Anticoagulant Effect of Standard Dose Heparin During Peripheral Endovascular Intervention

The objective of this clinical study was to investigate the anticoagulant effect of standard fixed dose of heparin during endovascular intervention in the lower extremity arteries.

A prospective clinical pilot study was completed with retrospective quality review of patients between 2015 and 2017 (n = 61). Patients undergoing elective endovascular intervention for arterial insufficiency in the lower extremities were enrolled. A standard fixed intra-arterial dose of 5000 IU of unfractionated heparin (UFH) was administered during the procedure without adjustment for weight or monitoring. Activated clotting time (ACT) was measured before and ten minutes after heparin administration and at the end of the procedure. The primary study end point was the level of heparin anticoagulation after standard perioperative administration.

Mean age was 74 ± 9 years, 48% women. Mean weight was 74 ± 15 kg, and mean BMI, 25.6 ± 4.7 kg/m². The endovascular interventions were performed at the iliac arteries 19.7% (12/61), at the femoral popliteal segment 50.8 % (31/61), below the knee arteries 6.6% (4/61), and at multiple levels 13% (8/61). The perioperative mean ACT increased from baseline 155 ± 43 s (n = 31) to ten minutes after heparin administration 290 ± 70 s (n = 60) (P < 0.01) and was at the end of the procedure 276 ± 73 s (n = 59). Perioperative ACT ten minutes after heparin administration: 5.0% (3/60) of the patients had ACT <200 s, 25.0% (15/60) had ACT 200-250 s, 48.3% (29/60) ACT 251-349, and 21.7% (13/60) ACT ≥350 s. At the end of the procedure, 17.2 % (10/58) of the patients had ACT <200, 24.1 % (14/58) had ACT 200-250 s, 37.9% (22/58) ACT 251-349, and 20.7 % (12/58) ACT ≥350 s. The mean dose of heparin per kg body weight was 70 ± 15 IU/kg. There was a significant difference between the ACT groups when analyzing heparin dose per kg body weight: 54 ± 14 IU/kg for patients with ACT <200, 69 ± 13 IU/kg with ACT 200-250 s, 68 ± 13 IU/kg with ACT 251-349, and 81 ± 18 IU/kg with ACT >350 (P = 0.0095). The same pattern was seen for heparin dose per BMI and DuBois. In univariate logistic regression analysis, ACT ≥350 s was associated with lower body weight (OR 0.92; 95% CI 0.87-0.98; P = 0.008), lower BMI (OR 0.80; 95% CI 0.67-0.96; P = 0.014), and lower body surface area DuBois (OR 0.53; 95% 0.32-0.85; P = 0.009). In multivariable regression, the ACT association with body weight remained (OR 0.92; 95% 0.87-0.98; P = 0.008). There were no perioperative or immediate postoperative bleeding complications requiring blood transfusion or surgical intervention in this study cohort.

The standard heparin dosing of 5000 IU during endovascular intervention for arterial insufficiency in the lower extremities helps achieve ACT >200 s in almost all patients, but most patients were outside recommended target interval. To provide a more consistent and predictable heparinization, a weight-based bolus dose of 70 IU heparin/kg is recommended.