Jailed Artery Ostia Modifications After Flow-Diverting Stent Deployment at Arterial Bifurcations: A Scanning Electron Microscopy Translational Study.

BACKGROUND: Even though flow-diverting stents are being increasingly used to treat intracranial aneurysms, the fate of jailed side branches remains controversial, with recent clinical data contradicting finding of earlier animal studies that reported patency. OBJECTIVE: To quantify the surface area of the ostia after 3 months of jailing by flow-diverting stents as a more accurate means of patency evaluation. METHODS: Ten large white swine were stented by flow-diverting stents placed at common carotid-ascending pharyngeal arterial bifurcation sites. A dual antiplatelet regimen was initiated 72 hours before stenting and maintained during follow-up. Optical coherence tomography was used to search for per-procedural thrombus formation. Selective control digital subtraction angiography was performed 12 weeks post-stenting. Subsequently, the stented arterial segments were harvested en bloc and observed under scanning electron microscopy, photographed, and quantified. RESULTS: The absence of per-procedural thrombus formation was confirmed. All ostia were patent at 12 weeks (or 3 months) post stenting, with no angiographic or scanning electron microscopy-evident thrombus formation. The mean initial ostium surface was 2 048 617 ± 731 625 µm. At 3 months, the mean nonendothelialized ostium surface was 229 218 ± 140 172 µm, and mean endothelialized ostium surface was 1 819 399 ± 672 632 µm. A statistically significant difference (reduction) was observed between the initial and 12-week ostium surfaces (P < .001), with an significant statistical power (1.000). CONCLUSION: Jailed side branches remained patent after stenting, but the surface quantifications showed significant endothelial coverage, with a significant reduction of patent ostium surfaces at 12 weeks post-stenting. ABBREVIATIONS: APhA, ascending pharyngeal arteryCI, confidence interval3DRA, 3-dimensional rotational angiographyDSA, digital subtraction angiographyFDS, flow-diverting stentOCT, optical coherence tomographyOS, ostium surfaceSEM, scanning electron microscopy.

Role of terminal and anastomotic circulation in the patency of arteries jailed by flow-diverting stents: animal flow model evaluation and preliminary results.

OBJECTIVE The authors describe herein the creation of an animal model capable of producing quantifiable data regarding blood flow rate and velocity modifications in terminal and anastomotic types of cerebrofacial circulation. They also present the preliminary results of a translational study aimed at investigating the role of terminal and anastomotic types of circulation in arterial branches jailed by flow-diverting stents as factors contributing to arterial patency or occlusion. METHODS Two Large White swine were used to validate a terminal-type arterial model at the level of the right ascending pharyngeal artery (APhA), created exclusively by endovascular means. Subsequently 4 Large White swine, allocated to 2 groups corresponding to the presence (Group B) or absence (Group A) of terminal-type flow modification, underwent placement of flow-diverting stents. Blood flow rates and velocities were quantified using a dedicated time-resolved 3D phase-contrast MRA sequence before and after stenting. Three months after stent placement, the stented arteries were evaluated with digital subtraction angiography (DSA) and scanning electron microscopy (SEM). Patent (circulating) ostia quantification was performed on the SEM images. RESULTS Terminal-type flow modification was feasible; an increase of 75.8% in mean blood velocities was observed in the right APhAs. The mean blood flow rate for Group A was 0.31 ± 0.19 ml/sec (95% CI -1.39 to 2.01) before stenting and 0.21 ± 0.07 ml/sec (95% CI -0.45 to 0.87) after stenting. The mean blood flow rate for Group B was 0.87 ± 0.32 ml/sec (95% CI -1.98 to 3.73) before stenting and 0.76 ± 0.13 ml/sec (95% CI -0.41 to 1.93) after stenting. Mean flow rates after stenting showed a statistically significant difference between Groups A and B (Welch test). Mean and maximal blood velocities were reduced in Group A cases and did not decrease in Group B cases. Control DSA and SEM findings showed near occlusion of the jailed APhAs in both cases of anastomotic circulation (mean patent ostium surface 32,776 µm2) and patency in both cases of terminal-type circulation (mean patent ostium surface 422,334 µm2). CONCLUSIONS Terminal-type arterial modification in swine APhAs is feasible. Sufficient data were acquired to perform an a priori analysis for further research. Flow diversion at the level of the APhA ostium resulted in significant stenosis in cases of anastomotic circulation, while sufficient patency was observed in terminal-type circulation.

Endovascular transvenous cure for ruptured brain arteriovenous malformations in complex cases with high Spetzler-Martin grades.

OBJECT: Ruptured cerebral arteriovenous malformations (AVMs) with deep localization and high Spetzler-Martin grades are associated with considerable challenges regarding nidus eradication treatment. The authors report their experience with curative endovascular transvenous embolization in a series of patients harboring "untreatable" lesions. METHODS: Between January 2008 and June 2013, a transvenous endovascular embolization protocol was implemented at the authors' institution for consecutive patients with ruptured brain AVMs that were considered incurable by classic endovascular and surgical techniques. Therapeutic decision making was based on Spetzler-Martin grades, AVM location, type of venous drainage, and angioarchitectural evaluation. Complete exclusion of the nidus was the objective of treatment. RESULTS: Twenty patients (10 male and 10 female, mean age 36.7 ± 17.7 years) were included. Initial Spetzler-Martin grades were III-V for 90.0% of the patients. The lesions were deeply seated in 80% and in eloquent locations in 90% of cases. The preprocedural modified Rankin Scale score was 0-2 for 12 of the 20 patients (60.0%), 3 for 2 patients (10.0%), and 4 for 6 patients (30.0%). The postprocedural clinical status was unchanged for all patients. The procedure was technically feasible in all cases. Procedure-related mortality was 0%. Ninety percent of the patients were independent in their everyday lives (modified Rankin Scale Scores 0-2) at the 6-month follow-up. In all cases but one (95%) the embolization was curative, confirmed by selective DSA at 6 months and 18 months postintervention. CONCLUSIONS: Single-session endovascular transvenous embolization seems to be a safe and effective curative treatment for patients harboring complex brain AVMs with high Spetzler-Martin grade.