Effect of heparin on secondary brain injury in patients with subarachnoid hemorrhage: an additional ‘H’ therapy in vasospasm treatment

Effects of low-dose intravenous heparin therapy in aneurysmal subarachnoid hemorrhage: a randomized controlled clinical trial protocol

BACKGROUND

Heparin anticoagulation therapy is a widely used method to prevent cerebral vasospasm (CV) and venous thrombosis in patients with subarachnoid hemorrhage caused by ruptured cerebral aneurysms. Subcutaneous heparin injection is considered safe and effective, whereas continuous intravenous heparin infusion is still being debated due to the risk of bleeding. Although most retrospective studies have confirmed the safety and effectiveness of unfractionated heparin (UFH) after aneurysm embolization therapy and its ability to reduce CV, there is still no randomized clinical trial comparing UFH and subcutaneous low-molecular-weight heparin (LMWH) injection in this population. Therefore, this study aims to compare the clinical outcomes associated with these two treatment approaches.

METHODS

The study is an open-label, single-center, randomized controlled trial and aims to recruit 456 patients, with 228 patients in each group. The primary outcome was CV; the second outcomes measures are occurrence of bleeding events, ischemic events, heparin-induced thrombocytopenia, deep vein thrombosis, cerebral venous circulation time, brain edema score, and hydrocephalus incidence.

ETHICS AND DISSEMINATION

This study protocol obtained ethical approval from the Ethics Committee of Baoan People's Hospital, Shenzhen, Guangdong (approval number: BYL20220805). This work will be published in peer-reviewed international medical journals and presented at medical conferences.

TRIAL REGISTRATION

ClinicalTrials ID: NCT05696639. Registered on March 30, 2023.

Association between external ventricular drain removal or replacement and prophylactic anticoagulation in patients with aneurysmal subarachnoid hemorrhage: a propensity-adjusted analysis

BACKGROUND

Withholding prophylactic anticoagulation from patients with aneurysmal subarachnoid hemorrhage (aSAH) before external ventricular drain (EVD) removal or replacement remains controversial. This study analyzed whether prophylactic anticoagulation was associated with hemorrhagic complications related to EVD removal.

METHOD

All aSAH patients treated from January 1, 2014, to July 31, 2019, with an EVD placed were retrospectively analyzed. Patients were compared based on the number of prophylactic anticoagulant doses withheld for EVD removal (> 1 vs. ≤ 1). The primary outcome analyzed was deep venous thrombosis (DVT) or pulmonary embolism (PE) after EVD removal. A propensity-adjusted logistic-regression analysis was performed for confounding variables.

RESULTS

A total of 271 patients were analyzed. For EVD removal, > 1 dose was withheld from 116 (42.8%) patients. Six (2.2%) patients had a hemorrhage associated with EVD removal, and 17 (6.3%) patients had a DVT or PE. No significant difference in EVD-related hemorrhage after EVD removal was found between patients with  > 1 versus ≤ 1 dose of anticoagulant withheld (4 of 116 [3.5%] vs. 2 of 155 [1.3%]; p = 0.41) or between those with no doses withheld compared to ≥ 1 dose withheld (1 of 100 [1.0%] vs. 5 of 171 [2.9%]; p = 0.32). After adjustment, withholding > 1 dose of anticoagulant versus ≤ 1 dose was associated with the occurrence of DVT or PE (OR 4.8; 95% CI, 1.5-15.7; p = 0.009).

CONCLUSIONS

In aSAH patients with EVDs, withholding > 1 dose of prophylactic anticoagulant for EVD removal was associated with an increased risk of DVT or PE and no reduction in catheter removal-associated hemorrhage.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

Microclots in subarachnoid hemorrhage: an underestimated factor in delayed cerebral ischemia?

Subarachnoid hemorrhage has a poor prognosis due to the wide array of associated complications such as vasospasm, early brain injury, cortical spreading depression, oxidative stress, inflammation, and apoptosis. Each of these complications increases the risk of delayed cerebral ischemia (DCI), but recent research has suggested microclots play a substantial role in DCI incidence. This review will focus on the underlying inflammatory and coagulative mechanisms of microthrombosis while also outlining the current literature relating microclot burden to DCI. With a better understanding DCI pathophysiology as it relates to microthrombosis, more effective therapies can be developed in the future to improve clinical outcomes of SAH.

Heparin in the treatment of aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

OBJECTIVE

Cerebral vasospasm and the resulting infarction remain the most devastating complications of aneurysmal subarachnoid hemorrhage (aSAH). Limited treatment options are available, with nimodipine as the only approved prophylactic medication. In addition to its anticoagulant properties, heparin also has a pleiotropic and anti-inflammatory effect that could be beneficial in vasospasm. In this study, the authors sought to evaluate the efficacy and safety of heparin in the treatment of aSAH.

METHODS

The PubMed, EBSCOhost, Europe PMC, and Cochrane Central databases were searched to find studies including patients with aSAH who were treated with intravenous unfractionated heparin (UFH) after an aneurysm-securing procedure. Studies that did not include a comparison with UFH or low-molecular-weight heparin in deep vein thrombosis prophylactic doses were excluded. The primary outcome was cerebral vasospasm, and the secondary outcomes were cerebral infarction, clinical deterioration caused by delayed cerebral ischemia, bleeding complications, and thromboembolism complications.

RESULTS

Overall, 5 nonrandomized studies were included; 4 studies evaluated the safety and 3 studies evaluated the efficacy of intravenous heparin. From the analysis of 3 studies with a total of 895 patients, administration of intravenous UFH for > 48 hours was related to a significantly lower rate of cerebral infarction (OR 0.44, 95% CI 0.25–0.79). No significant association was found with other efficacy outcomes. Regarding cognitive outcome, one study found a significant improvement in Montreal Cognitive Assessment scores; however, the functional outcome as indicated by the modified Rankin Scale score was not improved by heparin administration. From the analysis of 4 studies with 1099 patients, no significant increases in bleeding and other complications were found.

CONCLUSIONS

Administration of intravenous UFH for more than 48 hours reduced the rate of cerebral infarction with a good safety profile. This result supports the ongoing clinical trial.

Hemostasis and Fibrinolysis following Aneurysmal Subarachnoid Hemorrhage: A Systematic Review on Additional Knowledge from Dynamic Assays and Potential Treatment Targets

Mortality after aneurysmal subarachnoid hemorrhage (aSAH) is augmented by rebleeding and delayed cerebral ischemia (DCI). A range of assays evaluating the dynamic process of blood coagulation, from activation of clotting factors to fibrinolysis, has emerged and a comprehensive review of hemostasis and fibrinolysis following aSAH may reveal targets of treatment. We conducted a systematic review of existing literature assessing coagulation and fibrinolysis following aSAH, but prior to treatment. PubMed, Embase, and Web of Science were searched on November 18, 2020, without time boundaries. In total, 45 original studies were eventually incorporated into this systematic review, divided into studies presenting data only from conventional or quantitative assays (n = 22) and studies employing dynamic assays (n = 23). Data from conventional or quantitative assays indicated increased platelet activation, whereas dynamic assays detected platelet dysfunction possibly related to an increased risk of rebleeding. Secondary hemostasis was activated in conventional, quantitative, and dynamic assays and this was related to poor neurological outcome and mortality. Studies systematically investigating fibrinolysis were sparse. Measurements from conventional or quantitative assays, as well as dynamic fibrinolysis assays, revealed conflicting results with normal or increased lysis and changes were not associated with outcome. In conclusion, dynamic assays were able to detect reduced platelet function, not revealed by conventional or quantitative assays. Activation of secondary hemostasis was found in both dynamic and nondynamic assays, while changes in fibrinolysis were not convincingly demonstrable in either dynamic or conventional or quantitative assays. Hence, from a mechanistic point of view, desmopressin to prevent rebleeding and heparin to prevent DCI may hold potential as therapeutic options. As changes in fibrinolysis were not convincingly demonstrated and not related to outcome, the use of tranexamic acid prior to aneurysm closure is not supported by this review.

Early prophylactic anticoagulation after subarachnoid hemorrhage decreases systemic ischemia and improves outcome

BACKGROUND

In neurosurgical perioperative treatment, especially in connection with subarachnoid hemorrhage (SAH), the prophylactic anticoagulation (AC) regimen is still considered controversial. The goal of this retrospective study was to assess how the time point of low-molecular-weight heparin (LMWH) initiation (ToH) affects ischemic and hemorrhagic events after SAH.

METHODS

370 patients who received acute treatment for non-traumatic SAH between 2011 and 2018 were included, and 208 patients were followed up after 12 months. We assessed how the ToH affects ischemic and hemorrhagic events as well as outcome scores. Statistical analysis was performed using the Mann-Whitney U-Test, the chi-squared test, Fisher's exact test, and univariate binomial logistic regression. P-values below 0.05 were considered statistically significant.

RESULTS

The incidence of systemic ischemia was 4.6%, cerebral ischemia 33.5%, and intracranial rebleeding 14.6%. Delaying ToH (measured in hours) increases systemic ischemia (p = 0.009). The odds ratio for the impact of delayed anticoagulation on systemic ischemia is 1.013 per hour (95%CI of OR 1.001-1.024). ToH has no influence on cerebral ischemia or intracranial rebleeding. Early anticoagulation was associated with a more favorable Glasgow Outcome Score 12 months after discharge (ToH within 48 h: p = 0.006). ToH did not affect mortality or readmission rates.

CONCLUSIONS

Initiating prophylactic AC with LMWH later than 48 h after aneurysm repair or admission impairs outcomes 12 months after discharge. It might be safe for patients with non-traumatic SAH to be anticoagulated with prophylactic doses of heparin within 24 h after admission or the treatment of source of bleeding (SoB). Early AC with prophylactic LMWH does not promote rebleeding.

Low-Dose Intravenous Heparin Infusion After Aneurysmal Subarachnoid Hemorrhage is Associated With Decreased Risk of Delayed Neurological Deficit and Cerebral Infarction

BACKGROUND

Patients who survive aneurysmal subarachnoid hemorrhage (aSAH) are at risk for delayed neurological deficits (DND) and cerebral infarction. In this exploratory cohort comparison analysis, we compared in-hospital outcomes of aSAH patients administered a low-dose intravenous heparin (LDIVH) infusion (12 U/kg/h) vs those administered standard subcutaneous heparin (SQH) prophylaxis for deep vein thrombosis (DVT; 5000 U, 3 × daily).

OBJECTIVE

To assess the safety and efficacy of LDIVH in aSAH patients.

METHODS

We retrospectively analyzed 556 consecutive cases of aSAH patients whose aneurysm was secured by clipping or coiling at a single institution over a 10-yr period, including 233 administered the LDIVH protocol and 323 administered the SQH protocol. Radiological and outcome data were compared between the 2 cohorts using multivariable logistic regression and propensity score-based inverse probability of treatment weighting (IPTW).

RESULTS

The unadjusted rate of cerebral infarction in the LDIVH cohort was half that in SQH cohort (9 vs 18%; P = .004). Multivariable logistic regression showed that patients in the LDIVH cohort were significantly less likely than those in the SQH cohort to have DND (odds ratio (OR) 0.53 [95% CI: 0.33, 0.85]) or cerebral infarction (OR 0.40 [95% CI: 0.23, 0.71]). Analysis following IPTW showed similar results. Rates of hemorrhagic complications, heparin-induced thrombocytopenia and DVT were not different between cohorts.

CONCLUSION

This cohort comparison analysis suggests that LDIVH infusion may favorably influence the outcome of patients after aSAH. Prospective studies are required to further assess the benefit of LDIVH infusion in patients with aSAH.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

Safety of heparin loading during endovascular embolization in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

Of the complications that can occur during endovascular surgery in aneurysmal subarachnoid hemorrhage (aSAH) patients, thromboembolism remains a particular challenge for many surgeons. Heparin has been widely used for its prevention, but it has not been able to eliminate concerns about bleeding. Therefore, in this study, we tried to determine the risk of rebleeding associated with heparin use.

METHODS

We retrospectively analyzed the medical and surgical records of 109 patients that underwent endovascular embolization for a ruptured cerebral aneurysm at a single institution from 2010 to 2014. These patients were divided into two groups according to whether heparin was loaded or not, to determine the effect of heparin on rebleeding and to identify other risk factors of rebleeding.

RESULTS

This series included 40 men (36.7 %) and 69 women (63.3 %) of mean age 57.9 ± 14.8 years. In 80 patients (73.4 %), endovascular embolization was conducted using an intraoperative bolus of 5000 units of heparin, whereas in the other 29 (26.6 %) endovascular embolization was performed without an intraoperative heparin bolus. After procedures, 16 patients (14.7 %) experienced rebleeding and 2 (1.8 %) a thromboembolic event. Intraoperative heparin loading (OR 0.683 [95 % CI 0.199-2.338]) was not found to be related to postoperative rebleeding. Rather, logistic regression analysis showed preoperative modified Fisher grade (OR 2.037 [95 % CI 1.077-3.853]) and external ventricular drainage (OR 5.389 [95 % CI 1.171-24.801]) independently predicted rebleeding.

CONCLUSIONS

Heparin loading during endovascular treatment of ruptured cerebral aneurysms did not affect rebleeding. We conclude heparin loading to prevent thromboembolism during endovascular treatment may be considered a good option in aSAH patients.

Post-treatment Antiplatelet Therapy Reduces Risk for Delayed Cerebral Ischemia due to Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) has a strong impact on outcome of patients with aneurysmal subarachnoid hemorrhage (SAH). Positive effect of antiplatelet therapy on DCI rates has been supposed upon smaller SAH series.

OBJECTIVE

To analyze the benefit/risk profile of antiplatelet use in SAH patients.

METHODS

This retrospective case-control study was based on institutional observational cohort with 994 SAH patients treated between January 2003 and June 2016. The individuals with postcoiling antiplatelet therapy (aspirin with/without clopidogrel) were compared to a control group without antiplatelet therapy. Occurrence of DCI, major/minor bleeding events in the follow-up computed tomography scans, and favorable outcome at 6 mo after SAH (modified Rankin scale < 3) were compared in both groups.

RESULTS

Of 580 patients in the final analysis, 329 patients received post-treatment antiplatelet medication. There were no significant differences between the compared groups with regard to basic outcome confounders. Aspirin use was independently associated with reduced DCI risk (P < .001, adjusted odds ratio = 0.41, 95% confidence interval 0.24-0.65) and favorable outcome (P = .02, adjusted odds ratio = 1.78, 95% confidence interval 1.06-2.98). Regarding bleeding complications, aspirin was associated only with minor bleeding events (P = .02 vs P = .51 for major bleeding events).

CONCLUSION

Regular administration of aspirin might have a positive impact on DCI risk and outcome of SAH patients, without increasing the risk for clinically relevant bleeding events. In our SAH cohort, dual antiplatelet therapy showed no additional benefit on DCI risk, but increased the likelihood of major bleeding events.

Admission neutrophil–lymphocyte ratio predicts delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Background

Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) has a multifactorial pathophysiology, with immune dysregulation being an important component. The neutrophil–lymphocyte ratio (NLR) is an established prognostic marker in patients with cancer, cardiac disease, and sepsis.

Objective

To determine whether there is a relationship between NLR and DCI in patients with aSAH.

Methods

We evaluated 1067 patients with aSAH between 2006 and 2015 enrolled in a single-center, prospective, observational cohort study. Admission white blood cell differentials (NLR) were analyzed using a cut-off point of ≥5.9. DCI from cerebral vasospasm was defined as the occurrence of focal neurological impairment, or a decrease in at least two points on the Glasgow Coma Scale, which was not apparent immediately after aneurysm occlusion, and could not be attributed to other causes. Cerebral infarct was defined as a new infarct on CT that was not visible on the admission or immediate postoperative scan, when the cause was thought to be vasospasm by the research team. Logistic regression models were generated.

Results

We found that 768 (72%) patients had an admission NLR ≥5.9. In a multivariable model, elevated NLR was associated with poor admission Hunt-Hess grade (OR=1.6, 95% CI 1.2 to 2.6, p=0.005), Caucasian ethnicity (OR=2.6, 95% CI 1.9 to 3.7, p<0.001), anterior aneurysm location (OR=1.7, 95% CI 1.2 to 2.4, p=0.004), loss of consciousness at ictus (OR=1.4, 95% CI 1.0 to 2.0, p=0.055), and thick SAH (modified Fisher grade ≥3) (OR=1.8, 95% CI 1.3 to 2.4, p<0.001). Admission NLR predicted development of delayed cerebral ischemia (DCI) (OR=1.7; 95% CI 1.1 to 2.5, p=0.008) after controlling for known predictors such as age, poor admission clinical grade, thick SAH blood, and elevated admission mean arterial pressure.

Conclusions

This study provides further evidence of the association between inflammation and DCI. Admission NLR is a readily available and convenient biomarker that may be a clinically useful tool for prognostication when evaluating aSAH.

Neuroanesthesiology Update

We provide a synopsis of innovative research, recurring themes, and novel experimental findings pertinent to the care of neurosurgical patients and critically ill patients with neurological diseases. We cover the following broad topics: general neurosurgery, spine surgery, stroke, traumatic brain injury, monitoring, and anesthetic neurotoxicity.

Low-Dose versus Therapeutic Range Intravenous Unfractionated Heparin Prophylaxis in the Treatment of Patients with Severe Aneurysmal Subarachnoid Hemorrhage After Aneurysm Occlusion

BACKGROUND

While prophylaxis with intravenous unfractionated heparin (UFH) can effectively prevent venous thromboembolism (VTE) during the neurocritical care of patients with severe aneurysmal subarachnoid hemorrhage (aSAH), the risk for intracranial bleeding complications might increase. Owing to this therapeutic dilemma, the UFH administration regimen in this critical patient population remains highly controversial.

METHODS

We performed a retrospective analysis of patients with severe aSAH (Fisher grade 3-4) receiving either low-dose (activated partial thromboplastin time [aPTT] <40 seconds) or therapeutic range (aPTT 50-60 seconds) UFH during intensive care unit (ICU) treatment after complete surgical/endovascular aneurysm occlusion. The primary outcome was the rate of bleeding/VTE complications and the investigation of potential risk factors.

RESULTS

This study series comprised 410 patients with aneurysmal SAH (aSAH), with a mean age of 54.7 ± 12.6 years, a male:female ratio of 1:2.2, and aSAH-associated intracerebral hemorrhage (ICH) in 33.2%. After complete aneurysm occlusion, 112 patients (27.3%) received therapeutic dose UFH and 298 patients (72.7%) received low-dose UFH. VTE events occurred in 5.4% of the low-dose UFH cohort and in 6.3% of the therapeutic dose UFH cohort, with no significant differences in the rate and severity of VTE events. However, an increase in initial SAH-associated ICH was significantly (P = 0.007) more frequent in the therapeutic dose cohort (18.8% vs. 3.4%). Heparin-induced thrombocytopenia (HIT) was the sole risk factor for VTE (P < 0.001), and both an aPTT ≥50 seconds under UFH administration (P = 0.007) and the initial presence of SAH-associated ICH (P = 0.035) were significant risk factors for intracranial bleeding complications.

CONCLUSIONS

Even in high-risk neurocritical patients with severe SAH and prolonged ICU treatment, low-dose UFH-administration for VTE prophylaxis is equally effective as therapeutic UFH administration and carries a lower risk of bleeding complications.

Successful use of continuous vasodilator infusion to treat critical vasospasm threatening a distal bypass

Vasospasm immediately after lower extremity arterial bypass may represent an uncommon cause of early graft failure. We report a successful case of catheter-directed, intra-arterial continuous vasodilator infusion to salvage a bypass graft threatened by severe, refractory vasospasm after incomplete response to nicardipine, verapamil, and nitroglycerin boluses. A continuous nitroglycerin infusion was administered for 24 hours, by which time the vasospasm resolved. At 12 months postoperatively, the graft remained patent with normal results of vascular laboratory studies. This report demonstrates that in cases of refractory vasospasm after peripheral bypass, continuous vasodilator infusion can be an effective treatment to prevent early graft failure.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.