The no-reflow phenomenon--reduction in distal flow without apparent dissection or distal embolization--occurs in 2% of coronary interventions. It generally responds promptly to intracoronary verapamil administration, suggesting that distal microvascular spasm may be its etiology.

The purpose of this study was to test the hypothesis that abnormal intracellular calcium handling characterizes myocardial stunning. Isolated, isovolumic, buffer-perfused ferret hearts were loaded with the bioluminescent calcium indicator aequorin for simultaneous measurement of After 20 minutes of reperfusion, myocardial stunning occurred, but [Ca2+1L was not significantly different from preischemic levels. Thus, myocardial stunning does not result from decreased levels of activator calcium. The force-pCa relation generated by the stunned hearts was shifted downward compared with that generated by the control hearts, consistent with a decrease in maximum calcium-activated force (Fmax). At steady state during tetanus, the decrease in Fmax was confirmed, but there was no significant difference in the slope of the force-pCa relation of the stunned hearts versus controls. Thus Materials and Methods After the intraperitoneal administration of 1,000 units heparin, male ferrets 10-14 weeks of age were anesthetized with chloroform. Hearts were rapidly excised through a midline sternotomy incision and by guest on