL/minute, respectively in the OPCAB, AESOP, and Zeus groups (p = 0.317, OPCAB vs AESOP and Zeus). There was no significant angiographic difference in the patency rate of the harvested left internal thoracic arteries in the three groups (p = 0.685, overall).
CONCLUSIONS: The left internal thoracic artery can be harvested safely and effectively using minimally invasive videoscopic and robotic-assisted telesurgical techniques. Although the less invasive approaches require specialized equipment and training as well as increased operative time, they offer the potential for less traumatic myocardial revascularization through smaller incisions and reduced postoperative morbidity.
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Introduction |
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The purpose of this paper was to compare the quality of LITA harvested by the conventional open sternotomy technique versus manual endoscopic technique using a single-arm robot (the automated endoscopic system for optimal positioning [AESOP; Computer Motion Inc, Goleta, CA]) and remote telesurgical endoscopic technique using a multiarm robotic telemanipulator system (Zeus) (Computer Motion Inc).
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Material and Methods |
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The patients in the OPCAB group had a midline sternotomy performed. The LITA was dissected from the first rib to the sixth rib as a pedicle under direct visualization using low voltage electrocautery and surgical clips. Dissection of the LITA was usually started distally with progression of the dissection toward the first rib. Once the LITA pedicle was completely free from the surrounding tissue it was ligated distally and divided after systemic heparinization. The single coronary artery bypass (LITA to LAD) was performed using the off-pump technique through the sternotomy.
The robotic system used in the AESOP group was the automated endoscope system for optimal positioning (AESOP 3000, Computer Motion Inc). The AESOP 3000 is a voice-activated single robotic arm capable of positioning an endoscope in response to verbal commands from a surgeon. In 50 patients, the AESOP 3000 robotic surgical assistant was positioned on the operating table directly opposite the proposed camera port-access site. Thoracoscopic LITA harvest was performed using three 5 mm incisions. A 5 mm 30-degree video thoracoscope was first placed through an insufflation port in the fifth intercostal space in the anterior axillary line and adapted to the robotic arm. The harmonic scalpel was then inserted through a 5 mm stab incision in the third intercostal space in the mid to anterior axillary line. A third 5 mm incision was made in the sixth intercostal space in the anterior axillary or lateral clavicular line for a Kittner dissector (Ethicon Endo-Surgery). During the procedure, warm CO2 was insufflated into the pleural cavity to a pressure of 5 to 10 mm Hg. A Veress needle was inserted near the camera port and vented under suction when higher CO2 flows were used to clear intrathoracic vapor created by the harmonic scalpel. The LITA was identified and dissected thoracoscopically as a pedicle from the first to sixth rib with voice-activated robotic and video assistance using the harmonic scalpel as described previously [2]. When the dissection reached the fifth or sixth intercostal space, it was sometimes necessary to change the harmonic scalpel to a lower interspace through the same skin incision because of excessive torque and limitations to maneuverability by the soft tissues, shoulder, and ribs. Occasionally it was necessary to interchange the harmonic scalpel and the Kittner sites to complete the dissection distally.
The Zeus robotic system (Computer Motion Inc) used in the other 50 patients has three robotic arms. One arm, the voice-activated robotic assistant (AESOP 3000; Computer Motion Inc) was positioned on the right side of the operating table directly opposite the proposed camera port-access site. The other two robotic arms were the right and left arms used for positioning the end-effectors. The right arm was mounted opposite the patient's head and the left arm mounted at the level of the patient's mid thigh on the left side of the operating table. Telesurgical thoracoscopic LITA harvesting was performed using three 5 mm incisions. A 5 mm 30-degree video thoracoscope was first placed through an insufflation port in the fifth intercostal space in the mid-to-anterior axillary line and adapted to the voice-activated robotic arm. In the third intercostal space in the mid-to-anterior axillary line a second 5 mm port was inserted for the harmonic scalpel. The harmonic scalpel was then attached to the right robotic arm. A third 5 mm port was placed in the sixth or seventh intercostal space in the mid-to-anterior axillary line for a Kittner dissector, which was adapted to the left robotic arm. The surgeon, seated at the console away from the operating table, performed the harvest by controlling the endoscope with voice commands and the instruments with handles that resemble conventional surgical instruments. The LITA was then harvested as a pedicle from the first to sixth rib in a similar fashion as described above using the straight hook blade of the harmonic scalpel. Occasionally it was necessary to interchange the harmonic scalpel and the Kittner sites to complete the dissection.
In the AESOP and Zeus group the patients had their single vessel bypass (LITA to LAD) performed through a small minithoracotomy using the off-pump technique.
The patencies of all LITAs were checked by demonstrating adequate flow and good diastolic waveform of each conduit with a transit time ultrasound flow probe (Transonic Systems, Ithaca, NY). Postoperative angiography was performed on the first postoperative day.
Statistical Analysis
Results are illustrated as mean ± standard deviation for continuous variables and as percentages for categoric variables. Comparisons of data were made using analysis of variance with the Tuckey or Bonferonni post-hoc tests for continuous variables and the Fisher exact test or Pearson 
2 test for categoric variables.
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Results |
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Endoscopic LITA harvesting resulted in longer harvest times, but was associated with shorter length of stay in-hospital (Table 2) and reduced postoperative morbidity (Table 3). Intraoperative LITA flows of the endoscopically harvested LITA groups were not significantly different (Table 2). Postoperative angiography demonstrated no difference in the patency rates of the LITA conduit in the OPCAB group compared with the AESOP and Zeus groups that was of statistical significance (Table 2). There was also no angiographic evidence of stenosis or injury in the LITA pedicles harvested endoscopically when compared with those conduits harvested with the open technique.
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There were no deaths or perioperative myocardial infarctions in this series. More patients developed atrial fibrillation postoperatively in the OPCAB group than in either the AESOP or Zeus groups. The OPCAB group who had sternotomy performed had more incidence of superficial wound infection compared with the other two groups who had minianterior thoracotomy.
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Comment |
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In this series of patients we have demonstrated that the quality of LITAs harvested using endoscopic technique are equivalent to those harvested through a conventional median sternotomy approach. The LITAs all had sufficient length for anastomosis. Postoperative angiographic patency was not significantly different among the three study groups.
Successful application of robot assistance to thoracoscopic LITA harvesting involves attention to several technical details, as previously described [1, 7]. Because of the concern regarding potential thermal injury with the use of diathermy as the method of hemostatic control of collateral branches during dissection of the LITA, our group adopted the harmonic scalpel for thoracoscopic conduit harvesting. In our experience and those of others [2, 7], the harmonic scalpel has been proven to be a safe and efficacious tool as it operates at a lower temperature than diathermy and does not require instrument transfer to control even large side branches.
When using the Zeus telesurgical system to perform the LITA dissection, robotic indexing allowed the operating surgeon to maintain a comfortable and ergonomic arm position while sitting at the console [9]. Moreover, robotic telemanipulation facilitates the training of this technique as it allows the mentor teaching the technique to stand over the shoulder of the trainee, guiding him or her through the procedure while viewing the same picture. Hand motions with the telepresence surgical system are more natural and mimic the hand motions of the open technique, which shortens the learning curve of totally thoracoscopic LITA harvesting. Surgical endoscopic skills learned from prior experience of harvesting LITAs with a voice-controlled robotic endoscope positioner (AESOP 3000) and the harmonic scalpel using manual techniques [2] greatly facilitated the transition to telerobotic LITA harvesting.
Remote robotic telesurgery can also have potential limitations. It presently lacks the haptic feedback, which is present in the open method. Although haptic sensation is somewhat reduced in video-enhanced procedures using conventional endoscopic instruments, the operator has to rely solely on visual cues when performing telepresence surgery. Another technical problem occasionally encountered with computer-aided LITA harvesting is that of robotic end-effector singularity. This mechanical loss of dexterity usually occurs at the distal extreme of dissection in patients with limited anteroposterior diameter. An ideal visualization system would allow a three-dimensional view at high resolution. Such a visualization system has been developed. The three-dimensional visualization system along with the wrist-enabled end-effector characteristic of the da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA) can further facilitate the endoscopic ITA harvesting and the transition from manual endoscopic procedures to robotically assisted endoscopic procedures
In conclusion, LITA harvest can be performed safely and effectively using minimally invasive videoscopic and telesurgical techniques. The quality and patency of the arterial conduit is not compromised. The use of robotic assistance and the harmonic scalpel greatly facilitates thoracoscopic LITA harvesting. Although the less invasive approaches require specialized equipment and training, as well as increased operating time, they offer the potential for less traumatic myocardial revascularization through smaller incisions. These techniques are the first in a series of important steps in the development of a totally endoscopic coronary bypass procedure. More importantly, these techniques are helping cardiac surgeons learn a new surgical skill set, which is essential in the quest for less traumatic surgical revascularization. This study demonstrates that these less-invasive approaches can reduce postoperative morbidity, and improve outcome in select patients undergoing coronary artery bypass grafting.
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