Cath Lab Digest

Background
As the population ages, an increasing number of patients are in need of lower extremity revascularization. Improvements in surgical, anesthetic, and endovascular techniques provide an increasingly aggressive approach to limb salvage that can be offered to these older and often sicker patients. There is little question that the autologous saphenous vein is the ideal conduit for surgical revascularization, especially to a tibial artery. However, the lack of adequate vein can present a major challenge in the care of these patients. Because of its utility in peripheral and coronary arterial beds, the saphenous vein has become a valuable commodity that is often in short supply. In those patients needing primary revascularization of the lower extremity, as many as 30% lack a suitable autogenous vein. This number increases to 50% in those patients requiring a secondary bypass procedure.¹ Although the use of duplex ultrasound has been implemented to locate veins that may not be readily apparent, there remains a significant number of patients in whom an adequate vein cannot be found. The most common reasons for this lack of vein include previous vein harvest for coronary revascularization or another peripheral bypass, excision of varicose veins or a vein that is unsuitable due to small size or post-phlebitic changes.

PTFE for Tibial Artery Bypass Grafts
Alternative conduits have not resulted in equivalent results when used for distal bypass to tibial arteries.^2-5 Polytetrafluoroethylene (PTFE) is recognized as a useful prosthetic conduit for lower extremity revascularization. However, tibial artery bypass with PTFE has not consistently led to successful revascularization. A prospective, multicenter, randomized trial compared saphenous vein and PTFE for infrainguinal arterial revascularization.⁶ Patency differences became apparent within one month of operation, and differences increased progressively thereafter. At the four-year interval, primary patency for vein bypasses was 49% as compared to a 12% patency rate for those randomized to PTFE. This well-known study supported previous suspicions of the inferior results for PTFE bypass grafts to tibial arteries.

Because of these poor results, primary amputation is often considered in certain patient subgroups without a vein.⁷ To deal with this problem, several authors have reported on the use of venous cuffs, collars and boots to improve the results of prosthetic grafts in these challenging patients.^8–10 These techniques have been proposed as an option for open revascularization in patients without an adequate saphenous vein to obtain limb salvage.

Vein Cuffs and Boots
In 1979, Siegman proposed using a vein cuff to ease the technical challenges of a difficult anastomosis to heavily calcified small arteries.¹¹ Subsequently, Miller proposed a variant of this vein cuff to overcome the technical difficulties of the anastomosis and to improve graft patency by influencing the elastic properties of the prosthetic graft and the target artery. The Miller vein cuff involved the longitudinal opening of a small piece of vein and a running suture to secure the edge of the vein to the arteriotomy. The two cut ends of the vein were then sutured together in order to construct an oval venous cuff. The prosthetic graft was then sutured directly to the oval vein cuff (Figure 1). Miller reported the initial experience of 114 infrainguinal procedures using this cuff technique.¹² The patient cohort included only 21 tibial artery bypass grafts. A patency rate of 72% was noted at 18 months. Since that initial report, several other authors have reported on their experience with the Miller cuff configuration.¹³

However, several potential disadvantages have been recognized in association with the Miller vein cuff technique. Significant turbulence has been noted due to the deep anastomotic reservoir and the difficulty of achieving a proper angle between the graft and recipient artery. This results in increased turbulence and shear stress at the distal anastomosis. These hemodynamic factors may help to explain the immediate and early graft failures reported in Miller’s initial series.¹⁴ Additionally, we have noticed that the oval formation of the Miller cuff is difficult to maintain in tight anatomic spaces, such as very distal bypasses to the dorsalis pedis artery of the forefoot and the plantaris pedis branches of the posterior tibial artery.