Kallmes, David F.

Background and Purpose: Rabbit aneurysm models are used in the testing of embolization devices as well as elucidating the mechanisms human intracranial aneurysm growth and healing. We employed ribonucleic acid sequencing (RNA-seq) technology to identify genes relevant to induced rabbit aneurysm biology and compare these with genes related to human intracranial aneurysms to identify genes of potential clinical interest. This included sequencing micro RNA, which are important regulatory non-coding RNA. Materials and Methods: Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery (CCA) in 5 rabbits. Messenger ribonucleic acid (mRNA) and micro ribonucleic acid (miRNA) was isolated from the aneurysm and the control unoperated left CCA at 12 weeks and was processed using RNA-seq technology. The results from RNA-seq were analyzed using Ingenuity Pathway Analysis. Results: 9396 genes were analyzed using RNA-seq, of which 649 (6.9%) were found to be significantly differentially expressed between aneurysm and control tissues (p < 0.05, false discovery rate 2). Of these, 500 were up-regulated in the aneurysm and 149 were down-regulated as compared to controls. Using the same criteria, 3 miRNA were identified as down regulated and 5 were identified as up regulated. Pathway analysis associated these genes with inflammatory response, cellular migration, and coagulation, among other functions and pathologies. Conclusion: RNA-seq next-gen analysis of rabbit aneurysms shows similarities to human intracranial aneurysms with respect to regulation of some key pathways.

Background and Purpose: The Hydrocoil Endovascular aneurysm occlusion and Packing Study (HELPS) was a randomized controlled trial comparing Hydrocoil to bare platinum coils . We performed a subgroup analysis of angiographic and clinical outcomes of medium sized aneurysms in the HELPS trial. Methods: We selected all patients with medium sized aneurysms (5mm-9.9mm) in the HELPS trial. The following outcomes were compared between the HydroCoil and control groups: 1) any recurrence, 2) major recurrence, 3) retreatment and 4) good neurological outcome defined as mRS≤2. Outcomes of recently ruptured and non-recently ruptured aneurysms were compared separately. Comparisons between groups were performed using Fisher’s exact test. A multivariate logistic regression analysis adjusting for aneurysm neck size, shape, use of adjunctive device and rupture status was performed. Results: A total of 288 patients with medium sized aneurysms were randomized (144 in each group). At 15-18 months post-treatment, major recurrence rate was significantly lower in the HydroCoil group than the control group (18.6% versus 30.8%, P=0.03, respectively). For recently ruptured aneurysm patients, major recurrence rate was significantly lower for HydroCoil than controls (20.3% versus 47.5%, P=0.003), while rates were similar between coil types for unruptured aneurysms (16.7% versus 14.8%, P=0.80). On multivariate analysis for patients with recently ruptured aneurysms, HydroCoil was associated with lower odds of any recurrence as compared to bare platinum (OR=0.37, 95%CI=0.18-0.76, P=0.006) and major recurrence (OR=0.27, 95%CI=0.12-0.58, P=0.0007). There was a trend towards lower retreatment rates in the recently ruptured group treated with HydroCoil (OR=0.00, 95%CI=0.00-2.01, P=0.12). Conclusion: For recently ruptured, medium sized aneurysms, as compared to bare platinum coils HydroCoils were associated with lower rates of major recurrence that were both statistically significant and clinically relevant. These findings suggest that HydroCoils should be the preferred treatment for this subset of patients.

Background: Flow diversion has been proposed as a valid option for patients with proximal internal carotid artery aneurysms. We analyzed a consecutive series of 38 patients with proximal (to the origin of the posterior communicating artery) internal carotid artery aneurysms treated with flow diversion over a 28-month interval. Methods: Clinical information and angiographic follow-up data were prospectively collected in a consecutive series of patients with proximal internal carotid artery aneurysms treated with flow diversion. No patients were lost to follow-up and every eligible patient (with at least 6 months of follow-up) underwent catheter angiography at 6 months. Results: The series include 38 patients (37 women and 1 man). Most of the aneurysms were large or giant and with a wide neck. In two patients, we failed to deliver the device to the target segment because of proximal vessel tortuosity; thus 36 patients underwent flow diversion. There were no permanent periprocedural neurological deficits. One patient experienced a transient neurological deficit and another patient suffered slight transient worsening of a third nerve paresis. Complete angiographic occlusion of the aneurysm was observed in 75% of patients at 6 months and in 87% of the eligible patients at one year. One patient was found to have asymptomatic internal carotid occlusion. Conclusion: Flow diversion is an effective and safe method to treat internal carotid artery aneurysms not amenable to other endovascular techniques.

Background and Purpose- It is important to know the costs for hospitalization for endovascular embolectomy patients so that comparisons can be made to payments to hospitals. Methods- Using the National Inpatient Sample, we evaluated the costs for hospitalization for patients treated with endovascular embolectomy in the United States from 2006-2008. The primary endpoint examined in this study was total hospital costs, and these were correlated with clinical outcome. Hospitalization costs were then compared with Medicare payments for their respective outcomes. MS-DRG 24 was the diagnostic related group code (DRG) for mechanical embolectomy with good outcome and MS-DRG 23 was the DRG code for mechanical embolectomy with major complications. Medicare payments were available at http://www.cms.hhs.gov . Results- A total of 3864 patients received endovascular embolectomy. 1649 patients were <65 years old and 2205 patients were ≥65 years old. Median hospital costs in 2008 dollars were $36,999 (IQR $26,662-$56,405) for patients with good outcome, $50,628 (IQR $33,135-$76,063) for patients with severe disability, and $35,109 (IQR $25,053-$62,621) for patients with mortality. Reimbursement in the year 2008 for DRG 24 (good outcome) was $22075 and reimbursement for DRG 23 (major complications) was $26639. Conclusions- Our study of the NIS shows that hospitalization costs in the United States for ischemic stroke patients treated with endovascular embolectomy are rather high, probably due to the serious nature of their illness. Medicare payments have not been adequate in reimbursing these hospitalizations. Further work is needed to ensure the future reconciliation of costs with payments.

Purpose: To assess the association of procedure time with neurologic adverse events post Pipeline Embolization Device (PED) placement for intracranial aneurysm treatment. Methods: In the IntrePED Registry, a retrospective review was performed at 17 centers to identify consecutive intracranial aneurysms treated with the PED following regulatory approval in the given country. All patients in whom at least one PED was placed and follow-up was available prior to IRB approval were enrolled. “Primary adverse events” included major stroke, major hemorrhage, and neurological mortality. Results: 793 patients with 906 aneurysms, including 311 large ICA, 536 other anterior and 59 posterior circulation aneurysms were enrolled and followed for a mean duration of 19.3 months. 689 (77%) of 906 aneurysms were saccular and 116(13%) were fusiform. 824 (91%) were unruptured. 308 (34%) treated with multiple PEDs. Incidence of major hemorrhage, stroke and neurological mortality was 2.4%, 4.7% and 3.8% respectively. Heparin was administered in 89% of the patients during the procedure. An average of 1.5 PEDs were utilized per case. The mean procedure time was 101.5 ± 50.5 mins. Patients with a major complication (major stroke, major hemorrhage, neurological mortality) had procedure time of 138.2 + 81.5 min, and those without a major complication had procedure time of 98.3 + 45.5 min (p< 0.001). A logistic regression incorporating aneurysm size and number of PEDs used still showed a highly significant relationship between major complications and procedure time (p<0.001) and also found aneurysm size to be an independent predictor of longer procedures (p=0.007). Conclusions: The present analysis of IntrePED Registry subjects demonstrates a strong association of procedure time with complication rates. Further analyses of factors leading to longer procedure times is needed.

Background and aim The use of endoluminal flow diversion in bifurcation aneurysms has been questioned due to the potential for complications and lower occlusion rates. In this study we assessed outcomes of endovascular treatment of intracranial sidewall and bifurcation aneurysms with flow diverters Methods In July 2020, a literature search for all studies utilizing endoluminal flow diverter treatment for sidewall or bifurcation aneurysms was performed. Data were collected from studies that met our inclusion/exclusion criteria by two independent reviewers and confirmed by a third reviewer. Using random-effects meta-analysis the target outcomes including overall complications (hematoma, ischemic events, minor ischemic stroke, aneurysm rupture, side vessel occlusion, stenosis, thrombosis, transient ischemic stroke, and other complications), perioperative complications, and follow-up (long-term) aneurysm occlusion were intestigated. Results Overall, we included 35 studies with 1084 patients with 1208 aneurysms. Of these aneurysms, 654 (54.14%) and 554 (45.86%) were classified as sidewall and bifurcation aneurysm, respectively, based on aneurysm location. Sidewall aneurysms had a similar total complication rate (R) of 27.12% (95% CI, 16.56%–41.09%), compared with bifurcation aneurysms (R, 20.40%, 95% CI, 13.24%–30.08%) (p = 0.3527). Follow-up angiographic outcome showed comparable complete occlusion rates for sidewall aneurysms (R 69.49%; 95%CI, 62.41%–75.75%) and bifurcation aneurysms (R 73.99%; 95% CI, 65.05%–81.31%; p = 0.4328). Conclusions This meta-analysis of sidewall and bifurcation aneurysms treated with endoluminal flow diverters demonstrated no significant differences in complications or occlusion rates. These data provide new information that can be used as a benchmark for comparison with emerging devices for the treatment of bifurcation aneurysms.

Introduction: Von Willebrand factor (VWF) is a key component of acute ischemic stroke (AIS) thrombi. The aim of our prospective study was to investigate the immunohistochemical expression of VWF in clots and to evaluate whether VWF is associated with certain subtypes of AIS. Methods: VWF immunostaining was performed on 79 thrombi collected as part of the multi-center Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) registry. The cases were classified according to TOAST criteria. The VWF expression was quantified using Orbit Image Analysis (www.Orbit.bio) machine learning software. IBM SPSS statistics 25 was used to assess the relationship between the VWF levels and different etiology subtypes. Results: A cardioembolic stroke was defined in 39 cases (49.4%) whereas an atherosclerotic origin was identified in 13 patients (16.5%). Other causes accounted for 12 cases (15.1%). Unknown etiology was reported in 15 cases (19%). The mean VWF content in the clots was 12.8%. According to the Mann-Whitney U-test, the level of VWF was significantly higher in the cases with unknown etiology compared to cardioembolic origin (p=0.044). We found also that patients with unknown etiology of stroke had higher VWF expression as compared to the other two subtypes, although this difference was not statistically significant. Conclusions: Among the patients with ischemic stroke included in this study, the VWF expression was significantly increased in those with unknown etiology compared to the group with cardioembolic stroke. Our finding provides new insights into clot composition in cryptogenic stroke and may influence the treatment and secondary prevention in these cases.

Introduction: Previous studies have successfully created blood clot analogues for In-vitro testing using animal blood. Blood components vary greatly among species and thus, creating clot analogues with human blood is likely a more accurate representation of thrombi formed in the human vasculature. We present a novel method of creating clot analogues from human blood and platelets that mimic the process by which clots form In-vivo . Methods: Following IRB approval from Mayo Clinic, human whole blood and platelets donations were obtained from the Blood Transfusion service. The whole blood was centrifuged at 1,200RPM for 20 minutes to separate it into its constituents. Plasma was removed and the remaining Red Blood Cells and Buffy Coat were mixed together by inverting. A total of 12 clot analogues were created with varying concentrations of components; Red Blood cells/Buffy Coat, Plasma and Platelets. Thrombin was added first to stimulate platelets activation for a total of 5 mins whilst continuously mixing by inversion. The RBC/WBC mixture was added next followed by CaCl2. The mixture was then quickly drawn into a 3cc syringe and spun overnight at 20RPM at room temperature to mimic dynamic flow conditions. Macro-photographs were taken to display the variation in texture and color between different clot analogue types. The clots were then fixed in 10% neutral buffered formalin for 24 hours prior to being processed. Histopathological analysis was performed using Hematoxylin and Eosin (H&E) and Martius Scarlet Blue (MSB) staining to confirm clot composition. Results: Red Blood cell-rich, Fibrin-rich, Platelet-rich and mixed clot analogues that accurately mimic clots retrieved from Acute Ischemic Stroke Patients were created. The range of histopathological compositions of the clot analogues is similar to that of the clinical samples. Conclusions: The addition and activation of platelets is key to creating accurate clot analogues for In-vitro testing. Spinning the clots is important to prevent natural sedimentation and mimic the In-vivo situation.

Background and Purpose: Leukoaraiosis is a poor prognostic marker for patients with acute ischemic stroke (AIS). This study sought to assess if severity of leukoaraiosis is associated with outcome in patients with AIS following endovascular thrombectomy, and to propose a leukoaraiosis-related modification to the ASPECTS score to improve its predictive value for good outcome. Methods: We analyzed consecutive patients with AIS that underwent mechanical thrombectomy for anterior circulation large vessel occlusion at our comprehensive stroke center. Leukoaraiosis burden was graded using the Fazekas scale (combined scores from two locations categorically divided into no leukoaraiosis (score = 0), mild (1-2), moderate (3-4) and severe (5-6)). The primary outcome measure was 90-day mRS. A proposed Leukoaraiosis-ASPECTS (“L-ASPECTS”) was calculated by subtracting values from the traditional ASPECT based on leukoaraiosis severity (1 point subtracted if mild, 2 if moderate, 3 if severe). Results: Of 174 included patients, 89 (51.2%) were female; average age was 68.0±9.1. 28 (16.1%) had no leukoaraiosis, 66 (37.9%) had mild, 62 (35.6%) had moderate, and 18 (10.3%) had severe. Leukoaraiosis severity was associated with worse 90-day mRS among all patients (p=0.0005) as well as those that were successfully revascularized (p=0.0002). A multivariate analysis confirmed that leukoaraiosis burden was associated with worse 90-day mRS among all patients (mild: p=0.006; moderate: p=0.002; severe: p=0.03), as well as those that underwent successful thrombectomies (p=0.005). Both L-ASPECTS and ASPECTS were associated with poor outcomes, but the association was stronger with L-ASPECTS (p<0.0001 and AUC=0.7 for L-ASPECTS; p=0.04 and AUC=0.59 for ASPECTS). Conclusion: Leukoaraiosis severity on pre-mechanical thrombectomy NCCT is associated with worse 90-day outcome in patients with AIS following endovascular recanalization, and is an independent risk factor for worse outcomes. A proposed L-ASPECTS score had stronger association with outcome than the traditional ASPECTS score.

Ischemic stroke results from thrombus becoming lodged in a vessel in the cerebrovascular circulation. The constituents of the thrombus can vary widely and have direct effects on the mechanical properties of the thrombus. Thrombectomy procedures could potentially be improved if the mechanical properties of the thrombus could be determined prior to treatment. In the study, we developed a new non-contact method associated with Rayleigh wave propagations for evaluating mechanical properties of human clotted blood, referred to as ultrasound-mediated optical coherence elastography (UOCE). Due to clot mechanical properties being associated with fibrin and platelet content, eight different clot analogues with varying fibrin/platelets concentrations, from 0.6% (control group) to 19.0%, were produced, and the clot analog in each concentration was repeatedly measured five times. A highly focused transducer with a center frequency of 7.5 MHz was used to generate acoustic radiation forces exerted on the surface of clotted blood to induce Rayleigh wave propagations. The transducer was driven by a 50 dB radio frequency amplifier a 4 ms pulse which was repeated at a rate of 19 Hz. The optical coherence tomography (OCT) acquisition was set to 50 lateral positions and 4000 A-scans for each lateral position at a 76 kHz scan rate for total acquisition time of 52.6 ms. The results demonstrated that the Rayleigh wave group velocities positively correlated with the concentrations of fibrin/platelets. The group velocities ranged from 0.78 ± 0.02 m/s for 0.6% fibrin/platelets and increased to 2.42 ± 0.06 m/s at a fibrin/platelets concentration of 19.0%. There are statistically significant difference ( p <0.05) between control group and all clot analogues with a fibrin/platelets concentration of greater than 2.3%. In conclusion, we propose UOCE as a novel approach capable of evaluating mechanical properties of human blood clots based on Rayleigh wave propagation. This sensitive method can be used for the evaluation of the mechanical properties of human blood clot analogues and thrombectomy samples.