Passing the thrombus in endovascular treatment of acute ischemic stroke: Do we penetrate the thrombus?

Mechanical thrombectomy is increasingly applied during the treatment of acute stroke. Various devices have been advocated with different sites of force effect at the thrombus. The purpose of this study was to evaluate the angiographic route of passing systematically and therefore to assess the site of deployment of mechanical devices in correlation to the thrombus in interventional stroke treatment. Twenty-one consecutive patients with endovascular treatment for acute ischemic stroke with 26 passing procedures were evaluated prospectively. Occlusion site was the M1-segment in 17 cases (65.4%), ICA termination in five cases (19.2%), M2-segment in two cases (7.7%), the A2-segment in one case (3.8%) and basilar artery in one case (3.8%). On angiographic images the microwire and microcatheter passage was evaluated by illustrating the entry point and course across the occlusion site in relation to the thrombus in different projections and in correlation to the recanalisation result. Results were correlated to the origin of the thrombi according to the TOAST criteria. In all cases the point of entry to the occlusion site was delineated laterally to the thrombus in at least one projection. The course of the wire across the occluded segment in relation to the thrombus was found to be laterally in 22 procedures (84.6%). In the majority of M1-occlusions (12/17, 70.6%) the passage was found in the cranial aspect of the thrombus. In four procedures (15.4%) angiograms in different projections did not unequivocally confirm a passage laterally to the thrombus. The route of passing the thrombus was independent of thrombus origin according to the TOAST criteria. In the majority of cases the complete route of passing the occlusion site was visualized angiographically. Entrance of the microwire and microcatheter at proximal surface of the thrombus takes place laterally to the thrombus and accordingly the passage takes place between the thrombus and the vessel wall independent of thrombus origin. A penetration of the thrombus was not observed. This route of passing has implications on deployment and transmission of force in relation to the thrombus in mechanical approaches and consequently on the development of retrieval devices.

CT-based intravenous thrombolysis 3-4.5 hours after acute ischemic stroke in clinical practice

Outcome of stroke patients selected with cerebral computed tomography for intravenous thrombolysis administered in clinical routine from 3 to 4.5 hours after symptoms onset is not well investigated. Aim of this single-center, prospective, observational study was to compare the safety and efficacy of intravenous alteplase given in routine clinical praxis 181-270 minutes (late) and within 180 minutes (early) after stroke onset in patients selected with cerebral computed tomography.

Endothelial dysfunction and arterial stiffness in ischemic stroke: the role of sleep-disordered breathing

Sleep-disordered breathing (SDB) represents a risk factor for cardiovascular morbidity after a cerebral ischemic event (acute ischemic event, ischemic stroke, or transient ischemic attack). In the present study, endothelial function and arterial stiffness were analyzed in patients who experienced a postacute ischemic event with relation to SDB, sleep disruption, and nocturnal oxygenation parameters.

Mechanical thrombectomy for acute ischemic stroke: thrombus-device interaction, efficiency, and complications in vivo

BACKGROUND AND PURPOSE: Mechanical thrombectomy is a promising new modality of interventional stroke treatment. The various devices differ with regard to where they apply force on the thrombus, taking a proximal approach such as aspiration devices or a distal approach such as basket-like devices. The study compares the in vivo effectiveness and thrombus-device interaction of these 2 approaches. METHODS: Angiography and embolization with a radioopaque whole blood thrombus was performed in 10 swine. Mechanical thrombectomy was performed in 20 cranial vessels using a proximal aspiration device (Vasco35) and a distal basket-like device (Catch) with and without proximal balloon occlusion. Fifty-six retrieval attempts were made. RESULTS: The proximal device allowed fast repeated application with a low risk of thromboembolic events (3%) and vasospasm, but it had a significantly lower success rate (39.4%) in retrieving thrombotic material than the distal device (DD) (82.6%; odds ratio, 7.3; 95% CI, 2.0 to 26.4). The compaction of the thrombus during retrieval with DD increased the risk of vessel wall irritation significantly (P<0.01) and complicated retrieval into the guiding catheter. The number of embolic events was significantly higher with DD (26%; odds ratio, 11.3; 95% CI, 1.35 to 101.6) unless proximal balloon occlusion was used. CONCLUSIONS: The proximal and the distal approaches to mechanical thrombectomy proved to be effective at achieving recanalization of cranial vessels. The proximal device is faster in application and allowed repeated attempts with a low complication rate. The DD is more successful at removing thrombotic material, but its method of application and attendant thrombus compaction increase the risk of thromboembolic events and vasospasms.

Time to admission in acute ischemic stroke and transient ischemic attack

BACKGROUND AND PURPOSE: The effect of thrombolysis depends on the time from stroke onset to treatment and therefore also on the time when patients come to the hospital. This study was designed to analyze the variables that influence the time from symptom onset to admission (TTA) to the stroke unit. METHODS: We evaluated the medical records of 615 consecutive stroke or transient ischemic attack (TIA) patients admitted to our neurological department within 48 hours after symptom onset. RESULTS: The median TTA was 180 minutes. Referral by emergency medical services (EMS; P<0.001), high National Institutes of Health Stroke Scale (NIHSS) scores (P<0.001), strokes in the carotid territory (P<0.001), and strokes not attributable to small vessel disease (P<0.001) were associated with shorter prehospital delays. The TTA was adjusted for travel times (adjTTA), and all these variables remained significantly associated with time to admission. In addition, patients with previous experience with stroke or TIA had longer adjTTA (P=0.028). Regression analysis confirmed the independent association between referral by EMS (P=0.010), high NIHSS scores (P<0.001), carotid territory stroke (P<0.001), and first-ever cerebrovascular event (P=0.022) with shorter adjTTA. CONCLUSIONS: Factors such as NIHSS scores and stroke location influence the time to admission but, unlike referral pathways, cannot be modified. Educational programs and stroke campaigns should therefore not only teach typical and less common stroke symptoms and signs but also that EMS provides the fastest means of transportation to a stroke unit and the best chances to get treatment early.

Sleep-disordered breathing and acute ischemic stroke: diagnosis, risk factors, treatment, evolution, and long-term clinical outcome

BACKGROUND AND PURPOSE: Sleep-disordered breathing (SDB) is frequent in stroke patients. Risk factors, treatment response, short-term and long-term outcome of SDB in stroke patients are poorly known. METHODS: We prospectively studied 152 patients (mean age 56+/-13 years) with acute ischemic stroke. Cardiovascular risk factors, Epworth sleepiness score (ESS), stroke severity/etiology, and time of stroke onset were assessed. The apnea-hypopnea index (AHI) was determined 3+/-2 days after stroke onset and 6 months later (subacute phase). Continuous positive airway pressure (CPAP) treatment was started acutely in patients with SDB (AHI > or =15 or AHI > or =10+ESS >10). CPAP compliance, incidence of vascular events, and stroke outcome were assessed 60+/-16 months later (chronic phase). RESULTS: Initial AHI was 18+/-16 (> or =10 in 58%, > or =30 in 17% of patients) and decreased in the subacute phase (P<0.001). Age, diabetes, and nighttime stroke onset were independent predictors of AHI (r2=0.34). In patients with AHI > or =30, age, male gender, body mass index, diabetes, hypertension, coronary heart disease, ESS, and macroangiopathic etiology of stroke were significantly higher/more common than in patients with AHI <10. Long-term incidence of vascular events and stroke outcome were similar in both groups. CPAP was started in 51% and continued chronically in 15% of SDB pts. Long-term stroke mortality was associated with initial AHI, age, hypertension, diabetes, and coronary heart disease. CONCLUSIONS: SDB is common particularly in elderly stroke male patients with diabetes, nighttime stroke onset, and macroangiopathy as cause of stroke; it improves after the acute phase, is associated with an increased poststroke mortality, and can be treated with CPAP in a small percentage of patients.

Early recurrent ischemic stroke in stroke patients undergoing intravenous thrombolysis

BACKGROUND: We assessed the incidence of early recurrent ischemic stroke in stroke patients treated with intravenous tissue-type plasminogen activator (tPA) and the temporal pattern of its occurrence compared with symptomatic intracranial hemorrhage (ICH). METHODS AND RESULTS: Prospectively collected, population-based data for 341 consecutive acute stroke patients (62% men; mean age, 66 years) treated with tPA according to the National Institute of Neurological Disorders and Stroke study protocol at 8 medical centers in Switzerland (3 academic and 5 community) between January 2001 and November 2004 were retrospectively analyzed. The primary outcome measure was neurological deterioration > or = 4 points on the National Institutes of Health Stroke Scale occurring within 24 hours of tPA treatment and caused either by recurrent ischemic stroke (defined as the occurrence of new neurological symptoms suggesting involvement of initially unaffected vascular territories and evidence of corresponding ischemic lesions on cranial computed tomography scans, in the absence of ICH) or by ICH. Early recurrent ischemic stroke was diagnosed in 2 patients (0.59%; 95% confidence interval, 0.07% to 2.10%) and symptomatic ICH in 15 patients (4.40%; 95% confidence interval, 2.48% to 7.15%). Both recurrent ischemic strokes occurred during thrombolysis, whereas symptomatic ICHs occurred 2 to 22 hours after termination of tPA infusion. CONCLUSIONS: Recurrent ischemic stroke is a rare cause of early neurological deterioration in acute stroke patients undergoing intravenous thrombolysis, with a different temporal pattern compared with that of symptomatic ICH.

Comparison of intraarterial and intravenous thrombolysis for ischemic stroke with hyperdense middle cerebral artery sign

BACKGROUND AND PURPOSE: It is unclear whether intraarterial (IAT) or intravenous (IVT) thrombolysis is more effective for ischemic stroke with hyperdense middle cerebral artery sign (HMCAS) on computed tomography (CT). The aim of this study was to compare IAT and IVT in stroke patients with HMCAS. METHODS: Comparison of data from 2 stroke units with similar management of stroke associated with HMCAS, except that 1 unit performed IAT with urokinase and the other IVT with plasminogen activator. Time to treatment was up to 6 hours for IAT and up to 3 hours for IVT. Outcome was measured by mortality and the modified Rankin Scale (mRS), dichotomized at 3 months into favorable (mRS 0 to 2) and unfavorable (mRS 3 to 6). RESULTS: One hundred twelve patients exhibited a HMCAS, 55 of 268 patients treated with IAT and 57 of 249 patients who underwent IVT. Stroke severity at baseline and patient age were similar in both groups. Mean time to treatment was longer in the IAT group (244+/-63 minutes) than in the IVT group (156+/-21 minutes; P=0.0001). However, favorable outcome was more frequent after IAT (n=29, 53%) than after IVT (n=13, 23%; P=0.001), and mortality was lower after IAT (n=4, 7%) than after IVT (n=13, 23%; P=0.022). After multiple regression analysis IAT was associated with a more favorable outcome than IVT (P=0.003) but similar mortality (P=0.192). CONCLUSIONS: In this observational study intraarterial thrombolysis was more beneficial than IVT in the specific group of stroke patients presenting with HMCAS on CT, even though IAT was started later. Our results indicate that a randomized trial comparing both thrombolytic treatments in patients with middle cerebral artery occlusion is warranted.

Neuro-imaging of cerebral ischemic stroke

Major progress has recently been made in the neuro-imaging of stroke as a result of improvements in imaging hardware and software. Imaging may be based on either magnetic resonance imaging (MRI) or computed tomography (CT) techniques. Imaging should provide information on the entire vascular cervical and intracranial network, from the aortic arch to the circle of Willis. Equally, it should also give information on the viability of brain tissue and brain hemodynamics. CT has the advantage in the detection of acute hemorrhage whereas MRI offers more accurate pathophysiological information in the follow-up of patients.

Mechanical thromboembolectomy for acute ischemic stroke: comparison of the catch thrombectomy device and the Merci Retriever in vivo

BACKGROUND AND PURPOSE: The purpose of the study was to compare efficacy and potential complications of 2 commercially available devices for mechanical thromboembolectomy. METHODS: Devices were tested in an established animal model allowing the use of routine angiography catheters and thrombectomy devices. Radio-opaque thrombi were used for visualization of thrombus-device interaction during angiography. The Merci Retrieval System and the Catch Thromboembolectomy System were assessed each in 10 vessel occlusions. For every occluded vessel up to 5 retrieval attempts were performed. RESULTS: Sufficient recanalization was achieved with the Merci Retriever in 90% of occlusions, and with the Catch device recanalization was achieved in 70% of occlusions. Recanalization at the first attempt occurred significantly more often with the Merci Retriever compared to the Catch device (OR, 21; 95% CI, 1.78-248.11). Consequently, significantly more attempts (P=0.02) had to be performed with the Catch device; therefore, time to recanalization was longer. Thrombus fragmentations during retrieval were caused more often by the Catch device compared to the Merci Retriever (OR, 15.6; 95% CI, 1.73-140.84), resulting in a higher distal embolization rate. During retrieval both devices lost thrombotic material at the tip of the guide catheter, which was then aspirated in most cases. CONCLUSIONS: Both distal devices are effective for thromboembolectomy. To avoid loss of thrombotic material and distal embolization, the use of large luminal balloon guide catheters and aspiration during retrieval seems to be mandatory. The design of the Merci Retriever appears to be more efficient during thrombus mobilization and retrieval with less fragmentation compared to the Catch Thromboembolectomy System.

Occlusion length is a crucial determinant of efficiency and complication rate in thrombectomy for acute ischemic stroke

BACKGROUND AND PURPOSE: Although mechanical thrombectomy (MT) has an encouragingly high recanalization rate in treating stroke, it is associated with severe complications of which the underlying factors have yet to be identified. Because MT is a mechanical approach, the mechanical properties of the thrombus might be crucial for its success. The present study assesses the effect of thrombus length on the in vivo effectiveness and complication rate of MT. MATERIALS AND METHODS: Angiography and embolization of 21 cranial vessels with radiopaque whole-blood thrombi 10, 20, and 40 mm in length (7 occlusions each) were performed in 7 swine. MT was carried out using a distal snarelike device (BCR Roadsaver) with proximal balloon occlusion. A total of 61 retrievals were attempted. RESULTS: In the group of 10-mm occlusions, 77.8% of the attempts achieved complete recanalisation. For longer occlusions, the success rates decreased significantly to 20% of attempts for 20-mm occlusions (odds ratio [OR], 14; 95% confidence interval [CI], 2.2-89.2) and 11.1% for 40-mm occlusions (OR, 28; 95% CI, 3.9-202.2; P < .005). The low success rates were largely due to complications associated with thrombus compaction during retrieval. Similarly, the rate of thromboembolic events increased from 0% in 10-mm occlusions to 14.8% in 40-mm occlusions. CONCLUSIONS: MT using a distal device proved to be a fast, effective, and safe procedure for recanalizing short (10-mm) occlusions in the animal model. However, occlusion length emerged as a crucial determinant for MT with a significant decrease in recanalization success per attempt and increased complication rates. These findings suggest limitations of MT in the clinical application.