Influence of framing coil orientation and its shape on the hemodynamics of a basilar aneurysm model.

Aneurysms are bulges of an artery, which require clinical management solutions. Due to the inherent advantages, endovascular coil filling is emerging as the treatment of choice for intracranial aneurysms (IAs). However, after successful treatment of coil embolization, there is a serious risk of recurrence. It is well known that optimal packing density will enhance treatment outcomes. The main objective of endovascular coil embolization is to achieve flow stasis by enabling significant reduction in intra-aneurysmal flow and facilitate thrombus formation. The present study numerically investigates the effect of framing coil orientation on intra-aneurysmal hemodynamics. For the purpose of analysis, actual shape of the embolic coil is used, instead of simplified ideal coil shape. Typically used details of the framing coil are resolved for the analysis. However, region above the framing coil is assumed to be filled with a porous medium. Present simulations have shown that orientation of the framing coil loop (FCL) greatly influences the intra-aneurysmal hemodynamics. The FCLs which were placed parallel to the outlets of basilar tip aneurysm (Coil A) were found to reduce intra-aneurysmal flow velocity that facilitates thrombus formation. Involving the coil for the region is modeled using a porous medium model with a packing density of 20 % . The simulations indicate that the framing coil loop (FCL) has a significant influence on the overall outcome.

CT angiographic patterns predict carotid pseudo-occlusion in acute ischemic stroke.

Background: Identifying carotid pseudo-occlusion (PO) from true occlusion (TO) has implications in determining the candidacy and feasibility of successful endovascular thrombectomy (EVT) in acute ischemic stroke (AIS). Purpose: We reviewed the computed tomography angiographic (CTA) patterns differentiating a PO from a TO and analyzed the rate of successful recanalization after EVT. Materials and Methods: Patients with AIS and proximal internal carotid artery (ICA) occlusion who underwent EVT from 2014 to 2021 were identified. The patterns of carotid occlusion in CTA were classified into beak, dome, and flat patterns and correlated with microcatheter digital subtraction angiography (DSA) as PO and TO. The rates of successful recanalization in PO and TO were analyzed. Results: Of the 24 patients, 16 (66%) had ICA PO and eight (33%) had TO in DSA. A beak pattern of the proximal ICA on CTA was significantly higher among the PO group patients (87.5% vs. 25%, P = 0.005), and a flat pattern was significantly higher among the TO group patients (50% vs. 12%, P = 0.005). A gradual contrast decline of the proximal ICA on CTA images was seen only in PO group patients (85.7% vs. 0%, P = 0.05). There was no significant difference in the rate of successful recanalization between PO and TO group patients (81.25% vs. 62.5%, P = 0.362). Conclusion: Beak pattern and gradual contrast decline at the proximal ICA occlusion site in CTA are suggestive of carotid PO. Identification of PO in CTA can help in planning intervention strategies and prognostication.

Numerical investigation of unruptured middle cerebral artery bifurcation aneurysms: influence of aspect ratio.

An aneurysm is a disease condition, which is due to the pathological weakening of an arterial wall. These aneurysms are often found in various branch points and bifurcations of an artery in the cerebral circulation. Most aneurysms come to medical attention, either due to brain hemorrhages caused by rupture or found unruptured. To consider surgically invasive treatment modalities, clinicians need scientific methods such as, hemodynamic analysis to assess rupture risk. The arterial wall loses its structural integrity when wall shear stress (WSS) and other hemodynamic parameters exceed a certain threshold. In the present study, numerical simulations are carried out for unruptured middle cerebral artery (MCA) aneurysms. Three distinct representative sizes are chosen from a larger patient pool of 26 MCA aneurysms. Logically, these aneurysms represent three growth stages of any patient with similar anatomical structure. Simulations are performed to compare the three growth phases (with different aspect ratios) of an aneurysm and correlate their hemodynamic parameters. Simulations with patient specific boundary conditions reveal that, aneurysms with a higher aspect ratio (AR) correspond to an attendant decrease in both time-averaged wall shear stress (TAWSS) and spatial wall shear stress gradients (WSSG). Smaller MCAs were observed to have higher positive wall shear stress divergence (WSSD), exemplifying the tensile nature of arterial wall stretching. Present study identifies positive wall shear stress divergence (PWSSD) to be a potential biomarker for evaluating the growth of an aneurysm.

A novel parameter for the prediction of rupture risk of cerebral aneurysms based on morphology.

Neurosurgeons often encounter dilemmas in the clinical management of cerebral aneurysms owing to an uncertainty of their rupture status and rupture risk. This study evaluates the influence of natural frequency of an aneurysm, as a novel morphological parameter to understand and analyze rupture status and risk prediction. In this work, we employ the natural frequency of 20 idealized and 50 patient specific aneurysms. The natural frequency of patient specific aneurysms is then compared against their rupture status. A strong correlation was observed between various morphological indicators and natural frequency for ideal and patient specific geometries. A statistical analysis with both Mann Whitney U test and T-test for rupture status against natural frequency has given a p-value less than 0.01 indicating a strong correlation between them. The correlation of morphological parameters with natural frequency from Pearson correlation coefficient and T-test suggests a holistic reflection of their effects on the natural frequency of an aneurysm. Thus, natural frequency could be a good indicator to discern the rupture potential of an aneurysm. The correlation between rupture status and natural frequency makes it a novel parameter that can differentiate between ruptured and unruptured patient specific aneurysms.

A Prospective Study Comparing the Three-Dimensional Rotational Angiography and Two-Dimensional Digital Subtraction Angiography in Evaluation of Brain Arteriovenous Malformations.

Background: Complex angioarchitecture of brain arteriovenous malformations (BAVM) are often difficult to evaluate with standard imaging technique of digital subtraction angiography (DSA). These details are better provided by 3D rotational angiography (3D-RA). Objective: The aim of the study is to compare two-dimensional digital subtraction angiography (2D-DSA) and 3D rotational angiography in the evaluation of BAVM angiographic architecture. Materials and Methods: 2D-DSA and 3D-RA of 167 consecutive patients with BAVM were analyzed for arterial feeders, nidal patterns, and detection of flow-related aneurysms, arteriovenous fistulous components, venous drainage, and draining vein stenosis. Results: 3D-RA detected a significantly higher number of aneurysms and draining venous stenoses (P < 0.001). The detected number of true intranidal aneurysms was significantly higher with 3D-RA (n = 94) vs 2D-DSA (n = 34) (P < 0.001). 2D-DSA has low sensitivity (43.1%) and specificity (73.4%) for detecting intranidal aneurysms. 3D-RA detected a significantly higher number (12.6%) of BAVM patients with feeding artery aneurysms as compared to 2D-DSA (8.4%), P value of 0.004. 3D-RA accurately depicted the distal course of dominant arterial feeders and fistulous sites in BAVMs. Direct arteriovenous communications were evident in 31.1% with 3D-RA, as compared to 2D-DSA (15%) with P value < 0.0001. A significantly higher number of draining vein stenosis was detected with 3D-RA (21.6%) as compared to 2D-DSA (13.2%), P value < 0.001. Conclusion: 3D-RA is better than 2D-DSA for detecting BAVM-associated flow-related aneurysms, distal course of the dominant arterial feeders, direct visualization of the fistulous components, deep venous drainage, and draining venous stenosis; findings imperative for making a prudent therapeutic decision.

Mechanical Thrombectomy in Acute Ischemic Stroke: Angiographic Predictors of Outcome.

Background: In patients with acute ischemic stroke with large vessel occlusion, various angiographic features are important in patient selection and predicting outcome. Objective: We evaluated angiographic features like collaterals, clot burden score, angiographic recanalization, number of passes, and intracranial atherosclerotic disease (ICAD) with the functional outcome at 90 days. Materials and Methods: This was a retrospective analysis of prospectively collected data of 163 patients with acute ischemic stroke with large vessel occlusion who underwent mechanical thrombectomy within 24 hours of symptom onset. Angiographic data were reviewed blinded to clinical data. The outcome was defined as modified Rankin scale (mRS) at 90 days (good outcome mRS ≤2). Results: The median age of patients was 60 years and 34.4% were females. The median National Institutes of Health Stroke Scale (NIHSS) and Alberta Stroke Programme Early CT Score (ASPECTS) at admission were 17 and 6, respectively. On bivariate analysis, ASPECTS was >6, clot burden score was ≥7, recanalization of TICI was ≥2b, absence of ICAD, showed a positive correlation with the good outcome at 90 days (P-values of 0.003, 0.0001, and 0.03, respectively). Multiple attempts of device passes were associated with poor recanalization (P = 0.001) and it was seen more in ICAD patients. On multivariate analysis, independent predictors of poor outcome were clot burden score <7 (P = 0.043) and TICI score <2b (P = 0.048). Out of 41 patients (26%) with ICAD, 29 had a poor outcome at 90 days. Conclusion: Lower clot burden and less degree of recanalization were associated with poor outcome in acute ischemic stroke due to Large vessel occlusion (LVO). The presence of ICAD also predicted poor outcome.

Republished: Primary intraventricular haemorrhage due to rupture of giant varix of the basal vein of Rosenthal in a patient with long-standing direct CCF: angiographic features and treatment considerations.

Direct carotid cavernous fistulae (CCF) are often detected early and treated promptly resulting in a paucity of literature regarding its long-term evolution. We present a case of high flow post-traumatic direct CCF that was neglected for over 6 years and presented with a rare manifestation of primary intraventricular haemorrhage. Occlusions of the primary venous outlets likely resulted in engorgement of the deep venous system. The segmental anatomy of the shunting basal vein is critical to the clinical presentation and may range from basal ganglia or brainstem oedema/infarctions to uniquely, as in our case, isolated intraventricular haemorrhage secondary to variceal rupture. Treatment in such chronic cases requires a consideration of cerebral hyperperfusion syndrome necessitating deconstructive techniques with subsequent anticoagulation to avoid accelerated thrombosis of the venous varices.

Prospective Evaluation of Factors Affecting the Safety and Efficacy of Perclose Proglide Vascular Closure Device in Neurovascular Interventions.

BACKGROUND: Most of the neurointerventional procedures use various anticoagulants, antiplatelets, and fibrinolytic drugs, and it can predispose arterial access site complications. Safe and efficient closure arteriotomy site has extreme importance in reducing the morbidity. Percutaneous vascular closure devices (VCDs) enable us to close the arteriotomy sites. In this prospective study, we evaluated the factors affecting the safety and efficacy of Perclose ProGlide VCD in neurovascular interventions. MATERIALS AND METHODS: In this prospective study, we have evaluated the safety and efficacy of 327 Perclose ProGlide devices deployed in 217 patients who underwent various neurointerventions in our institute from October 2014 to October 2016. Time to achieve hemostasis (TAH) was calculated for various groups and the statistical significance of mean values between groups was estimated. RESULTS: Out of the 327 Perclose ProGlide deployed, complication rate was 0.91% and the mean TAH was 77.14 s. Assessment of TAH mean value showed statistically significant prolongation of TAH in obesity and those with larger arterial sheaths. Age, sex, post-heparin ACT, peri-procedure medications, and type of diseases had no significant role in increasing TAH. The evaluation also showed the presence of a learning curve in using this device. CONCLUSION: Perclose ProGlide VCD is safe and effective in closing the arteriotomy after neurointerventions. Obesity and larger arterial sheaths are independent factors prolonging the TAH. Learning curve associated with this device mildly increases the hemostatic time and device-related complications.

Single centre experience of flow diverter treatment of complex intracranial aneurysms from South India: Intermediate and long-term outcomes.

BACKGROUND AND PURPOSE: To report the intermediate and long-term clinical and angiographic outcomes of the treatment of complex intracranial aneurysms with flow diverter (FD) stents. SETTING: A tertiary care centre from south India. MATERIALS AND METHODS: Patients treated with FD stents were retrospectively analyzed. The clinical demographics, technical success, angiographic, and long-term outcomes were recorded. RESULTS: A total of 13 patients underwent FD treatment, in whom 11 procedures were successful. The cohort included large or giant intracranial aneurysms and recurrent aneurysms following conventional endovascular treatment. Major morbidity was observed in 1 patient, who developed basal ganglia bleed that needed evacuation. Minor complications were seen in 36% of patients without clinical sequelae. Significant obliteration of aneurysm was noted on 1 month computed tomography angiogram in >80% of the patients. Angiographic complete obliteration was noted in 89% of the patients at 6 months. Cranial nerve deficits were noted in 2 patients that improved on subsequent follow up. There was no mortality observed in this cohort. CONCLUSION: FD treatment of complex cerebral aneurysms was associated with favorable clinical and angiographic outcomes in the intermediate and long-term follow up. Minor complications were common, which needed to be effectively managed to prevent major catastrophic events. The steep learning curve influenced the technical success of the procedure.

Primary intraventricular haemorrhage due to rupture of giant varix of the basal vein of Rosenthal in a patient with long-standing direct CCF: angiographic features and treatment considerations.

Direct carotid cavernous fistulae (CCF) are often detected early and treated promptly resulting in a paucity of literature regarding its long-term evolution. We present a case of high flow post-traumatic direct CCF that was neglected for over 6 years and presented with a rare manifestation of primary intraventricular haemorrhage. Occlusions of the primary venous outlets likely resulted in engorgement of the deep venous system. The segmental anatomy of the shunting basal vein is critical to the clinical presentation and may range from basal ganglia or brainstem oedema/infarctions to uniquely, as in our case, isolated intraventricular haemorrhage secondary to variceal rupture. Treatment in such chronic cases requires a consideration of cerebral hyperperfusion syndrome necessitating deconstructive techniques with subsequent anticoagulation to avoid accelerated thrombosis of the venous varices.