Ann Thorac Surg 2004;78:e38-e40
© 2004 The Society of Thoracic Surgeons
How to do it
Multivessel distal sutureless off-pump coronary artery bypass grafting procedure using magnetic connectors
Filip P. Casselman, MD, PhDa*,
Massimo Meco, MDa,
Helge Dom, MDa,
Luc Foubert, MD, PhDb,
Frank Van Praet, MD, FETCSa,
Hugo Vanermen, MD, FETCSa
a Department of Cardiovascular and Thoracic Surgery, OLV Clinic, Aalst, Belgium
b Anesthesia and Intensive Care, OLV Clinic, Aalst, Belgium
Accepted for publication July 3, 2003.
* Address reprint requests to Dr Casselman, Department of Cardiovascular and Thoracic Surgery, OLV Clinic, Moorselbaan 164, 9300 Aalst, Belgium
e-mail: filip.casselman{at}olvz-aalst.be
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Abstract
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Proximal anastomotic devices for beating heart coronary artery bypass grafting (CABG) have been developed to avoid ascending aortic manipulation. Distal anastomotic devices may become an extremely useful tool to assist in enabling minimally invasive (robotic) multivessel CABG. As a transition phase toward this ultimate goal we have been using a distal anastomotic device for the left internal mammary artery-left anterior descending artery (LIMA-LAD) anastomosis. In addition we recently performed two off-pump coronary artery bypass procedures that were distally completely sutureless.
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Introduction
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Off-pump coronary artery bypass surgery (OPCAB) is an increasingly popular procedure because of proven and speculative advantages that surpass on-pump surgery [1]. Because of its avoidance of the cardiopulmonary bypass system OPCAB is considered "minimally invasive." However a "maximally invasive" median sternotomy is still required to enable multivessel exposure. Therefore only a thoracoscopic (robotic) procedure can naturally be considered a truly minimally invasive procedure. This procedure is, however, unfortunately limited with regard to multivessel exposure. In particular a distal sewn anastomosis is difficult to perform on the lateral and posterior wall [2, 3]. Distal anastomotic devices could theoretically be an extremely helpful tool with regard to enabling multivessel (robotic) coronary artery bypass grafting (CABG). As a transition phase toward this ultimate goal we have been using a distal anastomotic device for the left internal mammary artery-left anterior descending artery (LIMA-LAD) anastomosis. In addition we recently performed two OPCAB procedures that were distally completely sutureless.
A 75-year-old patient with arterial hypertension and non-dialysis-dependent renal insufficiency was recently investigated for stable angina. A complete cardiac investigation revealed suitable left ventricular function and triple vessel disease. Both the proximal LAD and obtuse marginal branch exhibited a long severe stenosis of 90%. Distally both vessels were of suitable quality and diameter. The right coronary artery (RCA) was proximally occluded but was a very small vessel in the presence of a left dominant system. The lesions were not attractive for percutaneous intervention and bypass surgery to the LAD and obtuse marginal branch was proposed.
A 76-year-old patient underwent a percutaneous transluminal coronary angioplasty (PTCA) of the LAD 3 years ago but was recently examined for recurrent angina. A complete cardiac investigation revealed a normal left ventricular function and triple vessel disease. The RCA was dominant and indicated a proximal lesion of 30%. The LAD and obtuse marginal branch both exhibited a severe stenosis of approximately 80%. Distally both vessels were of satisfactory quality and diameter. Again both lesions were judged unsuitable for percutaneous intervention and two-vessel bypass surgery was proposed.
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Technique
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A standard median sternotomy was performed and the LIMA was harvested extrapleurally as a small pedicle (artery plus two satellite veins). One segment of saphenous vein (SVG) was harvested simultaneously from the lower leg. After systemic heparinization (2 mg/kg) and an additional intravenous dose of 500 mg of acetylsalicylic acid, an OPCAB procedure was performed using the Axius stabilizing system (Guidant, Santa Clara, CA) and additional gauzes were placed positioned behind the heart to optimize exposure.
First the LAD was exposed and a suitable target place was chosen. This portion of the LAD was extremely well isolated laterally from the surrounding epicardial fat. A 4-0 Gore-Tex suture (W.L. Gore & Associates, Flagstaff, AZ) was placed more proximal around the target vessel and later used as a coronary snare (no intraluminal shunt was used).
The instructions for use of the MVP series 6000 distal anastomotic device (Ventrica, Fremont, CA) we used are as follows. The LIMA graft pedicle is distally clipped and a longitudinal arteriotomy is performed 5 mm more proximally. The length of the arteriotomy depends on the size of the anastomotic device used (4.5 mm for a 1.5-mm device and 5 mm for a 2-mm device). The choice of the size is estimated by holding a vessel probe next to the target coronary vessel. The MVP series 6000 distal anastomotic device (Fig 1) was deployed at this arteriotomy site. This device consists of a graft portion and a target portion. Both portions are metallic, magnetic, and mounted on a separate delivery system and both portions also consist of an intraluminally placed central ring and two lateral pontoons (one for each side of the vessel wall) that are magnetically fixed to the intraluminal part and "sandwich" the vessel wall between the central ring and lateral pontoon. The deployment requires careful intraluminal insertion and positioning of the central ring (Fig 2). No more than 10% of the anastomotic lumen should be occupied by excess vessel wall. In addition enough vessel wall should be caught between the lateral pontoon and the central part to ensure anastomotic hemostasis.
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Fig 1. The magnetic vascular positioner (MVP) Series 6000 System (Ventrica, Fremont, CA). The delivery system (one system for the three parts) is illustrated on the left and the connecting device is illustrated on the right. Note the central ring, which will be placed intraluminally, and the two lateral pontoons.
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Fig 2. Different steps of the anastomosis: (a) the intraluminal central ring is positioned, (b) the deployment arms are lowered to deploy the lateral pontoons, (c) and the delivery system is removed. These steps are performed for the conduit and the target. (d) Finally both devices are coupled. (Reprinted from the "Instructions for use" manual with permission from Ventrica, Inc. [Fremont, CA].)
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When the graft is ready the same maneuver is repeated on the target vessel. The LAD is snared and an arteriotomy of equivalent length is performed. The target part is deployed at this site and checked for correct positioning. Now the graft is approximated to the target site and, at a distance of approximately 2 cm, the magnetic forces attract the graft and target part and seal the anastomosis. This is checked by opening the mammary artery and allowing perfusion of the LAD (Fig 3). If satisfactory the LIMA pedicle is secured distal and proximal to the anastomosis. Because magnetic forces are present the use of titanium instruments is mandatory during the anastomosis and within an area of approximately 5 cm from the anastomosis.
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Fig 3. Completed anastomoses: left internal mammary artery-left anterior descending artery anastomosis (white arrow) with control angiography (upper left and upper right); saphenous vein graft-obtuse marginal branch anastomosis with control angiography (lower left and lower right).
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When the LAD anastomosis was performed using a 2-mm device we executed exactly the same maneuver for the obtuse marginal branch using a 1.5-mm device. The SVG vein was clipped transversally and a venotomy was performed to allow graft deployment. The target part was deployed in the obtuse marginal branch and both parts were coupled (Fig 3). The vein was fixed distal to the anastomosis.
Both patients underwent an identical procedure except that the second patient employed a 1.5-mm device in the LAD. Before we performed these 2 OPCAB procedures we had accumulated experience in 18 LIMA-LAD anastomoses on the arrested heart as part of a multicenter trial. All of these patients gave informed consent for the usage of the device and all the anastomoses were patent on predischarge angiography.
With some experience the total anastomotic time spent using this device averages less than 3 minutes. The proximal anastomosis was manually sutured on the ascending aorta with a side clamp in the first patient and with a nontouch technique using the Hart-string device (Guidant, Santa Clara, CA) in the second patient. Postoperatively both patients received 160 mg of acetyl salicylic acid ad vitam and 75 mg of clopidogrel daily for 3 months. Both patients underwent a control angiography 1 week postoperatively that revealed nicely patent anastomoses (Fig 3).
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Comment
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Overall the MVP distal anastomotic device is a very user-friendly instrument. We adopted the technique during wet-lab training on a pig heart and could very easily deploy the device clinically, first on the arrested heart and ultimately during an OPCAB procedure. The device is easily handled and requires minimal intraluminal manipulation in contrast with other distal anastomotic devices [4].
As such the use of an anastomotic device does not provide an additional benefit to a coronary artery bypass procedure. The only advantage can be the reduced anastomotic time, which could be an issue in some difficult OPCAB procedures especially on the lateral or posterior wall. However the device still indicates some disadvantages that require further technical improvement. First the device is more difficult to deploy in vessels of inferior quality. That is to deploy the device it is necessary to "sandwich" the vessel wall between the central intraluminal ring and both lateral pontoons. This is obviously impossible in calcified or severely atherosclerotic vessels. Second at this point it is impossible to construct diamond-shaped side-to-side anastomoses. Therefore a sequential anastomosis can only be constructed automatically if the graft and target vessel are parallel to each other—a condition that is rarely fulfilled in daily practice. Third to date the sizes available are 1.5 and 2.0 mm. Generalizability of the technique probably requires the availability of multiple sizes. Finally to date there are no clinical studies available with regard to flow patterns across the anastomotic device. This issue particularly requires attention because flow patterns might influence long-term patency.
The most important value of distal anastomotic devices will, in our opinion, be their contribution toward thoracoscopic (robotic) multivessel CABG. However to reach this goal several milestones still have to be realized.
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Acknowledgments
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The authors wish to thank Karlien Meuleman for her secretarial assistance.
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References
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- Ascione R., Caputo M., Angelini G.D. Off-pump coronary artery bypass grafting: not a flash in the pan. Ann Thorac Surg 2003;75:306-313.[Abstract/Free Full Text]
- Dogan S., Aybek T., Andressen F., et al. Totally endoscopic coronary artery bypass grafting on cardiopulmonary bypass with robotically enhanced telemanipulation: report of forty-five cases. J Thorac Cardiovasc Surg 2002;123:1125-1131.[Abstract/Free Full Text]
- Vassiliades T.A. A unilateral approach to bilateral thoracoscopic internal mammary artery harvesting. Interact Cardiovasc Thorac Surg 2003;2:87-90.[Abstract/Free Full Text]
- Schaff H.V., Zehr K., Bonilla L.F., et al. An experimental model of saphenous vein-to-coronary artery anastomosis with the St. Jude Medical stainless steel connector. Ann Thorac Surg 2002;73:830-836.[Abstract/Free Full Text]
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Abstract
Introduction
