Individual Differences in Heparin Sensitivity and Their Effect on Heparin Anticoagulation During Arterial Vascular Surgery

Hypercoagulable state and effect of low-molecular-weight heparin prophylaxis on coagulation after lung cancer resection: results from thrombo-elastography

BACKGROUND

Lung cancer patients undergoing surgery are at increased risk for Venous thromboembolism (VTE). We monitored changes in perioperative coagulation status through Thrombo-elastography (TEG), and monitored the anticoagulant effect of low molecular weight heparin through TEG for the first time.

METHODS

From July 2019 to January 2020, 207 patients receiving curative surgery were retrospectively screened. and 23 patients were excluded because they did not meet the inclusion criteria. Blood samples were required at three time points (prior to, the first and third day after surgery). Some patients were administrated nadroparin calcium daily from the first day after surgery. Repeated measures ANOVA and Chi-square test were used to analyze the coagulation states variation. To balance the confounders, propensity score matching (PSM) was used to determine the differences of coagulation states between patients with or without Low-molecular-weight heparin (LMWH) prophylaxis.

RESULTS

In 184 patients, TEG parameters displayed significant procoagulant changes after lung surgery but conventional coagulation tests exhibited paradoxical trends. There were 6.5% (12/184) of patients identified as hypercoagulability before surgery. According to TEG results, the proportion of patients with hypercoagulability rose from 21.7% to 25% postoperatively, but more were classified into platelet or mixed hypercoagulability at third day compared with that at first day (3.8% vs 14.1%, P < 0.001). By PSM analysis, there were no significant differences in the proportion of hypercoagulable patients postoperatively between chemoprophylactic and nonprophylactic group.

CONCLUSIONS

TEG was eligible to distinguish changing states of hypercoagulability postoperatively and indicate the role of platelet in blood hypercoagulability. Administration of postoperative LMWH prophylaxis showed little mitigation on hypercoagulable states.

Development and Validation of a Nomogram for Predicting Heparin Resistance in Neonates and Young Infants Undergoing Cardiac Surgery: A Retrospective Study

BACKGROUND

Heparin resistance (HR) is a common finding in pediatric cardiac surgery and generally refers to decreased sensitivity to heparin. Antithrombin (AT) deficiency is considered the primary mechanism of HR; however, the etiology of HR may be multifactorial. Early identification of HR might help optimize heparin anticoagulation management. This study aimed to develop a predictive nomogram for HR in neonates and young infants undergoing cardiac surgery.

METHODS

From January 2020 to August 2022, a total of 296 pediatric patients 1 to 180 days of age were included in this retrospective study. The patients were randomly divided into development and validation cohorts in a 7:3 ratio. Univariable logistic regression and the Least Absolute Shrinkage and Selection Operator (LASSO) regularization were used for variable selection. A multivariable logistic regression was performed to identify predictors and establish a nomogram to predict HR risk. Discrimination, calibration, and clinical usefulness were assessed in the development and validation cohorts.

RESULTS

After the multistep variable selection, AT activity, platelet count, and fibrinogen were predictors for HR in neonates and young infants. The prediction model constructed using these 3 factors achieved an area under the receiver operating characteristic curve (ROC-AUC) of 0.874 and 0.873 in the development and validation cohorts. The Hosmer-Lemeshow test did not find evidence of a lack of fit ( P = .768). The calibration curve of the nomogram was close to the ideal diagonal line. Furthermore, the model performed well in neonate and infant subgroups.

CONCLUSIONS

A nomogram based on preoperative variables was developed to predict the HR risk in neonates and young infants undergoing cardiac surgery. This provides clinicians with a simple tool for the early prediction of HR, which may help optimize heparin anticoagulation strategies in this vulnerable patient population.

Unfractionated heparin and the activated clotting time in non-cardiac arterial procedures

INTRODUCTION

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.

EVIDENCE ACQUISITION

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.

EVIDENCE SYNTHESIS

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.

CONCLUSIONS

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.

Activity of anticoagulant proteins on the polymer-coated and heparin-coated membranes in an extracorporeal circulation circuit

INTRODUCTION

We performed in vitro experiments using whole human blood without anticoagulants to clarify the activity of anticoagulant proteins on membranes coated with acrylate-copolymer (ACP) with a hydrophilic blood-contacting layer compared to those coated by immobilizing heparin (IHP) in extracorporeal circulation.

METHODS

Whole human blood from healthy volunteers was recirculated in two types of experimental circuits with an ACP-coated reservoir and tubes and an ACP-coated or IHP-coated membrane. To compare the fluctuation of anticoagulant proteins, the circuit pressure at the inlet and outlet of the membrane was measured every 5 min; antithrombin antigen (ATQ), antithrombin activity, protein-C quantitation (PCQ), protein-C activity, protein-S free antigen (PSQ), and protein-S activity were measured at 0, 30, 60, 120, and 180 min in each experiment (n = 5).

RESULTS

The time taken to achieve high circuit pressure (> 300 mmHg) at the inlet of the membrane was significantly shorter in the ACP-coated membrane circuit (28 ± 2.7 min) than in the IHP-coated membrane circuit (54 ± 24 min); however, the ATQ, PCQ, and PSQ at 180 min of recirculation were significantly higher in the former than in the latter (all p < .05).

CONCLUSIONS

ACP-coated membranes can prevent the consumption of anticoagulant proteins but cannot delay circuit thrombogenicity compared to IHP-coated membranes. Considering patient care during the post-extracorporeal circulation period, the use of ACP coating, which can preserve anticoagulant protein, is better in extracorporeal circulation circuits.

Editor's Choice - Sex Differences in Response to Administration of Heparin During Non-Cardiac Arterial Procedures

OBJECTIVE

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.

METHODS

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).

RESULTS

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).

CONCLUSION

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.

Postoperative Intensive Care Management of Aortic Repair

Vascular surgery patients have multiple comorbidities and are at high risk for perioperative complications. Aortic repair surgery has greatly evolved in recent years, with an increasing predominance of endovascular techniques (EVAR). The incidence of cardiac complications is significantly reduced with endovascular repair, but high-risk patients require postoperative ST-segment monitoring. Open aortic repair may portend a prohibitive risk of respiratory complications that could be a contraindication for surgery. This risk is greatly reduced in the case of an endovascular approach, and general anesthesia should be avoided whenever possible in the case of endovascular repair. Preoperative renal function and postoperative kidney injury are powerful determinants of short- and long-term outcome, so that preoperative risk stratification and secondary prevention are critical tasks. Intraoperative renal protection with selective renal and distal aortic perfusion is essential during open repair. EVAR has lower rates of postoperative renal failure compared to open repair, with approximately half the risk for acute kidney injury (AKI) and one-third of the risk of hemodialysis requirement. Spinal cord ischemia used to be the most distinctive and feared complication of aortic repair. The risk has significantly decreased since the beginning of aortic surgery, with advances in surgical technique and spinal protection protocols, and is lower with endovascular repair. Endovascular repair avoids extensive aortic dissection and aortic cross-clamping and is generally associated with reduced blood loss and less coagulopathy. The intensive care physician must be aware that aortic repair surgery has an impact on every organ system, and the importance of early recognition of organ failure cannot be overemphasized.

ACTION-1: study protocol for a randomised controlled trial on ACT-guided heparinization during open abdominal aortic aneurysm repair

BACKGROUND

Heparin is used worldwide for 70 years during all non-cardiac arterial procedures (NCAP) to reduce thrombo-embolic complications (TEC). But heparin also increases blood loss causing possible harm for the patient. Heparin has an unpredictable effect in the individual patient. The activated clotting time (ACT) can measure the effect of heparin. Currently, this ACT is not measured during NCAP as the standard of care, contrary to during cardiac interventions, open and endovascular. A RCT will evaluate if ACT-guided heparinization results in less TEC than the current standard: a single bolus of 5000 IU of heparin and no measurements at all. A goal ACT of 200-220 s should be reached during ACT-guided heparinization and this should decrease (mortality caused by) TEC, while not increasing major bleeding complications. This RCT will be executed during open abdominal aortic aneurysm (AAA) surgery, as this is a standardized procedure throughout Europe.

METHODS

Seven hundred fifty patients, who will undergo open AAA repair of an aneurysm originating below the superior mesenteric artery, will be randomised in 2 treatment arms: 5000 IU of heparin and no ACT measurements and no additional doses of heparin, or a protocol of 100 IU/kg bolus of heparin and ACT measurements after 5 min, and then every 30 min. The goal ACT is 200-220 s. If the ACT after 5 min is < 180 s, 60 IU/kg will be administered; if the ACT is between 180 and 200 s, 30 IU/kg. If the ACT is > 220 s, no extra heparin is given, and the ACT is measured after 30 min and then the same protocol is applied. The expected incidence for the combined endpoint of TEC and mortality is 19% for the 5000 IU group and 11% for the ACT-guided group.

DISCUSSION

The ACTION-1 trial is an international RCT during open AAA surgery, designed to show superiority of ACT-guided heparinization compared to the current standard of a single bolus of 5000 IU of heparin. A significant reduction in TEC and mortality, without more major bleeding complications, must be proven with a relevant economic benefit. TRIAL REGISTRATION {2A}: NTR NL8421 ClinicalTrials.gov NCT04061798 . Registered on 20 August 2019 EudraCT 2018-003393-27 TRIAL REGISTRATION: DATA SET {2B}: Data category Information Primary registry and trial identifying number ClinicalTrials.gov : NCT04061798 Date of registration in primary registry 20-08-2019 Secondary identifying numbers NTR: NL8421 EudraCT: 2018-003393-27 Source(s) of monetary or material support ZonMw: The Netherlands Organisation for Health Research and Development Dijklander Ziekenhuis Amsterdam UMC Primary sponsor Dijklander Ziekenhuis Secondary sponsor(s) N/A Contact for public queries A.M. Wiersema, MD, PhD Arno@wiersema.nu 0031-229 208 206 Contact for scientific queries A.M. Wiersema, MD, PhD Arno@wiersema.nu 0031-229 208 206 Public title ACT Guided Heparinization During Open Abdominal Aortic Aneurysm Repair (ACTION-1) Scientific title ACTION-1: ACT Guided Heparinization During Open Abdominal Aortic Aneurysm Repair, a Randomised Trial Countries of recruitment The Netherlands. Soon the recruitment will start in Germany Health condition(s) or problem(s) studied Abdominal aortic aneurysm, arterial disease, surgery Intervention(s) ACT-guided heparinization 5000 IU of heparin Key inclusion and exclusion criteria Ages eligible for the study: ≥18 years Sexes eligible for the study: both Accepts healthy volunteers: no Inclusion criteria: Study type Interventional Allocation: randomized Intervention model: parallel assignment Masking: single blind (patient) Primary purpose: treatment Phase IV Date of first enrolment March 2020 Target sample size 750 Recruitment status Recruiting Primary outcome(s) The primary efficacy endpoint is 30-day mortality and in-hospital mortality during the same admission. The primary safety endpoint is the incidence of bleeding complications according to E-CABG classification, grade 1 and higher. Key secondary outcomes Serious complications as depicted in the Suggested Standards for Reports on Aneurysmal disease: all complications requiring re-operation, longer hospital stay, all complications.

A Standardized Bolus of 5 000 IU of Heparin Does not Lead to Adequate Heparinization during Non-cardiac Arterial Procedures

BACKGROUND

In non-cardiac arterial procedures (NCAP), heparin is administered to prevent arterial thromboembolic complications (ATEC). Heparin has a nonpredictable effect in the individual patient, also known as variation in heparin sensitivity. Various dosing protocols are in use, but the optimal dose is currently still unknown. A standardized bolus of 5 000 IU heparin is most frequently used by vascular surgeons and interventional radiologists. The activated clotting time (ACT) is an established method to measure the level of anticoagulation, but has, until now, not gained widespread use in NCAP. The purpose of this study was to evaluate the anticoagulant effect during NCAP of a standardized bolus of 5 000 IU heparin by measuring the ACT.

METHODS

In this prospective study, 190 patients undergoing NCAP were enrolled between December 2016 and September 2018. The ACT was measured during open and endovascular/hybrid procedures. All patients received a standardized bolus of 5 000 IU heparin. The ACT was measured by the Hemostasis Management System Plus (HMS Plus, Medtronic®), before, 5 minutes after administration of heparin, and every 30 minutes thereafter. The primary outcome was periprocedural ACT values measured. Secondary outcomes were ATEC and hemorrhagic complications.

RESULTS

A large individual patient variability in the response to heparin was found. The mean baseline ACT in all patients was 129 ± 18 s., and the mean ACT 5 minutes after the initial bolus of heparin was 191 ± 36 s. After the initial dose of 5 000 IU heparin 60 (33%) and 10 (6%) patients reached an ACT of 200 and 250 s., respectively. Despite the use of heparin, ATEC occurred in 17 patients (9%). The lowest number of ATEC occurred in the group of patients with an ACT between 200 and 250 s.

CONCLUSIONS

A standardized bolus of 5 000 IU heparin does not lead to adequate and safe heparinization in non-cardiac arterial procedures. Patient response to heparin shows a large individual variability. Therefore, routine ACT measurements are necessary to ascertain adequate anticoagulation. Further research is needed to investigate if heparin dosing based on the ACT could result in less arterial thromboembolic complications, without increasing hemorrhagic complications.

Anticoagulant Effect of Standard Dose Heparin During Peripheral Endovascular Intervention

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.