Open Surgery and Endovascular Management of Failing Infrainguinal Bypass Graft

Scott A. Berceli

Originally described in 1984, failing bypass grafts now include any stenosis or abnormal hemodynamics determined by clinical examination, duplex scanning, or arteriography. Although clinical examination provides an initial assessment for vein graft patency, this approach in isolation fails to identify up to 70% of significant lesions. Duplex ultrasound has evolved into the test of choice to identify significant vein graft lesions.

Pathology of the Failing Vein Graft

Multicenter prospective data demonstrate that only 50% of patients with infrainguinal vein grafts are free from clinically significant stenosis, revision, or major amputation at 1 year. The highest rate of graft failure occurs in the 3 months following implantation, where 15% of grafts are lost or require repair. Technical or judgment errors at the time of graft insertion dominate the underlying etiology for these early problems, with graft torsion, retained valves, unrecognized conduit abnormalities, and anastomotic narrowing being the most common. Progressive loss of primary graft patency in the 6- to 18-month time frame occurs predominantly through intimal hyperplasia development in the perianastomotic (53% incidence) or mid-graft (30% incidence) regions. After 2 years, graft loss is reduced to about 4% per year and results from either delayed intimal hyperplasia or progressive atherosclerosis in the proximal and distal arterial segments.

Development of optimal strategies for treating the failing graft has been hampered by the heterogeneity of lesion pathology. Although a specific open surgical or endovascular approach may be appropriate for pathologies observed within the initial month after implantation, this same treatment approach can have limited durability when applied to hyperplastic lesions that are observed in the range of 9 to 18 months postoperatively. Unfortunately, few published studies have sufficient statistical power to adequately examine the influence of lesion pathology on the success or failure of a specific treatment strategy.

Factors Influencing Repair Choice

Open surgical revision can be adapted to encompass the full spectrum of potential graft pathologies, but the durability of endovascular treatments for the failing vein graft are inherently linked to the characteristics of the lesion. Time after implantation, lesion location, stenosis length, and graft occlusion have been identified as important surrogates for lesion pathology that significantly influence the intermediate and long-term success of endovascular interventions, and they thus become important factors in directing the choice between open and endovascular revision (Figure 1).

Time after Graft Implantation

Flow-limiting lesions identified within the initial 3 months are usually secondary to technical or judgment issues at the time of graft implantation. Delayed identification of kinks, twists, and external constricting bands that result from creating the graft tunnel present a variety of technical challenges to endovascular therapies and are best approached with open surgical revision. Intraluminal pathologies such as retained valves or intraluminal webs are more amenable to endovascular interventions, and small series have described the use of atherectomy devices to treat these lesions. Despite the promising results in this select group of patients, direct excision and vein patch angioplasty remain the standard treatment for preexisting vein pathology. Selection of a suboptimal distal target with reductions in graft flow presents an early risk for vein graft failure.

Although advances in endovascular technologies have improved our ability to treat infrageniculate lesions, creation of a distal jump graft likely offers the most durable solution in patients with available autogenous conduit and a suitable distal target. Although these early lesions encompass a variety of underlying etiologies, in aggregate they present significant challenges to endovascular revisions, supported by numerous reports documenting a high failure rate for these less invasive approaches.

Stenosis Length

Stenosis length is well described as an important risk factor for influencing durability following endovascular interventions. Such less invasive therapies used in the treatment of lesions less than 2 cm in length are significantly more durable than those aimed at long-segment disease, with an approximate threefold increase in the need for reintervention in these longer lesions. Similarly, vein grafts undergoing endovascular treatment for tandem lesions are prone to earlier failure, with a 2.5-fold increase in the failure rate following an intervention to treat multiple lesions.

Lesion Location

The role of endovascular therapies in the treatment of perianastomotic lesions is less well established. Theoretically, the nonuniform geometries and abnormal flow dynamics, major components for the development of these lesions, are not improved by endovascular revision, and the forces leading to augmented hyperplastic growth remain unchanged. Studies examining this issue, however, have been mixed, with some suggesting an increased restenosis rate but others failing to demonstrate this association. On a practical level, endovascular repair of lesions located a short distance from the anastomosis likely respond similar to midgraft lesions, whereas those extending into the suture line are constrained by the local geometry and are at increased risk for failure.

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