This Small Business Innovation Research (SBIR) Phase I project aims to develop a mechanical system for facilitating vascular anastomoses (end-to-side, end-to-end) technology that allows for the rapid and reproducible production of a non-penetrating, compliant vascular reconstruction. This one-shot technology represents a technical advance over the serial clip applier because the entire anastomotic circumference is formed simultaneously, thus facilitating the vascular reconstruction. Currently, there are no one-shot anastomotic systems on the market, thus the proposed technology would fill that much needed demand. This Phase I effort also will develop the manufacturing methods needed to produce these low-cost anastomotic devices that feature compliant polyurethane clips. Bench testing of the anastomoses will be conducted using well-established in vitro procedures.
The broader impact/commercial potential of this project will be to reduce the time required to perform vascular anastomoses as well as vascular reconstruction in beating heart surgery. The $400 million surgical staples market urgently needs a new technology, as there is a significant unmet need to develop a novel, sutureless anastomotic device that applies 10 or 12 circumferential clips simultaneously. This should lead to rapid commercialization, especially since this advanced system will reduce surgical operating time.
Optimizing vascular access has become a national healthcare priority. In the United States, approximately 300,000 patients with end-stage renal disease currently undergo hemodialysis. Although an operational vascular access is vital, venous stenosis remains the weakest link in the entire process. For example, within the first year, an astonishing 25% of all patients starting hemodialysis will die because of inadequate vascular access or complications related to vascular access. The vascular access necessary for hemodialysis consumes about 8% of the monies spent by Medicare on end-stage renal disease (roughly $1.8 billion per year). In 2006, the cost of end stage renal disease rose to $2.3 billion, or 6.4% of the total Medicare budget of $355 billion. Synthetic expanded polytetrafluoroethylene (ePTFE) arteriovenous grafts are used to gain rapid access to the blood of patients undergoing dialysis treatment via a fistula. However, synthetic hemodialysis arteriovenous (AV) grafts in patients with end-stage kidney disease fail at an alarmingly high rate typically due to neointimal hyperplasia that occurs around the anastomoses between the native vessel and the synthetic graft. The current method of performing an anastomosis in an AV shunt utilizes a tedious and time-consuming hand-sewn suturing technique to connect a bypass graft between an artery and a vein. Proper vessel alignment and suture tension among the many individually-placed fine stitches are critical for optimal graft blood flow and function. Our answer to this issue was replace traditional hand-sewn sutures with an easy-to-use, one-shot, highly reliable and consistent automated system, which would significantly reduce the time required for completing the anastomoses. This, in turn, increases anastomotic radial and longitudinal compliance and results in a significant reduction of intimal hyperplasia, and a dramatic improvement of AV shunt patency. Under the Phase I project, we successfully constructed an experimental single-shot 12 clip mechanical applier. This applier was subsequently used to construct anastomoses in cadaveric vessels using interrupted compliant clips. Our results from these tests have been highly encouraging. We unequivocally demonstrated that (1) clips do not leak (2) clipped constructs are comparable in tensile strength to conventional running sutures, and (3)clips are more compliant at the anastomosis site than conventional running sutures. This work was singularly successful in developing an elastic clip that promises to create compliant anastomoses. We also confirmed that the clips resulted in vascular constructs similar to running features in terms of fluid flow and longitudinal tensile strength and are more compliant than sutures when used with biological vessels (cadaveric arteries and veins). We could not obtain any improvement in compliance using standard ePFTE grafts. This was not unexpected, since these synthetic vessels are notoriously non-compliant While the Phase I studies have confirmed the feasibility of our compliant clips, much work remains to be done before it reaches clinical trials. Vascular surgeons have to deal with older patients who present with more diseased vessels and co-morbidities. Automated anastomotic technologies will enable the creation of rapid, precise and consistent anastomoses at a reasonable price, and this perfectly matches the surgeon’s current needs.
