Effect of Progressive Pressure Reduction with Nitroprusside on Acute Myocardial Infarction in Humans

Abstract

The effect of nitroprusside-induced progressive systemic pressure reduction on segmental function in patients with acute myocardial infarction is unclear. In 15 patients control radionuclide angiograms were obtained at control within 24 hours of the onset of chest pain and during the administration of intravenous nitroprusside. The initial study showed a significant reduction in hemiaxial shortening in the zone of myocardial infarction. With nitroprusside, systolic pressure was decreased from a mean of 133 mm Hg to an intermediate pressure of 116 mm Hg (p < 0.001). At this pressure central chord hemiaxial shortening increased in eight of 15 zones with an average increase from 10.1% to 27.8% (p < 0.006). After further reduction in pressure to 87.1 mm Hg, an additional five of the seven remaining zones of acute infarction improved. However, of the eight zones that improved initially, four deteriorated at the lowest pressure. Similar changes were seen in the lateral chords. Thus, afterload reduction can improve hemiaxial shortening of the infarct zone. However, the degree of reduction in systemic pressure must be individualized to avoid adverse effects of an excessive decrease in perfusion pressure.