Platelet survival time following aortic valve replacement.

Abstract

Thromboembolism continues to complicate the course of patients following aortic valve replacement. In patients with prosthetic and homograft mitral valves, platelet survival time has been shown to correlate with occurrence of thromboembolism. This study extends these observations to patients with aortic valve disease. Platelet survival time was measured (by the chromium-51 method) in 73 patients with aortic valve disease. Eighteen patients were studied preoperatively and had platelet survival times of 3.4 plus or minus 0.14 days (mean plus or minus standard error of the mean), almost the same as normal (3.7 plus or minus 0.4 days). Platelet survival time was shortened (P less than 0.001) following aortic valve replacement with Starr-Edwards prosthesis - Model 1000: 2.5 plus or minus 0.13 days (N = 6); Model 1200-1260: 3.0 plus or minus 0.10 (n = 14); model 2300-2320: 3.0 plus or minus 0.15 days (N = 9) - and with stented aortic homografts: 3.0 plus or minus 0.10 days (N = 16). Platelet survival time was normal following aortic valve replacement in patients with directly sewn aortic homografts 3.7 dats plus or minus 0.24 days (N = 10). Eleven patients with Starr-Edwards prostheses had a history of thromboembolism and all also showed shortened platelet survival time (2.7 plus or minus 0.12 days, P less than 0.001), a measurement which was significantly different (P less than 0.01) from the 18 patients with Starr-Edwards prostheses and no thromboembolism (3.0 plus or minus 0.09 days). Platelet suppressant therapy prolonged platelet survival in eight patients with Starr-Edwards devices, thromboembolism, and shortened platelet survival time. These results suggest that insertion of Starr-Edwards valves and stented aortic homografts alter platelet survival time but that direct homografts do not. A correlation between occurrence of thromboembolism after aortic valve replacement and shortened platelet survival time has been shown.