Abstract
The requirement of heparin in experimental coronary thrombolysis induced by tissue-type plasminogen activator (t-PA) was studied in closed-chest dogs with one hour old coronary thrombi and compared with that in urokinase (UK)-induced coronary thrombolysis. Animals were divided into 5 treatment groups as follows: group 1 received intracoronary t-PA along (1, 000 IU/kg/min; n=5), and if thrombolysis was not induced within 40 to 50 min, dogs then received an intravenous injection of heparin (300 U/kg) plus intracoronary t-PA; group 2 received intravenous heparin at first, and if thrombolysis was not induced within 10 min, dogs subsequently received intracoronary t-PA (n=5); group 3 also received intravenous heparin at first, and if thrombolysis was not induced within 10 min, dogs subsequently received t-PA but intravenously, as compared with the groups administered by the intracoronary route (n=6); group 4 received intracoronary UK alone (1, 000 IU/kg/min; n=6); group 5 received intravenous heparin at first, and if thrombolysis was not induced within 10 min, dogs subsequently received intracoronary UK (n=5). Thrombolysis was confirmed angiographically. In group 1, coronary thrombolysis could not be induced within 444 min by intracoronary t-PA alone, but it occurred in 84 min when administered in combination with heparin in all dogs. Heparin alone failed to elicit reperfusion within 10 min in group 2, 3 and 5. t-PA, however, induced successful reperfusion in 165 min (group 2) and in 236 min (group 3), respectively. Intracoronary urokinase alone elicited thrombolysis in 274 min in group 4, but in group 5, treated in combination with heparin, rapid reperfusion was obtained in 125 min (p<0.001).
