| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 1999;68:1555-1557
© 1999 The Society of Thoracic Surgeons
a Intuitive Surgical Inc, Mountain View, CA, USA
b Heart Center, University of Leipzig, Leipzig, Germany
Presented at Evolving Techniques and Technologies in Minimally Invasive Cardiac Surgery, San Antonio, TX, Jan 22–23, 1999.
Abstract
Background. Due to limited range of motion, endoscopic multivessel revascularization is difficult through a thoracic approach.
Methods. A computer-enhanced surgical telemanipulation system was used to perform transabdominal endoscopic grafting (TCAB) in an experimental cadaver model. After incising the membranous portion of the diaphragm, pericardium, and pleura, dissection of the left (n = 10) and right internal thoracic arteries (n = 5) was performed. Coronary anastomoses were performed remotely and unassisted. In an animal model the hemodynamic consequences of the approach were assessed.
Results. In all cadavers TCAB was achieved through three abdominal ports. Time for internal thoracic arteries harvest was 48 ± 13 minutes (left) and 39 ± 10 minutes (right). Intimal dissection was found in one graft. Time for anastomosis was 23 ± 9 minutes and 27 ± 10 minutes for the left anterior descending (n = 10) and right coronary artery (n = 5), respectively. All anastomoses were patent. Opening the diaphragm in living animals led to a decrease of systolic blood pressure by 30 ± 16 mm Hg, but resolved with appropriate treatment.
Conclusions. TCAB is possible in cadavers using computer-enhanced telemanipulation technology. The transabdominal approach is a promising access for less invasive cardiac surgery.
Endoscopic multivessel revascularization using a left thoracic approach is difficult to achieve. To optimize access to the left and right internal thoracic arteries (ITA), the left anterior descending (LAD), and right coronary artery (RCA) through a limited number of ports, a transabdominal transdiaphragmatic approach was evaluated. To assess the access route, to define the anatomical landmarks of the approach, and to demonstrate the feasibility of both ITA harvest and performance of an endoscopic coronary anastomosis, the study was performed in human cadavers. In addition, a live animal model was used to assess the hemodynamic alterations of a transabdominal approach that are caused by insufflation of both the abdomen and the thorax.
Material and methods
Cadaver study
Transabdominal endoscopic computer-enhanced myocardial revascularization was performed in ten human cadavers (four male, six female; height 167 ± 9 cm, weight 75 ± 8 kg). A Veress needle was inserted through the umbilicus and CO2 was insufflated up to an intraabdominal pressure of 14 mm Hg. A scope port was inserted midline above the umbilicus. Two ports were placed in the anterior axillary line above the anterior superior iliac spine. The surgical telemanipulation system (Intuitive Surgical, Mountain View, CA) was placed cephalad to the patient and instruments were inserted. The whole procedure was then performed remotely from the surgeon’s console. A T-shaped incision was made in the membranous portion of the diaphragm. The diaphragm was incised and the LAD and RCA were identified. After opening the pleura, dissection of the left ITA (n = 10) and right ITA (n = 5) was performed beginning at the distal end (6th rib) using electrocautery. Large side branches were clipped (Fig 1). An accessory port was created in the left chest to bring in suture material. After the site of the anastomosis was prepared, using blunt dissection, the arteriotomy of the target vessel was performed remotely from the console using a sharp blade and Potts-scissors. The coronary anastomoses were performed using a parachute technique using a 7-cm, 7-0 custom-made, double-armed Prolene suture, unassisted as described elsewhere [1]. The diaphragm was closed directly or using a pericardial patch. After the procedure, a sternotomy was made to check for ITA injury, anastomotic leakage and patency.
|
Telemanipulation system
The principles of remote surgery using a telemanipulation system to enhance dexterity and the basic features of the Intuitive Surgical telemanipulation system have been described in detail elsewhere [2, 3]. In brief, the system consists of a master console that connects to a surgical "manipulator" with two instrument arms and a central arm to guide the videoscope. The operator is in steady control of the system via a human-machine interface. Two "master" handles at the surgeon’s console are manipulated by the surgeon. All motions are translated to the end of the instrument by electronic actuators using a matrix transform based on Cartesian coordinates. The actuators drive steel cables that couple to the end-effectors, passive detachable instruments. By means of a mechanical wrist, the end-effectors provide a total of 6 degrees of freedom plus tool function (ie, grip). The tools used were 10 cm longer than the standard end-effectors used with the system, since larger distances had to be overcome using the transabdominal approach. It is possible to temporarily disconnect the slave from the master, enabling repositioning of the master within its workspace while the position of the instruments remains unchanged. This allows the operator to always work in the most favorable ergonomic position. The system aligns the video image such that the tips of the tools appear to extend from the master handles, which the user is holding with their hands, thus providing optimal hand-eye alignment. For this study, motion scaling was set to 3:1 (except for rotation) and tremor filtering (greater than 6 Hz) was applied preventing unintended motions. Custom-made, three-dimensional videoscopes using two 3-chip-CCD cameras (0 degree and 30 degree) were used.
Results
In all cadavers, computer-enhanced endoscopic conduit harvesting and bypass grafting was achieved through three abdominal ports. In three cases peritoneal adhesions after prior abdominal surgery had to be taken down with the system before entering the chest. This was accomplished without problems. Incision of the diaphragm was performed midline in the membranous portion in order to facilitate later closure. After the pericardium was entered the heart was exposed and the LAD and RCA were identified. The pleura was opened and the course of the ITAs was identified. Dissection was started by making two lateral incisions using cautery and then working from the distal to the proximal end using some traction by either the left or right tool and using blunt dissection or cautery. Side branches could be identified and cauterized without problems. Time for ITA harvest was 48 ± 13 minutes for the left and 39 ± 10 minutes for the right, respectively. Internal thoracic arteries harvest was complete (origin from the subclavian artery to 6th intercostal space) in 13 out of 15 cases (in one cadaver, instruments were not long enough to dissect the ITA beyond the second rib). In two cadavers, mechanical limitations were encountered due to collision of the instrument shaft at the costal margin when working beyond the second rib. The grafts were clipped distally and brought into the pericardium. Stay sutures were performed to approximate the pedicles close to the site of the anastomoses. To expose the right coronary artery, a traction suture was made from the surrounding fat to the roof of the pericardium, which was still intact, with the transabdominal approach. Time for dissection of the target vessel and arteriotomy was 8 ± 2 minutes for the LAD and 10 ± 3 minutes for the RCA, respectively. Time for anastomosis was 23 ± 9 minutes and 27 ± 10 minutes for the LAD and RCA, respectively. Macroscopic evaluation of the grafts demonstrated intimal dissection in one graft. Most likely this was caused by tissue fragility (3-day-old cadaver) and traction on the graft during dissection. All other grafts were patent for a 2-mm coronary probe and showed no pathology during macroscopic inspection. All anastomoses were patent. In two anastomoses, minor strictures were found (one LAD and one RCA anastomosis).
Opening the diaphragm in living animals led to a sudden increase of intrathoracic pressure resulting in a decrease of systolic blood pressure by 30 ± 16 mm Hg that was resolved with appropriate fluid loading. Blood pressure recovered after a period of 15 to 30 minutes. To maintain sufficient oxygenation, an increase in peak inspiratory pressure (PIP) was necessary. With insufflation of the abdomen, higher PIP was necessary (20–25 cm H2O). After opening of the diaphragm, PIP had to be increased to 25–30 cm H2O in order to compensate for the increased intrathoracic pressure. Peak expiratory flow positive end expiratory pressure (PEEP) was kept at 10 cm H20. Internal thoracic artery dissections could be performed both on the left and right using the same approach as described above for the cadavers. In addition to cautery, clips were applied, using the system to control side branches. In all animals, grafts of sufficient length could be harvested. Patency of the grafts was confirmed by cutting the distal end.
Comment
A number of studies have addressed the use of a telemanipulation system to enable endoscopic cardiac surgery [1, 2] and have documented the usefulness of such systems to enhance dexterity [4, 5]. Clinically, single-vessel endoscopic bypass grafting to the LAD has been successfully performed using robotic assistance. However, endoscopic multiple vessel grafting is difficult to achieve without entering both sides of the chest through a number of ports. Due to the rigidness of the chest and limited space through the intercostal spaces, mobility of endoscopic instruments is altered. When a telemanipulation system is used, collisions between the arms, or the telemanipulator, and the patient’s shoulder or hip can occur depending on the individual anatomy (ie, small chest). To overcome these limitations an alternative approach was chosen in this feasibility study. Theoretically, by entering through the abdomen, the range of motion for endoscopic instruments is increased. A larger triangle can be created which gives the different arms of a telemanipulation system additional workspace. Except for 2 patients, no mechanical limitations occurred. This study demonstrates that transabdominal double vessel grafting using both ITAs is possible in cadavers using computer-enhanced telemanipulation technology. Some of the cadavers had severely calcified coronary arteries which make the model more realistic than an animal model. However, management of bleeding problems as well as the hemodynamic consequences of CO2 insufflation of both the abdomen and the thorax needed to be evaluated in an animal model.
The animal results demonstrate that one should strive for adequate intravascular volume and excellent hemodynamic values before entering the chest. High PEEP levels are required to maintain sufficient oxygen saturation. Although treatment was not too difficult in the animals, the observed hemodynamic alterations may limit the use of a transabdominal approach in patients with reduced left ventricular function or critical coronary perfusion.
In conclusion, the transabdominal telemanipulator-assisted approach is a promising new access route for less invasive cardiac surgery and may allow endoscopic, double-vessel grafting using both ITAs. Close hemodynamic monitoring will be necessary in clinical trials.
Footnotes
1 Frederic H. Moll is Founder and Medical Director of Intuitive Surgical, Mountain View, CA. David J. Rosa is a Clinical Engineer employed by Intuitive Surgical, Mountain View, CA. 
References
This article has been cited by other articles:
|
|
 |
|
  A. W Susilo and A. P Schulz Totally Robotic Technique in Multivessel Coronary Disease -- Is it Possible? Asian Cardiovasc Thorac Ann, March 1, 2002; 10(1): 92 - 94. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. W. Mohr, V. Falk, A. Diegeler, T. Walther, J. F. Gummert, J. Bucerius, S. Jacobs, and R. Autschbach Computer-enhanced ""robotic"" cardiac surgery: Experience in 148 patients J. Thorac. Cardiovasc. Surg., May 1, 2001; 121(5): 842 - 853. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Byhahn, S. Mierdl, D. Meininger, G. Wimmer-Greinecker, G. Matheis, and K. Westphal Hemodynamics and gas exchange during carbon dioxide insufflation for totally endoscopic coronary artery bypass grafting Ann. Thorac. Surg., May 1, 2001; 71(5): 1496 - 1501. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Falk, A. Diegeler, T. Walther, J. Banusch, J. Brucerius, J. Raumans, R. Autschbach, and F. W. Mohr Total endoscopic computer enhanced coronary artery bypass grafting Eur. J. Cardiothorac. Surg., January 1, 2000; 17(1): 38 - 45. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
