Intravenous thrombolysis for acute stroke

The core/penumbra model: implications for acute stroke treatment and patient selection in 2021

Despite major advances in prevention, ischaemic stroke remains one of the leading causes of death and disability worldwide. After centuries of nihilism and decades of failed neuroprotection trials, the discovery, initially in non-human primates and subsequently in man, that ischaemic brain tissue termed the ischaemic penumbra can be salvaged from infarction up to and perhaps beyond 24 h after stroke onset has underpinned the development of highly efficient reperfusion therapies, namely intravenous thrombolysis and endovascular thrombectomy, which have revolutionized the management of the acute stroke patient. Animal experiments have documented that how long the penumbra can survive depends not only on time elapsed since arterial occlusion ('time is brain'), but also on how severely perfusion is reduced. Novel imaging techniques allowing the penumbra and the already irreversibly damaged core in the individual subject to be mapped have documented that the time course of core growth at the expense of the penumbra widely differs from patient to patient, and hence that individual physiology should be considered in addition to time since stroke onset for decision-making. This concept has been implemented to optimize patient selection in pivotal trials of reperfusion therapies beyond 3 h after stroke onset and is now routinely applied in clinical practice, using computed tomography or magnetic resonance imaging. The notion that, in order to be both efficient and harmless, treatment should be tailored to each patient's physiological characteristics represents a radical move towards precision medicine.

Recent advances in stroke management

Major advances in stroke treatment and prevention have, occurred over the last several years. Recent studies have documented that appropriate modification of stroke risk factors can lead to, a substantial reduction in stroke incidence. In addition, a variety of new risk factors, such as elevated plasma homocysteine levels, antiphospholipid antibodies, and specific genetic factors, are being recognized. The most significant advance in acute stroke therapy is the use of intravenous tissue plasminogen activator, (t-PA) for treatment of patients with ischemic stroke within 3 hours of symptom onset. T-PA is currently the only stroke treatment approved by the Federal Drug Administration. There continues to be uncertainty and misunder-standing regarding the risks and benefits of this therapy. A variety of neuroprotective agents have been highly successful for reducing ischemic brain injury in animal stroke models. Recent clinical trials with these agents, however, have not produced beneficial effects in humans. Newer neuroprotective agents with more favorable safety profiles and improvements in clinical trial design may lead to therapeutic successes in the near future. It is apparent that both thrombolytic and neuroprotective treatments for acute stroke must be administered very rapidly, after stroke onset. Therefore, acute stroke teams are being developed to facilitate rapid diagnostic evaluation and treatment of stroke patients.

Discovery of Novel 2-Anilinopyrazolo[1,5-a]pyrimidine Derivatives as c-Src Kinase Inhibitors for the Treatment of Acute Ischemic Stroke

We synthesized a series of novel 2-anilinopyrazolo[1,5-a]pyrimidine derivatives and evaluated their ability to inhibit c-Src kinase; 7-(2-amino-2-methylpropylamino)-5-cyclopropyl-2-(3,5-dimethoxyphenylamino)pyrazolo[1,5-a]pyrimidine-3-carboxamide 7o and 7-(2-amino-2-methylpropylamino)-2-(3,5-dimethoxyphenylamino)-5-methylpyrazolo[1,5-a]pyrimidine-3-carboxamide 7f showed potent inhibitory activity. Compound 7f inhibited c-Src selectively and exhibited satisfactory central nervous system (CNS) penetration. Furthermore, 7f.HCl reduced the infarct volume in vivo in a rat middle cerebral artery (MCA) occlusion model when administrated intraperitoneally.

Microsomal prostaglandin E synthase-1 is a critical factor of stroke-reperfusion injury

Although augmented prostaglandin E(2) (PGE(2)) synthesis and accumulation have been demonstrated in the lesion sites of rodent transient focal ischemia models, the role of PGE(2) in neuronal survival has been controversial, showing both protective and toxic effects. Here we demonstrate the induction of microsomal PGE synthase 1 (mPGES-1), an inducible terminal enzyme for PGE(2) synthesis, in neurons, microglia, and endothelial cells in the cerebral cortex after transient focal ischemia. In mPGES-1 knockout (KO) mice, in which the postischemic PGE(2) production in the cortex was completely absent, the infarction, edema, apoptotic cell death, and caspase-3 activation in the cortex after ischemia were all reduced compared with those in wild-type (WT) mice. Furthermore, the behavioral neurological dysfunctions observed after ischemia in WT mice were significantly ameliorated in KO mice. The ameliorated symptoms observed in KO mice after ischemia were reversed to almost the same severity as WT mice by intracerebroventricular injection of PGE(2) into KO mice. Our observations suggest that mPGES-1 may be a critical determinant of postischemic neurological dysfunctions and a valuable therapeutic target for treatment of human stroke.

Eligibility of stroke units in Poland for administration of intravenous thrombolysis

Systemic thrombolysis treatment was approved in Poland in 2003 and should be performed in specialist stroke units (SU). We performed a survey to determine stroke service preparedness for thrombolysis treatment in Poland. We sent a questionnaire evaluating the neurological departments in Poland, where stroke patients are treated. We divided them into four categories: (i) class A SU (fulfilling criteria of the National Program for Stroke Prevention and Therapy and European Stroke Initiative guidelines), (ii) class B (conditionally fulfilling criteria), (iii) class C (not fulfilling criteria), and (iv) departments without SU. Only class A units are eligible for implementing thrombolysis. We obtained response from 194 of 222 (87.4%) departments; 90 (46.4%) declared having an SU. According to criteria, 20 class A, 56 class B, 14 class C. During one year, 71 208 patients were admitted to hospitals; 69,982 (98.2%) to neurological departments. A total of 10,959 (15.4%) were treated in class A SU, 23,650 (33.2%) in class B, 5153 (7.2%) in class C, whereas 30,220 (42.4%) in neurological departments without SU. Our survey showed that only 15.4% stroke patients in Poland are admitted to high-quality SU, where thrombolysis may potentially be administered. Improvement of SU quality in Poland is necessary for wide implementation of new methods of stroke therapy.

Rt-PA causes a significant increase in endogenous u-PA during experimental focal cerebral ischemia

The aim of this study was to investigate the effects of different doses of exogenous recombinant human tissue plasminogen activator (rt-PA) on the endogenous cerebral plasminogen-plasmin system in focal ischemia in rats. Ischemia was induced using the suture model. Each group of rats (n = 6) received either treatment (0.9, 9 or 18 mg rt-PA/kg body weight) or saline (control group) at the end of ischemia; a sham-operated group was added. The activity of the plasminogen activators was measured by casein-dependent plasminogen zymography. In the cortex urokinase (u-PA) rose from sham (no ischemia), 91 +/- 7% to ischemia, 176 +/- 10% (P < 0.005). Increasing rt-PA doses led to further significant (P < 0.001) cortical u-PA activation which was maximal at 18 mg: 249 +/- 13%. An extreme increase in the u-PA activity was observed in the basal ganglia to 1019 +/- 22% (P < 0.001). This increase was further aggravated by higher rt-PA doses (18 mg, 1236 +/- 15%; P < 0.001). The t-PA level did not change I3R24 during (3 h ischemia followed by reperfusion for 24 h); however, during low and moderate doses of rt-PA, endogenous t-PA was reduced. In conclusion, while ischemia leads to a significant increase in u-PA, mainly in the basal ganglia, t-PA is not altered. Increasing doses of rt-PA lead to a further elevation of u-PA. Thus, u-PA seems to play a major role in the endogenous plasminogen activator system following focal cerebral ischemia.

Antithrombotic and Thrombolytic Therapy for Ischemic Stroke

This chapter about treatment and prevention of stroke is part of the 7th ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al). Among the key recommendations in this chapter are the following: For patients with acute ischemic stroke (AIS), we recommend administration of i.v. tissue plasminogen activator (tPA), if treatment is initiated within 3 h of clearly defined symptom onset (Grade 1A). For patients with extensive and clearly identifiable hypodensity on CT, we recommend against thrombolytic therapy (Grade 1B). For unselected patients with AIS of > 3 h but < 6 h, we suggest clinicians not use i.v. tPA (Grade 2A). For patients with AIS, we recommend against streptokinase (Grade 1A) and suggest clinicians not use full-dose anticoagulation with i.v. or subcutaneous heparins or heparinoids (Grade 2B). For patients with AIS who are not receiving thrombolysis, we recommend early aspirin therapy, 160 to 325 mg qd (Grade 1A). For AIS patients with restricted mobility, we recommend prophylactic low-dose subcutaneous heparin or low molecular weight heparins or heparinoids (Grade 1A); and for patients who have contraindications to anticoagulants, we recommend use of intermittent pneumatic compression devices or elastic stockings (Grade 1C). In patients with acute intracerebral hematoma, we recommend the initial use of intermittent pneumatic compression (Grade 1C+). In patients with noncardioembolic stroke or transient ischemic attack (TIA) [ie, atherothrombotic, lacunar or cryptogenic], we recommend treatment with an antiplatelet agent (Grade 1A) including aspirin, 50 to 325 mg qd; the combination of aspirin and extended-release dipyridamole, 25 mg/200 mg bid; or clopidogrel, 75 mg qd. In these patients, we suggest use of the combination of aspirin and extended-release dipyridamole, 25/200 mg bid, over aspirin (Grade 2A) and clopidogrel over aspirin (Grade 2B). For patients who are allergic to aspirin, we recommend clopidogrel (Grade 1C+). In patients with atrial fibrillation and a recent stroke or TIA, we recommend long-term oral anticoagulation (target international normalized ratio, 2.5; range, 2.0 to 3.0) [Grade 1A]. In patients with venous sinus thrombosis, we recommend unfractionated heparin (Grade 1B) or low molecular weight heparin (Grade 1B) over no anticoagulant therapy during the acute phase.

Therapeutic yield and outcomes of a community teaching hospital code stroke protocol

OBJECTIVES

To describe the experience of a community teaching hospital emergency department (ED) Code Stroke Protocol (CSP) for identifying acute ischemic stroke (AIS) patients and treating them with tissue plasminogen activator (tPA) and to compare outcome measures with those achieved in the National Institute of Neurological Disorders and Stroke (NINDS) trial.

METHODS

This study was a retrospective review from a hospital CSP registry.

RESULTS

Over a 56-month period, CSP activation occurred 255 times, with 24% (n = 60) of patients treated with intravenous (IV) tPA. The most common reasons for thrombolytic therapy exclusion were mild or rapidly improving symptoms in 37% (n = 64), intracerebral hemorrhage (ICH) in 23% (n = 39), and unconfirmed symptom onset time for 14% (n = 24) of patients. Within 36 hours of IV tPA treatment, 10% (NINDS = 6%) of patients (n = 6) sustained a symptomatic ICH (SICH). Three months after IV tPA treatment, 60% of patients had achieved an excellent neurologic outcome, based on a Barthel Index of > or =95 (NINDS = 52%), while mortality measured 12% (NINDS = 17%). Among IV tPA-treated patients, those developing SICH were significantly older and had a significantly higher mean initial glucose value. Treatment protocol violations occurred in 32% of IV tPA-treated patients but were not significantly associated with SICH (Fisher's exact test).

CONCLUSIONS

Over the study period, the CSP yielded approximately one IV tPA-treated patient for every four screened and, despite prevalent protocol violations, attained three-month functional outcomes equal to those achieved in the NINDS trial. For community teaching hospitals, ED-directed CSPs are a feasible and effective means to screen AIS patients for treatment with thrombolysis.

Reduced susceptibility to ischemic brain injury and N-methyl-D-aspartate-mediated neurotoxicity in cyclooxygenase-2-deficient mice

Cyclooxygenase-2 (COX-2), a prostanoid-synthesizing enzyme that contributes to the toxicity associated with inflammation, has recently emerged as a promising therapeutic target for several illnesses, ranging from osteoarthritis to Alzheimer's disease. Although COX-2 has also been linked to ischemic stroke, its role in the mechanisms of ischemic brain injury remains controversial. We demonstrate that COX-2-deficient mice have a significant reduction in the brain injury produced by occlusion of the middle cerebral artery. The protection can be attributed to attenuation of glutamate neurotoxicity, a critical factor in the initiation of ischemic brain injury, and to abrogation of the deleterious effects of postischemic inflammation, a process contributing to the secondary progression of the damage. Thus, COX-2 is involved in pathogenic events occurring in both the early and late stages of cerebral ischemia and may be a valuable therapeutic target for treatment of human stroke.

Quantitative measurement of cerebral blood flow by (99m)Tc-HMPAO SPECT in acute ischaemic stroke: usefulness in determining therapeutic options

OBJECTIVE

Early recanalisation by thrombolysis is a conclusive therapy for acute ischaemic stroke. But this therapy may increase the risk of intracerebral haemorrhage or severe brain oedema. The purpose was to evaluate usefulness of quantitative measurement of cerebral blood flow by single photon emission computed tomography (SPECT) in predicting the risk of haemorrhage or oedema, and determining the therapeutic options in acute hemispheric ischaemic stroke.

METHODS

The relation was studied retrospectively between initial regional cerebral blood flow (rCBF) quantitatively measured by technetium-99m-labelled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) SPECT and final clinical and radiological outcome in 20 patients who presented hemispheric ischaemic stroke and were treated conservatively or received early recanalisation by local intra-arterial thrombolysis. The non-invasive Patlak plot method was used for quantitative measurement of rCBF by SPECT.

RESULTS

Regions where residual rCBF was preserved over 35 ml/100 g/min had a low possibility of infarction without recanalisation and regions where residual rCBF was preserved over 25 ml/100 g/min could be recovered by early recanalisation. However, regions where residual rCBF was severely decreased (< 20 ml/100 g/min) had a risk of intracerebral haemorrhage and severe oedema.

CONCLUSIONS

A quantitative assessment of residual rCBF by (99m)Tc-HMPAO SPECT is useful in predicting the risk of haemorrhage or severe oedema in acute ischaemic stroke. Therapeutic options should be determined based on the results of rCBF measurement.

Periinfarct and remote excitability changes after transient middle cerebral artery occlusion

Transient middle cerebral artery (MCA) occlusion results in substantially smaller cortical infarcts than permanent MCA occlusion if reperfusion is initiated within the first few hours. Only little information is available on the long-term functional outcome of the cortical regions "salvaged" by early reperfusion. To address this issue we examined basic electrophysiologic parameters in vitro using standard extracellular recording techniques at 7 and 28 days after transient MCA occlusion (1- and 2-hour ischemia) in rats. Both neocortical areas ipsi- and contralateral to MCA occlusion were systematically mapped to delineate the extent of periinfarct and remote alterations. In the periinfarct region we found a significant reduction of field potential amplitudes up to 3 mm when measuring from the infarct border at 7 days and up to 7 mm at 28 days. Paired-pulse inhibition, an indicator of GABAergic transmission, was only moderately impaired in this region at 7 days and not significantly different from control at 28 days. Remote effects were observed both ipsi- and contralaterally. Ipsilaterally they were restricted to a region close to the midline (presumably motor cortex) and were most likely attributable to the degeneration of corticostriatal connections. The extent of the contralateral excitability changes was clearly related to the size of the neocortical infarcts with large infarcts resulting in the widespread reduction of field potential amplitudes and an impairment of paired-pulse inhibition. The results show that there is a relatively large periinfarct region with decreased overall excitability after transient MCA occlusion which is likely to have a profound effect on perilesional processes involved in functional recovery. Remote excitability changes may contribute to the functional deficit and are probably related to deafferentation.

Thrombolysis with tissue plasminogen activator alters adhesion molecule expression in the ischemic rat brain

BACKGROUND AND PURPOSE

We tested the hypothesis that treatment of embolic stroke with recombinant human tissue plasminogen activator (rhtPA) alters cerebral expression of adhesion molecules.

METHODS

Male Wistar rats were subjected to middle cerebral artery occlusion by a single fibrin-rich clot. P-selectin, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) immunoreactivity was measured at 6 or 24 hours after embolic stroke in control rats and in rats treated with rhtPA at 1 or 4 hours after stroke. To examine the therapeutic efficacy of combined rhtPA and anti-ICAM-1 antibody treatment at 4 hours after embolization, ischemic lesion volumes were measured in rats treated with rhtPA alone, rats treated with rhtPA and anti-ICAM-1 antibody, and nontreated rats.

RESULTS

Administration of rhtPA at 1 hour after embolization resulted in a significant reduction of adhesion molecule vascular immunoreactivity after embolization in the ipsilateral hemisphere compared with corresponding control rats. However, when rhtPA was administered to rats at 4 hours after embolization, significant increases of adhesion molecule immunoreactivity in the ipsilateral hemisphere were detected. A significant increase of ICAM-1 immunoreactivity was also detected in the contralateral hemisphere at 24 hours after ischemia. A significant reduction in lesion volume was found in rats treated with the combination of rhtPA and anti-ICAM-1 antibody compared with rats treated only with rhtPA.

CONCLUSIONS

The present study suggests that the time of initiation of thrombolytic therapy alters vascular immunoreactivity of inflammatory adhesion molecules in the ischemic brain and that therapeutic benefit can be obtained by combining rhtPA and anti-ICAM-1 antibody treatment 4 hours after stroke.

Acute stroke teams: results of a national survey. National Acute Stroke Team Group

BACKGROUND AND PURPOSE

The sensitivity of the brain to brief periods of profound ischemia or prolonged periods of modest ischemia mandates an aggressive approach to acute stroke care. Past studies have shown that many stroke patients do not receive acute care in an urgent and timely fashion. The formation of acute stroke teams (AST) is one approach that can be used to accelerate the delivery of acute stroke care.

METHODS

We conducted a survey of major stroke program directors and neurovascular experts throughout the United States. The survey focused on issues related to the presence of AST, their staffing, operational features, and utilization at the surveyed programs and hospitals.

RESULTS

Surveys were returned from 45 of 60 centers. Ninety-one percent of the respondents indicated that they currently had an AST, with 66% formed between 1995 and 1997. Staffing of ASTs consisted of attending physicians (95%), nurses or study coordinators (73%), fellows (49%), and residents (46%). In almost all cases (98%), the AST was led by a neurologist or neurosurgeon, and 98% of the ASTs operated on a 24-hours-per-day, 7-days-per-week basis. The most common call frequency was 2 to 3 times per week (41%), followed by >5 calls per week (29%). In 59% of the cases, the teams cost </=$5000 per year to operate. The vast majority (78%) of ASTs responded within 10 minutes of receiving a call.

CONCLUSIONS

The formation of ASTs is quite common at the surveyed programs. Although staffing patterns vary, most teams are led by neurologists or neurosurgeons. The utilization of ASTs varies by facility, but they appear to be useful, with only a modest incremental financial cost. The use of ASTs may assist in providing more rapid medical care to stroke patients and increase the use of some acute therapies. Extension of the AST concept to nonacademic hospitals appears feasible.

Time course of lesion development in patients with acute stroke: serial diffusion- and hemodynamic-weighted magnetic resonance imaging

BACKGROUND AND PURPOSE

We sought to characterize the evolution of acute ischemic stroke by MRI and its relationship to patients' neurological outcome.

METHODS

Fourteen patients with acute ischemic stroke underwent MRI within 13 hours of symptom onset (mean, 7.4+/-3 hours) and underwent repeated imaging and concurrent neurological examination at 8, 24, 36, and 48 hours and 7 days and >42 days after first imaging.

RESULTS

Diffusion-weighted imaging (DWI) lesion volumes increased between the first and second scans in 10 of 14 patients; scans with maximum DWI lesion volume occurred at a mean of 70.4 hours. Initial DWI lesion volume correlated with the largest T2 lesion volume (r=0.97; P<0.001). Final lesion volume was smaller than maximum lesion volume in 12 of 14 patients. There was positive correlation between the follow-up National Institutes of Health Stroke Scale score and the initial DWI lesion volume (r=0.67; P=0. 01) and maximum T2 lesion volume (r=0.77; P<0.01) and negative correlation with initial mean apparent diffusion coefficient ratio (ADCr) (r=-0.64; P<0.05). The ADCr was 0.73 at initial imaging and fell between the initial and second scans in 10 of 14 patients. Mean ADCr did not rise above normal until 42 days after stroke onset (P<0. 001).

CONCLUSIONS

Serial MRI demonstrates the dynamic nature of progressive ischemic injury in acute stroke patients developing over hours to days, and it suggests that both primary and secondary pathophysiological processes can be valuable targets for neuroprotective interventions.

Early intravenous thrombolysis for acute ischemic stroke in a community-based approach

BACKGROUND AND PURPOSE

Controlled multicenter studies have demonstrated the efficacy of systemic recombinant tissue-type plasminogen activator (rtPA) treatment in selected cases of acute ischemic stroke. The feasibility of this therapeutic option in clinical practice was assessed in a community-based approach.

METHODS

We offered rtPA treatment to stroke patients in a prospective open-label monocenter study applying inclusion criteria similar to those of the National Institute of Neurological Disorders, and Stroke study. In order to treat patients within 3 hours of symptom onset, a referral system was used by which eligible patients from all over the city of Cologne, Federal Republic of Germany, were rushed to the Department of Neurology of the University Hospital. We present data on the effectiveness of the referral system and the outcome results of the first 100 consecutive patients treated within an 18-month period.

RESULTS

Of 453 consecutive patients with a presumed diagnosis of acute stroke referred to our department between March 1996 and August 1997, 100 patients (22%) were treated with intravenous thrombolysis, 26% of them within 90 minutes of symptom onset. The average time from stroke onset to arrival at our department was 78 minutes, and from arrival to treatment 48 minutes. After 3 months, 53 patients recovered to fully independent function. The rates of total, symptomatic, and fatal intracerebral hemorrhage were 11%, 5%, and 1%, respectively. Overall mortality was 12%.

CONCLUSIONS

Thrombolysis with rtPA was effectively applied in routine management of stroke patients in a community-based approach with acceptable efforts and without additional costs. Under these circumstances, outcome and complication rates were comparable to those of multicenter trials.

Early complete recanalization in internal carotid artery embolism treated with high-dose t-PA: a sequential angiographic study in a novel model of embolism in rats

Complete early recanalization rate of human internal carotid artery embolic occlusion treated with thrombolytic drugs is low. To study factors related with this difficulty to recanalize we have developed a novel model of rat ica embolism using a fragment of human embolus. In 50 male Wistar rats the ica was embolized through the external carotid artery with a fragment of an embolus obtained from a human embolectomy passed through a catheter of 0.8 mm diameter. Recanalization was assessed by sequential angiograms from 15 to 120 min after embolization. Reperfusion was classified according to TIMI grades. Emboli of either 1 (group 1) or 2 mm (group 2) in length were cut. In group 1, four groups of nine animals each were treated, 15 min after embolization, with i.v. t-PA at doses of 1 mg/kg, 10 mg/kg and 20 mg/kg or saline. In group 2 there was one control group of seven animals treated with saline and another of seven animals treated with 10 mg/kg t-PA. Complete recanalization (TIMI grade 3) within the first 30 min was present in two animals treated with 10 and 20 mg/kg. Complete recanalization within the first 60 min was present in 0% of controls and animals treated with 1 mg/kg and in 44% of the 10 and 20 mg/kg groups (P<0.05 in chi-square test). Incomplete recanalization (TIMI grades 0, 1 and 2) occurred in 33%. In group 2 total recanalization occurred in 1/7 controls and in 3/7 animals receiving 10 mg/kg of t-PA. Early (60 min) complete i.v. t-PA induced internal carotid artery embolic recanalization is low with standard doses and increases moderately when high doses are used. Further increases in the dose do not improve recanalization rate, which is not clearly influenced by embolus size. Complete recanalization within 30 min, the period after which infarction develops in the rat, is uncommon in our model.