The use of IV tPA for acute ischemic stroke is limited
by the strict guidelines set out by the American Heart
Association. In the ACLS course the inclusion of
patients into thrombolytic therapy includes criteria of;
pt must be 18 yrs +, have a clinical diagnosis of
ischemic stroke with a measurable neurological defect,
and onset of symptoms must be <180 minutes.  The
exclusion criteria precludes many more people from
thrombolytic therapy.  The obvious diagnosis of
intracranial hemorrhage is followed by exclusion with
clinical presentation suggestive of subarachnoid
hemorrhage even with normal CT.  Patients are also
excluded with multilobart infarction, history of
intracranial hemorrhage, uncontrolled hypertension
(systolic >185 mm Hg, or diastolic >110 mmHg), known
arteriovenous malfomation, neoplasm, or aneurysm,
witnessed seizure with stroke onset, active internal
bleeding or acute trauma, platelet count <100000/mm3,
heparin given within 48 hrs resulting in aPTT >than
upper normal limit, INR >1.7 or PT >15 seconds, within
three months of intracranial or intraspinal surgery,
head trauma, or previous stroke, arterial puncture
within the last 7 days at a site that cannot be
compressed.

These are the absolute contraindications, there are also
relative contraindications which must be weighed in a
risk-benefit ratio.  minor or improving stroke symptoms,
14 days within major surgery or serious trauma, GI or
urinary tract hemmorhage(within 3 weeks), MI within 3
months, post MI pericarditis, abnormal blood glucose
<2.8 or >22.2 mmol/l.

Feild, J.M. (Ed.). (2006). Advanced Cardiovascular Life
Support Provider Manual.