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Evaluation of platelet kinetics following porcine and mechanical valve replacement
Abstract:
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 (T 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 T 1/2 is germane to the test's thrombotic predictive value, yet platelet kinetics in PH require elucidation. Accordingly, 51chromium platelet T 1/2 was determined in 16 patients with substituted valves (10 PH and 6 MP). Average platelet T 1/2 in PH (2.9 +/- 0.6 d) was similar (p greater than 0.05) to MP (3.2 +/- 0.6 d), and both were considerably lower (p less than 0.05) than platelet T 1/2 in normal subjects (NL, 5.1 +/- 0.5 d). Furthermore, platelet T 1/2 was below the lowest NL platelet T 1/2 (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 predictability in patients with mechanical valves and, instead, favors prosthetic-induced physical trauma causing abnormal platelet survival.
Insights
Platelet half-life (T 1/2) does not predict thrombotic risk in patients with mechanical prosthetic valves (MP) or porcine heterografts (PH). Both valve types show reduced platelet survival, indicating prosthetic-induced trauma, not selective consumption.
Area of Science:
- Cardiovascular Science
- Hematology
- Biomedical Engineering
Background:
- Thromboembolic risk in mechanical prosthetic valves (MP) may involve platelet consumption and reduced platelet survival.
- Lowered platelet half-life (T 1/2) has been proposed as a predictor of postoperative thrombotic risk.
- Porcine heterografts (PH) have lower thromboembolic risks than MP, necessitating comparative platelet kinetic evaluation.
Purpose of the Study:
- To compare platelet T 1/2 in patients with PH versus MP.
- To evaluate the thrombotic predictive value of platelet T 1/2 in prosthetic valve patients.
- To elucidate platelet kinetics in PH.
Main Methods:
- Determined 51chromium platelet T 1/2 in 16 patients with prosthetic valves (10 PH, 6 MP).
- Compared platelet T 1/2 values between PH, MP, and normal subjects (NL).
Main Results:
- Average platelet T 1/2 was similar in PH (2.9 ± 0.6 d) and MP (3.2 ± 0.6 d).
- Both PH and MP groups had significantly lower platelet T 1/2 than NL (5.1 ± 0.5 d).
- Reduced platelet survival (<4.0 d) was observed in 7 PH and 3 MP patients.
Conclusions:
- Platelet survival is commonly reduced in both PH and MP patients, similar to MP.
- Platelet half-life does not predict thromboembolic risk in prosthetic valve patients.
- Abnormal platelet survival is likely caused by prosthetic-induced physical trauma rather than selective consumption.