Rational approach to use of heparin during cardiac catheterization in children

Objectives.: We sought to determine an anticoagulation protocol for use during cardiac catheterization in children. Background.: There are few data to indicate which dose of heparin represents adequate anticoagulation or how best to monitor its efficacy. In this study, adequate anticoagulation was defined as the amount of heparin needed to prevent a significant increase in serum fibrinopeptide A, a sensitive marker for thrombin activity. The degree of heparinization was estimated by the activated clotting time. Methods.: Thirty-six children (1 month to 19.5 years old) with congenital heart disease underwent diagnostic cardiac catheterization; 13 of these 36 patients had an additional interventional procedure. Sheaths and catheters were flushed with heparinized saline (1 IU/ml); during the procedure, 33 of the 36 patients received either a 50- or a 100-IU/kg heparin bolus. Paired fibrinopeptide A and activated clotting time samples were obtained throughout each procedure. Results.: Increasing the activated clotting time with heparin resulted in a dose-related decrease in fibrinopeptide A levels. A single heparin bolus of either 50 or 100 IU/kg elevated the activated clotting time above baseline level (209 ± 52 s after 50 IU/kg, 270 ± 57 s after 100 IU/kg vs. 133 ± 20 s at baseline [p < 0.0001]) and reduced fibrinopeptide A levels below baseline (7.9 ± 14 ng/ml after 50 IU/kg, 4.8 ± 3.7 ng/ml after 100 IU/kg vs. 38 ± 59 ng/ml at baseline [p < 0.0001]). Heparin flush alone did not increase the activated clotting time above baseline and failed to suppress an increase in fibrinopeptide A levels. There were no differences in activated clotting time and fibrinopeptide A values between patients undergoing diagnostic or interventional procedures. Conclusions.: Administration of a heparin bolus to maintain an activated clotting time >200 s prevented a significant increase in thrombin activity. Heparin flush alone did not provide adequate anticoagulation. Patients undergoing an interventional procedure did not require more heparin than that needed for a diagnostic procedure.