PURPOSE: To establish the optimal protocol of heparin administration d
uring interventional neuroradiology. METHODS: We assessed 100 cases of
neuroangiography, including endovascular surgery, and measured activa
ted coagulation time before and 5 minutes after heparin administration
, and before and 5 minutes after protamine neutralization. In some cas
es actual heparin concentration was assayed using a chromogenic substr
ate technique. RESULTS: The actual plasma heparin concentration signif
icantly correlated with the dose of heparin administered intravenously
(r=.98; P<.0001) and changes in activated coagulation time (r=.85; P<
.0001). The change in activated coagulation time significantly correla
ted with the dose of heparin injected intravenously (r=.54, P<.0001).
The ratio of change in activated coagulation time significantly correl
ated with time elapsed after heparin administration (r=-.70, P <.0001)
. CONCLUSIONS: The activated coagulation time is useful in monitoring
administration and neutralization of heparin during neuroangiography,
and a bolus injection of 60 U/kg heparin should be adequate to carry o
ut neuroangiography for 75 minutes safely, even for endovascular surge
ry.