Ann Thorac Surg 2007;84:254-257
© 2007 The Society of Thoracic Surgeons
New Technology
Spyder Aortic Connector System in Off-Pump Coronary Artery Bypass Surgery
Fausto Biancari, MD, PhDa,*,
Jarmo Lahtinen, MDa,
Risto Ojala, MD, PhDb,
Lauri Ahvenjärvi, MDb,
Airi Jartti, MD, PhDb,
Martti Mosorin, MDa,
Jouni Heikkinen, MDa,
Panu Taskinen, MD, PhDa,
Martti Lepojärvi, MD, PhDa
a Division of Cardiothoracic and Vascular Surgery, Department of Surgery, Oulu University Hospital, Oulu, Finland
b Department of Radiology, Oulu University Hospital, Oulu, Finland
Accepted for publication February 7, 2007.
* Address correspondence to Dr Biancari, Division of Cardiothoracic and Vascular Surgery, Department of Surgery, Oulu University Hospital, PO Box 21, Oulu, 90029, Finland (Email: faustobiancari{at}yahoo.it).
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Abstract
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Purpose: The Spyder aortic connector (Medtronic, Minneapolis, MN) is a new, promising connector device and its safety and efficacy have been evaluated in this study.
Description: Twenty-two patients were randomized to proximal vein graft anastomosis with the Spyder aortic connector (Medtronic) or hand-sewn technique.
Evaluation: Twenty patients underwent multi-detector computed tomographic scans of the chest 6 months after surgery to evaluate vein graft patency. We have failed to successfully deploy three Spyder connector devices. Thus in this study we have evaluated the graft patency of 19 hand-sewn grafts and of 19 vein grafts anastomosed with the Spyder anastomotic device. Three vein grafts whose proximal anastomosis was accomplished with the Spyder anastomotic connector were occluded and all hand-sewn vein grafts were patent (16% vs 0%; p = 0.23). Stenosis of the proximal anastomosis was observed in seven vein grafts (37%), accomplished with the Spyder anastomotic connector, and in one (5%) hand-sewn vein graft (p = 0.042).
Conclusions: The results of this study suggest that the use of the Spyder aortic connector device is associated with suboptimal 6-month graft patency.
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Technology
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During the last few years, there has been an increasing interest in proximal and distal anastomotic connector devices. A few studies have demonstrated that the use of proximal connector devices is associated with a significant risk of graft failure [1–6]. Recently, the Spyder proximal aortic anastomotic device (Medtronic, Minneapolis, MN) has been introduced in clinical use with promising perspectives [7]. The lack of a metallic ring, such as the one used in the previous devices, which could have acted as a "stent" and made the anastomosis stiff, along with the avoidance of any vein graft intimal injury is an important characteristic of this proximal aortic anastomotic device. Its safety and efficacy have been investigated in this small prospective, randomized study.
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Technique
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Material and Methods
From January to May 2006, a series of 22 patients, 16 men (73%) and 6 women (27%) with a mean age of 70.7 ± 6.4 years gave their written consent and were enrolled in a prospective, randomized study evaluating the early results of the Spyder proximal anastomotic device compared with the conventional hand-sewn technique in primary off-pump coronary artery bypass surgery. This study was approved by our Institutional Ethical Committee. Because this device was recently introduced in clinical use and there are no data about its safety, we have limited the size of the study to about 20 vein grafts per group. Randomization was based on a fixed operating list in which patients were blindly assigned to be operated on by one surgeon of our team. We decided that only two surgeons (FB, JL) would use the aortic connector device to avoid any major operator-related bias. Epi-aortic ultrasound scanning of the ascending aorta was performed in all patients. Patients with poor quality vein grafts or with a diameter out of the suggested range were excluded from the study. If the vein graft was judged to be of adequate size and quality, two of us (FB, JL) deployed it onto the device avoiding any instrumental dilation of the vein graft. The device was then deployed into the ascending aorta when the systemic arterial pressure ranged from 70 to 100 mm Hg. After having accomplished any distal anastomosis using mammary arteries, then proximal anastomosis with this connector device was first carried out to accomplish the other distal anastomosis.
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Clinical Experience
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At completion of the procedure, flow was measured in the vein grafts by a transit-time flow meter (Medi-Stim, Oslo, Norway). Peripheral resistance units were calculated by dividing mean radial artery pressure by mean vein graft flow. Heparin (2.5 mg/kg) was given intravenously after a sternotomy to maintain activated clotting time more than 400 s, and it was neutralized at the end of procedure by protamin sulphate (2.5 mg/kg). Acetylsalicylic acid (100 mg per day) was given to all patients. No patient received postoperative clopidogrel. In this series, heparin was administered postoperatively only in the case of atrial fibrillation.
These patients underwent multi-detector computed tomographic scan of the chest (GE LightSpeed Pro Advantage [General Electrics, Milwaukee, WI]) 6 months after surgery to evaluate graft patency. Scanning measurements were 120 kV, automatic modulated mAs (100–650 mA, Noise Index 20.0), 500-ms rotation time, 16 x 0.625-mm section collimation and pitch 0.938. Images were reconstructed at 0.3-mm intervals. All patients received 100 mL of a non-ionic contrast medium (Omnipaque, 350 mgI/mL [Amersham Health, Oslo, Norway]) infused through intravenous antecubital catheter at a flow rate of 4.5 mL/s for the first 50 mL and then 3.2 mL/s for the last 50 mL. The contrast agent was flushed with 30 mL of saline (3.2 mL/s). Smart Prep-automatic contrast medium detection software was used to determine the delay of the scan. Images were evaluated from axial image data, using multi-plane reconstruction and maximum intensity projection.
Statistical analysis was performed using SPSS statistical software (SPSS version 10.0.5, SPSS Inc, Chicago, IL). Continuous variables are reported as mean ± standard deviation. The Fisher’s exact test and the Mann-Whitney U test were used for univariate analysis. Logistic regression with the help of backward selection was used for multivariate analysis. A p < 0.05 was considered statistically significant.
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Results
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No postoperative death occurred in this series. One patient in the Spyder group without any signs of a diseased ascending aorta suffered a postoperative stroke.
We failed to successfully deploy three Spyder connector devices. In one patient, the proximal anastomosis of a 5-mm vein graft was accomplished with the connector device, but the blood flow (immediately after the proximal anastomosis was carried out) was not satisfactory. A new proximal anastomosis was successfully carried out with a Spyder connector device. In 2 other patients, two proximal anastomoses with the Spyder anastomosis device were attempted, but they failed because of significant bleeding at the time of insertion, despite the size of the vein graft, the device and the aortic hole were well matched. In these cases the vein graft device did not seal the aortic hole satisfactorily. In one case, the low arterial pressure (systolic pressure of about 70 mm Hg) possibly caused the technical problem. A hand-sewn proximal anastomosis was then accomplished. In the other patient, the vein graft was anastomosed to the left internal mammary artery graft.
Slight bleeding from two proximal anastomoses accomplished with the Spyder anastomotic device was controlled with 6-0 polypropylene stitches.
One patient in the hand-sewn group refused to attend the 6-month follow-up control, but he was otherwise asymptomatic. He had three distal anastomoses accomplished with two hand-sewn vein grafts to the ascending aorta with a left internal mammary artery. Another patient attended the 6-month follow-up control, but we were unable to perform a multi-detector computed tomographic scan because of lack of peripheral vein access for administration of contrast agent. He had four distal anastomoses, one with a vein graft anastomosed with the Spyder anastomotic device, another with the left internal mammary artery, and two with a radial artery graft. Thus 9 patients with 18 hand-sewn anastomoses and 11 patients with 19 proximal anastomoses performed with the Spyder device have been evaluated by multi-detector computed tomographic scans at 6-month follow-up analyses (Fig 1). Clinical data on these patients are summarized in Table 1. Because one hand-sewn proximal anastomosis was performed due to failure to deploy the Spyder connector device, we have considered it as a control vein graft in the final analysis. This patient had other two proximal anastomoses successfully performed with the Spyder connector device. Therefore in this study we have evaluated the graft patency status of 19 hand-sewn grafts and of 19 vein grafts anastomosed with the Spyder anastomotic device.
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Fig 1. (A) Stenosis of a proximal anastomosis carried out with a Spyder connector anastomosis device (Medtronic, Minneapolis, MN) as detected at 6-month follow-up. (B) Patent hand-sewn proximal anastomosis at 6-month follow-up. Arrows indicate proximal anastomosis.
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Vein graft flow (44 vs 39 mL/min; p = 0.42) as well peripheral resistance units (2.3 vs 2.5; p = 0.96) were slightly more favorable in the hand-sewn group.
Three vein grafts with proximal anastomoses accomplished with the Spyder anastomotic connector were occluded at the 6-month follow-up control multi-detector computed tomographic scans (16% vs 0%; p = 0.23) (Table 2). Data on these grafts and recipient coronary arteries are summarized in Table 2. None of the hand-sewn vein grafts was occluded.
Stenosis of the proximal anastomosis was observed in seven vein grafts (37%) accomplished with the Spyder anastomotic connector and in one hand-sewn vein graft (5%; p = 0.042).
The overall rate of graft stenoses and occlusion was 53% in the Spyder connector group and 5% in the hand-sewn group (p = 0.003). This difference also remained statistically significant when it was adjusted for peripheral resistance units (p = 0.008; odds ratio, 20.0; 95% confidence interval, 2.2–181.6).
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Comment
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The results of the present study suggest that early vein graft patency can be suboptimal when proximal aortic anastomosis is performed using the Spyder connector device. Importantly these findings are possibly influenced by the limited accuracy of computed tomographic scans in assessing the degree of graft stenosis [8–10], especially in these patients as nitinol clips of the Spyder connector device might have resulted in imaging artifacts. On the other hand, the diagnosis of vein graft occlusion made by multi-detector computed tomographic scan is rather accurate [8–10].
The small size of the study further prevents definitive conclusions of the safety and validity of this device. On the other hand, the rather poor results with the use of previously used proximal anastomosis connector devices [1–6] prompted us to not perform a much larger study. Indeed, in question it is the safety of a new method with failures that can be associated with immediate and late complications in patients with severe coronary artery disease. In this sense, the present can be defined as a pilot study.
Other factors such as technical details and hemodynamic factors might have negatively affected the results of this study. Of course, details in the technique of the device deployment as well as surgeons’ skills and experience are important determinants of outcome. However, besides a certain learning curve required with any new method or device, the latter should always be easy and safe enough to deploy their use with fast, reliable, and few device-related complications in the hands of experienced surgeons. Indeed, deployment of this anastomotic device is not always easy, despite having carefully taken care of technical details we encountered in a few cases, with problems such as bleeding and poor graft flow. In one patient, we believe that the difficulties in deploying the anastomotic were associated with the development of stroke, even in the absence of diseased ascending aorta.
Reported details regarding the occluded vein grafts are shown in Table 2. We observed intraoperative-measured pulsatile indexes that were good in these vein grafts with acceptable blood flow velocities. However the degree of stenosis of the recipient coronary artery was not hemodynamically significant, and this may have contributed to early vein graft occlusion.
In conclusion, we believe that the use of any effective proximal anastomotic connector device would be of great benefit in off-pump coronary artery bypass surgery, especially in patients with a diseased ascending aorta or unstable angina pectoris requiring a fast revascularization, or both. However the possible increased risk of early vein graft failure may greatly limit the value of this device, even in the emergency setting. This suggests that the efficacy of the Spyder anastomotic device should be evaluated in further studies to achieve more conclusive results.
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Disclosures and Freedom of Investigation
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We declare that this study was not financially supported by any foundation or firm and that the devices used herein were regularly purchased from Medtronic (Medtronic, Minneapolis, MN). Furthermore we declare that we 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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References
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- Lahtinen J, Biancari F, Mosorin M, et al. Fatal complications after use of the Symmetry Aortic Connector in coronary artery bypass surgery Ann Thorac Surg 2004;77:1817-1819.[Abstract/Free Full Text]
- Melero JM, Porras C, Such M, Olalla E, Alonso J. Severe stenosis of anastomoses by using the Symmetry Aortic Connector system Ann Thorac Surg 2004;78:1831-1833.[Abstract/Free Full Text]
- Bergsland J, Hol PK, Lingås PS, et al. Intraoperative and intermediate-term angiographic results of coronary artery bypass surgery with Symmetry proximal anastomotic device J Thorac Cardiovasc Surg 2004;128:718-723.[Abstract/Free Full Text]
- Cavendish JJ, Penny WF, Madani MM, et al. Severe ostial saphenous vein graft disease leading to acute coronary syndromes following proximal aorto-saphenous anastomoses with the Symmetry bypass connector device J Am Coll Cardiol 2004;43:133-139.[Abstract/Free Full Text]
- Traverse JH, Mooney MR, Pedersen WR, et al. Clinical, angiographic, and interventional follow-up pf patients with aortic-saphenous vein graft connectors Circulation 2003;108:452-456.[Abstract/Free Full Text]
- Lahtinen J, Biancari F, Ojala R, et al. Prospective, randomized study on the use of the cardica PAS-port aortic connector system in off-pump coronary artery bypass surgery Heart Surg Forum 2006;9:E568-E571.[Medline]
- Hamman BL, White CH, Fontes M, Labiche L. Clampless anastomosis: novel device for clampless proximal vein anastomosis in off-pump coronary artery bypass surgery: the initial Spyder experience Heart Surg Forum 2005;8:E443-E446.[Medline]
- Bartnes K, Sildnes T, Iqbal A, et al. Coronary bypass graft patency cannot be determined by multidetector spiral computed tomography Scand Cardiovasc J 2006;40:83-86.[Medline]
- Yamamoto M, Kimura F, Niinami H, Suda Y, Ueno E, Takeuchi Y. Noninvasive assessment of off-pump coronary artery bypass surgery by 16-channel multidetector-row computed tomography Ann Thorac Surg 2006;81:820-827.[Abstract/Free Full Text]
- Anders K, Baum U, Schmid M, et al. Coronary artery bypass graft (CABG) patency: assessment with high-resolution submillimeter 16-slice multidetector-row computed tomography (MDCT) versus coronary angiography Eur J Radiol 2006;57:336-344.[Medline]
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