What are our options for addressing this patient'sthrombosed vessel?

Intravenous thrombolytics and endovascular approaches can be used to restore perfusion to the infracted region. Thrombolysis is achieved by recombinant tissue plasminogen activator (rtPA). Criteria for its use are very strict, and contraindications are numerous, as outlined in Table 9.1. Recently, the time frame for receiving rtPA was extended from 3 to 4.5 hours in selected patients.12-13 The rtPA thrombolytic therapy in the 3-4.5 hour range is contraindicated if the patient is older than 80 years, on oral anticoagulants, has a baseline NIH stroke scale score >25 or has a medical history of both stroke and diabetes.14 The earlier treatment is initiated, the better the outcome, so it is recommended to begin the treatment as soon as possible. Serious risks of rtPA include symptomatic intracranial hemorrhage.

Intra-arterial thrombolysis is another technique, which has been attempted in acute ischemic stroke. Large-volume clots may fail to lyse with intravenous rtPA alone because of the greater thrombus burden and poor delivery of thrombolytic agents. Although an early study showed that intra-arterial thrombolysis with recombinant prourokinase in acute MCA stroke improved recanalization when given up to 6 hours after a stroke,15 intra-arterial thrombolysis for treatment of acute ischemic stroke is currently not FDA approved. Nevertheless, many centers now perform intra-arterial thrombolytics administration because it potentially maximizes thrombolytic action while minimizing the hemorrhagic effects.

Mechanical endovascular thrombectomy is another promising field of stroke treatment. Currently, 2 devices are FDA approved for endovascular removal of clots in acute stroke: the Merci Retriever and the Penumbra System. The Merci Retriever has a flexible wire with coil loops that removes clots, whereas the Penumbra System uses suction to break up and aspirate clots. These systems improve recanalization of occluded arteries and clinical outcomes (see Ref. [16]) and may be used with more traditional thrombolytic methods as adjuncts. They are particularly attractive because they can be used for the patients who are not eligible for rtPA treatment or have failed rtPA treatment.

TABLE 9.1 Guidelines for the Use of rtPA in Acute Ischemic Stroke.

Indications for rtPA

Contraindications for rtPA

• Clinical diagnosis of stroke

• BP >185/110 despite treatment

• Onset of symptoms to time

• Platelets <100,000; Hct <25%;

Of drug administration <3 h

Glucose <50 or >400 mg/dL

(or <4.5 h in selected patients)

• Use of heparin within 48 h and

• CT scan showing no

Prolonged PTT or elevated INR

Hemorrhage or edema of >1/3

• Rapidly improving symptoms

Of the MCA territory

• Prior stroke or head injury

• Age >18 y

Within 3 mo; prior intracranial

• Consent by patient or

Hemorrhage

Surrogate

•  Minor stroke symptoms

•  GI bleeding in preceding 21 d

•  Recent MI

•  Coma or stupor

Abbreviations: rtPA, recombinant tissue plasminogen activator; BP, blood pressure; CT, computed tomography; MCA, middle cerebral artery; PTT, partial thromboplastin time; INR, international normalized ratio; GI, gastrointestinal; MI, myocardial infarction.

Adapted from Kasper DL, et al. (2008). Harrison’s principles of internal medicine (17th ed.). New York: McGraw-Hill Medical Publishing Division.

Antithrombotic treatment: Aspirin is a safe treatment that reduces mortality and risk of stroke recurrence 19, and is recommended for the treatment of acute stroke when used within 48 hours.2,17 Other antiplatelet agents are used only for the secondary prevention of stroke and include clopidogrel, aspirin, warfarin (only w a-fib), and Aggrenox.

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