Conduits, Grafts, Stents, Stent-Grafts, and Device Evaluation

16.1Device evaluation before platform ranking

Device choice begins with the clinical problem, not with the catalogue. For lower-extremity peripheral artery disease, the useful first question is whether the patient is asymptomatic, claudicant, has chronic limb-threatening ischemia, or has acute limb ischemia; the answer determines the acceptable balance among durability, procedural risk, time to flow restoration, surveillance burden, and tolerance for reintervention. Evidence source 2024 In chronic limb-threatening ischemia, conduit and device decisions should be integrated with patient risk, limb severity, and anatomic complexity rather than reduced to a single patency statistic. Global vascular guidelines 2019

A vascular device should be judged against the outcome it is meant to improve. For limb-loss prevention, technical success alone is insufficient; reporting frameworks for lower-extremity peripheral artery disease emphasize hemodynamic improvement, target-lesion patency, freedom from clinically driven target-lesion revascularization, limb salvage, survival, and the patient’s clinical presentation and anatomy. PAD 2014 · Reporting standards Society 2016 Objective performance goals for critical limb ischemia provide benchmark endpoints for major adverse limb events and limb loss, and they remain useful when interpreting single-arm device studies that lack a surgical control group. Validation Society Vascular 2011

Anatomic eligibility is part of device evaluation. In aneurysm repair, the relevant device question is not simply whether an endograft can be delivered, but whether it can obtain durable seal and fixation, pass safely through the access vessels, and be followed reliably for endoleak, sac change, and migration. Society Vascular Surgery 2018 Hostile neck anatomy, including adverse neck length and angulation, is a failure-mode problem rather than a minor technical inconvenience; the more the anatomy strains the instructions and the biologic logic of seal, the more the surgeon must consider open repair, an alternative endovascular strategy, or a highly structured surveillance plan. Influence infrarenal neck 2006 · Aortic neck angulation 2002

The early success of a device class should not be mistaken for late durability. In EVAR-1, the early perioperative survival advantage of endovascular abdominal aortic aneurysm repair over open repair was lost after roughly 3 years, and long-term aneurysm-related mortality and reintervention were higher after EVAR; those findings came from early-generation devices, but they teach a durable principle: implanted aortic devices create a lifelong relationship among patient, anatomy, device, and imaging surveillance. Endovascular versus open 2016

Device evaluation must continue after implantation. Registry analyses after endovascular aneurysm repair show that endoleak, limb occlusion, migration, and sac enlargement generate a steady cumulative need for secondary intervention, and structured surveillance identifies many correctable failures before clinical presentation. Explanted graft and endograft analysis closes another loop: retrieved material can reveal structural fatigue, fabric failure, fixation problems, infection, thrombus organization, and design-related failure modes that clinical imaging alone may not fully explain. Explanted Vascular Endovascular 2018 · Secondary interventions following 2010

16.2Conduits and graft material

For infrainguinal bypass in chronic limb-threatening ischemia, the default conduit question is whether there is adequate autologous vein. Contemporary guidelines make autologous vein the preferred conduit, and they advise avoiding nonautologous conduit unless there is no suitable endovascular option and no adequate autologous vein. Global vascular guidelines 2019 This is not a sentimental preference for traditional surgery; it is a durability judgment that becomes especially important when the bypass must carry limb-salvage flow to a compromised distal bed. Evidence source 2024

Above the knee, prosthetic graft choice still matters when vein is unavailable. A systematic review of randomized trials in above-knee femoropopliteal bypass found that autologous vein had superior 60-month primary patency compared with prosthetic conduit, while a separate meta-analysis comparing Dacron with PTFE in above-knee prosthetic bypass found better primary patency for Dacron at 24, 36, and 60 months, with no significant difference in amputation, morbidity, or mortality. Graft type femoro-popliteal 2018 · Meta-analysis compare Dacron 2014 These data should be applied with attention to graft generation, runoff, antithrombotic regimen, and the patient’s expected survival.

When prosthetic conduit is required below the knee or to infrapopliteal targets, the operation should be treated as a higher-risk durability compromise. A 2024 meta-analysis found improved primary patency for heparin-bonded expanded PTFE compared with standard expanded PTFE when autogenous vein was unavailable, although outcomes generally remained inferior to good-quality great saphenous vein. Systematic Review Meta-Analysis 2024 The Scandinavian Propaten randomized trial similarly found higher 1-year primary patency with heparin-bonded PTFE than standard PTFE in lower-limb bypass overall, with stronger signals in femoropopliteal and critical-ischemia subgroups; those subgroup signals are useful but should not be overread beyond the trial population. Scandinavian Propaten trial 2011

Conduit quality begins before the proximal anastomosis. Great saphenous vein harvest technique can affect conduit integrity and wound morbidity, so the surgeon should regard harvest as part of device preparation rather than as a preliminary chore. When a prosthetic graft must be sewn to an infragenicular target, adjunctive vein cuffs or patches are used to modify anastomotic geometry and the biology of the prosthetic-to-artery interface; they are not substitutes for good inflow, outflow, and target selection. Great saphenous vein 2010 · Interposition vein cuff 2013

Patch material should be selected with the same attention to field, durability, and surveillance as a bypass conduit. In common femoral endarterectomy, mid-term data support bovine pericardium as a reasonable biological patch alternative to autologous vein or polyester, with high primary patency and low infection and pseudoaneurysm rates in a single-center cohort. Clinical Outcomes Common 2024 In the groin, this does not eliminate infection risk; it simply broadens the practical set of patch choices when vein preservation, patch handling, and local tissue conditions are considered.

Cryopreserved arterial allograft has a distinct role in infected or contaminated reconstructions, but it is not a benign permanent replacement for normal arterial tissue. Long-term and multicentre analyses describe acceptable early survival and limb salvage in selected infected aortic reconstructions, yet they also document substantial mid-term and late degeneration, pseudoaneurysm, anastomotic disruption, thrombosis, and reintervention. Cryopreserved Allograft Management 2019 · Late Fate Cryopreserved 2016 When an allograft is used, the operative success should be documented as infection control and viable reconstruction today, with explicit imaging surveillance for degeneration tomorrow.

16.3Stents, stent-grafts, and drug-device evidence

For aortoiliac occlusive disease, lesion complexity should guide the choice between bare-metal and covered balloon-expandable stents. In COBEST, covered balloon-expandable stents produced greater freedom from binary in-stent restenosis than bare-metal stents overall, with the clearest advantage in TASC II C and D lesions and no significant advantage in TASC II B lesions. Comparison covered 2011 · Increasing efficacy endovascular 2015 Five-year follow-up showed sustained primary patency benefit and fewer revascularisations with covered stents, although attrition and first-generation device technology temper the strength of late conclusions. Durability balloon-expandable covered 2016

The practical teaching from covered iliac stent data is anatomical restraint. Covered stents can exclude plaque, thrombus, and diseased wall from the lumen and may improve durability in complex aortoiliac disease, but branch coverage, landing-zone disease, and contralateral access remain decisive constraints. For a short focal lesion, the evidence supporting routine covered-stent use is weaker; for diffuse, complex, or occlusive TASC C/D disease, the threshold to choose a covered platform is lower if landing zones and access are suitable. Comparison covered 2011 · Increasing efficacy endovascular 2015

In the femoropopliteal segment, drug delivery should be evaluated by both antirestenotic benefit and safety signal. Earlier randomized-trial synthesis found that drug-eluting balloons reduced binary restenosis, target-lesion revascularization, and late lumen loss compared with uncoated balloon angioplasty, without a mortality or amputation difference at the time points reported. Drug-eluting balloon angioplasty 2016 The later paclitaxel mortality signal changed the consent discussion: a 2018 meta-analysis identified increased all-cause mortality at 2 and 5 years for paclitaxel-coated balloons and paclitaxel-eluting stents, and contemporary evaluations must incorporate updated mortality and revascularization analyses rather than relying only on restenosis endpoints. Safety paclitaxel-coated devices · Risk Death Following 2018

Drug-coated balloons and drug-eluting stents are not interchangeable simply because both carry an antiproliferative drug. A 2023 synthesis comparing primary drug-coated balloon angioplasty with primary drug-eluting stent placement for native femoropopliteal disease found broadly similar mid-term primary patency and target-lesion revascularization, while highlighting the importance of bail-out stenting after drug-coated balloon use for long lesions or flow-limiting dissections. Primary Drug-Coated Balloon 2023 The Zilver PTX randomized trial provides a separate long-term reference point for paclitaxel-eluting stent evaluation, reporting sustained event-free survival and patency superiority over plain balloon angioplasty with comparable safety in the femoropopliteal segment. Durable Clinical Effectiveness 2016

Carotid stent evaluation should include embolic protection as a design feature, not merely a procedural accessory. A randomized trial comparing MicroNet-covered carotid stents with conventional open-cell stents found fewer new ipsilateral ischemic lesions on post-procedural diffusion-weighted magnetic resonance imaging with the covered device. Randomized Controlled Trial 2021 For transcarotid artery revascularization, pooled data comparing dynamic flow reversal with carotid endarterectomy support comparable 30-day stroke and death profiles with potentially less cranial nerve injury, and contemporary prospective data extend TCAR device-class evaluation into standard-risk patients. TCAR 2021 · Prospective Multicenter Evaluation

Stent-graft adjuncts in the thoracic and complex aortic circulation must be evaluated by remodelling, branch preservation, endoleak behavior, and durability rather than deployment success alone. PETTICOAT and STABILISE techniques for complicated acute type B dissection add distal bare-metal stent extension or intentional septal disruption to proximal TEVAR, with pooled technical success near 97% to 100% and differing remodelling outcomes. PETTICOAT/STABILISE review 2023 Physician-modified endografts and off-the-shelf branched arch devices expand treatment options for juxtarenal and arch pathology, but their evaluation must remain anchored in morbidity, mortality, endoleak, sealing-zone durability, and the limits of the cohorts in which they were studied. Proximal Sealing Zone · Long-Term Results Physician-Modified 2024

16.4Clinical integration, follow-up, and evidence boundaries

The mature surgeon integrates conduit, device, anatomy, and follow-up capacity before committing the patient to a platform. For lower-extremity disease, this means matching the device plan to the presentation—claudication, chronic limb-threatening ischemia, or acute limb ischemia—and embedding the plan in risk-factor optimization and team-based care when limb threat is present. Evidence source 2024 For chronic limb-threatening ischemia, the PLAN approach keeps the discussion grounded in patient risk, limb severity, and anatomic complexity, which is more useful than asking whether “endovascular” or “open” is better in the abstract. Global vascular guidelines 2019

Follow-up should be designed around the known failure modes of the implanted material. EVAR follow-up seeks endoleak, migration, sac enlargement, and limb compromise; cryopreserved allograft follow-up seeks degeneration, pseudoaneurysm, anastomotic disruption, and thrombosis; infrainguinal bypass follow-up seeks inflow, conduit, anastomotic, and runoff failure before limb loss occurs. Late Fate Cryopreserved 2016 · Secondary interventions following 2010 The surveillance plan should be written into the operative strategy because a device that requires lifelong imaging is a poor choice for a patient unlikely to complete that surveillance unless no safer durable alternative exists. Society Vascular Surgery 2018

Infection changes the hierarchy of device selection. In aortic vascular graft or endograft infection, some patients can initially be stabilised with prolonged targeted antimicrobial therapy and imaging surveillance, but persistent sepsis, aortoenteric fistula, or anastomotic bleeding should trigger consideration of definitive surgical excision. Conservative Management First 2023 When in-situ reconstruction with cryopreserved arterial allograft is chosen for infected native or prosthetic aortic disease, the surgeon should plan for the possibility of later allograft degeneration and reintervention, especially when proximal anastomoses are placed in heavily infected tissue. Cryopreserved Allograft Management 2019

Venous stents require the same discipline in device evaluation as arterial platforms, even though the endpoints and failure modes differ. Dedicated venous self-expanding stents for iliofemoral venous outflow obstruction are being evaluated with prospective durability and patency outcomes, and their use should be framed around obstruction anatomy, expected venous inflow and outflow, symptom target, and the feasibility of follow-up. The important teaching point for trainees is that “venous” does not mean “low consequence”; stent occlusion, inadequate inflow, and poor surveillance can undermine an otherwise technically successful procedure. Three-Year Outcomes Abre 2024

Evidence boundaries should be made explicit during operative planning and consent. Many device trials are modest in size, enriched for favorable anatomy, or limited by attrition; systematic reviews may pool heterogeneous lesions, devices, antithrombotic regimens, and follow-up schedules. Subgroup signals—such as better outcomes for covered iliac stents in complex TASC C/D lesions or improved heparin-bonded PTFE performance in selected prosthetic bypass settings—are clinically useful, but they should guide judgment rather than replace individualized assessment of anatomy, conduit, infection risk, surveillance reliability, and patient goals. Systematic Review Meta-Analysis 2024 · Durability balloon-expandable covered 2016 · Scandinavian Propaten trial 2011