Exploring predictors of activated clotting time after unfractionated heparin administration in elective interventional neuroradiology

Anticoagulant Effect of Standard Dose Heparin During Peripheral Endovascular Intervention

EVALUATION OF AN ARTIFICIAL INTELLIGENCE HEPARIN DOSING ALGORITHM TO MAINTAIN THERAPEUTIC ANTICOAGULATION DURING ATRIAL FIBRILLATION ABLATION

Activated Clotting Times, Heparin Responses, and Antithrombin

Single centre evaluation of heparin administration by body mass index in elective cardiac surgery

BackgroundThe dose of unfractionated heparin (UFH) during cardiac catheterisation procedures is still an area of debate. The ESC guideline recommends using a weight adjusted dose where as the AHA guideline...

To investigate the activated clotting time (ACT) level after administration of guideline-recommended dose of unfractionated heparin (UFH) and to confirm the importance of ACT monitoring in percutaneous coronary intervention (PCI). We performed a retrospective study on 1 062 patients undergoing elective PCI in Peking Union Medical College Hospital from May 1, 2011 to December 31, 2012. All patients were administrated weight-adjusted UFH (70-100 U/kg) based on PCI guideline of ACCF/AHA/SCAI. Patients were divided into 3 groups: ACT < 300 s (598 cases), ACT 300-350 s (183 cases) and ACT > 350 s (281 cases). ACT level and factors that may affect UFH anticoagulation were analyzed. (1) The mean age was (63.0 ± 10.6) years and 751 (70.7%) patients were men. The mean weight was (70.5 ± 11.7) kg, and the mean UFH dose used was (100.7 ± 9.1) U/kg. (2) The median ACT was 285 (240-352) s after the UFH use. Pre-defined ACT target (300-350 s) was achieved only in 17.2% (183/1 062) patients. (3) Age, gender, height, weight, UFH/weight and the risk factors of coronary heart disease were similar among 3 groups (all P > 0.05). Multifactor linear correlation analysis showed that UFH/weight was related to ACT level (r = 0.07, P < 0.01), but other factors were not related to ACT level (all P > 0.05). (4) Among 598 patients with ACT < 300 s, 444 (74.2%) patients received additional UFH. No major bleeding events were observed in 1 062 patients. The incidence of minor bleeding and ischemic complications within 48 h after procedure were similar among 4 groups of ACT < 300 s with additional UFH, ACT < 300 s without additional UFH, ACT 300-350 s and ACT > 350 s (all P > 0.05). In this single-center study, only a small proportion of patients reached the ACT target after administration of weight-adjusted UFH. Our results supported the recommendation of ACT monitoring in current PCI guideline to improve efficacy and safety of UFH anticoagulation therapy.

Females are more prone to complications during non-cardiac arterial procedures (NCAPs) than males. The current study investigated the difference in the effect of peri-procedural prophylactic heparin in males and females, using the activated clotting time (ACT). This was a retrospective analysis of a prospective multicentre cohort study. All patients undergoing elective NCAP using heparin and ACT measurements between January 2016 and March 2020 were included. Two heparin dosage protocols were used: weight based dosing of 100 IU/kg (international units per kilogram) or a bolus of 5 000 IU. The primary outcome was the anticoagulatory effect of heparin after five minutes, measured by ACT. Secondary outcomes were the effect of heparin after 30 minutes, bleeding complications, and arterial thromboembolic complications (ATECs). A total of 778 patients were included; 26% were female. After 100 IU/kg (n= 300), females more often reached longer ACT (< 200 seconds: 22% vs. 25%, p= .62; 200 - 250 seconds: 41% vs. 53%, p= .058; 251 - 280 seconds, 26% vs. 15%, p= .030). The mean ACT after 100 IU/kg heparin was 233 seconds (95% confidence interval [CI] 224 - 243) for females and 226 seconds (95% CI 221 - 231) for males (p= .057). After a bolus of 5 000 IU of heparin (n= 411), females reached significantly higher levels of anticoagulation than males (mean ACT 204 seconds vs. 190 seconds: p ≤ .001; ACT < 200 seconds: 44% vs. 66%; p < .001; ACT 200 - 250 seconds: 47% vs. 30%, p= .001; ACT 251 - 280 seconds: 7.8% vs. 2.3%, p= .009). Thirty minutes after heparin administration, 58% of all patients had an ACT < 200 seconds. ATECs did not differ between females and males (6.9% vs. 5.1%, p= .33) but bleeding complications were higher in females (27% vs. 16%, p= .001). Heparin leads to significantly longer ACT in females during NCAP. Further research is needed to investigate whether individually based heparin protocols lead to fewer bleeding complications and lower incidence of ATECs.

Heparin concentrations in neonates during cardiopulmonary bypass

ObjectivesThis systematic review was performed to examine all published practice Guidelines and Consensus Statements (together: GCS) on heparin dosing and monitoring during non-cardiac arterial procedures (NCAP). The objective was to scrutinize the recommendations and advice outlined within these GCS documents and to evaluate the supporting evidence for these recommendations. Additionally, the use of the activated clotting time (ACT) and target ACT values were explored.MethodsThis systematic review was performed in accordance with the PRISMA Guidelines. Medline and Embase databases were searched to identify all GCSs in the English language on NCAP. The final literature search was performed in January 2023. This search was supplemented by searching websites of relevant professional vascular surgical organizations for GCSs. Titles and abstracts were assessed by two independent reviewers.ResultsOf 9716 titles identified, 27 GCSs met the predefined inclusion criteria: six GCSs regarding carotid intervention, seven regarding procedures for aneurysmal disease of the abdominal aorta and iliac arteries, 12 regarding interventions for acute and chronic peripheral arterial occlusive disease and two regarding open and endovascular interventions of thoraco-abdominal aortic aneurysms. Administration of heparin is advised for al NCAP. There was high variability concerning heparin dose: both standard dose as weight based dosing (30-150 IU/kg) was advised. Recommendations on repeated doses, ACT monitoring and heparin reversal using protamine also varied widely. In none of the GCSs, the type of the ACT measuring device or used cartridges were specified.ConclusionsLarge variability was found between the included GCSs with regard to the recommendations on heparin dose and target ACT values during NCAP. Advice and recommendations in GCSs were based on low-quality studies or without providing any reference at all. The described variability in recommendations emphasizes the need for large prospective (randomized) studies or the incorporation of data on heparin and the use of ACT monitoring into verified vascular surgery registries, to develop evidence-based, practical and uniform applicable recommendations.

There are two common approaches to heparin administration for pediatric bypass: one involves the empirical dosing of heparin based on the activated clotting time (ACT), and the other on heparin concentration. It has been observed that heparin requirements are substantially greater when maintaining a concentration as opposed to an ACT. This study gathered heparin administration data from five pediatric centers, two using an empirical regimen and ACT technique and three using heparin concentration as measured by the Heparin Management System (HMS). All patients less than or equal to 20 kg were evaluated and grouped by technique. There were 49 patients in the HMS group and 46 in the ACT group. There was no significant difference between groups for patient weight, bypass time, postheparin ACT, bypass ACT, protamine dose, or 24-h blood loss (mL/kg/24). There was a significant difference (p &lt; .01) for prime heparin (4.7 ± 1.3 units/cc HMS vs. 1.9 ± 0.4 units/cc ACT), heparin loading dose (476.5 ± 175.3 units/kg HMS vs. 384.6 ± 54.3 units/kg ACT), and total heparin (16.6 ± 6.7 units/kg/min HMS vs. 9.5 ± 5.9 units/kg/min ACT). The use of the HMS for heparin management in pediatric bypass required more heparin but no difference in protamine use or 24-h blood loss.

Background: Activated Clotting Time (ACT) guided heparinization is the gold standard for titrating unfractionated heparin (UFH) administration during atrial fibrillation (AF) ablation procedures. The current ACT target (300 s) is based on studies in patients receiving a vitamin K antagonist (VKA). Several studies have shown that in patients receiving Direct Oral Anticoagulants (DOACs), the correlation between ACT values and UFH delivered dose is weak. Objective: To assess the relationship between ACT and real heparin anticoagulant effect measured by anti-Xa activity in patients receiving different anticoagulant treatments. Methods: Patients referred for AF catheter ablation in our centre were prospectively included depending on their anticoagulant type. Results: 113 patients were included, receiving rivaroxaban (n = 30), apixaban (n = 30), dabigatran (n = 30), and VKA (n = 23). To meet target ACT, a higher UFH dose was required in DOAC than VKA patients (14,077.8 IU vs. 9565.2 IU, p < 0.001), leading to a longer time to achieve target ACT (46.5 min vs. 27.3 min, p = 0.001). The correlation of ACT and anti-Xa activity was tighter in the VKA group (Spearman correlation ρ = 0.53), compared to the DOAC group (ρ = 0.19). Despite lower ACT values in the DOAC group, this group demonstrated a higher mean anti-Xa activity compared to the VKA group (1.56 ± 0.39 vs. 1.14 ± 0.36; p = 0.002). Conclusion: Use of a conventional ACT threshold at 300 s during AF ablation procedures leads to a significant increase in UFH administration in patients treated with DOACs. This increase corresponds more likely to an overdosing than a real increase in UFH requirement.

The activated coagulation time: Suitability for monitoring heparin effect and neutralization during pediatric cardiac surgery

We investigated the effect of an injected bolus of 5 mg kg− heparin at one circadian stage (08:30 to 11:00) on blood coagulation during different months of the year. Activated clotting times (ACTs) were assessed before and 5 min after heparin dosing to ensure extracorporeal circulation during open-heart surgery. The ACT data of 1083 presumably day-active Turkish patients (816 men and 267 women, mostly older than 46 years) who underwent coronary bypass surgery between 08:30 and 11:00 in the years from 1994 to 1997 were analyzed for annual rhythmicity. The ACT values obtained just before and 5 min after heparinization were subjected to cosinor analysis using a 365.25-day period to assess seasonality in basal ACT level and heparin effect. A small-amplitude annual rhythm with a wintertime peak was documented in the morning ACT in the group of 1083 patients. Rhythms of similar magnitude and staging were also detected in heparin effect on ACT in the 1083 patients and in subgroups categorized by gender. Circannual rhythmicity in the heparin effect on ACT was also documented in the elderly (≥ 45 years old), but not young (18–45 years old) patients. The annual mean effect of heparin on the ACT was statistically significantly greater in younger than older patients. The relatively low-amplitude circannual rhythm in heparin effect on ACT (∼10% of the annual mean) is not viewed as being meaningful in patient preparation for bypass surgery for the 5 mg kg−1 level of heparin dosing. (Chronobiology International, 18(5), 865–873, 2001)

Adaptive control of anticoagulation during hemodialysis

Unfractionated heparin is administered during non-cardiac arterial procedures (NCAP) to prevent thromboembolic complications. In order to achieve a safe level of anticoagulation, the effect of heparin can be measured. The aim of this review was to provide an overview on what is known about heparin, suggested tests to monitor the effect of heparin, including the activated clotting time (ACT), and the factors that could influence that ACT. A literature search in PubMed was performed. Articles reporting on heparin, clotting time tests (including thrombin time, activated partial thromboplastin time, anti-activated factor X and ACT), and ACT measurement devices were selected. Heparin has a non-predictable effect in the individual patient, which could be measured using the ACT. However, ACT values can be influenced by many factors, such as hemodilution, hypothermia and thrombocytopenia. In addition, a high variation in ACT outcomes is found between measurement devices of different brands. In the sparse literature on the role of ACT during NCAP, no consensus has been reached on optimal target ACT values. An ACT >250 seconds leads to more bleeding complications. Females have a longer ACT after heparin administration, with a higher risk of bleeding complications. The effect of heparin is unpredictable. ACT can be used to monitor the effect of heparin and achieve individualized anticoagulation, tailored to the patient and the specifics of the operative procedure. However, the ACT itself can be affected by several factors and caution must be present, as measured ACT values differ between measurement devices.