Bedside coagulometry during intravenous heparin therapy after coronary angioplasty

In order to assess the applicability of a bedside coagulometer for measurem ent of b-APTT, serial blood samples were obtained from 20 patients receivin g intravenous heparin treatment following PTCA, and from 5 healthy voluntee rs. B-APTT was analysed bedside on the Hemochron (R) coagulometer; p-APTT a nd p-heparin, measured as factor anti-Xa activity, were analysed ex-vivo in the laboratory. B-APTT values, determined by the Hemochron coagulometer, w ere closely correlated to p-heparin (r=0.83, p <0.001, SD=52 seconds (sec), n=89), and duplicate determinations of b-APTT on the Hemochron coagulomete r showed an acceptable repeatability. However, an APTT ratio of 1.5-2.5 was not related to a therapeutic p-heparin level, neither as measured by the H emochron device nor in the laboratory.Background: When administering intrav enous heparin during angioplasty procedures, a quick and reliable method fo r safe and effective monitoring of anticoagulation is necessary. Objective: To assess the applicability of a bedside coagulometer, measuring the activated partial thromboplastin time (APTT) in patients receiving int ravenous heparin treatment after percutaneous transluminal coronary angiopl asty (PTCA). Methods: In patients with stable angina pectoris, receiving intravenous hep arin treatment following PTCA, serial blood samples were obtained by venipu ncture and from the arterial sheath for analysis of whole blood APTT (b-APT T), and plasma heparin concentration (p-heparin). Additionally, in healthy volunteers blood samples were obtained after a single bolus injection of he parin. B-APTT was analysed bedside on the Hemochron (R) coagulometer; p-APT T and p-heparin, measured as factor anti-Xa activity, were analysed ex-vivo in the laboratory using conventional analytical methods. Results: In 20 patients a total of 94 venous and 69 arterial blood samples were analysed, and in five healthy volunteers analyses were performed in 20 venous blood samples. B-APTT values, determined by the Hemochron coagulome ter, were closely correlated to p-heparin (r=0.83, p <0.001, SD=52 seconds (sec), n=89). An APTT ratio of 1.5-2.5 was not related to a therapeutic p-h eparin level, however, neither when using APTT assessed by the Hemochron de vice nor APTT measured in the laboratory. Duplicate determinations of b-APT T on the Hemochron coagulometer showed an acceptable repeatability; the mea n difference between duplicate measurements was 4[emsp4 ] sec (coefficient of variation (c.v.)=6%, p <0.05, n=163). Conclusions: In patients receiving intravenous heparin after PTCA treatment , b-APTT values measured by the Hemochron method showed an acceptable repea tability and were significantly correlated to p-heparin.