Evaluation of Platelet Kinetics following Porcine and Mechanical Valve Replacement

Abstract

Summary:Because thromboembolic pathogenesis in mechanical prosthetic valves (MP) might involve selective MP platelet consumption with consequent reduced platelet survival, it has been suggested that lowered platelet half-life (TI 1 2 ) detection provides identification of postoperative thrombotic risk. Porcine heterografts (PH) possess less thromboembolic hazards than MP; thus, comparative evaluation of PH versus MP platelet Tl/2 is germane to the test's thrombotic predictive value, yet platelet kinetics in PH require elucidation. Accordingly, 5khromium platelet Tl/2 was determined in 16 patients with substituted valves (10 PH and 6 MP). Average platelet Tl/2 in PH (2.9f0.6 d) was similar (p>0.05) to MP (3.2f0.6 d), and both were considerably lower (pC0.05) than platelet TI^ in normal subjects (NL, 5.1 f0.5 d). Furthermore, platelet T , p was below the lowest NL platelet T i p (4.0 d) in seven PH and three MP patients. Thus, frequency and extent of decreased platelet survival in PH are common and equal to MP. These results indicate that platelet half-life does not afford thromboembolic predict-* This work was supported in part by Program Project grant HL-14780 from the National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, and by California chapters of the American Heart Association, Dallas, Texas, USA.This work was presented in part at the 52nd Scientific Sessions of the American Heart Association, November 14, 1979, Anaheim, California, USA. ability in patients with mechanical valves and, instead, favors prosthetic-induced physical trauma causing abnormal platelet survival.