High rate of complete recanalization and dramatic clinical recovery during tPA infusion when continuously monitored with 2-MHz transcranial doppler monitoring

Platelet rich clots are resistant to lysis by thrombolytic therapy in a rat model of embolic stroke

Background

Early recanalization of occluded vessels in stroke is closely associated with improved clinical outcome. Microbubble-enhanced sonothrombolysis is a promising therapy to improve recanalization rates and reduce the time to recanalization. Testing any thrombolytic therapy requires a model of thromboembolic stroke, but to date these models have been highly variable with regards to clot stability. Here, we developed a model of thromboembolic stroke in rats with site-specific delivery of platelet-rich clots (PRC) to the main stem of the middle cerebral artery (MCA). This model was used in a subsequent study to test microbubble-enhanced sonothrombolysis.

Methods

In Study 1 we investigated spontaneous recanalization rates of PRC in vivo over 4 hours and measured infarct volumes at 24 hours. In Study 2 we investigated tPA-mediated thrombolysis and microbubble-enhanced sonothrombolysis in this model.

Results

Study 1 demonstrated stable occlusion out to 4 hours in 5 of 7 rats. Two rats spontaneously recanalized at 40 and 70 minutes post-embolism. Infarct volumes were not significantly different in recanalized rats, 43.93 ± 15.44% of the ischemic hemisphere, compared to 48.93 ± 3.9% in non-recanalized animals (p = 0.7). In Study 2, recanalization was not observed in any of the groups post-treatment.

Conclusions

Site specific delivery of platelet rich clots to the MCA origin resulted in high rates of MCA occlusion, low rates of spontaneous clot lysis and large infarction. These platelet rich clots were highly resistant to tPA with or without microbubble-enhanced sonothrombolysis. This resistance of platelet rich clots to enhanced thrombolysis may explain recanalization failures clinically and should be an impetus to better clot-type identification and alternative recanalization methods.

Electronic supplementary material

The online version of this article (doi:10.1186/s13231-014-0014-y) contains supplementary material, which is available to authorized users.

Predictors of major improvement after intravenous thrombolysis in acute ischemic stroke

BACKGROUND

Intravenous thrombolysis improves outcomes of stroke patients. The immediate response to thrombolysis is variable and few studies attempted to identify predictors of major neurological improvement (MNI) 24 h following thrombolysis. Our objective is to determine predictors of MNI 24 h following thrombolysis.

METHODS

We reviewed the prospective database of patients treated through our telestroke network and at our institution between November 2008 and June 2012. We included all patients who received IV t-PA and had a 24-h NIHSS score available. Similar to previous studies, we defined MNI as a reduction in NIHSS score by ≥8 points, or a score of 0 or 1 at 24 h. Demographics, risk factors, time to treatment, and clinical and laboratory data, were compared between MNI present or absent. Baseline predictors were compared using t- and Fisher's exact tests, and outcomes using multivariate logistic regression analysis.

RESULTS

Out of 316 patients, 306 had 24-h NIHSS scores and 38% of them experienced MNI. Patients with MNI were less likely to be older than 80 years (16% vs. 29%, p = 0.008) and to have atrial fibrillation (9% vs. 24%, p = 0.001) compared to those without; we found no other predictors of MNI. After adjusting for baseline demographics and risk factors, age less than 80 years (OR = 1.9, 95% CI 1.1-3.6) and absence of atrial fibrillation (OR = 3.0, 95% CI: 1.4-6.2) predicted MNI.

CONCLUSION

Major neurological improvement within 24 h after thrombolysis is more likely in younger patients and those without atrial fibrillation.

Incidence, causes and predictors of neurological deterioration occurring within 24 h following acute ischaemic stroke: a systematic review with pathophysiological implications

Early neurological deterioration (END) following ischaemic stroke is a serious event with manageable causes in only a fraction of patients. The incidence, causes and predictors of END occurring within 24 h of acute ischaemic stroke (END24) have not been systematically reviewed. We systematically reviewed Medline and Embase from January 1990 to April 2013 for all studies on END24 following acute ischaemic stroke (<8 h from onset). We recorded the incidence and presumed causes of and factors associated with END24. Thirty-six studies were included. Depending on the definition used, the incidence of END24 markedly varied among studies. Using the most widely used change in National Institutes of Health Stroke Scale ≥4 definition, the pooled incidence was 13.8% following thrombolysis, ascribed to intracranial haemorrhage and malignant oedema each in ∼20% of these. As other mechanisms were rarely reported, in the majority no clear cause was identified. Few data on END24 occurring in non-thrombolysed patients were available. Across thrombolysed and non-thrombolysed samples, the strongest and most consistent admission predictors were hyperglycaemia, no prior aspirin use, prior transient ischaemic attacks, proximal arterial occlusion and presence of early CT changes, and the most consistent 24 h follow-up associated factors were no recanalisation/reocclusion, large infarcts and intracranial haemorrhage. Finally, END24 was strongly predictive of poor outcome. The above findings are discussed with emphasis on END without a clear mechanism. Data on incidence and predictors of the latter subtype is scarce, and future studies using systematic imaging protocols should address its underlying pathophysiology. This may in turn lead to rational preventative and therapeutic measures for this ominous event.

Reperfusion therapies of acute ischemic stroke: potentials and failures

Over the past 20 years, clinical research has focused on the development of reperfusion therapies for acute ischemic stroke (AIS), which include the use of systemic intravenous thrombolytics (alteplase, desmoteplase, or tenecteplase), the augmentation of systemic intravenous recanalization with ultrasound, the bridging of intravenous with intra-arterial thrombolysis, the use of multi-modal approaches to reperfusion including thrombectomy and thromboaspiration with different available retrievers. Clinical trials testing these acute reperfusion therapies provided novel insight regarding the comparative safety and efficacy, but also raised new questions and further uncertainty on the field. Intravenous alteplase (tPA) remains the fastest and easiest way to initiate acute stroke reperfusion treatment, and should continue to be the first-line treatment for patients with AIS within 4.5 h from onset. The use of tenecteplase instead of tPA and the augmentation of systemic thrombolysis with ultrasound are both novel therapeutical modalities that may emerge as significant options in AIS treatment. Endovascular treatments for AIS are rapidly evolving due to technological advances in catheter-based interventions and are currently emphasizing speed in order to result in timely restoration of perfusion of still-salvageable, infarcted brain tissue, since delayed recanalization of proximal intracranial occlusions has not been associated with improved clinical outcomes. Comprehensive imaging protocols in AIS may enable better patient selection for endovascular interventions and for testing multi-modal combinatory strategies.

Tissue plasminogen activator-based clot busting: Controlled delivery approaches

Cardiovascular diseases are the leading cause of death worldwide. Thrombosis, the formation of blood clot (thrombus) in the circulatory system obstructing the blood flow, is one of the main causes behind various ischemic arterial syndromes such as ischemic stroke and myocardial infarction, as well as vein syndromes such as deep vein thrombosis, and consequently, pulmonary emboli. Several thrombolytic agents have been developed for treating thrombosis, the most common being tissue plasminogen activator (tPA), administrated systemically or locally via IV infusion directly proximal to the thrombus, with the aim of restoring and improving the blood flow. TPA triggers the dissolution of thrombi by inducing the conversion of plasminogen to protease plasmin followed by fibrin digestion that eventually leads to clot lysis. Although tPA provides powerful thrombolytic activity, it has many shortcomings, including poor pharmacokinetic profiles, impairment of the reestablishment of normal coronary flow, and impairment of hemostasis, leading to life-threatening bleeding consequences. The bleeding consequence is ascribed to the ability of tPA to circulate throughout the body and therefore can lysis all blood clots in the circulation system, even the good ones that prevent the bleeding and promote injury repair. This review provides an overview of the different delivery approaches for tPA including: liposomes, ultrasound-triggered thrombolysis, anti-fibrin antibody-targeted tPA, camouflaged-tPA, tpA-loaded microcarriers, and nano-modulated delivery approaches.

Determinants of early outcomes in patients with acute ischemic stroke and proximal artery occlusion

BACKGROUND

Proximal artery occlusions (PAO) recanalize in only a small percentage of acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (IV tPA) alone, yet the benefits of adjunctive or substitutive intra-arterial therapy (IAT) in this patient subgroup are not well established. We evaluated early poststroke outcomes in a cohort of AIS patients with PAO categorized as "likely to benefit" (LTB) from IAT using prespecified criteria.

METHODS

Using a prespecified protocol, 193 patients from our institutional stroke database admitted between January 1, 2007, and December 31, 2011, were prospectively deemed LTB from IAT. Logistic regression was used to determine independent predictors of favorable (discharge to home or acute rehabilitation) versus unfavorable (discharge to skilled nursing facility, hospice, or in-hospital mortality) outcome.

RESULTS

Of the patients included, 29.5% received IV tPA only, 11.4% underwent IAT only, and 37.8% had both. Overall in-hospital mortality was 19.2%. In a univariate analysis, age (odds ratio [OR], .95; 95% confidence interval [CI], .93-.98), IV tPA (OR, 2.3; 95% CI, 1.2-4.3), and history of atrial fibrillation (OR, .5; 95% CI, .28-.97) were associated with outcome. Effect of IAT was not statistically significant (OR, 1.3; 95% CI, .7-2.3; P = .4). In multivariate analysis, the only independent predictor of favorable outcome was IV tPA administration (OR, 2.4; 95% CI, 1.2-5.0). The odds of favorable poststroke outcome were significantly lowered (OR, .3; 95% CI, .1-.6; P = .0006) in those receiving neither IV tPA nor IAT.

CONCLUSIONS

In AIS patients with PAO thought most likely to benefit from IAT, IV tPA independently predicted favorable outcomes. These data reinforce the recommendation to provide early IV tPA to all eligible patients.

Computed tomographic angiography and cerebral blood volume can predict final infarct volume and outcome after recanalization

BACKGROUND AND PURPOSE

Recanalization rates are higher in acute anterior stroke treated with stent-retrievers when compared with older techniques. However, some still have sizeable infarcts and poor outcome. This may be related to underestimation of core infarct on nonenhanced computed tomography (NECT). CT angiography (CTA) source images (CTASI) and CT perfusion may be more informative. We hypothesize that core infarct estimation with NECT, CTA, and CT perfusion predicts infarct at 24 hours and outcome after fast recanalization.

METHODS

Consecutive good recanalization patients with proximal anterior circulation stroke were evaluated. We assessed Alberta Stroke Program Early CT Score (ASPECTs) on NECT for subtle early infarct, hypodensity, loss of gray-white (CTASI), and low cerebral blood volume (CBV; CT perfusion). Sensitivity and specificity for predicting infarct by region were calculated.

RESULTS

Of 46 patients, 36 (78%) had successful thrombectomy. Median ASPECTS was 10 for NECT early infarct and frank hypodensity; for CBV, CTASI-ASPECTS was 8. CTASI had the highest sensitivity of 71% and specificity of 82% for 24 hours NECT infarct. There was moderate correlation and concordance between CBV/24-hour NECT (Rp=0.51; Rc=0.50) and CTASI/24-hour NECT (Rp=0.54 and Rc=0.53). Thirty-four patients (74%) had good outcomes. Median ASPECTS was higher on CTASI (8 versus 5; P=0.04) and CBV (9 versus 5; P=0.03) for patients with good versus bad outcome. There were better outcomes with increasing CTASI-ASPECTS (P=0.004) and CBV-ASPECTS (P=0.02).

CONCLUSIONS

CTASI and CBV were better at predicting 24-hour infarct and outcome than NECT. Appropriate advanced imaged guided selection may improve outcomes in large-vessel stroke treated with the newest techniques.

Dramatic recovery after IV thrombolysis in anterior circulation ischemic stroke: predictive factors and prognosis

BACKGROUND AND PURPOSE

Dramatic recovery (DR) after thrombolysis is dependent of vessel recanalization and is predictive of favorable clinical outcome. Successful recanalization is not equivalent to DR. Our objective was to assess its frequency and evaluate clinical and biochemical predictors and their prognosis.

METHODS

We analyzed prospectively registered data from January 2007 to September 2012. All patients with anterior circulation stroke and NIHSS≥10 were included. Improvement of ≥10 or a score ≤3 24h after thrombolysis was defined as DR.

RESULTS

In the 230 patients included, DR frequency was 23% (53 patients). DR group had lower admission NIHSS (14 vs 17, p=0.024), less total anterior circulation infarcts (p=0.009), more partial anterior circulation infarcts (p=0.003) and lower blood glucose on admission (118 vs 128mg/dL, p=0.013). All patients with DR had an Alberta Stroke Program Early CT Score (ASPECTS) ≥7, vs 89.3% without DR (p=0.013). Arterial recanalization, defined as hyperdense middle cerebral artery sign disappearance on control CT, was more frequent in the DR group (68.4% vs 14.1%, p<0.001). Intracranial hemorrhage on 24h-control CT scan was less frequent in the DR group (p<0.001). Multinomial logistic regression analysis showed that ASPECTS score was an independent predictor of DR (OR=2.35, 95%CI=1.32-4.16, p=0.003) and CT evidence of recanalization was independently associated with DR (OR=11.60, 95%CI, 3.02-44.53, p<0.001).

CONCLUSION

DR is a frequent occurrence. ASPECTS score is an independent predictor of DR, which is also independently associated with CT evidence of middle cerebral artery recanalization.

Body temperature and major neurological improvement in tPA-treated stroke patients

BACKGROUND

Major neurological improvement (MNI) at 24 hours represents a marker of early recanalization in ischaemic stroke. Although low body temperature is considered neuroprotective in cerebral ischaemia, some studies have suggested that higher body temperature may promote clot lysis in the acute phase of ischaemic stroke. We hypothesized that higher body temperature was associated with MNI in severe stroke patients treated with tPA, suggesting a beneficial effect of higher body temperature on clot lysis and recanalization.

METHODS

Patients with ischaemic stroke or transient ischaemic attack (TIA) treated with tPA between February 2006 and August 2012 were prospectively included and retrospectively analysed. Body temperature was measured upon admission. MNI was defined by a ≥8 point improvement in NIHSS score at 24 hours as compared to NIHSS score on admission. No significant improvement (no-MNI) was defined by either an increase in NIHSS score or a decrease of ≤2 points at 24 hours in patients with an admission NIHSS score of ≥8.

RESULTS

Of the 2351 patients admitted with ischaemic stroke or TIA, 347 patients (14.8%) were treated with tPA. A total of 32 patients (9.2%) had MNI and 56 patients (16.1%) had no-MNI. Patients with MNI had higher body temperatures compared with patients with no-MNI (36.7°C vs 36.3°C, P = 0.004). Higher body temperature was independently associated with MNI when adjusted for confounders (OR 5.16, P = 0.003).

CONCLUSION

Higher body temperature was independently associated with MNI in severe ischaemic stroke patients treated with tPA. This may suggest a beneficial effect of higher body temperature on clot lysis and recanalization.

Advances in revascularization for acute ischemic stroke treatment

Intravenous thrombolysis with recombinant tissue plasminogen activator is the established treatment for acute ischemic stroke patients presenting within 3 h after stroke onset. In a significant number of patients, however, intravenous thrombolysis with recombinant tissue plasminogen activator remains ineffective. New thrombolytic agents, such as reteplase, tenecteplase or desmoteplase, offer pharmacokinetic and dynamic advantages over recombinant tissue plasminogen activator and have been or are currently being tested for safety and efficacy in clinical trials. Endovascular revascularization is an evolving treatment option enabling mechanical clot disruption or extraction in combination with thrombolysis. Several new endovascular devices have been successfully tested for safety in acute ischemic stroke patients and are now being tested for efficacy in larger clinical trials. Continued innovation and refinement of endovascular technology and techniques is expected to increase technical success with a minimal procedure-related morbidity in the treatment of acute ischemic stroke.

Advances and challenges in treatment and prevention of ischemic stroke

We review recent advances in the treatment and prevention of acute ischemic stroke, including the current state of endovascular therapy, in light of 5 randomized controlled trials published this past year. Although no benefit of endovascular therapy over intravenous (IV) recombinant tissue plasminogen activator (rt-PA) has been demonstrated, endovascular therapy is an appropriate treatment for acute ischemic stroke patients within the t-PA window who are ineligible for IV t-PA but have a large vascular occlusion. These trials reveal promises and current limitations of endovascular therapy, and comparison of reperfusion therapies remains an important area of research. One common theme is the strong association between a faster time to reperfusion, improved outcome, and reduced mortality. Primary and secondary stroke prevention trials emphasize the importance of aggressive management of medical risk factors as part of any preventative strategy. New oral anticoagulants, for example, offer cost-effective risk reduction in patients with atrial fibrillation, and may represent an opportunity for those with cryptogenic stroke. We highlight areas of unmet need and promising research in stroke, including the need to deliver proven therapies to more patients, and the need to recruit patients into clinical trials that better define the role of endovascular and other stroke therapies. Finally, improvement in strategies to recover speech, cognition, and motor function has the potential to benefit far more stroke patients than any acute stroke therapy, and represents the greatest opportunity for research in the coming century.

The exact science of stroke thrombolysis and the quiet art of patient selection

The science of metric-based patient stratification for intravenous thrombolysis, revolutionized by the landmark National Institute of Neurological Disorders and Stroke trial, has transformed acute ischaemic stroke therapy. Recanalization of an occluded artery produces tissue reperfusion that unequivocally improves outcome and function in patients with acute ischaemic stroke. Recanalization can be achieved mainly through intravenous thrombolysis, but other methods such as intra-arterial thrombolysis or mechanical thrombectomy can also be employed. Strict guidelines preclude many patients from being treated by intravenous thrombolysis due to the associated risks. The quiet art of informed patient selection by careful assessment of patient baseline factors and brain imaging could increase the number of eligible patients receiving intravenous thrombolysis. Outside of the existing eligibility criteria, patients may fall into therapeutic 'grey areas' and should be evaluated on a case by case basis. Important factors to consider include time of onset, age, and baseline blood glucose, blood pressure, stroke severity (as measured by National Institutes of Health Stroke Scale) and computer tomography changes (as measured by Alberta Stroke Programme Early Computed Tomography Score). Patients with traditional contraindications such as wake-up stroke, malignancy or dementia may have the potential to receive benefit from intravenous thrombolysis if they have favourable predictors of outcome from both clinical and imaging criteria. A proportion of patients experience complications or do not respond to intravenous thrombolysis. In these patients, other endovascular therapies or a combination of both may be used to provide benefit. Although an evidence-based approach to intravenous thrombolysis for acute ischaemic stroke is pivotal, it is imperative to examine those who might benefit outside of protocol-driven practice.

Early and continuous neurologic improvements after intravenous thrombolysis are strong predictors of favorable long-term outcomes in acute ischemic stroke

BACKGROUND

Intravenously administered tissue plasminogen activator (IV tPA) remains the only approved therapeutic agent for arterial recanalization in acute ischemic stroke (AIS). Considerable proportion of AIS patients demonstrate changes in their neurologic status within the first 24 hours of intravenous thrombolysis with IV tPA. However, there are little available data on the course of clinical recovery in subacute 2- to 24-hour window and its impact. We evaluated whether neurologic improvement at 2 and 24 hours after IV tPA bolus can predict functional outcomes in AIS patients at 3 months.

METHODS

Data for consecutive AIS patients treated with IV tPA within 4.5 hours of symptom onset during 2007-2011 were prospectively entered in our thrombolyzed registry. National Institutes of Health Stroke Scale (NIHSS) scores were recorded before IV tPA bolus, at 2 and 24 hours. Early neurologic improvement (ENI) at 2 hours was defined as a reduction in NIHSS score by 10 or more points from baseline or an absolute score of 4 or less points at 2 hours. Continuous neurologic improvement (CNI) was defined as a reduction of NIHSS score by 8 or more points between 2 and 24 hours or an absolute score of 4 or less points at 24 hours. Favorable functional outcomes at 3 months were determined by modified Rankin Scale (mRS) score of 0-1.

RESULTS

Of 2460 AIS patients admitted during the study period, 263 (10.7%) received IV tPA within the time window; median age was 64 years (range 19-92), with 63.9% being men, a median NIHSS score of 17 points (range 5-35), and a median onset-to-treatment time of 145 minutes (range 57-270). Overall, 130 (49.4%) thrombolyzed patients achieved an mRS score of 0-1 at 3 months. The female gender, age, and baseline NIHSS score were found to be significantly associated with CNI on univariate analysis. On multivariate analysis, NIHSS score at onset and female gender (odds ratio [OR]: 2.218, 95% confidence interval [CI]: 1.140-4.285; P=.024) were found to be independent predictors of CNI. Factors associated with favorable outcomes at 3 months on univariate analysis were younger age, female gender, hypertension, NIHSS score at onset, recanalization on transcranial Doppler (TCD) monitoring or repeat computed tomography (CT) angiography, ENI at 2 hours, and CNI. On multivariate analysis, NIHSS score at onset (OR per 1-point increase: .835, 95% CI: .751-.929, P<.001), 2-hour TCD recanalization (OR: 3.048, 95% CI: 1.537-6.046; P=.001), 24-hour CT angiographic recanalization (OR: 4.329, 95% CI: 2.382-9.974; P=.001), ENI at 2 hours (OR: 2.536, 95% CI: 1.321-5.102; P=.004), and CNI (OR: 7.253, 95% CI: 3.682-15.115; P<.001) were independent predictors of favorable outcomes at 3 months.

CONCLUSIONS

Women are twice as likely to have CNI from the 2- to 24-hour period after IV tPA. ENI and CNI within the first 24 hours are strong predictors of favorable functional outcomes in thrombolyzed AIS patients.

Monitoring of brain tissue perfusion utilizing a transducer holder for transcranial color duplex sonography

OBJECTIVE

We have improved a transducer holder for transcranial color duplex sonography (TCDS) monitoring via both the temporal and foraminal windows (TW/FW). The objective is to clarify the clinical usefulness of and identify problems with TCDS monitoring in the evaluation of brain tissue perfusion.

METHODS

Brain tissue perfusion was monitored in 11 patients (ages 31-94, mean 66). After an intravenous bolus, power modulation imaging (PMI) in all cases and second harmonic imaging (SHI) in two cases were evaluated at the diencephalic horizontal plain via bilateral (6 cases) and unilateral (5 cases) TWs. After a transducer was installed into the holder, acetazolamide (ACZ) cerebral vasoreactivity utilizing PMI was evaluated in ten cases.

RESULTS

PMI proved superior to SHI in the quantitative evaluation of the bilateral hemispheres via the unilateral TWs. Brain tissue perfusion could be precisely quantified before/after ACZ in the same regions of interest (ROI). All patients could be monitored continuously by one examiner. Fixed-probe shifts during monitoring were easily readjustable. Owing to re-fixation for contra-lateral TW monitoring, it was not possible to evaluate precisely in the same ROIs.

CONCLUSION

TCDS monitoring succeeds in continuously and quantitatively evaluating precise and reproducible intracranial hemodynamics in the brain tissue.

Advances in transcranial Doppler clinical applications

IMPORTANCE OF THE FIELD

Diagnostic neurosonology techniques including transcranial Doppler (TCD), transcranial color Doppler imaging (TCDI) and power motion-mode (PMD) TCD provide information about various aspects of cerebrovascular status such as microemboli detection, dynamic autoregulation and long-duration real-time monitoring of flow characteristics. Although most of the information provided cannot be obtained by any other imaging methodology, and is critical in clinical decision-making in the care of various neurovascular diseases, these modalities are widely underutilized. Increasing the familiarity to neurosonological techniques is of crucial importance.

AREAS COVERED IN THIS REVIEW

After briefly reviewing TCD, TCDI and PMD techniques, classical features are summarized and recent developments in the clinical neurosonology applications with specific interest in the neurovascular disorders.

WHAT THE READER WILL GAIN

Practical perspectives of ultrasound evaluation of intracranial arterial status in various neurovascular diseases including sickle cell vasculopathy and vasospasm are reviewed in detail. Pearls on the neurosonological monitoring of acute ischemic stroke and increased intracranial pressure increase is provided. Standards of cerebral microembolism detection, right to left shunts diagnosis and cerebral autoregulation assessment are discussed methodologically. Future perspectives of therapeutic neurosonology including sonothrombolysis, microbubble-ultrasound-mediated gene and drug delivery into the brain, and alteration of the brain-blood barrier permeability are summarized.

TAKE HOME MESSAGE

Suitable with future medicine, neurosonology brings imaging to the bedside, which enables the treating physician to monitor a given intervention in real time. A non-invasive neurosonology-guided treatment of various diseases could be possible in the near future. The first and foremost step in gaining mastery in this very fruitful field is beginning to use it.

Impact of diffusion-weighted imaging lesion volume on the success of endovascular reperfusion therapy

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) lesion volume is associated with poor outcome after thrombolysis, and it is unclear whether endovascular therapies are beneficial for large DWI lesion. Our aim was to assess the impact of pretreatment DWI lesion volume on outcomes after endovascular therapy, with a special emphasis on patients with complete recanalization.

METHODS

We analyzed data collected between April 2007 and November 2011 in a prospective clinical registry. All acute ischemic stroke patients with complete occlusion of internal carotid artery or middle cerebral artery treated by endovascular therapy were included. DWI lesion volumes were measured by the RAPID software. Favorable outcome was defined by modified Rankin Scale of 0 to 2 at 90 days.

RESULTS

A total of 139 acute ischemic stroke patients were included. Median DWI lesion volume was 14 cc (interquartile range, 5-43) after a median onset time to imaging of 110 minutes (interquartile range, 77-178). Higher volume was associated with less favorable outcome (adjusted odds ratio, 0.55; 95% confidence interval, 0.31-0.96). A complete recanalization was achieved in 65 (47%) patients after a median onset time of 238 minutes (interquartile range, 206-285). After adjustment for volume, complete recanalization was associated with more favorable outcome (adjusted odds ratio, 6.32; 95% confidence interval, 2.90-13.78). After stratification of volume by tertiles, complete recanalization was similarly associated with favorable outcome in the upper 2 tertiles (P<0.005).

CONCLUSIONS

Our results emphasize the importance of initial DWI volume and recanalization on clinical outcome after endovascular treatment. Large DWI lesions may still benefit from recanalization in selected patients.

Mechanically assisted intra-arterial thrombolysis in acute cerebral infarction

The aim of this study was to assess the clinical efficacy and safety of mechanically assisted thrombolysis in the treatment of acute cerebral infarction. Mechanically assisted intra-arterial urokinase thrombolysis was conducted on 28 patients with acute cerebral infarction with a disease onset time of 90–450 min. The maximum level of urokinase was 1,150,000 units. Thrombus disruption with a microwire, retrieval with a microcatheter and stent-assisted revascularization were performed. The recanalization rate, bleeding complications and modified Rankin scale (mRS) score were observed within 3 months of surgery. Our results showed that mechanically assisted thrombolysis was successfully conducted on 23 patients, with a recanalization rate of 82.1% (23/28), average recanalization time of 65.22 min and mRS score ≤3.5. Five cases of recanalization were invalid, including 2 cases of mortality, 1 case with an mRS score of 4 and 2 cases with an mRS score ≤3. In the recanalization group, the mechanically assisted thrombolysis did not increase the number of bleeding complications. Our study demonstrated that the safety of mechanically assisted thrombolysis for the treatment of acute cerebral infarction is equivalent to that of simple intra-arterial thrombolysis, but that the former has a higher efficiency. Mechanically assisted thrombolysis is able to reduce the urokinase dosage and recanalization time, and increase the recanalization rate.

Development of endovascular vibrating polymer actuator probe for mechanical thrombolysis: in vivo study

In this study, we propose a new method for the enhancement of intraarterial thrombolysis by use of an endovascular vibrating polymer actuator probe (VPAP), which is fabricated from an ionic polymer metal composite (IPMC) actuator. The endovascular VPAP was fabricated by combining 0.8 × 0.8 × 10 mm3 IPMC samples, 0.22 mm × 50 cm copper wires, and 40 cm of Teflon tube. The purpose of this study was to evaluate the thrombolysis efficiency of an endovascular VPAP in a dog model. Both renal arteries of the enrolled dogs (n = 5) were used in the current study. A distal portion of the renal artery in a mongrel dog was occluded by a blood clot from autologous venous whole blood. Intraarterial thrombolysis was performed by use of a VPAP without the actuation force (control group), by a VPAP-only (VPAP-only group), or with a combination of recombinant tissue plasminogen activator (rtPA) and a VPAP (VPAP + rtPA group). The thrombolysis efficiency was evaluated by the modified Thrombolysis in Myocardial Infarction (TIMI) grading system based on the consensus between two radiologists. The grading scales were compared according to each intraarterial thrombolysis method. The VPAP + rtPA and VPAP-only groups showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP-only group also showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP+ rtPA group showed a significantly higher thrombolysis efficiency than did the VPAP-only group (p < 0.05). The use of an endovascular VPAP was a feasible and useful method for intraarterial thrombolysis, and it enhanced the thrombolysis efficiency when combined with the thrombolytic agent rtPA.

Ancillary approaches to plasminogen activators

Acute ischemic stroke develops from an interruption in focal cerebral blood flow. In many cases, it is caused by an acute thromboembolism. Although systemic fibrinolytic therapy for acute ischemic stroke has been a significant breakthrough in the management of this disease, additional agents and methods that could improve or restore cerebral flow are necessary. Similarly to findings in acute myocardial infarction, combination pharmacotherapy has the potential to improve current thrombolytic treatment in acute ischemic stroke. In recent years, research efforts were directed toward various combination therapy with pharmacological and nonpharmacological methods. Several trials tested tissue plasminogen activator (t-PA) in combination with antiplateletes and anticoagulants. Combination of t-PA with nonpharmacological agents included sonothrombolysis (amplifying the thrombolytic effect), laser (neuro-recovery), hypothermia (cytoprotection and decreasing brain swelling), and blood flow augmentation (increasing residual flow and recruitment of collateral vessels). This paper will review ongoing clinical trials and safety of these promising combinatory treatments.

Safety and efficacy of sonothrombolysis using bilateral TCD monitoring by diagnostic 2 MHz probes - a pilot study

INTRODUCTION

Sonothrombolysis is a new treatment method for patients with acute ischemic stroke (IS). Various ultrasound frequencies and intensities are being tested these days. The aim of this pilot study was to assess the safety and efficacy of sonothrombolysis using 2 diagnostic probes and bilateral monitoring in patients with acute occlusion of the middle cerebral artery (MCA).

PATIENTS AND METHODS

Twelve consecutive IS patients (7 males; age 47 - 78, average 64.1 ± 9.4 years) with acute MCA occlusion and contraindication of thrombolysis were included in the study. 60-min bilateral 2-MHz pulsed-wave Doppler monitoring of the area of occlusion was performed in all patients (Group 1). The control group consisted of 37 IS patients (20 males; age 32 - 78, average 62.2 ± 12.1 years) treated with standard sonothrombolysis and selected from the Thrombotripsy Study database (Group 2). The differences in number of recanalized arteries after a 1 h treatment, independent patients (modified Rankin scale [mRS] value of 0 - 2) after 90 days and symptomatic intracerebral hemorrhages (SICH) were statistically evaluated.

RESULTS

Complete recanalization was found in 4 (30.0%) Group 1 and in 12 (32.4%) Group 2 patients. Seven (58.3%) Group 1 and 22 (59.5%) Group 2 patients were independent after 90 days. SICH was found in none of Group 1 patients and in 1 (2.7%) of the Group 2 patients (P>0.05 in all cases).

CONCLUSION

In this pilot study, sonothrombolysis using 2 probes and bilateral monitoring is safe but not more effective than standard sonothrombolysis in acute IS patients with MCA occlusion.

Changes in middle cerebral artery blood flow velocity during sonolysis using a diagnostic transcranial probe with a 2-MHz Doppler frequency in healthy volunteers

OBJECTIVES

Ultrasound has various biological effects in the human body. The effects of continuous monitoring with ultrasound (sonolysis) on vasodilatation of the radial artery were described recently. We wanted to ascertain whether similar changes in the blood flow velocity during sonolysis could also be detected in the middle cerebral artery.

METHODS

Fifteen healthy volunteers (6 male and 9 female; age range, 23-68 years; mean ± SD, 47.1 ± 15.1 years) were subjected to 1 hour of middle cerebral artery sonolysis using a diagnostic transcranial probe with a 2-MHz Doppler frequency and measurement of the blood flow velocity at 2-minute intervals. During a second session, a flow curve was recorded for 10 seconds at 2-minute intervals. The peak systolic velocity, end-diastolic velocity, mean flow velocity, pulsatility index, and resistive index were recorded during both measurements.

RESULTS

Irregular changes in the measured blood flow parameters were recorded during both sessions. Changes in particular hemodynamic parameters during both measurements were similar. The changes in the peak systolic velocity, end-diastolic velocity, mean flow velocity, pulsatility index, and resistive index were not significantly different between the two measurements (P < .05 in all cases).

CONCLUSIONS

As opposed to sonolysis of the radial artery, sonolysis of the middle cerebral artery using a diagnostic 2-MHz frequency in healthy volunteers did not lead to changes in the flow curve or peripheral vasodilatation.

Recanalization of large intracranial vessels using the penumbra system: a single-center experience

BACKGROUND AND PURPOSE

The PS is an innovative mechanical device designed to recanalize large-vessel occlusions by thrombus aspiration. The purpose of this study was to evaluate the effectiveness and neurologic outcome of patients treated with the PS in the setting of acute ischemic stroke.

MATERIALS AND METHODS

A total of 91 patients with acute ischemic stroke due to large-vessel occlusion were treated with the PS and were included in our retrospective study. In 14 patients, only the PS was used for treatment; in 77 patients, mechanical recanalization was combined with IA and/or IV thrombolysis. Outcome was measured by using the mRS; recanalization was assessed with the TICI score.

RESULTS

Mean patient age was 62 ± 19.4 years; the average NIHSS score at hospital admission was 17. Successful recanalization was achieved in 77% of patients. Median time from arterial puncture to recanalization was 49 minutes (quartiles, 31-86 minutes). At follow-up, 36% of the patients showed an NIHSS improvement of ≥10%, and 34% of the patients with an anterior circulation occlusion had an mRS score of ≤2, whereas only 7% of the patients with a posterior occlusion had a favorable outcome at follow-up. In total, 20 patients died during hospitalization; none of these deaths were device-related.

CONCLUSIONS

In this study, the PS was an effective device for mechanical recanalization. Successful recanalization with the PS was associated with significant improvement of functional outcome in patients experiencing ischemic stroke secondary to anterior circulation occlusions.

Dramatic recovery in acute ischemic stroke is associated with arterial recanalization grade and speed

BACKGROUND AND PURPOSE

Dramatic recovery (DR) is a predictor of stroke outcome among others. However, after successful recanalization, systematic favorable outcome is not the rule. We sought to analyze the impact of recanalization on DR in patients with acute ischemic stroke eligible for any revascularization strategies (either intravenous or endovascular).

METHODS

We analyzed data collected between April 2007 and May 2011 in our prospective clinical registry. All patients with acute ischemic stroke with National Institutes of Health Stroke Scale≥10 at admission and an identification of arterial status before treatment were included. DR was defined as National Institutes of Health Stroke Scale≤3 at 24 hours or a decrease of ≥10 points within 24 hours.

RESULTS

DR occurred in 75 of 255 patients with acute ischemic stroke (29.4%). Patients with persistent occlusion had a low DR rate (11.1%) than those with no documented occlusion (36.5%) and those with occlusion followed by recanalization (35.3%; both P<0.001). Among patients with recanalization monitored by angiography, DR was higher among patients with complete recanalization than among those with partial recanalization (46.8% versus 14.3%; P<0.001) and increased with tertiles of time to recanalization (Ptrend=0.002). In multivariable logistic regression analysis, grade and time to recanalization appeared independently associated with DR; the adjusted ORs were 4.17 (95% CI, 1.61-10.77) for complete recanalization and 1.24 (95% CI, 1.04-1.48) for each 30-minute time decrease. Patients with versus without DR more frequently had modified Rankin Scale≤1 (67.6% versus 9.0%; P<0.001) and less frequently had hemorrhage (17.3% versus 33.9%; P=0.024).

CONCLUSIONS

DR is strongly associated with favorable clinical outcome and is dependent on complete recanalization and time to recanalization.

Trevo versus solitaire a head-to-head comparison between two heavy weights of clot retrieval

BACKGROUND AND PURPOSE

Recent reports have indicated that mechanical thrombectomy may have potential to treat acute ischemic stroke. However, few comparative studies of neurothrombectomy devices are reported. This study aims to compare the safety and effectiveness of two retrievable stent systems in acute ischemic stroke patients.

METHODS

A prospective study comparing the clinical, radiological, and functional outcome of 33 patients with an angiographically verified occlusion of the anterior cerebral circulation. Patients were treated either with Trevo Retriever(TM) or Solitaire Stent(TM) according to the neurointerventionalist preference. Successful recanalization was defined as TICI grade 2a to 3. Good outcome was defined as a modified Rankin Scale score ≤ 2 at 3 months.

RESULTS

Revascularization was achieved in 10 patients (77%) in the Trevo group and in 12 (60%) of the Solitaire group (P = .456). Rate of symptomatic ICH was 0% for Trevo versus 15% for Solitaire (P = .261). Four patients (30%) died during the 3-month follow-up period in the Trevo versus 5 patients (25%) in the solitaire group (P = 1.000). Rate of good outcome was 38% and 40% for Trevo and Solitaire respectively (P = .435).

CONCLUSIONS

Our study showed no significant differences between both stentrievers. Moderately high recanalization rates are possible with both, however larger series may depict safety-related variations.

Sonothrombolysis for acute ischemic stroke: a systematic review of randomized controlled trials

OBJECT

Sonothrombolysis has recently been considered an emerging modality for the treatment of stroke. The purpose of the present paper was to review randomized clinical studies concerning the effects of sonothrombolysis associated with tissue plasminogen activator (tPA) on acute ischemic stroke.

METHODS

Systematic searches for literature published between January 1996 and July 2011 were performed for studies regarding sonothrombolysis combined with tPA for acute ischemic stroke. Only randomized controlled trials were included. Data extraction was based on ultrasound variables, patient characteristics, and outcome variables (rate of intracranial hemorrhages and arterial recanalization).

RESULTS

Four trials were included in this study; 2 trials evaluated the effect of transcranial Doppler (TCD) ultrasonography on sonothrombolysis, and 2 addressed transcranial color-coded duplex (TCCD) ultrasonography. The frequency of ultrasound waves varied from 1.8 to 2 MHz. The duration of thrombus exposure to ultrasound energy ranged from 60 to 120 minutes. Sample sizes were small, recanalization was evaluated at different time points (60 and 120 minutes), and inclusion criteria were heterogeneous. Sonothrombolysis combined with tPA did not lead to an increase in symptomatic intracranial hemorrhagic complications. Two studies demonstrated that patients treated with ultrasound combined with tPA had statistically significant higher rates of recanalization than patients treated with tPA alone.

CONCLUSIONS

Despite the heterogeneity and the limitations of the reviewed studies, there is evidence that sonothrombolysis associated with tPA is a safe procedure and results in an increased rate of recanalization in the setting of acute ischemic stroke when wave frequencies and energy intensities of diagnostic ultrasound systems are used.

Trevo System: single-center experience with a novel mechanical thrombectomy device

BACKGROUND AND PURPOSE

Recent reports have indicated that mechanical thrombectomy may have the potential to treat acute ischemic stroke. This study aims to describe the safety and effectiveness of Trevo Retriever, using Stentriever technology, in revascularization of patients with acute ischemic stroke.

METHODS

Prospective study evaluating the clinical, radiological, and functional outcome of 13 patients with an angiographically verified occlusion of the anterior cerebral circulation. All patients underwent thrombectomy with TR as monotherapy or in combination with intra-arterial thrombolysis, within the first 8 hours from the onset of symptoms. Successful revascularization was defined as thrombolysis in cerebral ischemia grade 2a to 3. Good outcome was defined as modified Rankin Scale score ≤ 2.

RESULTS

Median baseline National Institutes of Health Stroke Scale score was 19(16-22). The occlusion site was middle cerebral artery in 8 patients and internal carotid artery in 5 patients. Revascularization was achieved in 10 of 13 patients (77%). The mean time from groin puncture to recanalization was 95 ± 31 minutes. No significant intra-procedural complications occurred. Four patients (30%) died during the 90-day follow-up period and 4 patients (30%) achieved functional independence.

CONCLUSION

Early clinical experience suggests that the TR can allow safe and effective revascularization in certain subjects with acute ischemic stroke.

Endovascular management in patients with acute basilar artery obstruction: low-dose intra-arterial urokinase and mechanical clot disruption

Mechanical clot disruption for the treatment of acute basilar artery occlusion (BAO) is known to provide a benefit. We aimed to determine the safety, recanalization rate and time-to-flow restoration of mechanical clot disruption and low dose urokinase (UK) infusions for the treatment of patients with acute BAO. Between June 2006 and June 2010, 21 patients with acute BAO underwent endovascular treatment that included angioplasty or stent placement. The time to treatment, duration of the procedure, dose of urokinase (UK), recanalization rates and symptomatic hemorrhages were analyzed. Clinical outcome measures were assessed at admission and at the time of discharge using the National Institutes of Health Stroke Scale (NIHSS) score and at three months after treatment using the modified Rankin Score (mRS). On admission, the median NIHSS score was 13.2. Median time from symptom onset to arrival at hospital was 356 minutes, and median time from symptom onset to intraarterial thrombolysis (IAT) was 49 minutes. We used the following interventional treatment regimens: Intra-arterial (IA) UK and a minimal mechanical procedure (n=14), IA UK with angioplasty (n=1), IA UK with angioplasty and stent placement (n=3) and IA UK with HyperForm (n=3). The recanalization (thrombolysis in cerebral ischemia grade II or III) rate was 90.5% (19/21). There was symptomatic hemorrhage in one patient (4.8%). The median NIHSS score at discharge was 6.3. The three-month outcome was favorable (mRS: 0-2) for 14 patients (66.7%) and poor (mRS: 3-6) for seven patients (33.3%). The overall mortality at three months was 14.3% (three patients died). Low-dose IAT with mechanical clot disruption is a safe and effective treatment for treatment for acute BAO.

Sonothrombolysis for the treatment of acute stroke: current concepts and future directions

Achieving rapid reperfusion transcranial color-coded duplex is the critical issue in acute stroke treatment. Ultrasound (US) generates negative pressure waves that are associated with an increase in either intrinsic or intravenous tissue plasminogen activator (tPA)-induced fibrinolytic activity. Higher rates of tPA-induced arterial recanalization, associated with a trend towards better functional outcome, have been safely achieved by using high-frequency US. By contrast, the use of low-frequency US and transcranial color-coded duplex has been linked to significant hemorrhagic complications. US-accelerated thrombolysis has been safely enhanced by lowering the amount of energy needed for acoustic cavitation with the administration of microbubbles. Other applications of US are being studied, including its intra-arterial use. Operator-independent devices, which will spread the use of these US techniques further, are also being developed. This article reviews the present status of sonothrombolysis in acute stroke treatment, highlighting both experimental and clinical studies addressing this issue, and discusses its future regarding both efficacy and safety.

Clinical and MRI predictors of no early recanalization within 1 hour after tissue-type plasminogen activator administration

BACKGROUND AND PURPOSE

The aim of the present study was to investigate independent clinical and MRI factors associated with no early recanalization within 1 hour after tissue-type plasminogen activator (tPA) administration.

METHODS

Patients with acute stroke within 3 hours of onset who were treated with tPA were studied prospectively. Patients with internal carotid artery, M1, and M2 occlusion were enrolled, and independent clinical and MRI factors associated with no early recanalization within 1 hour after tPA administration were examined using multivariate logistic regression analysis.

RESULTS

One hundred thirty-two patients (63 men; mean age, 76.4±10.2 years; internal carotid artery occlusion in 37 patients, M1 occlusion in 58, and M2 occlusion in 37) were enrolled. Follow-up MR angiography within 60 minutes after tPA infusion revealed early recanalization in 49 (37.1%) patients (complete in 16 patients, partial in 33) and no recanalization in 83 (62.9%). Using 8 variables (atrial fibrillation, time from stroke onset to treatment ≥140 minutes, use of warfarin, glucose ≥135 mg/dL, large artery diseases, internal carotid artery occlusion, M1 occlusion, and M1 susceptibility vessel sign on T2*) identified on univariate analysis at P<0.2, multivariate logistic regression analysis revealed that M1 susceptibility vessel sign was the only independent factor associated with no early recanalization (OR, 7.157; 95% CI, 1.756 to 29.172; P=0.006). The sensitivity, specificity, positive predictive value, and negative predictive value of M1 susceptibility vessel sign for predicting no early recanalization were 31.3%, 93.9%, 89.7%, and 44.7%, respectively.

CONCLUSIONS

Of clinical and MRI factors before tPA infusion, M1 susceptibility vessel sign on T* is the only independent factor associated with no early recanalization within 1 hour after tPA administration.

Minimally invasive evacuation of spontaneous intracerebral hemorrhage using sonothrombolysis

OBJECT

Catheter-based evacuation is a novel surgical approach for the treatment of brain hemorrhage. The object of this study was to evaluate the safety and efficacy of ultrasound in combination with recombinant tissue plasminogen activator (rt-PA) delivered through a microcatheter directly into spontaneous intraventricular (IVH) or intracerebral (ICH) hemorrhage in humans.

METHODS

Thirty-three patients presenting to the Swedish Medical Center in Seattle, Washington, with ICH and IVH were screened between November 21, 2008, and July 13, 2009, for entry into this study. Entry criteria included the spontaneous onset of intracranial hemorrhage ≥ 25 ml and/or IVH producing ventricular obstruction. Nine patients (6 males and 3 females, with an average age of 63 years [range 38-83 years]) who met the entry criteria consented to participate and were entered into the trial. A ventricular drainage catheter and an ultrasound microcatheter were stereotactically delivered together, directly into the IVH or ICH. Recombinant tissue plasminogen activator and 24 hours of continuous ultrasound were delivered to the clot. Gravity drainage was performed. In patients with IVHs, 3 mg of rt-PA was injected; in patients with intraparenchymal hemorrhages, 0.9 mg of rt-PA was injected. The rt-PA was delivered in 3 doses over 24 hours.

RESULTS

All patients had significant volume reductions in the treated hemorrhage. The mean percentage volume reduction after 24 hours of therapy, as determined on CT and compared with pretreatment stability scans, was 59 ± 5% (mean ± SEM) for ICH and 45.1 ± 13% for IVH (1 patient with ICH was excluded from analysis because of catheter breakage). There were no intracranial infections and no significant episodes of rebleeding according to clinical or CT assessment. One death occurred by 30 days after admission. Clinical improvements as determined by a decrease in the National Institutes of Health Stroke Scale score were demonstrated at 30 days after treatment in 7 of 9 patients. The rate of hemorrhage lysis was compared between 8 patients who completed treatment, and patient cohorts treated for IVH and ICH using identical doses of rt-PA and catheter drainage but without the ultrasound (courtesy of the MISTIE [Minimally Invasive Surgery plus T-PA for Intracerebral Hemorrhage Evacuation] and CLEAR II [Clot Lysis Evaluating Accelerated Resolution of Intraventricular Hemorrhage II] studies). Compared with the MISTIE and CLEAR data, the authors observed a faster rate of lysis during treatment for IVH and ICH in the patients treated with sonolysis plus rt-PA versus rt-PA alone.

CONCLUSIONS

Lysis and drainage of spontaneous ICH and IVH with a reduction in mass effect can be accomplished rapidly and safely through sonothrombolysis using stereotactically delivered drainage and ultrasound catheters via a bur hole. A larger clinical trial with catheters specifically designed for brain blood clot removal is warranted.

Association of Early National Institutes of Health Stroke Scale Improvement With Vessel Recanalization and Functional Outcome After Intravenous Thrombolysis in Ischemic Stroke

Background and Purpose—

Early neurological improvement (ENI) after thrombolytic therapy of acute stroke has been linked with recanalization and favorable outcome, although its definition shows considerable variation. We tested the ability of ENI, as defined in previous publications, to predict vessel recanalization and 3-month functional outcome after intravenous thrombolysis recorded in an extensive patient cohort in the Safe Implementation of Thrombolysis in Stroke–International Stroke Thrombolysis Register (SITS-ISTR).

Methods—

Of 21 534 patients registered between December 2002 and December 2008, 798 patients (3.7%) had CT- or MR angiography-documented baseline vessel occlusion and also angiography data at 22 to 36 hours post-treatment. ENI definitions assessed at 2 hours and 24 hours post-treatment were (1) National Institutes of Health Stroke Scale (NIHSS) score improvement ≥4 points from baseline; (2) NIHSS 0, 1, or improvement ≥8; (3) NIHSS ≤3 or improvement ≥10; (4) improvement by 20%; (5) 40% from baseline; or (6) NIHSS score 0 to 1. Receiver operating curve analysis and multiple logistic regression were performed to evaluate the association of ENI with vessel recanalization and favorable functional outcome (modified Rankin Scale score 0 to 2 at 3 months).

Results—

ENI at 2 hours had fair accuracy to diagnose recanalization as derived from receiver operating curve analysis. Definitions of improvement based on percent of NIHSS score change from baseline demonstrate better accuracy to diagnose recanalization at 2 hours and 24 hours than the definitions based on NIHSS cutoffs (the best performance at 2 hours was area under the curve 0.633, sensitivity 58%, specificity 69%, positive predictive value 68%, and negative predictive value 59% for 20% improvement; and area under the curve 0.692, sensitivity 69%, specificity 70%, positive predictive value 70%, and negative predictive value 62% for 40% improvement at 24 hours). ENI-predicted functional outcome with OR 2.8 to 6.0 independently from recanalization in the angiography cohort (n=695) and with OR of 6.9 to 9.7 in the whole cohort (n=18 181).

Conclusions—

Early 20% neurological improvement at 2 hours was the best predictor of 3-month functional outcome and recanalization after thrombolysis, although fairly accurate, and may serve as a surrogate marker of recanalization if only imaging evaluation of vessel status is not available. If recanalization status is required after intravenous thrombolysis, vascular imaging is recommended despite ENI.

Is the Maximum Dose of 90 mg Alteplase Sufficient for Patients With Ischemic Stroke Weighing >100 kg?

Background and Purpose—

Intravenous alteplase for acute ischemic stroke has a maximum dose limit of 90 mg. Consequently, patients >100 kg body weight receive a lower per-kilogram dose compared with those ≤100 kg. We investigated if the lower per-kilogram dose is associated with poor early neurological improvement and worse outcome after thrombolysis.

Methods—

Of 27 910 patients registered in Safe Implementation of Treatment in Stroke–International Stroke Thrombolysis Register (SITS-ISTR; 2002 to 2009), 1190 (4.3%) weighed >100 kg. Major neurological improvement was used to estimate recanalization (National Institutes of Health Stroke Scale improvement ≥8 points or score of 0 at 24 hours). Outcome measures included symptomatic intracerebral hemorrhage (National Institutes of Health Stroke Scale deterioration ≥4 points within 24 hours and Type 2 parenchymal hemorrhage), functional independence (modified Rankin Scale 0 to 2), and mortality at 3 months.

Results—

Patients >100 kg received a lower per-kilogram alteplase dose (0.82 versus 0.90, P <0.001), were younger (62 versus 70 years, P <0.001), had a lower baseline National Institutes of Health Stroke Scale (10 versus 12, P <0.001), but more frequently had cardiovascular risk factors. Major neurological improvement at 24 hours occurred in 27.7% in both groups. Symptomatic intracerebral hemorrhage occurred in 2.6% versus 1.7% ( P =0.03) in >100 kg versus ≤100 kg. Functional independence was 59.7% versus 53.6% ( P <0.001) and mortality was 14.4% versus 15.1% ( P =0.54). After adjustment for baseline characteristics, there was no significant difference for major neurological improvement or functional independence between >100 kg and ≤100 kg, but >100-kg patients had a higher odds ratio for symptomatic intracerebral hemorrhage (OR, 1.6; 95% CI, 1.06 to 2.41; P =0.02) and mortality (OR, 1.37; 95% CI, 1.08 to 1.74; P =0.01).

Conclusions—

Our results support the current upper dose limit. There was a higher incidence of symptomatic intracerebral hemorrhage in patients >100 kg despite the lower per-kilogram recombinant tissue plasminogen activator dose. Major neurological improvement and functional independence were similar.

Introduction of a new model for time-continuous and non-contact investigations of in-vitro thrombolysis under physiological flow conditions

Background

Thrombolysis is a dynamic and time-dependent process influenced by the haemodynamic conditions. Currently there is no model that allows for time-continuous, non-contact measurements under physiological flow conditions. The aim of this work was to introduce such a model.

Methods

The model is based on a computer-controlled pump providing variable constant or pulsatile flows in a tube system filled with blood substitute. Clots can be fixed in a custom-built clot carrier within the tube system. The pressure decline at the clot carrier is measured as a novel way to measure lysis of the clot. With different experiments the hydrodynamic properties and reliability of the model were analyzed. Finally, the lysis rate of clots generated from human platelet rich plasma (PRP) was measured during a one hour combined application of diagnostic ultrasound (2 MHz, 0.179 W/cm²) and a thrombolytic agent (rt-PA) as it is commonly used for clinical sonothrombolysis treatments.

Results

All hydrodynamic parameters can be adjusted and measured with high accuracy. First experiments with sonothrombolysis demonstrated the feasibility of the model despite low lysis rates.

Conclusions

The model allows to adjust accurately all hydrodynamic parameters affecting thrombolysis under physiological flow conditions and for non-contact, time-continuous measurements. Low lysis rates of first sonothrombolysis experiments are primarily attributable to the high stability of the used PRP-clots.

Sonothrombolysis: an emerging modality for the treatment of acute ischemic and hemorrhagic stroke

To date, it is believed that rapid removal of impedances hindering normal blood circulation in the brain would salvage ischemic tissue. Hence, most treatment modalities undergoing clinical evaluation for treatment of stroke are focused on faster recanalization in acute ischemic stroke or faster hematoma mass reduction in hemorrhagic stroke. Therapeutic ultrasound is among the promising emerging modalities being clinically evaluated to meet this purpose. This review provides an overview of existing clinical data in evaluating sonothrombolysis applications in treatment of acute ischemic and hemorrhagic stroke. Furthermore, the present status of clinical evaluation of microbubbles as a potential adjuvant to this modality is reviewed.

Failure of complete recanalization is associated with poor outcome after cardioembolic stroke

BACKGROUND

  Recanalization is strongly associated with outcomes after thrombolytic treatment. Cardiac emboli are known as better response to fibrinolytic agents because they are fibrin-rich; however, cardioembolic stroke itself is associated with poor outcomes and high mortality. Completeness of recanalization may therefore affect the outcome of cardioembolic stroke. We investigated whether degree of recanalization influences outcomes following fibrinolytic therapy in cardioembolic stroke.

METHODS

  Consecutive stroke patients with relevant artery occlusions on baseline CT angiography who had received thrombolytic treatment were enrolled. Completeness of recanalization was assessed by the Thrombolysis in Myocardial Infarction (TIMI) grade, which was compared between patients with and without cardiac sources of embolism (CSE). We also investigated independent predictors of poor outcome (modified Rankin scale score 3-6) at 3 months.

RESULTS

  Of the 127 patients enrolled, 65 (51%) had one or more CSE. Although the overall recanalization rates (TIMI 2 or 3) in patients with CSE (65%) and patients without CSE (68%) were similar (P=0.710), patients with CSE were less likely to show complete recanalization (TIMI 3) compared with those without CSE (19% vs. 39%, P=0.011). Multivariate analysis revealed that CSE was associated with failure of complete recanalization (OR 2.809, 95% CI 1.097-7.192) and was an independent predictor of poor outcome at 3months (OR 3.629, 95% CI 1.205-8.869).

CONCLUSIONS

  In cardioembolic strokes, failure of complete recanalization following thrombolytic therapy was frequent and was associated with poor outcome after thrombolysis.

Emerging diagnostic and therapeutic molecular imaging applications in vascular disease

Assessment of vascular disease has evolved from mere indirect and direct measurements of luminal stenosis to sophisticated imaging methods to depict millimeter structural changes of the vasculature. In the near future, the emergence of multimodal molecular imaging strategies may enable robust therapeutic and diagnostic ('theragnostic') approaches to vascular diseases that comprehensively consider structural, functional, biological and genomic characteristics of the disease in individualized risk assessment, early diagnosis and delivery of targeted interventions.This review presents a summary of recent preclinical and clinical developments in molecular imaging and theragnostic applications covering diverse atherosclerosis events such as endothelial activation, macrophage inflammatory activity, plaque neovascularization and arterial thrombosis. The main focus is on molecular targets designed for imaging platforms commonly used in clinical medicine including magnetic resonance, computed tomography and positron emission tomography. A special emphasis is given to vascular ultrasound applications, considering the important role this imaging platform plays in the clinical and research practice of the vascular medicine specialty.