A device for proximal anastomosis of autologous coronary vein grafts: report from the meeting of the Circulatory System Devices Panel of the Food and Drug Administration Center for Devices and Radiologic Health.

The Food and Drug Administration (FDA) Circulatory System Devices Advisory Panel was asked to make recommendations on the PAS-Port Proximal Anastomosis System (Cardica, Inc), a device intended to create an end-toside anastomosis between the aorta and autologous vein graft during coronary artery bypass graft surgery. Advisory panels make nonbinding recommendations to the FDA. Classically, coronary artery bypass graft surgery (CABG) has been performed with hypothermic cardiac arrest, aortic cross-clamping, and extracorporeal circulatory support to provide the “clean” field demanded by the challenge of suturing small vessels. These factors may contribute to the neurocognitive decline, strokes, and other adverse patient outcomes often observed after CABG. “Off-pump” and “beating-heart” bypass procedures have been developed in an effort to minimize the untoward effects of circulatory support and to permit faster postoperative recovery. Facilitation of vascular anastomoses may permit faster and less invasive CABG. Anastomotic devices may not only simplify the procedural mechanics for the operator but also potentially obviate the need for many of the factors that contribute to poor patient outcomes, including extracorporeal circulatory support, induced hypothermic cardiac arrest, and aortic cross-clamping. Ultimately, these devices may simplify beating-heart surgery and reduce complications, although this remains to be proved. In 2001, the Symmetry Bypass Aortic Connector (St Jude Medical, Inc) became the first automated vascular anastomotic device cleared for marketing in the United States by the Food and Drug Administration (FDA). After device clearance and marketing, and after tens of thousands of implantations in patients worldwide, a number of apparently device-related adverse events were reported to FDA. More than 180 injuries and 20 deaths were observed, apparently as a result of occlusion, thrombus, or stenosis at the connector site, aortic dissection associated with device deployment, graft kinking, and postoperative device detachment resulting in hemorrhagic shock and/or death. Ultimately, the Symmetry device was voluntarily withdrawn from the market in 2004. It is on this backdrop that the FDA Circulatory System Devices Panel was asked to consider the PAS-Port Proximal Anastomosis system (Figure). The device consists of the implant (9 barbed tines that penetrate the vein to secure it to the aorta) and the delivery system. Importantly, several differences distinguish the PAS-Port from the Symmetry device. In contrast to the Symmetry device, the PAS-Port does not expose the endothelium of the implanted graft to metal, avoids contact with conduit intimal lining, has a lower profile, substantially reduces exposure of blood and subintimal tissue to metal, has an 150% larger orifice, and creates an aortotomy and deploys the implant in one action (by turning a knob at the end of the tool). Ultimately, any vascular anastomosis device must be evaluated on clinical grounds. The Circulatory System Device Panel, at a March 2004 meeting on the topic of Vascular Anastomosis Devices for CABG, recommended quantitative angiography at a minimum of 6 months of follow-up as a surrogate for anastomotic device performance. Meta-analysis of studies conducted between 1979 and 2001 suggests handsewn vein graft patency rates at 12 months in excess of 80%. The FDA determined that for these anastomotic devices, clinical data should demonstrate a lower 95% confidence interval for 6-month vein graft patency 80%. Many factors affect graft patency, including the technical quality of the anastomosis, graft quality and trauma during harvest, target vessel selection, effective orifice size, graft kinking, progression of underlying atherosclerotic disease, concurrently administered medications, and the presence of comorbidities (ie, diabetes, dyslipidemia, etc). As CABG is increasingly performed in patients who fail or are not good candidates for percutaneous revascularization, vein patency rates may be expected to decrease, as observed in the more recent PREVENT IV and PRAGUE trials, which had 12month venous graft patency rates of 50% to 70%.