Kissing Iliac Stents vs. Open Bypass and CERAB

Kissing iliac stents are a pair of stents placed side by side at the point where the aorta splits into the two iliac arteries, restoring blood flow to both legs simultaneously. The technique treats aortoiliac occlusive disease, a condition where plaque narrows or blocks the lower aorta and iliac arteries, and it has become an established less-invasive alternative to open surgical bypass for patients who are poor candidates for major abdominal surgery.¹ The name comes from the way the two stents touch or “kiss” where they sit next to each other inside the aorta, just above the bifurcation. Despite looking straightforward in concept, the procedure involves real tradeoffs in stent choice, flow dynamics, and long-term durability that are worth understanding.

Why This Technique Exists

The lower aorta and iliac arteries supply blood to the pelvis and legs. When atherosclerosis narrows this region, especially right at the fork where the aorta divides, patients develop claudication (leg pain with walking), and in severe cases, critical limb ischemia that threatens the leg itself. Historically, the standard fix was open surgery, typically an aortobifemoral bypass graft, which reroutes blood around the blockages using a synthetic tube. That operation has excellent long-term results, with patency rates around 90% at five years, but it carries meaningful surgical risk because it requires opening the abdomen.²

Kissing stents offered a way to treat both iliac arteries through small punctures in the groin rather than a large incision. The technique works particularly well when the disease involves the bifurcation itself, where a single stent in one iliac artery could distort or compromise flow into the other. By placing two stents that extend from the iliac arteries up into the distal aorta, with their upper ends overlapping side by side, both outflow channels stay open and supported.

How the Procedure Is Performed

The procedure requires access to both femoral arteries, usually through punctures or small cuts at each groin. Guidewires are advanced up through both iliac arteries into the aorta. Stents are positioned so their upper ends sit side by side in the lower aorta, extending down into each common iliac artery. The two stents are then deployed simultaneously, so that neither one gets a head start and pushes the other aside. This simultaneous inflation is the hallmark of the technique and where the “kissing” label originates.

Getting the positioning right matters. If the stents extend too far into the aorta, they create an unnecessarily long segment of paired metal. If they do not extend far enough, the bifurcation lesion is not adequately covered. Operators typically use fluoroscopy to guide placement, and increasingly, intravascular ultrasound (IVUS) to check the result. In one study of patients with severe disease, IVUS found significant technical problems in about a quarter of procedures that the standard completion X-ray images had missed, prompting corrections during the same operation that led to strong two-year results.³

Covered Versus Bare Metal Stents

One of the ongoing debates is whether to use bare metal stents, which are essentially wire mesh scaffolding, or covered stents, which have a fabric layer over the metal frame that acts as a barrier between the blood and the vessel wall. The intuition behind covered stents is that the fabric prevents plaque and tissue from growing through the mesh, potentially reducing re-narrowing over time.

An early comparative study found a notable difference: covered stents had a two-year patency of about 92%, while bare metal stents dropped to around 62% at the same point.⁴ A larger registry, however, found the two types performed similarly at three years when looking at the overall population, with both hovering around 92% primary patency. The registry did find that covered stents outperformed bare metal in patients with moderate to severe calcification, where the covered group maintained 100% patency versus about 89% for bare metal at 36 months. That same analysis found that stent diameter of 8 mm or larger was a strong independent predictor of staying open.⁵

A 2024 meta-analysis that pooled individual patient data from three studies found a similar trend: covered stents showed numerically higher patency at every time point (roughly 88% versus 75% at four years), but the difference did not reach statistical significance, partly because the total number of patients was still modest.⁶ The picture that emerges is that covered stents probably have an edge, especially in heavily calcified arteries, but the evidence is not yet definitive enough to declare bare metal obsolete for all patients.

What Predicts Failure

Two factors consistently emerge as the strongest predictors of kissing stent failure: heavy calcification in the artery wall and small stent diameter. In a study focused on covered kissing stents, severe calcification was the only factor that remained significant in multivariate analysis, with a roughly 12-fold higher risk of restenosis compared to patients without severe calcification. Stent diameter of 7 mm or smaller also carried about a 9-fold higher risk in univariate analysis.⁷ That finding lines up with the ILIACS registry data showing that stent diameter of 8 mm or more was independently protective.

Anatomy also plays a role. A recent study found that patients with a higher ratio between their common iliac artery diameter and external iliac artery diameter, along with a smaller aortic diameter, were more likely to lose patency over time. The authors suggested these anatomical features should weigh into treatment decisions, particularly for younger patients who need their stents to last decades.⁸

The Hemodynamic Trade-Off

Every kissing stent configuration creates something that does not exist in normal anatomy: a “neobifurcation” where the two stent tops sit side by side in the aorta, slightly above the natural fork. Between the real bifurcation and this artificial one, there is a wedge-shaped gap, sometimes called the “gutter.” Blood flow in this zone behaves differently from what the body was designed for.

Laboratory flow models show that bare metal kissing stents tend to have a persistent area of sluggish flow between the anatomic bifurcation and the neobifurcation throughout the cardiac cycle. Covered kissing stents develop recirculation zones near the stent inflow area, with low wall shear stress values that are associated with clot and plaque buildup. During late systole and early diastole, the aortic wall between and around the stent tops can partially collapse in the front-to-back plane, producing disturbed flow and potential recirculation in precisely the area where you want smooth, laminar flow.⁹ The covered stent configuration tends to have the highest mismatch between the stent cross-section and the aortic lumen, because the fabric prevents the stents from conforming as well to each other and the vessel wall.

These flow disturbances are not just academic curiosities. The regions of low and oscillating wall shear stress that form around kissing stent gutters are the same hemodynamic conditions known to promote neointimal growth and thrombosis. Understanding where each stent type creates its trouble zones helps explain why some configurations fail over time and has driven the search for alternatives that better mimic normal aortic geometry.¹⁰

CERAB as a Newer Alternative

The covered endovascular reconstruction of the aortic bifurcation, or CERAB, was developed specifically to address the hemodynamic shortcomings of kissing stents. Instead of two stents meeting side by side, CERAB places a single large covered stent in the distal aorta that flares into two smaller covered stents extending into the iliac arteries, mimicking the natural Y-shape of the bifurcation more closely.

In flow models, CERAB produces less radial mismatch and fewer recirculation zones than either bare metal or covered kissing stents. It is the configuration closest to undisturbed physiological flow.¹¹ Clinical data have been encouraging, with a German review reporting that CERAB shows better five-year outcomes than the kissing stent technique and recommending it for patients with complex aortoiliac disease who are too high-risk for open surgery.¹²

That said, the advantage is not as clear-cut as flow models might suggest. A comparative study found that after adjusting for patient differences, the primary patency rates between CERAB and kissing stents were not significantly different, even though CERAB showed hemodynamic and morphological advantages. The CERAB group had no complications within 30 days, while the kissing stent group had a small number.¹³ CERAB also requires more hardware and can be technically more demanding, so it has not replaced kissing stents universally.

How Kissing Stents Compare to Open Bypass

For patients healthy enough to tolerate a major abdominal operation, the question of kissing stents versus aortobifemoral bypass remains relevant. A direct comparison found that patency rates at matched follow-up intervals were similar between the two approaches, but the complication profile differed sharply. About 20% of bypass patients experienced postoperative complications (local or systemic), versus roughly 7% in the stent group. Reintervention rates were not significantly different, at about 6% for bypass and 11% for stents.¹⁴

A matched-cohort study using covered self-expanding kissing stents found similar five-year primary patency in both groups: about 85% for stents and 88% for bypass, a gap that was not statistically meaningful.¹⁵ The takeaway is that for many patients, kissing stents deliver durability that is competitive with major surgery, while involving a fraction of the perioperative risk and recovery time. Open bypass still has a role, especially in younger, fitter patients with complex anatomy where you want the longest possible durability from a single procedure.

Reintervention Rates and Costs

One important practical consideration is how often patients need another procedure after their initial treatment. A cost-effectiveness analysis compared kissing stents, CERAB, and open surgery and found meaningful differences in reintervention probability: open surgery had the lowest rate at about 6%, CERAB was intermediate at roughly 17%, and kissing stents had the highest at about 29%.¹⁶ That higher reintervention rate is arguably the biggest practical downside of kissing stents. You are trading lower up-front risk for a higher chance of needing a touch-up procedure down the line.

Interestingly, when researchers compared the total cumulative cost of hospitalization between open repair and endovascular repair with covered stents for complex disease, they found no significant difference. The higher initial surgical costs of open repair were offset by the follow-up procedures needed after stenting.¹⁷ For patients, this means the financial argument does not strongly favor one approach over the other, leaving the decision to rest more on clinical and anatomical factors.

Complications Beyond Restenosis

The most feared acute complication of kissing stent placement is distal embolization, where debris from the plaque breaks loose during the procedure and travels downstream to block smaller arteries in the leg or foot. This appears to be uncommon: one study of self-expandable kissing stents reported only a single major complication, which was distal limb ischemia from emboli.¹⁸

A less obvious concern is what happens to the other leg. Because kissing stents treat both iliac arteries even when only one side has symptoms, the “asymptomatic limb” is also exposed to the risks of having a stent. A study tracking these asymptomatic limbs found six ischemic events, including three cases of late stent thrombosis. One patient developed bilateral stent occlusion at four months and eventually needed surgical bypass, while another with bilateral occlusion at ten months was managed conservatively because of other health problems.¹⁹ This is a real trade-off worth understanding: you are treating one symptomatic leg, but both legs now carry stent-related risk.

When a Single Stent Might Be Enough

Not every bifurcation lesion needs two stents. When the disease is primarily on one side, with only mild involvement of the opposite iliac artery, a single stent crossing or abutting the bifurcation can sometimes do the job. A comparison of single-stent versus kissing-stent approaches for asymmetric bifurcation lesions found that the single-stent group needed fewer stents (about 1.3 versus 2.3 on average) and was less likely to require bilateral femoral access (55% versus 100%). The complication rates were similar between groups, at roughly 8% for single stents and 13% for kissing stents, a difference that was not statistically significant.²⁰

A separate study comparing single stenting to kissing stenting for one-sided ostial common iliac lesions found a 95% primary patency at one year for the single-stent group versus 85% for kissing stents, with both groups achieving 100% technical success. The single-stent approach avoids the hemodynamic compromises of the kissing configuration and spares the patient a second groin access. However, it only works when the contralateral iliac artery is reasonably healthy and the plaque does not truly straddle the bifurcation.

Handling In-Stent Restenosis

When kissing stents do narrow or occlude over time, the reintervention options range from balloon angioplasty to additional stenting to, in the worst cases, conversion to open bypass. Heavily calcified in-stent restenosis presents a particular challenge because standard balloons may not adequately expand against rigid calcium deposits embedded in or around the stent.

A newer technique called intravascular lithotripsy, which uses sonic pressure waves to crack calcium (similar in principle to the technology that breaks kidney stones), has been applied in this setting. A case report described “kissing IVL,” where lithotripsy balloons were inflated simultaneously in both limbs to treat bilateral in-stent restenosis caused by underexpanded stents in calcified common iliac arteries. The procedure was performed through a combination of right femoral and left axillary access, and the authors reported a safe and effective result when other standard techniques had failed to achieve adequate stent expansion.²¹ This remains a niche rescue strategy, but it illustrates how the toolbox for managing failed kissing stents continues to expand.

Image Fusion and Reducing Radiation

Kissing stent procedures are performed under fluoroscopy, meaning both the patient and the procedural team receive radiation exposure throughout the case. A technique that has shown promise for aortoiliac interventions is image fusion, where a preoperative CT or MR angiogram is overlaid onto the live fluoroscopy images in the operating room. In a preliminary experience with this approach, the mean radiation dose was about 60 Gy·cm² with a mean fluoroscopy time of around 12 minutes.²² The merged images give operators a roadmap of the diseased anatomy without requiring as many contrast injections or as much X-ray time to figure out where they are. For complex bifurcation cases requiring precise stent positioning, this kind of guidance can make the procedure safer for everyone in the room.