Bedside Coagulometry During Intravenous Heparin Therapy after Coronary Angioplasty

In order to assess the applicability of a bedside coagulometer for measurement of b-APTT, serial blood samples were obtained from 20 patients receiving intravenous heparin treatment following PTCA, and from 5 healthy volunteers. B-APTT was analysed bedside on the Hemochron® coagulometer; p-APTT and p-heparin, measured asfactor anti-Xa activity, were analysed ex-vivo in the laboratory. B-APTT values, determined by the Hemochron coagulometer, were 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 coagulometer 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 Hemochron device nor in the laboratory. Abstract. Background: When administering intravenous heparin during angioplasty procedures, a quick and reliable method for 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 intravenous heparin treatment after percutaneous transluminal coronary angioplasty (PTCA). Methods: In patients with stable angina pectoris, receiving intravenous heparin treatment following PTCA, serial blood samples were obtained by venipuncture and from the arterial sheath for analysis of whole blood APTT (b-APTT), and plasma heparin concentration (p-heparin). Additionally, in healthy volunteers blood samples were obtained after a single bolus injection of heparin. B-APTT was analysed bedside on the Hemochron® coagulometer; p-APTT 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 coagulometer, 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-heparin level, however, neither when using APTT assessed by the Hemochron device nor APTT measured in the laboratory. Duplicate determinations of b-APTT on the Hemochron coagulometer showed an acceptable repeatability; the mean 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 repeatability and were significantly correlated to p-heparin.