A comparison of intra-arterial and intravenous tissue-type plasminogen activator on autologous arterial emboli in the cerebral circulation of rabbits.

BACKGROUND AND PURPOSE The efficacy of thrombolytic therapy for treatment of embolic stroke has been a subject of both experimental and clinical examination. The aim of this study was to compare the efficacy, in regard to reduction of volume of ischemic brain, of two different modes of administration (ie, intra-arterial and intravenous) of tissue-type plasminogen activator (TPA) given 30 minutes after experimental embolic stroke in rabbits. METHODS A randomized, blinded, controlled experimental trial was undertaken. Embolic stroke was simulated in rabbits by injecting fragments of autologous arterial thrombus into one internal carotid artery. Thirty minutes after embolization, the rabbits were blindly treated with 2 mg/kg intra-arterial TPA, 2 mg/kg intravenous TPA, or saline (all n = 10). Six hours after embolization the rabbits were killed. The brains were perfused with triphenyltetrazolium chloride and cut into 0.5-cm-thick coronal sections, and the areas of ischemia were measured. RESULTS Administration of TPA resulted in a significant reduction in the volume of ischemic cerebral injury (P < .0001): control animals sustained ischemic injury to 20.1 +/- 4.6% (mean +/- SD) of total brain compared with 4.6 +/- 4.1% for animals treated with intra-arterial TPA and 3.4 +/- 2.6% for those treated with intravenous TPA. The difference between intra-arterial and intravenous TPA treatment was not significant (P = .786). CONCLUSIONS In this rabbit model of embolic stroke, administration of TPA within 30 minutes resulted in a dramatic reduction in the amount of ischemic injury, with equal efficacy for the two modes of administration. These results favor the treatment of acute embolic stroke with intravenous TPA, given the rapidity with which intravenous therapy can be established in the clinical setting.