Determinants of Stent Expansion in Curved Stenotic Lesions: An In Vitro Experimental Study

Construction of an in vivo carotid siphon model for testing endovascular devices for neuro-interventions

Objective The aim of this study was to construct an in vivo carotid siphon model for testing neurovascular devices for endovascular interventions. Methods A model of a human carotid siphon was pre-shaped using a glass tube from a human cadaver and used to confine a segment of one side of the common carotid artery (CCA) in canines. This segment of CCA with the glass carotid siphon on was interposed end-to-end onto the contralateral CCA so as to simulate a human carotid artery siphon in vivo. Two weeks later, the siphon model was evaluated using computed tomography angiography and digital subtraction angiography, and the covered stent specially designed for intracranial vasculature was navigated through the siphon model for a longitudinal flexibility test. Results All dogs tolerated the procedures well, and the artificial siphon model in vivo provided realistic conditions for device testing. Two weeks later, the in vivo carotid siphon model remained patent with no thrombosis. Five covered stents were navigated to pass through five siphon models successfully, with vasospasm occurring in two siphons. Conclusion Construction of an in vivo siphon model in dogs with a glass tube is feasible and useful for the test of endovascular devices for treating neurovascular diseases.

Surgical construction of a novel simulated carotid siphon in dogs

Object

The development and preclinical assessment of new endovascular devices necessitate readily available and reproducible animal models. The purpose of this study was to develop an in vivo carotid siphon model for testing the properties of covered stents specially designed for the intracranial vasculature.

Methods

Six carotid siphon–shaped devices were created. Six dogs underwent surgery to expose and isolate both common carotid arteries (CCAs). The right CCA origin was ligated and incised distal to the ligation point after temporary constriction of the distal right CCA. The distal left CCA was ligated and incised proximal to the ligation point after the left CCA origin was temporarily clamped. The proximal isolated left CCA was passed through the shaped device and then anastomosed end-to-end to the distal isolated right CCA. Finally, the shaped device was fixed and embedded in the neck. Intraarterial digital subtraction angiography was performed at 7 days, 2 weeks, and 1 month postprocedure. All models underwent endovascular interventional simulation. The carotid siphon models were evaluated.

Results

The animals tolerated the surgical procedure well. The mean time for surgical construction of the model was 90 minutes. The morphology and endovascular manipulation of the siphon models were similar to those in humans. Stenosis of anastomotic stoma occurred in 2 models, and mural thrombosis of anastomotic stoma occurred in 1 model; however, all models were patent at postprocedural follow-up angiography.

Conclusions

Surgical construction of an in vivo carotid siphon model in dogs with carotid siphon–shaped devices is feasible and potentially useful for testing neurovascular devices.

Does Carbofilm Coating Affect In-Stent Intimal Proliferation? A Randomized Trial Comparing Rx Multi-Link Penta and Tecnic Carbostent? Stents: SIROCCO Trial

OBJECTIVES

To compare the volume of in-stent neointimal proliferation, assessed by intravascular ultrasound (IVUS), at 6-month follow-up after implantation of a coronary Carbofilm-coated stent (Tecnic Carbostent, Sorin Biomedica Cardio, Saluggia, Italy) versus a conventional 316 L stent (Rx Multi-Link Penta, Abbott Laboratories, Abbott Park, IL).

BACKGROUND

Many trials suggest that stent characteristics and coating could be important determinants of restenosis.

METHODS

From October 2004 to May 2005, 63 patients were randomized to Tecnic (T, n = 30) or Penta (P, n = 33). The primary end-point was in-stent volume of neointimal hyperplasia (NIH) measured by IVUS at 6 months. The secondary end-points included binary restenosis, minimal luminal diameter (MLD), target lesion revascularization, and major adverse cardiac events.

RESULTS

There were no significant differences between T and P as to mean age, male gender, clinical status, complexity of the lesion, lesion length, reference vessel diameter before percutaneous coronary intervention (PCI), MLD pre-PCI, and stent-to-artery ratio. However, MLD poststenting was greater in P group than T group (2.81 +/- 0.45 mm vs. 2.49 +/- 0.33 mm, P < 0.002). At 6 months, angiographic late lumen loss (0.61 +/- 0.51 mm vs. 0.92 +/- 0.61 mm, P < 0.043), in-stent obstruction (25.86 +/- 16.48% vs. 38.33 +/- 19.56%, P = 0.021), and in-stent late loss volume (31.62 +/- 29.75 mm(3) vs. 57.28 +/- 37.16 mm(3), P = 0.016) were significantly lower in T group than in P group.

CONCLUSION

Penta stent appears to offer a better deployment and a larger MLD post-PCI than Carbofilm-coated stent. However, a thicker NIH was observed on Penta stent at 6-month follow-up, when compared to Tecnic.

Conformation of Adjacent Self-expanding Stents: A Cross-Sectional In Vitro Study

We examined the proximal conformation of three commonly used self-expanding stents when the stents were deployed adjacent to one another in a tubular model, simulating a "kissing" stent technique. The stent pairs were evaluated by computed tomogrphy to determine the cross-sectional area excluded by the stents within the model. The mean areas associated with each stent pair were compared and significance evaluated by a t-test. A statistically significant difference was found when the area excluded by adjacent Wallstents was compared with both the Luminexx and SMART stents (p < 0.001 and p < 0.002, respectively). The difference in the area excluded and differences in conformation might play a role in the lower patencies that have been observed in "kissing" stent series.