Sibylle Stampfl

Mechanical Thrombectomy in Acute Embolic Stroke: Preliminary Results With the Revive Device

Background and Purpose— The purpose of this study was to evaluate the safety and technical feasibility of a new thrombectomy device (Revive; Micrus Endovascular) in the endovascular treatment of acute ischemic stroke. Methods— Ten patients with acute large vessel occlusions were treated with the Revive device between October 2010 and December 2010. Mean National Institutes of Health Stroke Scale on admission was 19.0; mean duration of symptoms was 172 minutes. Recanalization was assessed using the Thrombolysis In Cerebral Infarction score. Clinical outcome (National Institutes of Health Stroke Scale) after thrombectomy was determined on Day 1, at discharge, and at Day 30. Results— Vessel recanalization (Thrombolysis In Cerebral Infarction 2b or 3) was successful in all patients without device-related complications. Mean National Institutes of Health Stroke Scale 24 hours after the intervention, at discharge, and at Day 30 was 14.0, 11.5, and 5.1, respectively. At Day 30, 6 patients had a clinical improvement of >8 points or an National Institutes of Health Stroke Scale of 0 to 1, 1 patient showed minor improvement, and 3 patients had died. Symptomatic intracranial hemorrhage occurred in 2 patients, of which 1 was fatal. Conclusions— Thrombectomy with the Revive device in patients with stroke with acute large vessel occlusions demonstrated to be technically safe and highly effective. Clinical safety and efficacy have to be established in larger clinical trials.

Endovascular Stroke Therapy Tirofiban Is Associated With Risk of Fatal Intracerebral Hemorrhage and Poor Outcome

Background and Purpose— To investigate the relationship between severe bleeding complications and outcome after mechanical thrombectomy with or without glycoprotein-IIb/IIIa inhibitor tirofiban treatment. Methods— The study included prospectively collected data of consecutive patients with acute ischemic stroke in whom mechanical thrombectomy was perfomed in the years 2006 to 2011. Results— Of 162 patients, 128 patients had anterior circulation stroke, and 34 patients had posterior circulation stroke. Additional treatment with tirofiban was given to 30 of 128 patients with anterior circulation stroke and to 20 of 34 patients with posterior circulation stroke. Treatment with tirofiban did not influence recanalization rates. Fatal intracerebral hemorrhage occurred more frequently in tirofiban-treated patients in the entire cohort (12.0% vs 2.7%; P=0.03) and in tirofiban-treated patients with anterior circulation stroke (13.3% vs 3.1%; P=0.05). Logistic regression found age (odds ratio, 1.17; 95% confidence interval, 1.00–1.37; P=0.05) and tirofiban treatment (odds ratio, 3.03; 95% confidence interval, 1.50–4.05; P=0.04) to be independent predictors for fatal intracerebral hemorrhage. Tirofiban treatment was also an independent predictor for poor outcome (odds ratio, 6.60; 95% confidence interval, 1.06–41.52; P=0.04) in addition to National Institute of Health Stroke Scale (odds ratio, 1.08; 95% confidence interval, 1.00–1.17; P=0.05). Conclusions— In endovascular stroke therapy, additional treatment with the glycoprotein-IIb/IIIa inhibitor tirofiban is associated with increased risk of fatal intracerebral hemorrhage and poor outcome.

Arterial Distribution Characteristics of Embozene Particles and Comparison with Other Spherical Embolic Agents in the Porcine Acute Embolization Model

PURPOSE To determine the arterial distribution pattern of the embolic agent Embozene within the porcine kidney and compare it with those of other spherical embolic agents. MATERIALS AND METHODS Embozene, Embosphere, Bead Block, and Contour SE in size classes of 100-300 microm, 500-700 microm, and 700-900 microm and Embozene and Embosphere in the size class of 40-120 microm were used for total arterial occlusion in minipig kidneys. Organs were evaluated microscopically regarding vascular distribution of the different embolic agents and particle sizes. RESULTS The following variations of arterial distribution were identified. In the 40-120-microm size class, Embosphere particles penetrated significantly deeper compared with Embozene (P = .04). In the 100-300-microm size class, Bead Block showed a significantly deeper distribution as microscopy identified particles in arteries much smaller than their nominal size. In the 500-700-microm size class, Embosphere and Contour SE showed a deeper distribution. The most uniform arterial distribution was observed in the 700-900 microm size class,. However, few Embosphere and Contour SE particles were found in arcuate arteries, also indicating a distal distribution. CONCLUSIONS Throughout the four most-used size classes, from very small (40-120 microm) to large (700-900 microm), the distribution characteristics of the four tested materials vary substantially. Particularly, small Embosphere particles and small Bead Block particles showed a more distal distribution, as did medium-sized Embosphere and Contour SE particles. In the largest investigated size class, the distribution was more uniform. In general, the Embozene particles are very uniform in size, and they seem to reach vessels closely corresponding to their nominal size.

Inflammation and Recanalization of Four Different Spherical Embolization Agents in the Porcine Kidney Model

PURPOSE To evaluate the pattern of recanalization and specific inflammatory reaction after superselective embolization with four commercially available spherical embolic agents of different sizes in the mini pig kidney model. MATERIALS AND METHODS In 40 mini pigs, the lower poles of both kidneys were superselectively embolized with Embozene, Embosphere, Bead Block, and Contour SE particles in sizes of 40-120 mircom (Embozene, Embosphere) and 100-300 microm, 500-700 microm, and 700-900 microm (Embozene, Embosphere, Bead Block, Contour SE). After a follow-up time of 4 or 12 weeks, recanalization was determined with angiography. Pathologic and histologic evaluation of the kidneys was performed, and the Banff 97 classification was used to evaluate the extent of vessel wall inflammation. Macroscopically visible ischemic changes were evaluated by using a specific ischemia score. RESULTS After embolization with Embozene microspheres, larger Embosphere particles, and Bead Block and Contour SE particles, the absence of inflammation or a low inflammation score was observed. Significantly elevated inflammation scores were evident with small Embosphere particles after 4 weeks (mean score, 1.21 +/- 1.0). Distinct recanalization occurred with Contour SE particles (100% recanalization with 100-300-microm particles at 12 weeks, 500-700-microm particles at 4 and 12 weeks, and 700-900-microm particles at 4 weeks). Ischemia scores were highest in the target area in all specimens. Mildly elevated ischemia scores in nontarget tissue areas were indicative of minor nontarget embolization. CONCLUSIONS Except for small Embosphere particles at 4 weeks, the absence of inflammatory reaction to the embolization procedure or only low inflammatory changes were observed with all embolic agents, particle sizes, and follow-up intervals. Recanalization was evident with all embolic agents; however, it was pronounced with Contour SE particles.

A new polymer concept for coating of vascular stents using PTFEP (poly(bis(trifluoroethoxy)phosphazene) to reduce thrombogenicity and late in-stent stenosis

Objectives:We sought to evaluate the new polymer PTFEP (poly(bis(trifluoroethoxy)phosphazene) for (1) its ability to reduce thrombogenicity and late in-stent stenosis and (2) its effect on endothelialization in a rabbit iliac artery model. Materials and Methods:Nanocoated (∼50 nm) and bare stainless-steel stents were implanted bilaterally in the iliac arteries of 30 New Zealand White rabbits (1, 4, 8, 12, and 16 weeks follow-up) and evaluated by angiography, light, and scanning electron microscopy. Results:Bilateral stent placement was successful in 27 of 30 rabbits. Thrombus depositions occurred in none of the 27 coated but in 4 of the 27 bare stents (P = 0.037). A normal angiogram was obtained in 18 of 22 coated stents at risk for restenosis (follow-up ≥4 weeks) but only in 13 of 22 bare stents (P = 0.023). Marked restenosis (luminal loss >30%) was found in 6 bare stents (P = 0.011) but not in any coated stents. The neointima was 47.7–73.9 μm on coated and 66.9–115.2 μm on bare stents (statistically significant at 4, 8, and 16 weeks). Scanning electron microscopy detected full endothelialization in all stents from 4 weeks on (22 stents in both groups). Conclusion:PTFEP nanocoating successfully showed thromboresistance and reduced late in-stent stenosis. Endothelialization was equal in both stent types. Studies in more human-like models and human feasibility studies in human arteries are encouraged.

The efficacy of nanoscale poly[bis(trifluoroethoxy) phosphazene] (PTFEP) coatings in reducing thrombogenicity and late in-stent stenosis in a porcine coronary artery model.

Objectives:Previous experimental studies have demonstrated that poly[bis(trifluoroethoxy)phosphazene] (PTFEP) nanocoated stents have antithrombotic characteristics, reduce in-stent stenosis, prevent wall inflammation, and do not hamper endothelialization. This study was designed to validate these findings in a porcine coronary artery model. Materials and Methods:PTFEP-coated (n = 15) and bare stents (n= 13) were implanted in coronary arteries of 18 mini-pigs (4- and 12-week follow-up). Primary study endpoints were thrombogenicity and in-stent stenosis, secondary study endpoints were inflammatory response and re-endothelialization evaluated by quantitative angiography and light microscopy. Results:No thrombus deposition occurred on any stent. At 4 weeks follow-up, the bare stents (n = 4) had a significantly smaller neointimal area (1.93 vs. 3.20 mm2, P = 0.009). At 12 weeks, PTFEP-coated stents (n = 11) had significantly superior results in almost all parameters: neointimal area (2.25 vs. 2.65 mm2, P = 0.034), neointimal height (204.46 vs. 299.41 &mgr;m, P = 0.048), percentage stenosis (38.25 vs. 50.42%, P = 0.019), and inflammation score (0.12 vs. 0.30, P = 0.029). Complete re-endothelialization was seen in both stent types at both intervals. Conclusion:At long-term follow-up, the superior results of PTFEP-coated stents were characterized by a noteworthy reduction of neointimal growth and inflammatory response.

Effect of thrombus size on recanalization by bridging intravenous thrombolysis

Thrombus length has been reported as an important predictor of successful recanalization by intravenous thrombolysis but its influence on bridging thrombolysis has not been investigated yet. The effect of thrombus length on recanalization rates evaluated by catheter angiography early after intravenous bridging thrombolysis was analyzed.

Immunohistochemical Characterization of Specific Inflammatory Tissue Reactions following Embolization with Four Different Spherical Agents in the Minipig Kidney Model

PURPOSE To evaluate the immunohistochemical inflammatory reaction after porcine renal embolization with the new spherical embolic agent Embozene and to compare it with other spherical embolic agents. MATERIALS AND METHODS After superselective porcine renal embolization (40 pigs) with different sizes of embolic agents (Embozene, Embosphere, Bead Block, Contour SE), tissue arrays were obtained (size ranges, 40-120 microm, 100-300 microm, 500-700 microm, 700-900 microm). After immunostaining for CD subtyping (CD45 and CD68) and cytokines (C-reactive protein [CRP] and interleukin-1 beta), a semiquantitative immunoreactivity score was calculated for each marker: intensity of staining was scored between 0 (negative) and 3 (intensive) and extent of staining between 0 and 4 (>80%), indicating the percentage of positive staining. The intensity score (0-3) was multiplied by the extent of staining score (0-4), resulting in a semiquantitative immunoreactivity score (0-12). RESULTS Analysis of cellular expression profiles (ie, CD45, CD68) revealed a significantly higher inflammatory score 4 weeks after embolization with Embosphere 100-300 microm particles than after embolization with Embozene, Bead Block, and Contour SE. After 12 weeks, the Embosphere 100-300 microm score decreased. Analysis of CRP expression showed similar results, with a significantly higher score 4 weeks after embolization with Embosphere 100-300 microm. In the size class used most frequently for uterine artery emboliation (500-700 microm), all scores were low (<2.5) and there was no significant difference among particle types. CONCLUSIONS Pronounced immunomarker expression was seen 4 weeks after embolization with small Embosphere particles. However, in general, modern spherical embolic agents cause a fairly low level of inflammatory reaction. In the present experimental setting, which is highly sensitive for specific tissue-to-agent reactivity, Embozene presented with low inflammatory results.

Recanalization with stent-retriever devices in patients with wake-up stroke.

BACKGROUND AND PURPOSE: Stent-retriever devices play an increasing role in the interventional treatment of acute stroke patients, because fast recanalization can be achieved. The purpose of this study was to evaluate the feasibility of stent-retriever recanalization in patients with wake-up stroke in the anterior circulation. MATERIALS AND METHODS: We retrospectively analyzed clinical and angiographic data of 19 consecutive patients with wake-up stroke who were treated with stent-retriever devices between 2009 and October 2011. Recanalization was assessed by using the Thrombolysis in Cerebral Infarction score. Clinical outcome was evaluated at discharge and after 90 days by using the modified Rankin Scale. RESULTS: Median NIHSS score at admission was 17 (IQR, 15–20). Before the procedure, the TICI score was 0 in 18 patients and 1 in 1 patient. Recanalization with stent-retriever devices was successful (TICI ≥ 2) in 94.7%. Mean time to flow restoration was 36.7 minutes and to complete recanalization 83.7 minutes. Symptomatic intracranial hemorrhage occurred in 4 patients (21.1%). Eight patients had an NIHSS improvement of ≥4 points between admission and discharge. After 90 days, 2 (10.5%) of our patients presented with mRS 0–2; seven (36.8%) died. CONCLUSIONS: Despite successful and rapid recanalization with stent-retriever devices, good clinical outcome in patients with wake-up stroke is achieved in a minority of patients. Clinical outcome remains poor. Bleeding rates were higher compared with recanalization procedures within 6 hours after stroke onset.

Noninvasive cerebral oximetry during endovascular therapy for acute ischemic stroke: an observational study.

Implementing endovascular stroke care often impedes neurologic assessment in patients who need sedation or general anesthesia. Cerebral near-infrared spectroscopy (NIRS) may help physicians monitor cerebral tissue viability, but data in hyperacute stroke patients receiving endovascular treatment are sparse. In this observational study, the NIRS index regional oxygen saturation (rSO2) was measured noninvasively before, during, and after endovascular therapy via bilateral forehead NIRS optodes. During the study period, 63 patients were monitored with NIRS; 43 qualified for analysis. Before recanalization, 10 distinct rSO2 decreases occurred in 11 patients with respect to time to intubation. During recanalization, two kinds of unilateral rSO2 changes occurred in the affected hemisphere: small peaks throughout the treatment (n = 14, 32.6%) and sustained increases immediately after recanalization (n = 2, 4.7%). Lower area under the curve 10% below baseline was associated with better reperfusion status (thrombolysis in cerebral infarction ≥ 2b, P = 0.009). At the end of the intervention, lower interhemispheric rSO2 difference predicted death within 90 days (P = 0.037). After the intervention, higher rSO2 variability predicted poor outcome (modified Rankin scale > 3, P = 0.032). Our findings suggest that bi-channel rSO2-NIRS has potential for guiding neuroanesthesia and predicting outcome. To better monitor local revascularization, an improved stroke-specific set-up in future studies is necessary.