Comparison of activated coagulation time and whole blood heparin measurements with laboratory plasma anti-Xa heparin concentration in patients having cardiac operations - Despotis, G J; Summerfield, A L; Joist, J H; Foodnough, L T; Santoro, S A; Spitznagel, E; Cox, J L; Lappas, D G (J Thorac Cardiovasc Surg, 1994)