An Experimental Study Of Preventive Effect Of Recombinant Tissue-type Plasminogen Activator On Delayed Cerebral Vasopasm After Subarchnoid Hemorrhage

Objective : To develop a model of delayed cerebral vasopasm(DCVS)after subarchnoid hemorrhage(SAH)in rabbits by"Two-hemorrhage"method. Preventive effect of recombinant tissue-type plasminogen activator(rt-PA) on DCVS after SAH were applied by once injection into cisterna magna in the model,and to disscuss the clinical mechanism of rt-PA in cerebral vasopasm.Method: Cerebral vasopasm model in rabbits was made by"Two-hemorrhage"method. Forty rabbits were randomly divided into six groups: normal control group (n=4),SAH group(n=4)and experimental groups[including 24 hours(n=8),48 hours(n=8),72 hours(n=8)and 96 hours(n=8)after SAH].Before the experiment,the angiogram of basilar artery(BA)and PET-CT were performed.The PET-CT was performed again after cerebral vasopasm model in rabbits was made. Then 1mg rt-PA soluted in 1ml saline was injected into cisterna magna after 24 hours,48 hours,72 hours and 96 hours.On the 10th day of experiment(8 days after second blood injection),the second angiography of BA and the third PET-CT examination were performed. BA were taken for light microscope from each rabbit.Results:There are not differences in weighs between every groups (P>0.05). On the third PET-CT examination,the levels of standardized uptake value(SUV)was decreased obviously in SAH group,and increased in experimental groups. It can have varying degrees of recovery among the five groups F = 7.533 (P = 0.001). There was significant difference between 48 hours group treating and 72 hours group after administration (P= 0.040).On the angiography of BA examination,the diameter of BA was decreased obviously in SAH group,and increased in experimental groups.It can have varying degrees of recovery among the five groups F=5.088 (P = 0.003). There was significant difference between 48 hours group treating and 72 hours group after administration(P=0.045).The historlogy showed that in 24 hours group and 48 hours group BA was little blood clot around blood vessel.However,in 72 hours group and 96 hours group blood clot was around blood vessel,the endorsembrance of BA was shrinkage.Conclusion: Our results suggested that: 1.Intracisternal once injection of rt-PA could resolve blood clots in the subarachnoid and prevent DCVS effectively in certain rabbits injection of rt-PA could resolve blood clots in the subarachnoid and prevent DCVS.2. Injection of rt-PA could resolve blood clots in the subarachnoid and prevent DCVS within 48 hours.Its′change pattern during the time course of cerebral vasopasm not only suggest rt-PA might have some important role in the formation of DCVS but also provide ideal strategy in the preventive effect of DCVS used rt-PA.