Stroke Intervention

Hyperacute therapy of acute ischemic stroke: intraarterial thrombolysis and mechanical revascularization strategies

Ischemic stroke is a major cause of morbidity and mortality. Despite the fact that it is the third most common cause of death in the United States, there is only one FDA approved treatment for patients. This is Intravenous recombinant tissue plasminogen activator given within 3 hours of symptom onset. Furthermore, despite the approval of this drug, it has been underutilized in the community. The limited time window of 3 hours disqualifies many patients from receiving the drug. In addition, fears of intracranial hemorrhage have resulted in underutilization of the drug in the community setting. Efforts to increase the time window to treatment include utilization of the intraarterial route for delivery of thrombolytic drug and interventional mechanical strategies to revascularize intracranial vessels. In this report we review the major intraarterial thrombolysis trials and review the mechanical strategies being developed to treat patients with acute ischemic stroke.

Recent Advances in the Interventional Treatment of Acute Ischemic Stroke

BACKGROUND

Acute ischemic stroke is a major cause of morbidity and mortality in Europe, North America, and Asia. Recent advances over the past decade have been made in the interventional approach to patients with a stroke. These include intravenous (i.v.) trials, intra-arterial (i.a.) trials, combined i.v./i.a. trials, and newer devices undergoing current clinical evaluation to mechanically remove clot within the cerebral circulation.

METHODS

A summary of the latest interventional approaches to stroke, from the interventional neuroradiology perspective, is presented. Results of the major thrombolytic trials over the past decade are summarized. Newer devices and approaches for ischemic stroke patients, including the recently completed Phase 1/2 MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial are presented.

RESULTS

The Proact 1 and 2 trials involving i.a. thrombolytic therapy in patients who present with an acute middle cerebral artery stroke within 6 h from symptom onset have demonstrated significant benefit over the control group, for improved outcomes at 90 days. The MERCI trial has demonstrated, in 114 patients with moderate to severe strokes, that patients who are able to be recanalized have significant neurological improvement versus those who were not able to be recanalized.

CONCLUSIONS

Continued advances in the interventional approach to acute stroke treatment, with further clinical trials, are warranted. Early reports are encouraging regarding both combination thrombolytic drug trials and mechanical device trials for these patients.

Hyperacute Therapy of Ischemic Stroke: Intravenous Thrombolysis

Stroke is the third most common cause of death in the United States following heart disease and cancer. Following the success of thrombolysis for myocardial infarction in the early 1990s, major trials for evaluation of this new therapeutic approach for ischemic stroke were initiated. The majority of ischemic strokes are due to occlusion of a cerebral vessel by a blood clot. Occlusion of a cerebral blood vessel leads to a core of infracted tissue surrounded by a relatively hypoperfused but viable brain tissue (the ischemic penumbra), which can be potentially salvaged by rapid recanalization of the target vessel. The underlying rationale for introduction of thrombolytic drugs is the lysis of an obliterating thrombus and reestablishment of blood flow. In this article we review the major intravenous thrombolysis trials leading to approval of intravenous recombinant tissue plasminogen activator, the only FDA approved treatment available today for acute ischemic stroke.

Intraarterial Thrombolysis Trials in Acute Ischemic Stroke

Stroke is a common cause of death and disability in industrialized nations. Technical advances and the increased availability of noninvasive brain imaging techniques have permitted precise and early diagnosis of acute cerebral ischemia. This has made emergent thrombolytic therapy for rapid restoration of cerebral perfusion increasingly possible. Herein, the authors present a review of the clinical trials investigating acute stroke treatment with intraarterial thrombolysis.

Radiologic intervention in the acute stroke patient

Overall, stroke is a common disease that can have devastating results. Treatment of stoke has been, for the most part, supportive in nature. Recently, more aggressive intervention has been used, particularly thrombolysis. Although such intervention can have devastating consequences, it has shown some promise, particularly in the arena of intraarterial administration. Although much work is needed to find the ideal agents and methods of administration, screening of patients may hold the key to success and the limitations of complications. Determination of exactly which patients will benefit and which will not and which will have complications and which will not, remains for the most part an enigma. Only through further investigation in a controlled, collaborative manner can such information be obtained.

"Brain attack": the rationale for treating stroke as a medical emergency

Stroke is the third leading cause of death in the United States, behind only heart disease and cancer. With an estimated three million survivors of stroke in the United States, the cost to society, both directly in health care and indirectly in lost income, is staggering. Despite recent advances in basic and clinical neurosciences, which have the potential to improve the treatment of acute stroke, the general approach to the acute stroke patient remains one of therapeutic nihilism. Most basic science studies show that to be effective, acute intervention to reperfuse ischemic tissue must take place within the first several hours, as is the case with ischemic myocardium. In addition, most neuroprotective agents must also be administered within a short time frame to be effective at salvaging at-risk tissue. Recent studies have suggested that the outcome after intracerebral and subarachnoid hemorrhage is improved with early intervention. However, most stroke patients fail to present to medical attention within this short "window of opportunity." The public's knowledge about stroke is woefully inadequate. However, clinicians who deal with stroke can use the dramatic changes in the treatment of acute myocardial infarction over the last 2 decades as a guide for shaping changes in the management of acute stroke. Comprehensive educational efforts aimed at clinicians and the public at large have dramatically reduced the time from symptom onset to presentation and treatment for acute myocardial infarction, enabling treatment methods such as thrombolysis to be effective. The Decade of the Brain offers a unique opportunity to all concerned with the treatment of the patient with acute stroke to engage in a concerted effort to bring patients with a "brain attack" to specialized neurological attention within the same timeframe that the "heart attack" patient is handled. Such an effort is justified because, although at the present time there are few therapeutic interventions of "proven" value in the treatment of acute stroke, there is more than sufficient suggestive evidence that a number of approaches may be beneficial within the first few hours after the onset of the stroke.