Initial Assessment

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A detailed clinical history, past medical and surgical history, medications, allergies, laboratory work-up, physical examination, and NIHSS should be obtained as quickly as possible for assessment of inclusion and exclusion criteria for IAT. Table 4.1 lists the criteria for catheter-based reperfusion therapy currently in place at the Massachusetts General Hospital (Table 4.1; see also www.acutestroke.com for updated criteria).

After the clinical and imaging evaluation suggests the need for IAT, the anesthesia team is contacted and informed of the estimated time of arrival of the patient to the interventional neuroradiology suite. Qualifying patients referred from other

TABLE 4.1 Criteria for Catheter-based Reperfusion Therapy Currently in Place at the Massachusetts General Hospital.

IA inclusion criteria

A significant neurologic deficit expected to result in long-term disability, and attributable to large vessel occlusion (basilar, vertebral, internal carotid, or middle cerebral artery Ml or M2 branches).

Noncontrast CT scan without hemorrhage or well-established infarct. Acute ischemic stroke symptoms with onset or last known well, clearly defined. Treatment within 6 h of established, nonfluctuating deficits due to Anterior Circulation (carotid/MCA) stroke, between 6 and 8 h mechanical treatment (e.g., Concentric Retriever) should be considered. The window of opportunity for treatment is less well defined in posterior circulation (vertebral/basilar) ischemia, and patients may have fluctuating, reversible ischemic symptoms over many hours or even days and still be appropriate candidates for therapy.

Absolute contraindications

Hemorrhage or well-established acute infarct on CT involving greater than one third of the affected vascular territory. CNS lesion with high likelihood of hemorrhage s/p chemical thrombolytic agents (e.g., brain tumors, abscess, vascular malformation, aneurysm, contusion) Established bacterial endocarditis.

Relative contraindications

Mild or rapidly improving deficits

Significant trauma within 3 months*

CPR with chest compressions within past 10 days*

Stroke within 3 months

History of intracranial hemorrhage; or symptoms suspicious for subarachnoid hemorrhage Major surgery within past 14 days*

Minor surgery within past 10 days, including liver and kidney biopsy, thoracocentesis, lumbar puncture* Arterial puncture at a noncompressible site within past 14 days* Pregnant (up to 10 days postpartum) or nursing woman* Suspected bacterial endocarditis

Gastrointestinal, urologic, or respiratory hemorrhage within past 21 days* Known bleeding diathesis (includes renal and hepatic insufficiency)* Life expectancy < 1 year from other causes Peritoneal dialysis or hemodialysis* PTT > 40 s; platelet count < 100,000*

INR > 1.7 (PT > 15 if no INR available) with or without chronic oral anticoagulant use* Seizure at onset of stroke (This relative contraindication is intended to prevent treatment of patients with a deficit due to postictal ''Todd's'' paralysis or with seizure due to some other CNS lesion that precludes thrombolytic therapy. If rapid diagnosis of vascular occlusion can be made, treatment may be given.) Glucose < 50 or > 400 (This relative contraindication is intended to prevent treatment of patients with focal deficits due to hypo- or hyperglycemia. If the deficit persists after correction of the serum glucose, or if rapid diagnosis of vascular occlusion can be made, treatment may be given.)

Items marked with an asterisk may not be exclusions for mechanical thrombolysis with or without limited dose chemical agents.

institutions may receive IV rt-PA before transfer and while en route as part of a "bridging" approach.34 If a noncontrast brain CT does not identify any contradictions (e.g., advanced infarction, other nonstroke etiology, brain hemorrhage), and CT angiography (CTA) confirms the presence of a large vessel occlusion (ICA, Ml or 2, A1, basilar or P1 segments), the patient is brought emergently to angiography. Soft-copy review of noncontrast CT with variable window width and center level settings to accentuate the contrast between normal and edematous tissue (e.g., width ^30, level ^30) may optimize the recognition of early ischemic changes.40 We consider the presence of a readily visible hypodensity on noncontrast CT involving greater than one third of the affected vascular territory a contraindication to thrombolysis.41

Review of postcontrast CTA source images might provide a good estimate of whole-brain perfusion.42 If time allows, MR or CT perfusion maps are obtained to characterize more accurately the ischemic penumbra.43 Careful but expedited preprocedural analysis of the CTA, done in parallel with transport of the patient to the treatment area, may be extremely helpful in establishing the presence of anatomic variants (e.g., bovine aortic arch) or pathological states (e.g., vessel origin or carotid bifurcation disease) prior to the catheterization procedure.

MRI with MRA as well as DWI and PWI has the advantage of providing more complete information on brain parenchymal injury and penumbral tissue at risk. MRI can be particularly helpful in selected difficult cases. Patients who present with seizures at stroke onset (which was a contraindication to IV rt-PA treament in the NINDS trial) should undergo MRI to exclude the possibility of postictal Todd's paralysis, unless a vascular occlusion compatible with the patient's clinical syndrome is clearly seen on CTA.44 Similarly, in other situations (such as complex migraine, functional disorder, transient global amnesia, acute demyelination, cerebral amyloid angiopathy, or brain neoplasm), the diagnostic abilities of MRI can be useful in distinguishing a stroke mimic from an acute ischemic stroke.45 It should be noted, however, that prolonged seizures and acute demyelination can also cause restricted diffusion.46 Of particular importance is the fact that DWI lesions can be reversed to some extent by IAT in as many as 19% of the cases.47,48 The application of DWI and PWI in the extension of the therapeutic time window for thrombolysis in acute stroke is currently under investigation in several clinical trials.7,49,50

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