Ann Thorac Surg 2007;84:1724-1727. doi:10.1016/j.athoracsur.2007.04.045
© 2007 The Society of Thoracic Surgeons
New Technology
Catheter-Based Endoscopic Bypass Grafting: An Experimental Feasibility Study
Stephan Jacobs, MDa,*,
David Holzhey, MDa,
Hubert Stein, BS, BMEb,
Friedrich W. Mohr, MD, PhDa,
Volkmar Falk, MD, PhDa
a Department of Cardiac Surgery, Heartcenter, University of Leipzig, Leipzig, Germany
b Department of Clinical Development Engineering, Intuitive Surgical, Sunnyvale, California
Accepted for publication April 13, 2007.
* Address correspondence to Dr Jacobs, Klinik für Herzchirurgie, Universität Leipzig, Herzzentrum, Strümpelstrasse 39, Leipzig, 04289, Germany (Email: stjacobs{at}aol.com).
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Abstract
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Purpose: Construction of an endoscopic catheter-guided, bonded anastomosis to facilitate total endoscopic coronary artery bypass.
Description: Total endoscopic coronary artery bypass of the left internal thoracic artery to the left anterior descending coronary artery was performed on the beating heart in six pigs using a telemanipulation system. An angioplasty catheter was advanced through the left internal thoracic artery to stabilize the anastomotic site. The anastomosis was created by applying glue externally to the surrounding tissue of the left internal thoracic artery and the left anterior descending coronary artery while it was kept open by an inflated angioplasty catheter.
Evaluation: Angiography and catheter placement at the graft site was performed in 12 minutes (10 to 28 minutes). The anastomotic constructions were easily accomplished in 3.5 minutes (2 to 4.5 minutes). The adverse events that were encountered were anastomotic leakage requiring additional glue and left anterior descending artery dissection due to the guidewire. All except one animal with an open graft and anastomosis survived the procedure. Patency was 5 of 6.
Conclusions: Catheter-based endoscopic bypass grafting is feasible. The combination of robotic technology and this simple technique for anastomotic construction may facilitate beating heart total endoscopic coronary artery bypass.
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Technology
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Performing a coronary anastomosis endoscopically remains technically challenging. A number of devices have been developed to facilitate construction of a distal graft to coronary anastomosis, most of which can not be used in an endoscopic environment [1, 2]. Very few anastomotic couplers have been applied in an endoscopic setting [3], but due to nonmedical reasons they have never made it into clinical practice.
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Technique
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Bypass grafting of the left anterior descending coronary artery (LAD) using the internal thoracic artery provides excellent long-term patency and better outcomes than percutaneous transluminal coronary angioplasty using stents [4–6]. In an effort to evaluate the potential effect of a simple, cost and time-effective technique to facilitate endoscopic bypass grafting, an endoscopic beating heart porcine study was performed using a catheter-guided, bonded construction of a distal graft to coronary anastomosis.
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Clinical Experience
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Patients
An approval of the study was made by the governmental office (Regierungspräsidium). Six pigs (range, 30 to 35 kg) were operated on after induction with ketamine (10 mg/kg intravenously) and diazepam (0.5 mg/kg intravenously) for endotracheal intubation. Inhalation anesthesia was maintained with isoflurane 1.5% to 2.5%. Amiodarone (150 mg) was given to prevent arrhythmias. An arterial line was placed in the left femoral artery, a 6-French guiding catheter in the right femoral artery, and a central venous line was placed in the right jugular vein. Monitoring included electrocardiogram, arterial blood pressure, central venous pressure, and oxygen saturation. A sternotomy was chosen for the surgical approach because there is less intrathoracic space in pigs. Heparin (100 units/kg) was administered intravenously and the activated clotting time was kept above 300 seconds. The procedure was performed off-pump on the beating heart. A handsewn anastomosis to the distal LAD was performed with the right internal thoracic artery in advance to avoid ventricular arrhythmia during proximal occlusion of the LAD. Except for the distal right internal mammary artery to LAD anastomosis, the entire operation was performed using the telemanipulation system (daVinci Surgical System [Intuitive Surgical Inc, Mountain View, CA). A vacuum-assisted endoscopic stabilizer with an irrigation channel (Intuitive Surgical Inc) was used.
The left internal thoracic artery (LITA) was harvested and the distal segment was skeletonized. The internal thoracic artery (ITA) was temporarily occluded using a vascular occluder (Scanlan, St. Paul, MN) and the distal end was clipped. Angiography of the left internal mammary artery was performed and the percutaneous transluminal coronary angiography (PTCA) balloon catheter (Monorail Maverick 4.0 mm x 20 mm PTCA Dilatation Catheter; Boston Scientific, Natick, MA) was advanced from the femoral artery into the proximal portion of the LITA. A sharp arteriotomy of 1.5 mm was made in the distal portion of the ITA and the distal end of the PTCA balloon catheter was passed forward through the arteriotomy.
The target site (mid-portion of the LAD after the first diagonal branch) was then immobilized by the vacuum-assisted stabilizer. The LAD was occluded proximally and distally to the anastomotic site using two self-locking silastic tapes. A 1.5-mm arteriotomy was made in the LAD. The distal end of the PTCA balloon catheter was placed into the LAD with a length of 15 mm after release of the distal occlusion tape (Fig 1). Two stay sutures were performed to fix the ITA pedicle to the epicardium at the anastomotic site. Connection of the coronary anastomosis was achieved by gluing the surrounding tissue (BioGlue [CryoLife Inc, Kennesaw, GA]) of the LITA to the LAD while the anastomosis was stabilized and dilated by the inflated PTCA balloon catheter. Inadvertent injection of glue into the anastomosis was prevented by keeping the balloon inflated until curing of the glue was completed. After 2 minutes the catheter was deflated and pulled back into the proximal portion of the LITA. To control and confirm the quality of the side-to-side (functional end-to-side) anastomosis, an angiography was performed while the proximal silastic occlusion tape was still in place (Fig 2). After 1 hour, all animals except one underwent a second angiography after which they were sacrificed (Fig 3). Postmortem gross inspection of the anastomotic site was performed after excision of the hearts.
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Fig 1. Bypass placement with the distal end of the internal thoracic artery to the left anterior descending coronary artery. The proximal occlusion tape and the endoscopic stabilizer are still in place.
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Fig 2. Open side-to-side (functional end-to-side) anastomosis, confirmed by angiography while the proximal silastic occlusion tape is still in place.
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All animals received humane care in compliance with the "Principles of Laboratory Animal Care" formulated by the National Society of Medical Research and the "Guide for the Care and Use of Laboratory Animals" prepared by the Institute of Laboratory Animal resources and published by the National Institutes of Health (NIH Publication No. 85-23, revised 1985). All data are presented as median and range.
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Results
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The procedure was accomplished in all animals in 129 minutes (range, 101 to 182 minutes). The distal right internal mammary artery to the LAD anastomosis on the beating heart including right internal mammary artery takedown was completed in 34 minutes (range, 29 to 44 minutes). The left ITA takedown was completed in 42 minutes (range, 32 to 50 minutes). Then the angiography and catheter placement in the proximal portion of the LITA (12 minutes; range, 10 to 28 minutes) was performed. Positioning of the stabilizer (4.5 minutes; range, 3 to 7.5 minutes), the LAD dissection using a blunt knife (4.5 minutes; range, 2 to 7 minutes), and placement of the silastic occlusion tapes proximally and distally of the target site (4.3 minutes; range, 3 to 7 minutes) were achieved without problems. Passage of the PTCA balloon catheter through the arteriotomy of the LITA was accomplished in 5.3 minutes (range, 3.4 to 7.3 minutes).
Placement of the balloon catheter into the LAD and gluing was achieved in 3.5 minutes (range, 2.2 to 4.5 minutes). In the first animal the guidewire caused a dissection of the LAD. As a consequence the PTCA balloon catheter was placed into the LAD without a guidewire, only by using the endoscopic instruments. In animal three there was not enough tissue caught between the graft and target vessel tissue, which caused leakage on reperfusion that required another dose of BoiGlue (CryoLife Inc). Angiographic data and the results of gross inspection of the anastomosis are summarized in Table 1. All the animals survived except for one, which died from ventricular fibrillation during performance of the anastomosis (ie, animal five). Postmortem angiography of animal five revealed an open anastomosis.
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Comment
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This study demonstrates the feasibility of using an endoscopic beating heart bypass procedure with a catheter-guided, bonded construction for the distal anastomosis. In all animals an anastomosis could be created on the beating heart, which saved anastomotic time in comparison with robotically sutured anastomosis [7, 8]. The connection of the anastomosis through a catheter and glue eliminates some of the problems associated with endoscopic suturing. Creation of an ideal-sized incision in the graft and coronary remains challenging, as an anastomosis that is too wide can cause leakage or penetration of glue into the anastomosis. A standardized incision tool may help to overcome this problem. In this study, one animal required a second dose of BioGlue to close a leakage due to incomplete tissue capture between the graft and the coronary artery. The use of the BioGlue for the anastomotic connection is certainly very simple but critical. Repair of the anastomosis (once the glue is cured) is almost impossible without collateral damage to the vessels. On the other hand, at completion of the anastomosis and retraction of the catheter it is possible to obtain immediate completion angiography, assuring the adequacy of the anastomosis before closure.
Due to the lack of any foreign material within the anastomosis, the glued anastomosis has the potential to minimize the blood exposed nonintimal surface and showed no evidence of thrombus in the acute phase. Cannulation of the ITA and the LAD may theoretically have the disadvantage of intimal injury rendering it to have less quality than if it were not manipulated from within. As we have no long-term follow-up we cannot state whether intimal hyperplasia of the ITA will become a significant problem. Vessel spasm after catheter manipulation of the LITA is a problem that has been infrequently reported, but was not observed.
Placement of the balloon catheter was achieved with robotic instruments during angiography. The robotic technology allowing for dexterous manipulation in a closed chest environment has helped to overcome difficulties of catheter manipulation and anastomosis construction in regard to the study by Soulez and colleagues [9]. The use of the hybrid angiographic suite (Siemens AXIOM Artis; Siemens, München, Germany) provides the ability of interventional and surgical treatment at the same time. The best angiographic visualization that avoids collision with the instrument cart of the telemanipulator was achieved in the left anterior oblique projection.
Despite the LAD dissection due to the rigid guidewire in the first case, all other anastomoses were patent using angiography as well as gross inspection. As a result, the use of a guidewire for intubation of the LAD was omitted, and the balloon catheter was placed directly under endoscopic vision. The PTCA balloon catheter could be manipulated easily with the endoscopic instruments. In comparison with ischemic times reported for total endoscopic coronary artery bypass or LAD occlusion times in the beating heart, the total endoscopic coronary artery bypass procedure [10] using the catheter-guided, bonded anastomosis clearly shortened the time necessary to construct an endoscopic graft to coronary anastomosis.
Limitation
This study is designed as an acute experimental study to demonstrate the feasibility of this approach. Proof of an open anastomosis by postoperative and intervention angiograms 1 hour after bypass grafting is of limited value. To provide further evidence of anastomotic patency, histologic investigation of sections through the anastomotic site and endothelial staining would have been of interest, given the substantial intraluminal manipulation and the claimed intima to intima approximation. In addition, a chronic study could provide information about long-term patency and late stenosis and occlusion due to subintimal hyperplasia, thrombus formation, or foreign body reaction due to the glue.
Conclusions
Catheter-based bypass grafting is feasible in combination with robotic technology. This simple yet effective and timesaving technique for anastomotic construction may facilitate endoscopic beating heart bypass grafting and accelerate the adoption of this procedure.
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Disclosures and Freedom of Investigation
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The source of all funds used to perform the evaluation and the tested technology was purchased, borrowed, or donated to the study. The authors had full control of the design of the study, methods used, outcome measurements, analysis of data, and production of the written report.
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Disclaimer
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The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
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Acknowledgments
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The authors wish to thank all the collaborators at the Medical Faculty at University of Leipzig and ICCAS. The Innovation Center of Computer Assisted Surgery (ICCAS) at the Faculty of Medicine at the University of Leipzig is funded by the German Federal Ministry for Education and Research (BMBF) and the Saxon Ministry of Science and Fine Arts (SMWK) in the scope of the initiative Unternehmen Region with the grant numbers 03 ZIK 031 and 03 ZIK 032.
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References
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- Falk V, Walther T, Gummert J. Anastomotic devices in cardiac surgery Expert Rev Med Devices 2005;2:223-233.[Medline]
- Matschke KE, Gummert JF, Demertzis S, et al. The Cardica C-Port System: clinical and angiographic evaluation of a new device for automated, compliant distal anastomoses in coronary artery bypass grafting surgery—a multicenter prospective clinical trial J Thorac Cardiovasc Surg 2005;130:1645-1652.[Abstract/Free Full Text]
- Falk V, Walther T, Stein H, et al. Facilitated endoscopic beating heart coronary artery bypass grafting using a magnetic coupling device J Thorac Cardiovasc Surg 2003;126:1575-1579.[Abstract/Free Full Text]
- Serrys PW, Andrew TL, van Herwerden LA, et al. Five-year outcome after coronary stenting versus bypass surgery for treatment of multi vessel disease (the final analysis of ARTS trial) J Am Coll Cardiol 2005;46:575-581.[Abstract/Free Full Text]
- Thiele H, Oettel S, Jacobs S, et al. Comparison of bare-metal stenting with minimally invasive bypass surgery for stenosis of the left anterior descending coronary artery: 5 years follow up Circulation 2005;112:3445-3450.[Abstract/Free Full Text]
- Ben-Gal Y, Mohr R, Braunstein R, et al. Revascularization of left anterior descending artery with drug-eluting stents: comparison with minimally invasive direct coronary artery bypass surgery Ann Thorac Surg 2006;82:2067-2071.[Abstract/Free Full Text]
- Falk V, Jacobs S, Gummert JF, Walther T, Mohr FW. Computer-enhanced endoscopic coronary artery bypass grafting: the da Vinci experience Semin Thorac Cardiovasc Surg 2003;15:104-111(Review).[Medline]
- Bonatti J, Alfadlhi J, Schachner T, Bonaros N, Rutzler E, Laufer G. Do manual assisting maneuvers increase speed and technical performance in robotically sutured coronary bypass graft anastomoses? Surg Endosc 2007;21:1715-1718.[Medline]
- Soulez G, Gagner M, Therasse E, et al. Catheter-assisted totally thorascopic coronary artery bypass grafting: A feasibility study Ann Thorac Surg 1997;64:1036-1040.[Abstract/Free Full Text]
- Fleck T, Tschernko T, Hutschala D, et al. Total endoscopic CABG using robotics on beating heart Heart Surg Forum 2005;8:e266-e268.[Medline]
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H. C. Ott
Invited commentary
Ann. Thorac. Surg.,
November 1, 2007;
84(5):
1727 - 1728.
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