Reduced platelet adhesiveness in patients with prosthetic ball valves: Relation to adenosine diphosphate and mechanical trauma

Abstract

Summary The whole blood content of ADP and ATP was normal in patients with prosthetic aortic ball valves, in spite of increased red cell breakdown. During passage of EDTA-anticoagulated blood through glass bead columns a slight, but quite constant degree of hemolysis was produced, similar in blood from healthy individuals and ball-valve patients. The adenine nucleotides were liberated largely in the same proportions as hemoglobin, and ADP appeared in mean concentrations of 0.10 μM in each group of subjects. The results indicate that the ADP necessary for normal platelet retention is mainly derived from red cells and not from platelets. The retention of platelets by passage of native blood through the columns was significantly reduced in the patients in spite of the normal liberation of ADP. This low platelet adhesiveness could possibly be due to refractoriness towards ADP liberated from red cells during intravascular hemolysis. The ADP concentrations that could be derived from red cells were, however, calculated to be far lower than the levels known to affect platelet behavior, and ADP is rapidly eliminated from plasma. It is concluded that the reduced platelet retention in blood from ballvalve patients was most probably a result of trauma to the platelets inflicted by the valve, and was not secondary to intravascular hemolysis.