Heparin administration and monitoring for neuroangiography.

PURPOSE To establish the optimal protocol of heparin administration during interventional neuroradiology. METHODS We assessed 100 cases of neuroangiography, including endovascular surgery, and measured activated coagulation time before and 5 minutes after heparin administration, and before and 5 minutes after protamine neutralization. In some cases actual heparin concentration was assayed using a chromogenic substrate technique. RESULTS The actual plasma heparin concentration significantly 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 correlated with the dose of heparin injected intravenously (r = .54, P < .0001). The ratio of change in activated coagulation time significantly correlated 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 out neuroangiography for 75 minutes safely, even for endovascular surgery.