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J Thorac Cardiovasc Surg 2003;125:27-29
© 2003 The American Association for Thoracic Surgery
Editorials |
From the Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
Received for publication Sept 13, 2002. Accepted for publication Sept 24, 2002. Address for reprints: Terrence M. Yau, MD, MSc, 13EN-239, Toronto General Hospital, 200 Elizabeth St, Toronto, Ontario, Canada M5G 2C4 (E-mail: terry.yau{at}utoronto.ca).
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Introduction |
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 Top Introduction Potential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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Coronary artery bypass surgery (CABG) has undergone a host of changes since its initial description by Favaloro. Throughout the progressive refinements of cardiopulmonary bypass technologies, myocardial protection strategies, and the rise in popularity of off-pump coronary bypass (OPCAB) and other techniques of "less-invasive" surgery, the actual technical aspects of creating a coronary anastomosis have remained relatively constant. A new class of anastomotic devices may change this process and, with it, some of our fundamental assumptions about what is required to perform this operation.
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Potential advantages and applications |
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TopIntroductionPotential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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The most intuitively attractive application of devices like the Symmetry Aortic Connector System (St Jude Medical Anastomotic Technology Group, St Paul, Minn),
1 which creates a sutureless proximal saphenous vein graft anastomosis, is in OPCAB. Although proponents of OPCAB frequently cite the deleterious effects of cardiopulmonary bypass on postoperative neuropsychologic outcomes, the use of a side-biting clamp during OPCAB procedures to construct proximal anastomoses may dislodge particulate emboli and cause similar neurologic sequelae. The complete elimination of aortic clamping from OPCAB surgery may be the only way in which the purported neuropsychologic benefits of this technique may be demonstrable. Although early experience with these connectors has been promising, 2,3 their potential in this regard has yet to be proven.
Another application in which anastomotic devices may be advantageous is in minimal-access CABG. The use of robotic telemanipulation to perform sutured coronary anastomoses in a closed chest requires expensive equipment, extreme patience, and a significant learning curve. Although advances in robotic technology continue, its ability to simplify CABG remains unclear. This is an area, however, in which anastomotic devices may prove invaluable. Sutureless connectors may represent the enabling technology that allows minimal-access CABG to become more than a curiosity.
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Potential drawbacks and the burden of proof |
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TopIntroductionPotential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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years.
The more significant concerns regarding such devices relate to potential early problems with hemostasis, device dislodgment, or graft occlusion. These issues can be clarified relatively easily, in clinical series with short-term follow-up. Worldwide clinical experience with the Symmetry system has been generally very favorable, with only very isolated reports of device-related complications. Nonhemostatic device deployments are easily remedied with additional sutures and have been less frequent in our experience than nonhemostatic hand-sewn anastomoses. A dislodged connector can be amputated, the vein graft reloaded onto a new system, and the proximal anastomosis constructed again without difficulty. Of more concern is the potential for early graft occlusion, as reported by Donsky and associates. 4 The prevalence of this complication appears to be extremely low and may be related to a systemic prothrombotic state in a small number of patients, but these observations highlight the fact, among others, that the optimal antiplatelet regimen after anastomotic device implantation has not yet been defined.
The greatest issue will be determining the effect of these devices on long-term graft patency. Given the 35-year track record of the "current technology," a substantial burden of proof exists on proponents of the new technology to demonstrate at least equivalence in late outcomes. These data, however, are difficult to obtain and require a substantial investment of time, money, and effort. The most appropriate substitute is short-term to medium-term evaluation of graft patency to assess early technical failures and potentially accelerated intimal hyperplasia. In our initial clinical series of 25 patients in whom Symmetry connectors were implanted, follow-up angiography at 6 to 12 months demonstrated a reassuring 100% patency of connector vein grafts (unpublished data). In contrast, the occurrence of late graft atherosclerosis in connector grafts will not be known for years but may be less influenced by these devices than early and midterm modes of graft failure. The demonstration of comparable midterm graft patency alone may therefore do much to facilitate the widespread acceptance of these devices.
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Defining a niche |
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TopIntroductionPotential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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5 report on their experience with the Symmetry sutureless connector for proximal vein graft anastomoses in 15 patients undergoing video-assisted on-pump multivessel CABG through a left anterior small thoracotomy approach, selected for a variety of indications including coronary reoperation, anticipated sternal fragility, and cosmesis. They report good clinical outcomes, with no operative mortality. On early postoperative angiography, 86% of grafts were widely patent. Two vein grafts were occluded, and one patient, in whom two graft stenoses were noted, underwent percutaneous transluminal coronary angioplasty. Semrád and colleagues conclude that this approach represents a safe alternative to conventional sternotomy in these selected patients. In this nominally less-invasive approach, a potential advantage of the sutureless aortic connector system is demonstrated, that is, suitability to minimal access approaches. Application of the device generally required insertion of additional ports to obtain the right-angled access to the ascending aorta that is required for connector deployment, but this series is a good example of how these devices can simplify and expedite a "minimally invasive" operation. This case series, lacking a comparison group, cannot, however, conclude that the left anterior small thoracotomy approach reduces complications or length of stay compared with sternotomy.
This series raises a number of other interesting issues. The detection of ascending aortic atherosclerosis by preoperative echocardiography constituted an exclusion criterion in this study. However, the aorta with patchy atherosclerosis (rather than the completely calcified, porcelain variety) may be the strongest indication for use of this sutureless connector, as aortic clamping is rendered unnecessary. Because the 1-cm circle of aorta in which the device is deployed should, however, be reasonably free of atherosclerosis, intraoperative assessment of the aorta by epiaortic echocardiography is advisable to precisely localize segments of atherosclerotic versus normal aorta. Graft positioning in reoperations via a limited-access approach is also critical. The combination of the 90° proximal anastomosis and limited mediastinal dissection may permit less room to position grafts and predispose to graft kinking.
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Future devices, future studies |
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TopIntroductionPotential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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6 will be significantly easier and quicker to load and deploy and will permit construction of anastomoses in any order. The ability to instrument the graft only through the portion to be discarded, rather than the portion that will remain to serve as a conduit, will minimize the potential for endothelial injury and lead to greater use of these devices with arterial conduits. As these devices mature, it may become possible, in as little as 2 to 3 years, to perform multivessel CABG, without cardiopulmonary bypass, in less than half the time and with significantly less morbidity than today. The potential of these anastomotic devices is staggering, although the realization of that potential will face a number of obstacles. One challenge facing device engineers may be, in fact, to limit the perfect reproducibility that has been one of the most touted advantages of these devices. The tradeoff for perfect reproducibility of the anastomotic technique is some loss of flexibility—the bite-by-bite adjustments that surgeons make in creating hand-sewn anastomoses to atherosclerotic target vessels. The development of devices that can adapt to, or are tolerant of, local variations in vessel wall thickness, mural plaques, or calcification will prove increasingly important as patients with progressively more advanced coronary atherosclerosis are treated.
A number of questions remain to be answered, related both to safety and to efficacy. Is long-term graft patency equivalent? Although initial experience with these devices in hundreds of centers worldwide has been extremely favorable, longer-term clinical and angiographic follow-up will be required to ensure that the most important characteristic of our bypass grafts, late patency, is not compromised. What is the optimal antiplatelet regimen after device implantation? Many centers have empirically prescribed clopidogrel alone or in combination with aspirin, in a protocol similar to that used after coronary stent implantation, but there are as yet no data to validate this approach. Can these devices be used safely in arterial grafts as the prevalence of multiple arterial grafting continues to increase? Will the purported advantages of OPCAB finally be convincingly demonstrated in patients in whom anastomotic devices obviate the need for aortic clamping? Will minimally invasive video-assisted CABG become a practical, 2-hour operation? Are these devices cost-effective for cash-strapped hospitals to use? And last, do previously implanted devices pose an impediment to the creation of new anastomoses at reoperation? Of all of the above questions, this is the only one to which we can be assured that the answer will inevitably be found.
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References |
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TopIntroductionPotential advantages and...Potential drawbacks and the...Defining a nicheFuture devices, future studiesReferences |
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ítesk
M, Vondrá
ek V, Urban T, Vyhnalová P, et al. Video-assisted multivessel revascularization through a left anterior small thoracotomy approach with the Symmetry Aortic Connector System. J Thorac Cardiovasc Surg. 2002;125:129-34.Related Article
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  T. A. Vassiliades Jr Multivessel, All-Arterial, Off-Pump Surgical Revascularization Without Disruption of the Thoracic Skeleton Ann. Thorac. Surg., October 1, 2004; 78(4): 1441 - 1445. [Abstract] [Full Text] [PDF]
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J. Lahtinen, F. Biancari, M. Mosorin, J. Heikkinen, P. Rainio, T. S. Juvonen, and M. Lepojarvi Fatal complications after use of the symmetry aortic connector in coronary artery bypass surgery Ann. Thorac. Surg., May 1, 2004; 77(5): 1817 - 1819. [Abstract] [Full Text] [PDF]
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