Ann Thorac Surg 2009;87:1910-1913. doi:10.1016/j.athoracsur.2008.12.094
© 2009 The Society of Thoracic Surgeons
New Technology
Use of Skeletonized Radial Artery Graft with the PAS-Port Proximal Anastomotic Device
Shohjiro Yamaguchi, MD, PhD*,
Go Watanabe, MD, PhD,
Shigeyuki Tomita, MD, PhD,
Hiroshi Ohtake, MD, PhD,
Hiroshi Nagamine, MD, PhD,
Kenji Iino, MD
Department of General and Cardiothoracic Surgery, Kanazawa University School of Medicine, Kanazawa, Japan
Accepted for publication December 30, 2008.
* Address correspondence to Dr Yamaguchi, Department of General and Cardiothoracic Surgery, Kanazawa University School of Medicine, 13-1 Takaramachi, Kanazawa, Ishikawa, 920-8641, Japan (Email: gucci-s{at}ya2.so-net.ne.jp).
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Abstract
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Purpose: We report our initial experience with the PAS-Port proximal anastomosis system (Cardica Inc, Redwood City, CA) using full-skeletonized radial artery (RA) in patients requiring off-pump coronary artery bypass grafting.
Description: The PAS-Port system (Cardica Inc) was used in 25 patients undergoing off-pump coronary artery bypass surgery. All patients received at least one RA graft using the PAS-Port system on the proximal anastomosis. The radial arteries were harvested in a fully skeletonized fashion before loading to the PAS-Port system.
Evaluation: Our attempt to use the PAS-Port system for proximal anastomosis of the RA was successful in 25 anastomoses. Postoperative angiography showed 24 grafts to be widely patent. During the mean postoperative follow-up of 9.2 ± 3.1 months, there was no cardiac-related event in any patient. Mid-term patency collected from the first 8 patients was 87.5% (mean follow-up, 12.8 ± 2.8 months).
Conclusions: The PAS-Port system does not require aortic clamping and enables the creation of uniform and widely patent anastomosis with use of RA grafts.
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Technology
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Off-pump coronary artery bypass grafting is a safe alternative to conventional coronary artery bypass grafting with cardiopulmonary bypass. However, partial clamping of the ascending aorta is recognized as a possible cause for increased incidents of postoperative cerebral vascular complications during coronary revascularization. The growing interest in less invasive coronary artery bypass grafting techniques has generated a need for facilitated automatic device to create proximal anastomosis [1, 2]. The PAS-Port system (Cardica Inc, Redwood City, CA) has been available in Japan since 2004 and it was recently granted 510(k) clearance by the Food and Drug Administration in the United States. The device is commonly used with a saphenous vein graft (SVG); however, in cases in which multi-vessel revascularization is required, an alternative graft for use with the PAS-Port system (Cardica Inc) provides more options to the graft strategy. We report here our initial experience with the PAS-Port system using full-skeletonized RAs in 22 patients who underwent off-pump coronary artery bypass grafting.
PAS-Port Proximal Anastomosis System
The PAS-Port system is an integrated device that instantly creates an aortotomy and an anastomosis between the aorta and a vein graft (conduit). The implant is a self-closing stainless steel clip that will create a complete end-to-side anastomosis, which is 4.65 mm in internal diameter when deployed (Fig 1A). The recommended size of the conduit is between 4 mm to 6 mm in diameter. The PAS-Port system is designed so that the implant has no interluminal exposure in the conduit at the proximal anastomotic site and no metal rods pass through the lumen of the conduit during loading. These design considerations prevent any damage being made to the endothelium of the conduit, thus reducing the risk for thrombosis or re-stenosis that may result from reactive intimal hyperplasia.
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Fig 1. (A) Implant, the self-closing stainless steel clip for implantation. (B) The components of the PAS-Port System (Cardica Inc, Redwood City, CA). (C) Poke-through tool piercing the conduit, which is fixed with the nine tines of implant. (D) Deployment of the conduit to the aorta.
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Technique
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The advantages of using the PAS-Port system include the rapid creation of an aortotomy and an anastomosis (typically in less than a minute), consistency and reliability in the quality of the anastomosis compared with the hand-sewn technique, and the avoidance of aortic clamping, which may potentially reduce the occurrence of postoperative cerebrovascular events.
The components of the PAS-Port system include the delivery tool, the poke-through tool, the pull-through tool, and the cartridge with the implant attached at the tip (Fig 1B, C, D). The PAS-Port system is designed for single use.
Here we present the technique we have established through our collective experience at our institutions of using more than 880 PAS-Port system devices with SVGs and RAs.
Conduits and Harvesting
The PAS-Port system device requires a harvested conduit to be loaded into the cartridge. When using a radial artery (RA) as the conduit, it should be prepared in a full-skeltonized fashion [3]. It should be noted that if the size of the conduit exceeds the diameter of the cartridge, it can make it difficult to release the conduit after deployment and may potentially damage the conduit in the process. For this reason, a fully skeltonized RA, which has its excess tissues removed, is easier and safer to handle.
Deployment
The prepared RA graft is then loaded into the cartridge using the pull-through tool (Fig 2A). The graft needs to be everted over the nine implant tines at the tip of the cartridge; however, because some RAs have elastic fibers unlike SVGs, it can easily flip back during the eversion. A useful technique here is to hold the everted RA graft using fine tip forceps and quickly use the poke-through tool to attach the graft to the implant tines (Fig 2B). The preparatory stage for the PAS-Port system is complete once the cartridge is loaded into the delivery tool.
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Fig 2. (A) The prepared radial artery (RA) graft is then loaded into the cartridge using the pull-through tool. (B) The graft needs to be everted over the 9 implant tines at the tip of the cartridge. (C) The aorta was stabilized and exposed to deploy the conduit by device. (D) The RA was connected to the aorta instantly without any bleeding.
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As we have previously reported, we also use the Acrobat vacuum stabilizer (Maquet cardiovascular LLC, San Jose, CA) to stabilize the selected anastomotic site (Fig 2C) [4].
A disadvantage with automated proximal anastomotic devices is that the bypass graft will be attached perpendicular to the aorta, which could potentially result in kinking of the graft. However, this can be overcome, for example, when targeting the left coronary artery by rotating the aorta slightly when firing (to expose the lateral side of the aorta). As a result, the graft will run laterally once the aorta is placed back in its original position. With this method, an ideal graft course can be achieved.
Proximal anastomosis using the PAS-Port system can be created by simply placing it over the selected anastomotic site and turning the knob at the end of the device (Fig 2D). The time required for the actual anastomosis is only a few seconds.
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Clinical Experience
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Patients
This study was approved by the local ethics committee and all patients provided informed consent. From January 2006 to November 2008, the PAS-Port system was used on 25 patients with the RA grafts. Twenty-four patients had a median sternotomy for multi-vascular coronary revascularization. One patient had a left thoracotomy through the fifth intercostal space for a double grafting re-do case. There were 22 men and 3 women aged 40 to 83 years (mean, 65 ± 12 years). Preoperative evaluation of left ventricular systolic function determined the left ventricular ejection fraction to be 51 ± 18% (Table 1).
Complete revascularization was achieved in all patients. Mean operating time was 3.1 ± 0.9 hours. An average of 4.1 ± 1.1 bypass grafts was performed. The target vessel distribution of the RA grafts using the PAS-Port system was as follows: 5 patients had the RA graft anastomosed to the diagonal branch, 19 to the circumflex branch, 1 to the left anterior descending branch, and 2 to the right coronary artery. Twenty-four patients experienced revascularization of the left anterior descending with the left internal thoracic artery. The right gastroepiploic artery was used for revascularization of the right coronary system in 5 patients. In some patients, additional PAS-Port system was used for proximal anastomosis, but with SVG, the distribution of the distal anastomoses for the SVG was as follows: 4 to the diagonal branch, 15 to the right coronary branch, and 6 to the circumflex branch.
Time to complete the deployment included loading of the RA graft to the PAS-Port system, which was less than 5 minutes in all cases. All RA grafts were patent at discharge. No patient experienced postoperative neurologic complications or postoperative cardiac events.
Twenty-six grafts were widely patent except for one. Early patency was 96.3%. During the mean postoperative follow-up of 9.2 ± 3.1 months, there was no cardiac event or angina with any patient. Postoperative angiography showed a widely patent proximal anastomosis of the RA (Fig 3A).
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Fig 3. (A) Postoperative angiograms showing a widely patent radial artery graft at the proximal anastomosis site. (B) Postoperative angiograms showing a good result where the PAS-Port system (Cardica Inc, Redwood City, CA) was deployed to the descending aorta.
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We also used the PAS-Port system with an RA graft to the descending aorta for a re-do case. Postoperative angiography revealed excellent results (Fig 3B).
We collected the mid-term patency in the first eight grafts (mean follow up time, 12.8 ± 2.8 months) in which 5 patients were evaluated by angiography and 3 patients by computed tomography. One graft had occluded at 13 months. The target distal site of this RA graft was a severe calcified obtuse marginal branch. Overall, the mid-term patency was 87.5%.
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Comment
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There have been several attempts to develop automated proximal anastomosis devices for coronary artery bypass surgery and only a few devices are now commercially available worldwide. Gummert and colleagues [5] have reported successful clinical results with the PAS-Port system. We too, have seen very positive results with the PAS-Port system and the cumulative number of the PAS-Port system devices we have used at our institutions is now in excess of 880 units.
Proximal anastomosis devices are especially attractive in the off-pump coronary artery bypass grafting procedure as they do not require clamping of the aorta. The avoidance of major aortic manipulation ensures stable hemodynamics, thus minimizing the risk of atheromatous emboli. Atheromatous plaques in the ascending aorta that may be released during aortic manipulation often cause embolization, which could result in preoperative neurologic morbidity. However, these commercially available automated proximal anastomosis devices are limited to the deployment of venous conduits and can not be used for arterial grafts, such as the RA or free internal thoracic arteries, because these grafts are normally harvested as a pedicled graft.
In recent years, the use of arterial conduits and total arterial revascularization has become a standard procedure in many institutions. Arterial grafts have proven to be easy to use and versatile for planning revascularization with multiple grafts, whether it is sequential anastomoses, T grafts, or Y grafts. The application of these techniques allows the conservation of available conduits when performing total arterial revascularization. Enthusiasm for these techniques is supported by early-term and mid-term data showing excellent patency of the RA and reduced in-hospital mortality in patients with multiple vessel diseases [6].
Currently most RA grafts for revascularization are harvested as a pedicled graft as common practice; however, pedicled RA grafts with excess tissues can not be loaded in to the cartridge of the PAS-Port system. Therefore, in our attempt to use the PAS-Port system for proximal anastomosis with arterial grafts, we routinely harvested the RAs as a skeletonized graft. The advantages of this harvesting technique are reported elsewhere [7]. Although we have used RA grafts instead of SVGs, we did not observe any kinking of the RA graft at the proximal site, which could potentially cause a stenosis or an occlusion. In this study, satisfactory automated proximal anastomosis could be achieved without any complications or any technical difficulties.
It should be noted that the long-term implications of this proximal anastomotic device is unknown and long-term follow-up studies are necessary to prove that patency rates are comparable with hand-sewn anastomoses, in addition to such reports by Kempfert and colleagues [8]. Mid-term patency was 87.5% in this study (one graft had occluded). Occlusions with RA may be influenced by poor quality of its target vessels. The limitation of this study is that the study population was small. However, this study is the first report on the PAS-Port system with the use of RA, and we intend to report on a larger scale in the future.
In conclusion, the PAS-Port system is an effective and reliable device that produces uniform proximal anastomoses with the use of RA, in addition to SVG. It also has the potential to contribute to further development in less invasive coronary artery bypass grafting techniques due to its ease of use and the operative time it can save.
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Disclosures and Freedom of Investigation
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We performed this study without any financial support from Cardica Inc. We purchased this device for clinical use and had full control of the design of this study.
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Footnotes
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Disclaimer 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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References
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- Calafiore AM, Bar-El Y, Vitolla G, et al. Early clinical experience with a new sutureless anastomotic devices for proximal anastomosis of the saphenous vein to the aorta J Thorac Cardiovasc Surg 2001;121:854-858.[Abstract/Free Full Text]
- Wiklund L, Bugge M, Berglin E. Angiographic results after the use of a sutureless aortic connector for proximal vein graft anastomoses Ann Thorac Surg 2002;731993–3.
- Yamaguchi S, Watanabe G, Higashidani K, et al. Skeletonized radial artery graft prepared with phosphodiesterase-III inhibitors indicates favorable results compared with pedicled radial artery graft in angiographic studies Innovations 2006;1:251-252.
- Yasuda T, Watanabe G, Tomita S, Higashidani K. Immobilization of ascending aorta with Starfish positioner in off-pump CABG Heart Surg Forum 2006;9:E488-E489.[Medline]
- Gummert JF, Demertzis S, Matschke K, et al. Six-month angiographic follow-up of the PAS-Port II clinical traial Ann Thorac Surg 2006;81:90-96.[Abstract/Free Full Text]
- Marasco S, Esmore D. A novel method for performing sequential grafts with the radial artery Ann Thorac Surg 2001;72:298-299.[Abstract/Free Full Text]
- Taggert DP, Mathus MN, Ahmea I. Skeletonaization of the radial artery: advantages over the pedicled technique Ann Thorac Surg 2001;72:298-299.[Abstract/Free Full Text]
- Kempfert J, Opfermann UT, Richter M, Bossert T, Mohr FW, Gummert JF. Twelve-month patency with the pas-port proximal connector device: a single center prospective randomized trial Ann Thorac Surg 2008;85:1579-1585.[Abstract/Free Full Text]
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