Seon Moon Hwang

Evaluation of the Solitaire system in a canine arterial thromboembolic occlusion model: is it safe for the endothelium?

The Solitaire system has recently been increasingly used for acute stroke treatment in which the endothelial safety immediately after its use has not been evaluated. This study was performed to evaluate the endothelial status when using a Solitaire system in a canine arterial occlusion model. Thromboembolic occlusion of both internal maxillary arteries was achieved in five mongrel dogs. In each animal, the Solitaire system (ev3, Irvine, CA, USA) was used for primary thrombectomy on the right side and for temporary stenting on the left side. Efficacy was assessed by comparing the recanalization rates, and safety was assessed using angiographic and microscopic assessments. Endothelial injuries were evaluated with light microscopy (LM) and scanning electron microscopy (SEM). Successful revascularizations were observed following primary thrombectomy in all five animals (100%) and after temporary stenting in two (40%). There was no incidence of vasospasm or vessel perforation in either group. Distal migration of the clot occurred in two animals that underwent primary thrombectomy. Endothelial injury was seen after primary thrombectomy in two animals (40%) and after temporary stenting in one (20%). The lesions presented as defects of the internal elastic lamina on LM and denudation of the wavy endothelial surface on SEM. During mechanical thrombectomy, the Solitaire system can cause endothelial injury both in primary thrombectomy and temporary stenting. Primary thrombectomy is likely to have a higher recanalization rate with increased endothelial injury.

A Study Design to Evaluate Association between Smoking and Intracranial Atherosclerotic Stenosis

Purpose Smoking is a well known risk factor for stroke. The cerebral arteries may be uniquely susceptible to the atherosclerotic effects of smoking, such that it has a different risk profile for stroke compared with other atherosclerosis risk factors. It remains uncertain whether smoking is associated specifically with intracranial (IC) or extracranial (EC) atherosclerotic cerebrovascular disease. The aim of this study design will be to evaluate the association between smoking and severe IC stenosis, adjusting for other atherosclerosis risk factors, particularly age distribution. Study design This is a retrospective cohort study design. Participants are patients (n=1714) with severe atherosclerotic stenosis undergoing cerebral catheter angiography because of stroke or transient ischaemic attack. All atherosclerotic steno-occlusive lesions are described in terms of location (anterior versus posterior circulation, IC versus EC, or intradural versus extradural). The atherosclerotic or stroke risk factors for analysis include age, gender, smoking history, number of lesions (single versus multiple), cardiac disease, diabetes mellitus, hypertension, family history, dyslipidemia, history of previous stroke, alcohol intake, metabolic syndrome and body mass index. Statistical analysis includes univariate analysis followed by multivariate logistic regression. The relationship between IC atherosclerotic stenosis and smoking will be assessed. Differences in risk factor distribution is analysed according to age at intervals of 10 years. Significant risk factors associated with IC atherosclerotic stenosis will also be assessed by multivariate logistic regression analysis. Summary This is an analytical study design that intends to measure the association between IC or EC atherosclerotic stenosis and smoking and other risk factors. We anticipate that it will have the power to detect any relationship between smoking and IC atherosclerotic lesions especially in younger patients.

In Vitro Observation of Air Bubbles during Delivery of Various Detachable Aneurysm Embolization Coils

Objective Device- or technique-related air embolism is a drawback of various neuro-endovascular procedures. Detachable aneurysm embolization coils can be sources of such air bubbles. We therefore assessed the formation of air bubbles during in vitro delivery of various detachable coils. Materials and Methods A closed circuit simulating a typical endovascular coiling procedure was primed with saline solution degassed by a sonification device. Thirty commercially available detachable coils (7 Axium, 4 GDCs, 5 MicroPlex, 7 Target, and 7 Trufill coils) were tested by using the standard coil flushing and delivery techniques suggested by each manufacturer. The emergence of any air bubbles was monitored with a digital microscope and the images were captured to measure total volumes of air bubbles during coil insertion and detachment and after coil pusher removal. Results Air bubbles were seen during insertion or removal of 23 of 30 coils (76.7%), with volumes ranging from 0 to 23.42 mm3 (median: 0.16 mm3). Air bubbles were observed most frequently after removal of the coil pusher. Significantly larger amounts of air bubbles were observed in Target coils. Conclusion Variable volumes of air bubbles are observed while delivering detachable embolization coils, particularly after removal of the coil pusher and especially with Target coils.

Current Status of Neurointerventional Activities in Korea

Neurointervention which deals with neurovascular disease in brain, head-and-neck and spines are one of the rapidly evolving medical fields. Several indices representing neurointerventional activities are still increasing year-by-year in Korea. We review current trend in major neurovascular diseases requiring usage of specific medical devices and some issues related to administrative process of the government approval.

Compliant neurovascular balloon catheters may not be compatible with liquid embolic materials: intraprocedural rupture of the protecting balloon during tumor embolization using n-butyl cyanoacrylate and lipiodol mixture

Background Simultaneous use of balloon catheters with embolic materials can cause unwanted rupture of the balloon occlusion catheters, which might cause a serious problem. Therefore, knowledge of the compatibility of occlusion balloon catheters with liquid embolic materials is important in various interventional procedures. Objective To determine the compatibility of occlusion balloon catheters with commonly used embolic materials in vitro. Methods We used three types of occlusion balloon catheters (Scepter C, Microvention, Tustin, California, USA; Hyperform, Covidien, Irvine, California, USA; and Ascent, Codman Neurovascular, Raynham, Massachusetts, USA) to test their tolerances to Lipiodol, n-butyl cyanoacrylate (NBCA; Histoacryl; B Braun, Melsungen, Germany), and dimethyl sulfoxide (DMSO) with Onyx. The balloon was inflated just as it is in an endovascular procedure, then put on a Petri dish to observe its morphological change after one drop of liquid embolic material was added using a 1 mL syringe. The presence of rupture and the time to rupture were evaluated by constant video monitoring. Additionally, we observed morphological changes of the balloon catheter surface after contact with embolic materials with a scanning electron microscope. Results Lipiodol or a 33% NBCA–Lipiodol mixture dropping onto the three types of balloon catheter resulted in ruptures of all three. All three types of balloon catheter were tolerant to NBCA and to DMSO followed by Onyx. Conclusions Glue embolization should not be performed with all three kinds of balloon catheter on the market, but DMSO and Onyx are compatible with those balloon catheters.

In Vitro Evaluation of Fusiform-Shaped Stents for Wide-Neck Intracranial Aneurysm Treatment

Purpose Wide-neck aneurysms (WNAs) associated with a dilated parent artery (PA) are not uncommon morphological abnormalities and usually cause inappropriate wall apposition and incomplete neck coverage of a tubular stent in stent-assisted coiling of aneurysms. We aimed to introduce a fusiform-shaped stent (FSS) and test its effectiveness in treating intracranial WNAs associated with a dilated PA using a three-dimensional (3D) model. Materials and Methods Two FSS types were designed with the middle one-third segment dilated by 10% (FSS10) and 20% (FSS20) and were compared with the tubular-shaped stent (TSS). A patient-specific 3D WNA model was prototyped and produced, and in vitro stent placement was performed. Angiographic images of the three stent types were analyzed and compared using predetermined parameters. Results The stent lumens were significantly larger in FSS10 and FSS20 than in TSS in the middle segments (P=0.046), particularly FSS20 (P=0.018). The non-covered area at the ostium tended to be smaller in FSS10 and FSS20 than in TSS, but the difference was not significant (P>0.05). The stent length was significantly longer in FSS10 and FSS20 than in TSS. The stent cell size was significantly larger in FSS than in TSS. Conclusion Better vessel wall apposition and aneurysmal neck coverage was observed for FSS than for TSS. No significant difference was observed between FSS10 and FSS20.