The Influence of streptokinase(SK) on myocardial perfusion in ischemic and non-ischemic muscle was studied in 10 open-chest dogs, on each animal a sequential occlusion of 2 medium-sized coronary arteries was performed (90 min.), followed by reperfusion. Each dog served as its own control. After occlusion and reperfusion of the control artery (CA), the inital dose of SK was given (1,5 mega IU/20 min.). Thereafter test artery (TA) was occluded, followed by a maintenance dose of SK (500.000 IU/h). LVP, AOP, LVdp/dt and heart rate were recorded, MV02 was calculated by the computer (Bretschneider’s equation). Myocardial perfusion was measured after 90 min. of occlusion (tracer microspheres). M VO2 was comparable during both occlusion periods. CO (dye dilution technique) was 1,38±0,2 during CA-occlusion and 1,71±0,3 1/min. during TA-occlusion (p<0,01). In the non ischemic myocardium subepicardial and subendocardial perfusion was of equal value in both perfusion areas. Coronary ligation reduced flow drastically in the CA-region collateral flow (CF) in subendocardium was 11,8 ± 8 and 31,4 ± 12 ml/min.x100 g in the subepicardium. In The TA-region CF in the subendocardjum was 12,6 ± 5 and in the subepicardium 27,8 ± 14 ml/min.x100 g. CF was in the subendocardium significantly lower than in subepicardium in both perfusion areas (p<0,01). The present results show that CF in the ischemic myocardium cannot be modified by fibrinolysis. SK did not redistribute flow from subepicardium to subendocardium.
Improved visualization of the coronary arteries using motion correction during vasodilator stress CT myocardial perfusion imaging
