Acquired decrease in platelet secretory ADP associated with increased postoperative bleeding in post-cardiopulmonary bypass patients and in patients with severe valvular heart disease.

The purpose of this study was to assess (1) whether or not cardiopulmonary bypass surgery would decrease platelet secretory ADP, (2) whether or not patients with severe valvular disease have a decrease in platelet secretory ADP, and (3) whether or not such a decrease in secretory ADP is associated with surgical bleeding. Total and releasable platelet ADP and ATP were measured by the luciferase method. Platelet size was measured on a Coulter H4 system. Postoperative bleeding was assessed by volume of chest tube drainage. Pr.versus postoperative assessment of releasable and total ADP and ATP in 66 patients revealed a significant decrease in both (paired t test, p < 0.001). The decrease in secretory ADP was significantly correlated with postoperative bleeding and with duration of bypass. Duration of bypass alone did not correlate with postoperative bleeding. Preversus postoperative platelet size did not change significantly; thus large granule-rich platelets were not selectively removed. Forty-three valve patients with disease severe enough to require surgery were compared with 22 concurrent controls; patients had significantly less releasable ADP and ATP, as well as significantly less total ADP (nonpaired ttestp < 0.01),and total ATP was lower but not significantly different. Thus patients with severe valvular disease also had a decrease in secretory ADP, and this decrease was correlated with surgical and postsurgical bleeding.