Institutional experience of in-stent stenosis after pipeline flow diverter implantation: A retrospective analysis of 6 isolated cases out of 118 patients

Abstract

Pipeline embolization devices (PLEDs) are flow diverting stents that have exhibited be safe and efficient in the treatment of complex aneurysms. Nevertheless, in-stent stenosis (ISS) has been reported as one of the cardinal complications associated with PLED. The association of wall malapposition and ISS in patient treated with PLED has not been reported.A retrospective study was conducted to identify patients with ISS after implantation of PLED as treatment for intracranial aneurysms from April 25, 2018 to April 24, 2019. Incidence of ISS and its associated causes such as sharp change of the PLED, distal wall malapposition, inconsistent compliance between parent artery as well as the PLED occlusion due to intimal hyperplasia and vessel tortuosity. Assessment of conservative treatment and retreatment outcomes of ISS were documented.In all, 6 ISS cases were identified by 2 independent neurointerventionalists out of 118 aneurysm patients treated with PLED. Thus, the incidence rate of ISS in patients treated with PLED was as low as 5% at our institution compared to other studies. The follow-up time for detection of ISS ranged from 6 to 12 months after implantation. Several combinations of reasons such as sharp change of the PLED, distal wall malapposition, inconsistent compliance between parent arteries as well as PLED occlusion due to intimal hyperplasia and vessel tortuosity accounted for the causes of ISS during our analysis. Conservative treatment with a combination of antiplatelet during follow-ups did not resolve the ISS in our study probably due to associated underlying factors above.

Figure 1

(Case 2): Are images associating shape change of PLED as the cause of ISS. A: shows 2 aneurysms in the right ophthalmic segment of internal carotid artery (ICA). B: shows the lateral view of the parent artery. C: Shows un-subtracted image of implanted PLED intraoperatively. D: is a diluted contrast Xper-CT image of the stent intraoperatively. E: shows a little residual in 1 aneurysm while another was completely occluded on 6-month follow-up images. F&G: Are lateral view of parent artery showing vessel lumen stenosis. H: shows the proximal shape change of the stent on a diluted contrast Xper-CT image.

Figure 2

(Case 4): Are images demonstrating the association of distal malapposition of PLED as the cause of ISS. A: displays the ophthalmic segment aneurysm of right ICA intraoperatively. B: shows the distal end of PLED intraoperatively. C: Shows distal malapposition of the stent in diluted contrast Xper-ct image. Fig 2d-f were 6-month follow-up angiography of lateral views. D: shows loss of vessel lumen in the distal end of PLED on 6-month follow-up angiograph. E: Is an un-subtracted image showing the relationship between the opacified vessel lumen and the inner contour of the metallic mesh. F: shows the shape of the stent.

Figure 3

(Case 5): Are images demonstrating the association of inconsistent compliance between parent artery and the PLED as the cause of ISS. A: show the size and location of the aneurysm. B: show inconsistent compliance between parent artery and the distal end of the stent before coiling. C: is the diluted contrast Xper-ct image showing the inconsistent compliance clearer. D: show no stenosis in the distal end of the stent immediately after the procedure. E: display stenosis at the site of inconsistent compliance on 6-month follow-up images. F: is a casted image showing the inconsistent compliance on 6-month follow-up.

Figure 4

(Case 1): Are imaging showing the PLED occlusion due to intimal hyperplasia and vessel tortuosity as cause of ISS. A: shows the frontal views of bilateral ICA. Initially, the right was occluded while the left A1 segment of anterior cerebral artery was patent with compensation from the contralateral anterior communicating artery. B: shows the aneurysm in cavernous segment of ICA. C: shows the shape of the stent as well as confirmation that, the stent covered the aneurysm centrally. D: is 3-months follow-up frontal and lateral views of left ICA showing ISS at the distal and proximal end of the stent. The ISS is severe at the distal end while the aneurysm is completely occluded. E: Shows diffuse intimal hyperplasia inside the stent. F: shows tortuosity of terminal segment of ICA. G: Is a 12-month follow-up frontal and lateral views of left ICA showing obvious flow restriction of left anterior cerebral artery an obstructed anterior communicating artery. The ISS of proximal end was relieved to some extent. H&I: shows diffuse intimal hyperplasia is still present.