Human platelet reactivity during stressful diagnostic procedures.

Conscious subjects undergoing cardiac catheterization and other diagnostic procedures showed a rise in platelet-aggregation response to adenosine diphosphate (ADP) one hour before and during the procedure. The responses returned towards normal one hour afterwards. The response to glass beads was decreased one hour before the procedure, but was unchanged in subsequent samples. Plasma-free fatty acid (FFA) levels were increased during the procedure, and one hour afterwards, but had returned to normal by the following day. Platelet counts were slightly reduced on the day after the procedure. It is suggested that catecholamines released due to emotional stress may be responsible for the increased platelet responses to ADP and that this could influence the development of thrombosis and atherosclerosis.