Technical feasibility and tissue reaction after silicone-covered biodegradable magnesium stent insertion in the oesophagus: a primary study in vitro and in vivo.

OBJECTIVES: Determine the feasibility of and tissue response to biodegradable magnesium-silicone stent insertion into the oesophagus of rabbits. METHODS: Mechanical compression-recovery and degradation behaviours of the stents were investigated in vitro. Thirty rabbits were randomly divided into a magnesium-silicone stent group (n = 15) that received stent insertion into the lower 1/3 of the oesophagus under fluoroscopic guidance and a control group (n = 15). Oesophagography was performed at 1, 2 and 4 weeks. Five rabbits in each group were euthanized at each time point for histological examination. RESULTS: Magnesium-silicone stents showed good flexibility and elasticity, and degraded more slowly than bare stents at pH 4.0 and 7.4. All stent insertions were well tolerated. The oesophageal diameters at 1, 2 and 4 weeks were 9.7 ± 0.7, 9.6 ± 0.8 and 9.6 ± 0.5 mm, respectively (vs. 9.2 ± 0.8 mm before intervention; P > 0.05). Stent migration occurred in six rabbits (one at 1 week, one at 2 and four at 4). Microscopy demonstrated dilation of the oesophageal wall within 1 week of insertion. Oesophageal injury and collagen deposition following stent insertion were similar to control (P > 0.05). CONCLUSIONS: Oesophageal magnesium-silicone stent insertion was feasible and provided reliable support for 2 weeks without causing oesophageal injury or collagen deposition. KEY POINTS: • Mg stent provided apparently adequate radial force and silicone membrane reduced magnesium biodegradation • Stent insertion provided good support for at least 2 weeks before biodegradation • Stenting effectively resulted in oesophageal wall remodelling, without demonstrable injury.

Silicone-covered biodegradable magnesium stent for treating benign esophageal stricture in a rabbit model.

BACKGROUND: Stent insertion can effective alleviate the symptoms of benign esophageal strictures (BES). Magnesium alloy stents are a good candidate because of biological safety, but show a poor corrosion resistance and a quick loss of mechanical support in vivo. AIM: To test the therapeutic and adverse effects of a silicone-covered magnesium alloy biodegradable esophageal stent. METHODS: Fifteen rabbits underwent silicone-covered biodegradable magnesium stent insertion into the benign esophageal stricture under fluoroscopic guidance (stent group). The wall reconstruction and tissue reaction of stenotic esophagus in the stent group were compared with those of six esophageal stricture models (control group). Esophagography was performed at 1, 2, and 3 weeks. Four, six, and five rabbits in the stent group and two rabbits in the control groups were euthanized, respectively, at each time point for histological examination. RESULTS: All stent insertions were well tolerated. The esophageal diameters at immediately, 1, 2 and 3 wk were 9.8 ± 0.3 mm, 9.7 ± 0.7 mm, 9.4 ± 0.8 mm, and 9.2 ± 0.5 mm, respectively (vs 4.9 ± 0.3 mm before stent insertion; P < 0.05). Magnesium stents migrated in eight rabbits [one at 1 wk (1/15), three at 2 wk (3/11), and four at 3 wk (4/5)]. Esophageal wall remodeling (thinner epithelial and smooth muscle layers) was found significantly thinner in the stent group than in the control group (P < 0.05). Esophageal injury and collagen deposition following stent insertion were similar and did not differ compared to rabbits with esophageal stricture and normal rabbits (P > 0.05). CONCLUSION: Esophageal silicone-covered biodegradable magnesium stent insertion is feasible for BES without causing severe injury or tissue reaction. Our study suggests that insertion of silicone-covered magnesium esophageal stent is a promising approach for treating BES.

Trans-arterial embolisation therapy of dural carotid-cavernous fistulae using low concentration n-butyl-cyanoacrylate.

BACKGROUND: Trans-venous embolisation has been accepted as the preferred treatment for dural carotid-cavernous fistulae (DCCF). However, such an approach is not always feasible. In this circumstance, trans-arterial embolisation with low concentration n-butyl-cyanoacrylate glue (NBCA) may be a feasible alternative. We report our results and experience of this method for DCCF. MATERIALS AND METHODS: Five patients with DCCF were treated by trans-arterial embolisation using low concentration NBCA by wedging the microcatheter into the main feeding artery. All five lesions were associated with venous drainage into the superior ophthalmic vein. The inferior petrosal sinus was patent in one patient and thrombosed in four. Additional venous drainage into the Sylvian vein and the superior petrosal sinus was observed in two patients. FINDINGS: The definitive NBCA injection was performed via the branches of the middle meningeal artery in three patients and accessory meningeal artery as well as ascending pharyngeal artery in two patients. Four patients showed complete obliteration of the DCCF on the post-embolisation angiogram, and follow-up studies showed clinical cure or improvement and successful obliteration of the DCCF. One patient had a residual DCCF after the procedure, but showed complete obliteration and clinical cure at 5-month follow-up. Glue penetrated into the Sylvian vein in one patient during the procedure without sequelae. Two patients had transient worsening of ocular symptoms after the procedure. CONCLUSIONS: Trans-arterial embolisation with low concentration NBCA using a wedged microcatheter technique is still a safe and effective treatment for DCCF when the transvenous approach is not feasible. However, care must be taken to prevent inadvertent arterial and venous embolisation.

Concomitant aneurysm detection in an intracranial dolichoectasia mouse model using a MicroFil polymer perfusion technique.

OBJECTIVE: To assess the feasibility of using MicroFil polymer perfusion to detect concomitant saccular aneurysms in an intracranial arterial dolichoectasia (IADE) model in mice, and to report detailed histomorphometric features of these aneurysms. MATERIALS AND METHODS: IADE models were created in C57/BL6 mice via microsurgical injection of 25 mU elastase into the cisterna magna. The cerebral vasculature was perfused with MicroFil polymer and harvested at 1, 3, and 7 days, and 2 and 4 weeks (n=8 for each group). IADE was defined by a tortuosity index >10 combined with a 25% increase in diameter of the A1 segment of the anterior cerebral artery (ACA), internal carotid artery (ICA), or basilar artery compared with the baseline of controls, which received heat-inactivated elastase. Saccular aneurysm occurrence rate, location, and morphological parameters were investigated using macroscopic and microscopic analysis. RESULTS: IADE was present in 95% (36/38) of the subjects, with a mortality rate of 5% (2/40). Fifteen concomitant saccular aneurysms were detected in 8 (21%) of the 38 surviving mice, including 6 at the posterior communicating artery, 1 along the ACA, 2 along the anterior communicating artery complex, 3 along the ICA, and 3 along the middle cerebral artery. Rupture was confirmed in two aneurysms. Histological examination indicated that the aneurysms develop via arterial-wall remodelling, which is characterized by internal elastic lamina disruptions and muscular layer discontinuity in the media. CONCLUSIONS: The proportion of subjects developing saccular aneurysms in addition to IADE in our mouse model is similar to the 15% of patients with IADE who have concomitant saccular aneurysms.

Reconstructive endovascular treatment of intracranial aneurysms with the Willis covered stent: medium-term clinical and angiographic follow-up.

OBJECT: Placement of covered stents has emerged as a promising therapeutic option for cerebrovascular diseases. However, the medium- and long-term efficacy and safety of covered stents in the treatment of these diseases remain unclear. The purpose of this study was to evaluate the medium-term clinical and angiographic outcomes of covered stent placement for the treatment of intracranial aneurysms. METHODS: The authors' institutional review board approved the study. Thirty-four patients (13 females and 21 males; mean age 41.9 years) with 38 intracranial aneurysms were treated with the Willis covered stent. Clinical and angiographic follow-up were performed at 3 months, at 6-12 months, and annually thereafter. The initial procedural and follow-up outcomes were collected and analyzed retrospectively. RESULTS: Forty-two covered stents were successfully implanted into the target artery in 33 patients with 37 aneurysms, and 1 covered stent navigation failed in 1 patient. A complete aneurysm exclusion was initially achieved in 24 patients with 28 aneurysms, and a minor endoleak occurred in 9 patients with 9 aneurysms. Postoperatively, 2 patients died of complications related to the procedure. Angiographic and clinical follow-up data are available in 30 patients. The angiographic follow-up (17.5 ± 9.4 months [mean ± SD]) exhibited complete occlusion in 28 patients with 31 aneurysms, and incomplete occlusion in 2 aneurysms, with an asymptomatic in-stent stenosis in 3 patients (10%). The clinical follow-up (26.7 ± 13 months [mean ± SD]) demonstrated that 16 patients (53.3%) experienced a full recovery, and 14 patients (46.7%) improved. No aneurysm rupture, thromboembolic events, or neurological deficits resulting from closure of a perforating vessel by covered stent placement occurred. CONCLUSIONS: Endovascular reconstruction with the Willis covered stent represents a safe, durable, and curative treatment option for selected intracranial aneurysms, yielding an excellent medium-term patency of the parent artery and excellent clinical outcomes.