Chinese Neurosurgical Journal study shows LVIS stent alters blood flow in aneurysms

Intracranial aneurysms are among the most dangerous abnormalities of the cerebral circulation. These weakened sections of an artery expand outward under blood pressure and may eventually rupture, triggering a subarachnoid hemorrhage that can cause permanent disability or death. Treating aneurysms with endovascular techniques has become increasingly common, but wide-necked aneurysms remain particularly difficult. Their broad openings can allow embolization coils to shift or protrude into the parent artery, reducing the stability of the repair and potentially obstructing normal blood flow.

A research team led by Professor Xiang Xu of Tangshan Gongren Hospital in China has now examined how a braided device known as the low-profile visualized intraluminal support, or LVIS, stent performs when combined with coil embolization. The stent is deployed across the aneurysm’s neck, where it acts as a scaffold to hold the coils inside the bulging vessel. Because the LVIS device has relatively high metal coverage, it may also modify the flow of blood entering the aneurysm, encouraging the gradual formation of a clot and promoting more durable healing.

The retrospective study included 61 patients treated for wide-necked intracranial aneurysms between January and December 2023. Thirty-five patients had ruptured aneurysms, while 26 had unruptured aneurysms. The investigators assessed the immediate angiographic result using the Raymond-Roy Occlusion Classification, a commonly used scale ranging from complete occlusion to persistent aneurysm filling. They also evaluated neurological function with the modified Rankin Scale, reviewed follow-up angiograms, examined whether the parent artery remained open, and recorded recurrence and treatment-related complications.

Initial angiography showed complete occlusion, classified as Raymond-Roy class I, in 28 of the 35 ruptured aneurysms, corresponding to 80 percent. Among unruptured aneurysms, 22 of 26, or 84.6 percent, were completely occluded immediately after treatment. Follow-up angiography was available for 27 patients between six and 12 months after the procedure. Every aneurysm that had been completely occluded initially remained stable during the available follow-up period. Several aneurysms with residual filling classified as class II improved to complete occlusion, suggesting that thrombosis and tissue remodeling continued after the intervention.

Functional outcomes also differed according to whether the aneurysm had ruptured before treatment. In the ruptured group, the proportion of patients with a favorable modified Rankin Scale score of 0 or 1 increased from 57.1 percent at hospital discharge to 77.1 percent at three to six months. In the unruptured group, 25 of 26 patients, or 96.2 percent, had favorable functional scores at discharge, and all surviving patients maintained favorable outcomes during follow-up. The results indicate that recovery can continue after the initial hospitalization, particularly among patients whose neurological injury was caused by the hemorrhage itself rather than by the procedure.

To investigate the biological effect of the stent more closely, the researchers performed computational fluid dynamics analysis in a subset of 14 patients. This technique uses medical imaging to reconstruct the aneurysm and surrounding blood vessels, then applies mathematical models to estimate how blood moves through the reconstructed anatomy. The analysis can measure variables that are difficult to observe directly, including the amount of blood entering the aneurysm, the distribution of flow within the sac, and wall shear stress—the frictional force exerted by moving blood against the vessel wall.

The computational analysis showed that LVIS-assisted coiling reduced blood-flow activity inside the aneurysm. After treatment, less blood entered the aneurysm, a smaller proportion of the aneurysm was exposed to higher-flow conditions, and the average wall shear stress decreased. These changes remained significantly different from baseline at six months, with all reported P values below 0.001. From a mechanistic perspective, the findings support the idea that the treatment does more than physically fill the aneurysm with coils. The stent’s mesh may divert blood away from the aneurysm opening, while the coils further disrupt circulation inside the sac, creating conditions that favor clot formation and progressive sealing.

However, the study also documented clinically important risks. Two patients with ruptured aneurysms developed thrombosis during the procedure but were treated successfully without permanent neurological deficits. Incomplete apposition, meaning that part of the stent did not lie firmly against the vessel wall, occurred in six of the 61 patients, or 9.8 percent. One patient treated for an unruptured aneurysm developed delayed in-stent thrombosis and died after rescue treatment failed and a secondary cerebral hemorrhage occurred. The overall procedure-related mortality was therefore 1.6 percent. These events emphasize that the same device designed to support healing can also create a surface on which clot formation becomes dangerous if deployment, vessel geometry, or antiplatelet therapy is inadequate.

The investigators caution that their findings should not be interpreted as proof that LVIS stents caused the observed improvements. The research was conducted retrospectively at a single center, included clinically heterogeneous patients, and had angiographic follow-up for only 44.3 percent of the original cohort. The CFD analysis involved just 14 patients, and its conclusions depend on imaging quality and modeling assumptions. Larger prospective studies comparing LVIS-assisted coiling with other stent-assisted or flow-diversion strategies will be needed to establish which patients benefit most and how thrombotic complications can be prevented. Even with these limitations, the study provides a detailed view of how a widely used endovascular device may combine mechanical stabilization with measurable changes in cerebral blood flow.

Web References: Chinese Neurosurgical Journal: https://cnjournal.biomedcentral.com/ ; DOI: https://doi.org/10.1186/s41016-026-00435-9

References: 10.1186/s41016-026-00435-9

Keywords

Intracranial aneurysms, LVIS stent, stent-assisted coiling, cerebral blood flow, computational fluid dynamics, wall shear stress, endovascular neurosurgery, aneurysm thrombosis, neurointervention, cerebrovascular disease