Spontaneous Recanalization Research Articles

Incidence and predictors of radial artery occlusion following transradial coronary procedures

Abstract Background Transradial access for percutaneous coronary procedures has grown in popularity because of its advantages over the femoral approach. However, the benefit is overshadowed by an increased rate of radial artery occlusion (RAO). We aim to assess incidence and predictors of RAO after transradial catheterization. The anatomic variations of the radial artery (RA) were also studied. Methods This prospective study enrolled 427 patients who underwent coronary angiography or angioplasty via transradial access. An ultrasound evaluation of forearm arteries was performed. In case of RAO, another ultrasound check-up was performed after 1 month and 3 months of the procedure. Results Our study population includes 288 patients (32.6% female). The mean age was 61.9 ± 11.1 years. RAO occured in 48 patients (11.24%), among whom spontaneous recanalization was observed within 3 months in 15 patients (32.6%). On multivariate analysis, a younger age (OR 0.642 [CI 95%: 0.480 – 0.858], P = 0.031), low periprocedural systolic blood pressure, (OR 0.598 [CI 95%: 0.415 – 0.862], P = 0.007), a small radial diameter (OR 0.371 [CI 95%: 0.323 – 0.618], P = 0.031), insufficient anticoagulation (OR 0.287 [CI 95%: 0.163 – 0.505], P < 0.001), occlusive hemostasis (OR 0.128 [CI 95%: 0.047 – 0.353], P < 0.001), and a long duration of hemostasis emerged as independent predictors of radial occlusion. The overall incidence of radial artery anatomic variations was 14,8% (n=63). Among these patients, 40 (63.5%) had a high radial origin, 18 (28.6%) had extreme radial artery tortuosity, and 5 (7.9%) had a full radioulnar loop. Conclusion The incidence and prevalence of radial artery occlusion is expected to increase. Insufficient heparinization and occlusive hemostasis are the main modifiable predictors. The preventive strategy should focus primarily on these 2 predictive factors.

Spontaneous recanalization in acute large core ischemic stroke due to large vessel occlusion: a post-hoc analysis of the ANGEL-ASPECT trial

BackgroundPrevious studies have indicated that a subset of patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO) experience spontaneous recanalization (SR), but the prognosis and factors associated...

Safety and Efficacy Comparison of Tenecteplase and Alteplase for Clinically Suspected Large Vessel Occlusion Strokes without Thrombectomy

Introduction: Tenecteplase is a thrombolytic with higher fibrin affinity and is potentially better in clot lysis. A higher spontaneous recanalisation rate for large vessel occlusion (LVO) strokes had been shown in comparison studies with alteplase. Results of the LVO studies reflect the composite effect of the thrombolytic and thrombectomy, as patients would be treated by thrombectomy had they not been recanalised by intravenous thrombolysis alone. Thrombectomy is not readily available in many parts of the world. Our study aimed to compare the outcomes of suspected LVO patients treated with tenecteplase versus alteplase only, without the confounding effect of thrombectomy. Methods: This is a retrospective review. Data of patients given tenecteplase from May 2020 to August 2023 and those given alteplase 0.9 mg/kg from January 2019 to August 2023 were retrieved. Due to fluctuation in supply of tenecteplase during the COVID pandemic, some LVO patients were given alteplase. Patients with anterior circulation, clinically suspected LVO strokes (defined as National Institutes of Health Stroke Scale (NIHSS) score ≥6, plus cortical signs or hyperdense vessel sign), with thrombolysis given within 4.5 h of stroke onset were analysed. Patients with thrombectomy done were excluded. Safety and efficacy outcomes were compared. Results: There were 245 tenecteplase-treated patients treated between May 1, 2020, and August 31, 2023, and 732 patients were treated with alteplase between January 1, 2019, to August 31, 2023. Out of these, 148 tenecteplase patients and 138 alteplase 0.9 mg/kg patients fulfilled the study criteria. The symptomatic intracerebral haemorrhage rate was non-significantly lower in the tenecteplase group (2.1% vs. 5.8%, p = 0.13). There were no significant differences in the rate of ≥8-point NIHSS improvement (23.6% vs. 23.7%, p = 1) or the ≥4-point improvement (40.5% vs. 40.7%, p = 1) at 24 h. At 3 months, 21.6% of tenecteplase patients had good functional outcome (modified Rankin scale [mRS] 0–2), compared to 26.3% in the alteplase group (p = 0.40). Conclusion: In this pragmatic study of clinically suspected anterior circulation LVO patients without thrombectomy, outcome solely reflects the effects of tenecteplase. Tenecteplase showed comparable safety and efficacy to alteplase, but the result should be interpreted with caution in view of its small sample size and non-randomised study design.

Angiopoietin-like protein 2 inhibits thrombus formation.

Acute myocardial infarction is mainly caused by a lack of blood flood in the coronary artery. Angiopoietin-like protein 2 (ANGPTL2) induces platelet activation and thrombus formation in vitro through binding with immunoglobulin-like receptor B, an immunoglobulin superfamily receptor. However, the mechanism by which it regulates platelet function in vivo remains unclear. In this study, we investigated the role of ANGPTL2 during thrombosis in relationship with ST-segment elevation myocardial infarction (STEMI) with spontaneous recanalization (SR). In a cohort of 276 male and female patients, we measured plasma ANGPTL2 protein levels. Using male Angptl2-knockout and wild-type mice, we examined the inhibitory effect of Angptl2 on thrombosis and platelet activation both in vivo and ex vivo. We found that plasma and platelet ANGPTL2 levels were elevated in patients with STEMI with SR compared to those in non-SR (NSR) patients, and was an independent predictor of SR. Angptl2 deficiency accelerated mesenteric artery thrombosis induced by FeCl3 in Angptl2-/- compared to WT animals, promoted platelet granule secretion and aggregation induced by thrombin and collogen while purified ANGPTL2 protein supplementation reversed collagen-induced platelet aggregation. Angptl2 deficiency also increased platelet spreading on immobilized fibrinogen and clot contraction. In collagen-stimulated Angptl2-/- platelets, Src homology region 2 domain-containing phosphatase (Shp)1-Y564 and Shp2-Y580 phosphorylation were attenuated while Src, Syk, and Phospholipase Cγ2 (PLCγ2) phosphorylation increased. Our results demonstrate that ANGPTL2 negatively regulated thrombus formation by activating ITIM which can suppress ITAM signaling pathway. This new knowledge provides a new perspective for designing future antiplatelet aggregation therapies.

Number needed to treat with intravenous tenecteplase to reduce the need for mechanical thrombectomy in large vessel occlusion acute ischemic stroke patients: A retrospective look at real-world experience data

ObjectiveWe sought to describe short term outcomes in patients with large vessel occlusion acute ischemic stroke (LVOAIS) who were treated with intravenous tenecteplase (TNK) as compared to alteplase (tPA), focusing on reduction in the need for mechanical thrombectomy (MT). BackgroundIn LVOAIS, TNK has shown improved reperfusion and outcomes with a similar safety profile to tPA. Ultra-early reperfusion has been described with TNK which would prevent the need for MT. We analyze the magnitude of this effect in a “real-world” setting. Design/MethodsIn this retrospective study, demographic, clinical, and imaging information from patients with LVOAIS treated with intravenous thrombolysis was collected. Data was compared between the group treated with TNK and tPA. ResultsOne hundred eighty-six patients met the criteria for the study. Of these,144patients received tPA and 42 received TNK. Nine had clinical improvement prior to groin puncture and did not require angiography.When combining the number of patients who had recanalization on angiography before MT and those who had clinical improvement prior to angiography, there were a total of 23 patients. This was noted in 9.7 % of patients who received tPA and 21.4 % of those who received TNK (p = 0.043). For patients treated with TNK we observed a rapid clinical improvement, improved NIHSS, improved functional outcomes and decreased length of stay compared to patients treated with tPA. For patients with spontaneous recanalization either angiographically or with clinical improvement from intravenous thrombolysis, MT may not be required. ConclusionsIntravenous TNK in patients with LVOAIS decreases the need for MT, and is associated with improved outcomes and reduced length of stay.

Clinical features of pediatric patients with cerebral venous sinus thrombosis after isolated head trauma.

An association between blunt head trauma and cerebral venous sinus thrombosis (CVST) has been recognized, but its symptoms are nonspecific and the duration of symptoms remains unclear. Anticoagulation therapy is not considered necessary in most cases of traumatic CVST; however, this is controversial. The aim of this study was to describe the clinical characteristics and outcomes of children with CVST after isolated head trauma. The records of pediatric patients with isolated head trauma admitted for observation at 3 medical centers between January 2018 and May 2023 were reviewed retrospectively. CVST was diagnosed on MR venography (MRV). Clinical presentation, therapeutic management, and outcomes were evaluated in patients who had follow-up MRV. Of 260 pediatric patients with head trauma admitted to the 3 hospitals, 26 patients underwent MRV and 8 (30.8%) were diagnosed with CVST. One patient was treated with heparin, while the others received conservative treatment. All patients were discharged home asymptomatic. MRV performed during follow-up displayed complete recanalization in all cases, except for 1 case with partial recanalization. The median hospital stay was longer in patients with CVST than in those without CVST (9.5 vs 3.0 days, p = 0.001). The length of stay of pediatric patients with traumatic CVST was prolonged compared with those without CVST, but most patients had good outcomes with spontaneous recanalization following conservative treatment.

Parabiosis Discriminates the Circulating, Endothelial, and Parenchymal Contributions of Endogenous Tissue-Type Plasminogen Activator to Stroke.

Intravenous injection of alteplase, a recombinant tPA (tissue-type plasminogen activator) as a thrombolytic agent has revolutionized ischemic stroke management. However, tPA is a more complex enzyme than expected, being for instance able to promote thrombolysis, but at the same time, also able to influence neuronal survival and to affect the integrity of the blood-brain barrier. Accordingly, the respective impact of endogenous tPA expressed/present in the brain parenchyma versus in the circulation during stroke remains debated. To address this issue, we used mice with constitutive deletion of tPA (tPANull [tPA-deficient mice]) or conditional deletion of endothelial tPA (VECad [vascular endothelial-Cadherin-Cre-recombinase]-Cre∆tPA). We also developed parabioses between tPANull and wild-type mice (tPAWT), anticipating that a tPAWT donor would restore levels of tPA to normal ones, in the circulation but not in the brain parenchyma of a tPANull recipient. Stroke outcomes were investigated by magnetic resonance imaging in a thrombo-embolic or a thrombotic stroke model, induced by local thrombin injection or FeCl3 application on the endothelium, respectively. First, our data show that endothelial tPA, released into the circulation after stroke onset, plays an overall beneficial role following thrombo-embolic stroke. Accordingly, after 24 hours, tPANull/tPANull parabionts displayed less spontaneous recanalization and reperfusion and larger infarcts compared with tPAWT/tPAWT littermates. However, when associated to tPAWT littermates, tPANull mice had similar perfusion deficits, but less severe brain infarcts. In the thrombotic stroke model, homo- and hetero-typic parabionts did not differ in the extent of brain damages and did not differentially recanalize and reperfuse. Together, our data reveal that during thromboembolic stroke, endogenous circulating tPA from endothelial cells sustains a spontaneous recanalization and reperfusion of the tissue, thus, limiting the extension of ischemic lesions. In this context, the impact of endogenous parenchymal tPA is limited.

Sonothrombolysis for Ischemic Stroke.

Stroke is a major cause of death and disability globally, with ischemic stroke being the predominant mechanism. While spontaneous recanalization may occur, significant neuronal injury would have occurred in the interim. Intravenous thrombolysis administered within the first 4.5 h after stroke onset and endovascular thrombectomy within 24 h in patients with a salvageable penumbra improves functional independence. Ultrasound has been shown in both in vivo and in vitro models to enhance clot lysis, even more-so in the presence of thrombolytic agents. The use of transcranial Doppler and transcranial color-coded Doppler ultrasound in acute IS has been reported in case series, case-controlled studies, and clinical trials. While ultrasound at a frequency of 300 kHz increases the risk of intracranial hemorrhage, the 2 MHz range ultrasound aids thrombolysis and improves recanalization without significantly increasing the risk of symptomatic intracranial hemorrhage. Despite this, functional independence was not increased in clinical trials, nor was a benefit shown with the adjunctive use of microbubbles or microspheres. Nonetheless, newer technologies such as endovascular ultrasound, endovascular delivery of microbubbles, and thrombolytic-filled microbubbles await clinical trials. More evidence is needed before sonothrombolysis can be routinely used in the hyperacute management of ischemic stroke.

Abstract TP209: Prevalence of Spontaneous Recanalization of Internal Carotid Occlusion: A Systematic Scoping Review

Introduction: Spontaneous recanalization of occluded internal carotid arteries (ICAs) is thought to be an uncommon etiology of recurrent ischemic stroke. However, there is a growing number of reports describing this phenomenon, suggesting that follow-up investigations and/or intervention may be warranted. Our objective was to perform a scoping review of the literature to estimate the prevalence of spontaneous ICA recanalization and the timing of recanalization, and to describe imaging modalities used in follow-up as well as any post-recanalization interventions. Methods: MEDLINE, Embase, Cochrane Central Register of Controlled Trials and Web of Science were searched from inception to June 2022 for studies that included adults with spontaneous recanalization or transient occlusion of the internal carotid artery. Two investigators independently screened the studies and extracted data around recanalization prevalence, timepoints, imaging, and treatment. These results were described qualitatively, and descriptive statistics were calculated where appropriate. Results: Among the 2384 studies retrieved, 51 met inclusion criteria, of which 34 were case studies and 17 were cohort studies, with a total of 816 patients. Prevalence of recanalization was reported in 20 studies (3 case studies, 17 cohort studies) at a median of 40.0% (IQR 22.5 - 40.0%) in case studies, and 21.2% (IQR 9.2 - 37.5%) in cohort studies. Forty-one studies reported a time frame for when recanalization was identified, with 53.7% individual cases in case studies and 33.3% amongst cohort studies identified within the first 3 months after occlusion. When reported, antiplatelet treatment was the most common medical treatment pre- and post-recanalization with 189 and 36 individuals, respectively. Finally, doppler imaging was used in 70.6% of studies to identify recanalization, with angiography as the next most common modality at 54.9%. Twenty studies reported an endovascular intervention. Conclusions: Spontaneous recanalization occurs more commonly than previously thought. Currently there is no consensus on what intervention is needed (if any), or when this intervention would occur. More data is needed to confirm this data and determine the best time frame to re-image.

Presentation and Management of Cerebral Venous Sinus Thrombosis After Supratentorial Craniotomy.

Cerebral venous sinus thrombosis (CVST) after supratentorial craniotomy is a poorly studied complication, for which there are no management guidelines. This study assessed the incidence, associated risk factors, and management of postoperative CVST after awake craniotomy. This is an observational, retrospective, monocentric analysis of patients who underwent a supratentorial awake craniotomy. Postoperative CVST was defined as a flow defect on the postoperative contrast-enhanced 3D T1-weighted sequence and/or as a T2* hypointensity within the sinus. In 401 supratentorial awake craniotomies (87.3% of diffuse glioma), the incidence of postoperative CVST was 4.0% (95% CI 2.5-6.4): 14/16 thromboses located in the superior sagittal sinus and 12/16 located in the transverse sinus. A venous sinus was exposed during craniotomy in 45.4% of cases, and no intraoperative injury to a cerebral venous sinus was reported. All thromboses were asymptomatic, and only two cases were diagnosed at the time of the first postoperative imaging (0.5%). Postoperative complications, early postoperative Karnofsky Performance Status score, and duration of hospital stay did not significantly differ between patients with and without postoperative CVST. Adjusted independent risk factors of postoperative CVST were female sex (adjusted Odds Ratio 4.00, 95% CI 1.24-12.91, P = .021) and a lesion ≤1 cm to a venous sinus (adjusted Odds Ratio 10.58, 95% CI 2.93-38.20, P < .001). All patients received standard prophylactic-dose anticoagulant therapy, and none received treatment-dose anticoagulant therapy. No thrombosis-related adverse event was reported. All thromboses presented spontaneous sinus recanalization radiologically at a mean of 89 ± 41 days (range, 7-171). CVST after supratentorial awake craniotomy is a rare event with satisfactory clinical outcomes and spontaneous sinus recanalization under conservative management without treatment-dose anticoagulant therapy. These findings are comforting to neurosurgeons confronted with postoperative MRI reports suggesting CVST.

Superior cerebellar artery occlusion remaining after thrombectomy for acute basilar artery occlusion

To investigate the incidence and impact of superior cerebellar artery (SCA) occlusion remaining after thrombectomy for acute basilar artery occlusion (BAO). We retrospectively analyzed data from 116 patients who underwent thrombectomy for BAO. The patency of SCA was assessed on final angiograms. Clinical and radiologic data of the patients were retrieved from a prospectively collected database and analyzed. All patients underwent pretreatment and follow-up DWI to detect new infarctions in SCA territory. Ten patients (8.6%) had SCA occlusions on final angiograms. Of these, two patients had bilateral occlusions. A new infarction with a diameter ranged from 4 to 11 mm in corresponding SCA territory occurred in 5 of 10 patients. No patients with SCA occlusions experienced symptomatic cerebellar hemorrhage or malignant cerebellar infarction. Nine of 12 SCA occlusions showed spontaneous recanalization on follow-up CT angiography. Four of 10 patients showed 90-day favorable outcome (mRS 0–3) and 90-day mortality occurred in one patient. SCA occlusions remaining after thrombectomy for acute BAO had a benign clinical course. Most of these lesions recanalized spontaneously. Our study suggests that attempts to recanalize remnant SCA occlusion may be unnecessary after basilar artery thrombectomy.

Prognostic impact of ventricular tachycardia/fibrillation timing on cardio-vascular death in STEMI patients: 5 years of follow-up

Abstract Objectives Ventricular tachycardia (VT) and ventricular fibrillation (VF) are life-threatening arrhythmias that have negative impact on prognosis. This study investigated the relationship between the timing of VT or VF and long-term prognosis among ST-elevation myocardial infarction (STEMI) patients. Background It is unknown whether the timing of VT/VF occurrence affects the prognosis of patients with STEMI. Methods From 2001 to 2011 among 1621 STEMI patients (mean age 54,4±9,3 years) who participated in a prospective study, 221 (13.6%) had VT/VF during in-hospital stay. The mean time from STEMI symptoms onset was 4,5±0,1 h. 632 patients underwent TLT (39.0%), 267 (16.5%) - primary PCI. 772 (44,5%) patients did not undergo revascularization due to spontaneous recanalization or late admission. Patients with VT/VF were divided into two groups: early VT/VF - within 24 hour (h) of admission, 154 patients and late VT/VF - &amp;gt;24 h after admission, 67 patients. Patients have been monitored for 5 years of follow-up (FU). Cardiovascular (CV) death was the primary end-point. Results Patients with VT/VF were more likely to have cardiogenic shock, Killip Class II-III, AV block, and recurrent MI. Among STEMI patients the frequency of VT/VF occurrence was higher in patients with TLT – 19,0% and PTCA - 15,0% in compare to those without revascularization - 7,9%. However, the late VT/VF was 3.4 times less frequent among patients with TLT, 2.9 times - in PTCA, and twice less in patients without revascularization, compared to patients with early VT/VF. During FU long-term mortality has differed (Fig. 1). Kaplan-Mayer curves have significantly separated in late VT/VF group (p&amp;lt;0.01) during the first year (Fig. 2). Independent predictors of CV death in STEMI patients with late VT/VF were: higher Killip class (OR: 1.372, 95%CI 1.023-2.174, p&amp;lt;0.01), and higher peak CK-MB (OR: 1.031, 95% CI: 1.014-1.048, p&amp;lt;0.05). Conclusions VT and VF are frequent complications in STEMI and are powerful and independent predictors of 5-year survival. The timing of VT/VF occurrence had a peak during the first 24 h. However, patients with late VT/VF are at high risk of CV death in long-term FU and therefore require an individualized approach.

The impact of blood pressure variability on the development of parenchymal hematoma in acute cerebral infarction with atrial fibrillation.

Although blood pressure variability (BPV) and reperfusion are associated with parenchymal hematoma (PH) after stroke, the relationship between BPV and PH in atrial fibrillation (AF) patients who are at risk of reperfusion injury with frequent spontaneous recanalization is unknown. This study aimed to investigate whether BPV within the first 48 h is associated with PH within 72 h in patients with AF and stroke in terms of major vessel occlusion status. A total of 131 patients with AF that were admitted within 24 h after stroke onset were enrolled. PH was defined as a confluent hemorrhage with mass effect. The maximum (max), minimum (min), and average blood pressure (BP) during the first 48 h after admission were calculated. BPV was analyzed by using range between maximum and minimum (max-min), successive variation (SV), standard deviation (SD), and coefficient of variation (CV). All parameters were applied for systemic (SBP), diastolic (DBP), and pulse pressure (PP). After adjusting for confounding variables, various BPV parameters were associated with PH, including SBPmax (p = 0.0426), SBPSV (p = 0.0006), DBPmax-min (p = 0.0437), DBPSV (p = 0.0358), DBPSD (p = 0.0393), PPmax-min (p = 0.0478), PPSV (p < 0.0001), PPSD (p = 0.0034), and PPCV (p = 0.0120). The relationship remained significant in patients with a patent major vessel responsible for infarction but not in patients with an occluded major vessel. In conclusion, this study revealed that high BPV was associated with PH in patients with AF and acute stroke, particularly for those with a patent major vessel. The control of BP and BPV after stroke may be considered in patients with AF.

Natural history of portal vein thrombosis in cirrhosis: A systematic review with meta-analysis.

Progression of liver disease in cirrhosis is associated with an increased incidence of portal vein thrombosis (PVT) in cirrhosis. However, evidence suggests that spontaneous recanalization of PVT may occur even without anti-thrombotic therapy. Thus, the present meta-analysis was conducted to study the natural history of PVT in cirrhosis, facilitating decisions regarding anticoagulation. Three electronic databases were searched from 2000 to August 2022 for studies reporting the outcome of PVT in cirrhotics without anticoagulation. The pooled proportions with their 95% confidence intervals (CIs) were calculated using a random-effect model. A total of 26 studies (n=1441) were included in the final analysis. Progression of PVT on follow-up was seen in 22.2% (95% CI 16.1-28.4), while 77.7% (95% CI 71.6-83.9) remained non-progressive (improved or stable). The most common outcome was a stable PVT with a pooled event rate of 44.6% (95% CI 34.4-54.7). The pooled rates of regression and complete recanalization of PVT in cirrhotics were 29.3% (95% CI 20.9-37.7) and 10.4% (95% CI 5.0-15.8), respectively. On follow-up after improvement, pooled recurrence rate of PVT was 24.0% (95% CI 14.7-33.4). MELD score, and presence of ascites had a negative association, while a longer follow-up duration had positive association with PVT regression. Approximately 25% of the cases of PVT in cirrhosis are progressive, 30% cases improve, and 45% remain stable. Future studies are needed to analyze the predictors of spontaneous regression.

Teaching NeuroImages: Pathology and thromboembolism of carotid web

A 43-year-old woman without relevant medical history presented with acute middle cerebral artery (MCA) occlusion (figure 1A). Thrombophilia and vasculitis were ruled out and echocardiography was normal. Carotid web was considered because a shelf-like protrusion arising from the left carotid bulb (figure 1C) was found, which is suspected as the cause of embolization in MCA.1 Carotid endarterectomy was performed. The diaphragm-like structure demonstrated smooth muscle cell–rich intima, increased elastic tissue, and myxoid degeneration (figure 2, A and B). The superimposed thrombosis was identified in the web pocket (figure 2C). Postoperative CT angiography showed spontaneous recanalization of left MCA (figure 1B).

Nonstandard approach to the ischemic stroke treatment

Ischemic stroke is one of the most common causes of disability and mortality worldwide. Occlusive-stenotic lesion of the extra- and intracranial carotid arteries, which developed acutely and led to acute cerebrovascular accident, is a prognostically unfavorable factor. The appearance of endovascular technologies has revolutionized the salvation of this category of patients; however, they are sometimes powerless in the fight against nature. The article presents a case of tandem and bilateral lesions of the extra- and intracranial internal carotid artery, the successful result of treatment of which became possible only due to the development of spontaneous recanalization.

A canine thromboembolic model of anterior circulation large vessel occlusion stroke

PurposeTo develop a large animal preclinical model of thromboembolic stroke with stable, protracted large vessel occlusion (LVO) utilizing an autologous clot. Materials and methodsA reproducible canine model of large vessel occlusion stroke was established by endovascular placement of an autologous clot into the middle cerebral artery (MCA) of six adult hounds and confirmed using digital subtraction angiography (DSA). Infarct volume and evidence of hemorrhage were determined by magnetic resonance imaging (MRI) 7 h after occlusion and Thrombolysis in Cerebral Infarction scale (TICI) was assessed before and after clot placement and at 1, 6, 7, and 9 h after middle cerebral artery occlusion (MCAO). Heart rate (HR) and blood pressure (BP) were monitored continuously and invasively through an arterial sheath throughout the procedures and complete blood count and blood gas analysis completed at time of sacrifice. Histopathological findings at time of sacrifice were used to confirm stroke volume and hemorrhage. ResultsMCAO with resulting TICI 0 flow was observed in all six animals, verified by serial DSA, and lack of collateral flow persisted for 9 h after clot placement until time of sacrifice. The mean infarct volume was 47.0 ± 6.7% of the ipsilateral hemisphere and no events of spontaneous recanalization or clot autolysis were observed. ConclusionWe demonstrate a thromboembolic canine model of MCAO that is both feasible and results in consistent infarct volumes to generate a clinically relevant LVO. This model is important to evaluate treatment of LVO in acute ischemic stroke (AIS) outside the established 4.5 h recombinant tissue plasminogen activator (rTPA) therapeutic window utilizing a prolonged occlusive thrombus.

Prevalence of spontaneous recanalisation of complete internal carotid occlusion: protocol for a systematic scoping review

IntroductionAlthough previously thought to be a rare occurrence, spontaneous recanalisation is not uncommon, with a growing number of reports describing this phenomenon. However, the frequency, time course and mechanism of...

Abstract Number ‐ 223: Spontaneous Revascularization of Completely Occluded Internal Carotid Artery: Case Report

Introduction Occlusion of the internal carotid artery (ICA), caused by atherosclerotic thrombosis, arterial embolism, or dissection, is associated with high morbidity and mortality of acute stroke. Commonly, these lesions are managed with aggressive medical treatment due to their chronic and usually irreversible nature. Spontaneous recanalization of the occluded ICA has been described in rare instances. Methods We present a report here on three cases with spontaneous recanalization of complete occluded carotid arteries. Results Our first patient was a 62‐year‐old male with a history of hypertension, who presented with transient left eye vision loss. CT angiography of the head and neck (CTA HN) demonstrated left ICA complete occlusion while the left middle cerebral artery (MCA) and anterior cerebral arteries (ACA) were patent. He was treated with apixaban. At the two‐month follow‐up, the repeat CTA HN demonstrated complete recanalization of the left ICA. The etiology of the occlusion remained cryptogenic. Our second patient was a 71‐year‐old male with a prior history of right carotid endarterectomy, peripheral vascular disease, coronary artery disease, hypertension, and dyslipidemia, who presented with acute right MCA stroke. Work‐up with CTA HN demonstrated right ICA complete occlusion. He was treated medically with aspirin and clopidogrel. Six months later, he presented with a two‐week history of intermittent confusion and left‐sided weakness. His MRI brain was negative foracute stroke. Interestingly, CTA HN demonstrated that the right ICA had complete recanalization. The cause of carotid thrombosis remained cryptogenic. Our third patient was a 46‐year‐old female with a history of hypertension, hyperlipidemia, remote low‐speed vehicle collision, and cervical spine chiropractic treatment (the last neck manipulation was about two years prior), presenting with sudden onset dizziness, right‐sided neck pain, and left homonymous hemianopia. Brain MRI showed acute right posterior cerebral artery (PCA) stroke. CTA HN revealed occlusion of the right ICA with a flare‐up appearance suggestive of a carotid dissection. She also had a right fetal PCA. She was treated medically with rivaroxaban. Four months later, a follow‐up MR angiogramof the neck showed a fully revascularized right ICA. Her hypercoagulable workup revealed that she had a rare form of breast cancer. Conclusions Although ICA occlusion is generally considered chronic and irreversible, our case series suggests that the lesion can have spontaneous recanalization with medical treatment. Further studies of characterizing carotid occlusion to predict recanalization are warranted.

Abstract Number ‐ 249: Differential Ischemic Vulnerability depicted by White Matter‐Sparing Infarction following Alteplase Recanalization

Introduction Gray and white matter possess different ischemic thresholds and therefore will undergo infarction at different rates of cerebral blood flow. We present a patient that presented with a large vessel occlusion and recanalized following alteplase administration within hours of symptom onset. Follow‐up imaging revealed a white matter‐sparing infarction, visually depicting the differential ischemic vulnerability between gray and white matter. Methods Case Report. Results An 83‐year‐old woman with a medical history of dementia, hypertension, and atrial fibrillation, not on anticoagulation due to recent gastrointestinal hemorrhage, presented with speech difficulty and right sided weakness. Her blood pressure was elevated at 170/86 and neurological exam demonstrated mixed aphasia, right homonymous hemianopia, left gaze deviation, and dense right hemiparesis with a National Institutes of Health Stroke Scale of 23. Non‐contrast CT of the head showed a hyperdense left terminal internal cerebral artery (ICA) and was otherwise unremarkable (Figure 1, A). CT angiography of the head and neck revealed an ICA “T” occlusion with no flow seen at the ICA terminus, the left anterior cerebral (A1) and middle cerebral (M1) segments (Figure 1, B). She was treated with intravenous alteplase 132 minutes from when she was last known normal. She was transferred to our comprehensive stroke center for mechanical thrombectomy, however, catheter angiography showed spontaneous recanalization of left ICA (Figure 1, C). Brain MRI the following day showed a white matter‐sparing infarction involving the left ICA territory (Figure 1, D‐F). She was discharged to rehab with moderate improvement in her aphasia and right hemiparesis. Conclusions This case visually depicts the differential ischemic vulnerability between gray and white matter since recanalization likely occurred at a cerebral blood flow level below the gray matter ischemic threshold while remaining above the white matter threshold. While pretreatment ischemic core volumes are inversely correlated with functional outcomes after recanalization of large vessel occlusions,1 selective white matter‐sparing infarction on post‐treatment MRI is associated with more favorable outcomes.2 Predicting ischemic core volume with perfusion imaging using the same CBF threshold for both gray and white matter may over‐estimate the ischemic core if CBF is between the gray and white matter thresholds.