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Anastomotic Devices in Coronary Artery Bypass Grafting
03 March 2017
03 March 2017
07 April 2017 (online)
In coronary artery bypass surgery, high quality anastomoses are most important for successful outcomes. Despite the fact that well trained and skilled surgeons can do perfect anastomoses routinely, realizing the idea of a perfect anastomosis using an automatic device is intriguing. In theory, automatic anastomotic devices could lead to reduced complication rates, especially by avoiding the need for side clamping of the aorta, and also facilitate minimally invasive procedures.
Therefore, Prof. Mohr's team focused on evaluating different anastomotic device developments. This was mainly driven by the rapid expansion of the minimally invasive and off-pump coronary bypass (OPCAB) program in Leipzig.
The major advantages of OPCAB procedures are avoiding cardiopulmonary bypass and aortic clamping. However, proximal side clamping of the aorta can still be necessary to perform a proximal anastomosis. With the development of safe proximal anastomotic connectors side clamping could potentially be avoided, aortic manipulation minimized, and stroke risk further reduced.
Proximal connectors were developed by several start-up companies in the first decade of this century. Most of them have been evaluated at the Leipzig Heart Center, first in the experimental laboratory and then eventually clinically. This included the Symmetry Aortic Connector System (St. Jude Medical, St. Paul, Minnesota, United States), a nitinol stent to connect the vein graft to the aorta ([Fig. 1]), the CorLink automated aortic anastomotic system (Cardiovations, Irvine, California, United States), a self-expanding nitinol extraluminal device ([Fig. 2]), and the PAS-Port System (Cardica, Redwood City, California, United States), a single use device for proximal vein graft anastomosis to the aorta ([Fig. 3]).
The PAS-Port System as a proximal connector device was tested more extensively in several studies. In our single center study twelve-month was analyzed in a prospectively randomized trial in which a total of 99 patients was included. There was a trend toward a lower rate of postoperative delirium in the PAS-Port group (11.7% versus 25%, p = 0.088). Patency at discharge (100% in the PAS-Port group versus 97.8% in the control group), and after one year (97.8% in the PAS-Port group versus 93.7% in the control group), were comparable. In addition to this experience we also participated in multicenter trials. After all studies had demonstrated safety and efficacy of the system the PAS-Port device is currently used in clinical practice in many countries around the world.   
OPCAB procedures in general as well as limited access procedures such as minimally invasive direct coronary artery bypass grafting (MIDCAB) or total endoscopic coronary artery bypass grafting (TECAB) created the need for distal anastomotic devices to reduce the time necessary for an anastomosis and to facilitate an anastomosis in anatomically difficult situations.
Many distal connectors developed have been tested in Leipzig as well. Those included the SJM Distal Connector, a stainless steel clip system from St. Jude Medical (Maple Grove, Minnesota, United States) ([Fig. 4A-D]), and the U-Clip (Medtronic, Minneapolis, Minnesota, United States) ([Fig. 5]).
The Magnetic Vascular Positioner (MVP) System (Ventrica Inc, Fremont, California, United States) ([Fig. 6]) was tested in several studies and animal projects. In the first multicenter trial the MVP was successfully implanted in 32 of 41 cases (78%). The anastomotic time ranged from 65 to 370 seconds. Pre-discharge angiograms demonstrated an overall patency rate of 93.5% versus 91.7% in hand-sewn grafts. For the internal thoracic artery (ITA) grafts (n = 9) early patency was 100%. The device has been used in MIDCAB with a mean anastomotic time of 199 seconds and 100% 6-month patency (n = 8),  as well as in multivessel OPCAB procedures. A prototype delivery system also allowed usage of the device for experimental TECAB in a canine model. The combination of robotic technology allowing for dexterous manipulation in a closed chest environment and a simple yet effective and time saving technique for anastomotic coupling greatly facilitated beating heart TECAB.
The Leipzig Heart Center was part of the C-Port (Cardica, Redwood City, California, United States) device studies. The C-Port system ([Fig. 7]) produces a compliant anastomosis with a graft vessel and coronary vessel configuration similar to a single stitch hand-sewn anastomosis ([Fig. 8]). In a multicenter study, the safety and efficacy of the system were evaluated. At discharge, 113 patients had a C-Port implant in place, and 104 C-Port anastomoses were studied by means of angiography. At 6 months, one patient had died of a device-unrelated cause, and 98 patients were evaluated by means of angiography (n = 89). Overall patency was 92.1%. At 12 months, 107 (98.2%) of 109 alive patients were followed without any reports of device-related major adverse cardiac events.
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