Economics of an Interrupted, Non-Penetrating Clip Anastomosis for Vascular Access Procedures

Introduction

End-stage renal disease (ESRD) is increasing in epidemic proportions worldwide. Therefore, vascular access procedures are rapidly becoming the most common surgery performed in the world. In the United States, there are approximately 300,000 people on dialysis. This number is growing by 15% or more each year, and will consequently double this patient population in 4 to 6 years. Total annual costs are expected to exceed $28 billion by 2010. Vascular anastomosis has evolved over a long period of time. The early vascular surgeons were hampered by their lack of medical experience and technology in the repair of vessels. Accordingly, they turned to more inventive means and utilized various devices made of bone, glass, ivory, rubber and metals to aid in vascular repair.¹ There are many influential people who have greatly contributed to the progress of this emergent field. Hallowell was the first to successfully accomplish surgery on arteries in 1759. Hallowell’s device to aid in vascular repair was reported to control arterial hemorrhage while preserving the vessel lumen. He closed a brachial artery wound by thrusting a pin through the tear and ligating around the pin in a figure-8 stitch. The ligation was tightened as the pin was removed.¹ John B. Murphy performed the first vascular anastomosis in human patients in 1897. He used a different vascular invagination method in which one severed end of the blood vessel was inserted into the other end. A clamp with 2 halves of a split metal cylinder was attached to a straight hemostat. The 2 cylinder halves were placed over one end of the severed vessel and the clamp closed to form a complete cylinder.¹ In 1899, J. Dorfler adopted a technique in which he deliberately penetrated all layers of the vessel with a fine round needle and a fine silk suture. He used continuous suture that embraced all three layers. He concluded that aseptic silk thread in the lumen did not necessarily lead to thrombosis, and therefore was not contraindicated. Through his work, vascular suture development followed.¹ Edwin Payr, in 1904, described a vessel coupling apparatus which had two matted flanged rings, with pins on one flange to match holes in the other flange. One end of the vessel was threaded through the ring with the pins, while the second end of the vessel was threaded through the ring with the holes. The ends of the vessel were everted over the rings, and the rings brought together and secured by bending the pins.¹ Alexis Carrel made the most notable contributions to the field of vascular surgery at the turn of the 20th century. At the age of 29, his classic paper on blood-vessel anastomosis was published just two years after receiving his medical degree. In 1902, he originated the three-stay suture (triangulation method) of blood vessels to perform arterial and venous anastomosis.¹ At the turn of the 20th century, many of the principles of vascular anastomosis had been attempted and were established. Great advances in technology have occurred in the last two decades. Despite these improvements in anastomosis, vascular access surgery is still associated with a high rate of early stenosis and hyperplasia. New mechanical closure systems have been devised to hopefully address this problem. In the early 1990s, Dr. Wolfe Kirsch in Loma Linda, California, developed a non-penetrating arcuate-legged titanium clip to create an interrupted, non-penetrating, yet compliant vascular anastomosis. His Vessel Closure System (Anastoclip VCS, LeMaitre Vascular, Burlington, Massachusetts) has been evaluated to replace sutures in creating autologous arteriovenous anastomosis, as well as non-autologous anastomosis. There is considerable data to show that an interrupted anastomosis is superior to a running anastomosis.^2–4 The hope is to generate a better anastomosis than obtained with running sutures, while minimizing operative time, reducing complications, minimizing trauma and improving clinical patency. If accomplished, these studies should help in lowering overall costs due to fewer re-operations, interventions and complications.

Methods

The surgical procedures were carried out with autologous fistulae as well as with non-autologous grafts. The technique for accomplishing the interrupted Anastoclip VCS requires a short learning curve. To facilitate an end-to-side anastomosis, one should place a vertical mattress stay suture at the heel and interrupted stay sutures at the toe and three and nine o’clock positions. This helps to stabilize the vessels and begins the eversion process, which is critical in making an Anastoclip VCS anastomosis. A necessary instrument is an everting forceps. The stay sutures are held taut, which initiates the everting process. The everting forceps are used to complete the everting process and clips can then be applied a little less than one millimeter apart. Since these clips are non-penetrating, there should be little to no bleeding when the vascular clamps are removed. Many studies have been performed comparing a running polypropylene suture to an interrupted anastomosis created with Anastoclip VCS. Schild et al. carried out a published study on the first use of Anastoclip VCS in humans. The study evaluated 96 patients, prospectively randomized to clip versus suture.⁵ A second, multicenter study completed by Shenoy et al. compared the use of sutures and clips in 1,387 autologous fistulae and polytetrafluoroethylene grafts.² Another study by Shenoy et al. assessed the economic impact of the beneficial effect of changing the vascular anastomotic technique in hemodialysis access. Finally, in his book, Zeegbrets also evaluated the superiority of Anastoclip VCS.⁶

Results

Anastoclip VCS provides many operative advantages over running sutures for arteriovenous fistulae (AVF) and arteriovenous grafts (AVG). The Anastoclip VCS is easy to handle, and anastomotic time was significantly lower, 14 minutes versus 22 minutes in the creation of an autologous fistulae (p = 0.0001).^2–11 Less anastomotic bleeding was appreciated at the time of the procedure (p = 0.001).^2,3,5,7,8 Healing pattern for the Anastoclip VCS is equivalent, if not superior, to a running suture.^5,8–10 Post-operatively, the clips help create a smooth interface between endothelial cells, which reduces intimal hyperplasia.^4,5,8–10 The interrupted Anastoclip VCS provides superior burst and tensile strength.⁹ Studies have shown that fistulae created using Anastoclip VCS have smoother laminar flow.⁹ Most importantly, Anastoclip VCS has superior primary and secondary patency when compared to a running suture in both autologous fistulae and grafts.^2,3,5,7,11 Primary patency rates at 24 months were 67% for clips, and 48% for sutures in the creation of autologous arteriovenous fistulae (p = 0.007).² Primary patency in grafts at 24 months was 39% for Anastoclip VCS and 19% for running sutures (p = 0.0001).² All data was statistically significant in favor of the Anastoclip VCS. Evaluation of cost savings was carried out by Zeegbrets et al. and showed that due to decreased operating time, fewer adverse events and better patency, the Anastoclip VCS was cost-effective.⁶ Further analysis by Shenoy et al.² strengthens the hypothesis that Anastoclip VCS was more economical.¹² Financial analysis was based on patients who underwent access procedures at Washington University-affiliated hospitals in St. Louis, Missouri. Financial data was compiled from outpatient access procedures performed in 316 patients: 131 AVF and 185 AVG. Primary patency and overall patency of the clip AVF cohort were significantly improved over suture. Primary, secondary and overall patencies were significantly better in the clip AVG group versus suture. Clipped AVF required 0.22 procedures per fistula-year to maintain patency, in comparison to 0.37 for sutured AVF per fistula-year.¹²

Conclusion

Vascular access surgery has made great progress since its inception in the early 1960s. Access procedures are becoming the most common surgery performed in the United States. Anastoclip VCS is among the best contributions to this rapidly growing field.The Anastoclip VCS is non-penetrating and forms a smooth intimal, interrupted anastomosis. Anastoclip VCS should be considered as the standard of care in the creation of AV fistulae and grafts. There is sufficient data to show that the interrupted anastomosis is superior to running suture in every case, with fewer incidences of bleeding, shortened operating room time, superior healing pattern with a smoother intimal anastomosis, greater strength and superior patency. As a result of these ameliorations across the board when using clip versus suture, Anastoclip VCS has the potential to reduce long-term costs associated with maintaining hemodialysis vascular access, due to fewer complications and revisions. In the opinion of the authors, vascular access should be a multidisciplinary effort. Vascular access surgery encompasses many difficult problems, and should be only performed by those dedicated to its success.