Blood coagulation and fibrinolysis after experimental subarachnoid hemorrhage

Adverse events during endovascular treatment of ruptured aneurysms: A prospective nationwide study on subarachnoid hemorrhage in Sweden

Introduction

A range of adverse events (AEs) may occur in patients with subarachnoid hemorrhage (SAH). Endovascular treatment is commonly used to prevent aneurysm re-rupture.

Research question

The aim of this study was to identify AEs related to endovascular treatment, analyze risk factors for AEs and how AEs affect patient outcome.

Material and methods

Patients with aneurysmal SAH admitted to all neurosurgical centers in Sweden during a 3.5-year period (2014-2018) were prospectively registered. AEs related to endovascular aneurysm treatment were thromboembolic events, aneurysm re-rupture, vessel dissection and puncture site hematoma. Potential risk factors for the AEs were analyzed using multivariate logistic regression. Functional outcome was assessed at one year using the extended Glasgow outcome scale.

Results

In total, 1037 patients were treated for ruptured aneurysms. Of which, 715 patients were treated with endovascular occlusion. There were 115 AEs reported in 113 patients (16%). Thromboembolic events were noted in 78 patients (11%). Aneurysm re-rupture occurred in 28 (4%), vessel dissection in 4 (0.6%) and puncture site hematoma in 5 (0.7%). Blister type aneurysm, aneurysm smaller than 5 mm and endovascular techniques other than coiling were risk factors for treatment-related AEs. At follow-up, 230 (32%) of the patients had unfavorable outcome. Patients suffering intraprocedural aneurysm re-rupture were more likely to have unfavorable outcome (OR 6.9, 95% CI 2.3-20.9).

Discussion and conclusion

Adverse events related to endovascular occlusion of a ruptured aneurysm were seen in 16% of patients. Aneurysm re-rupture during endovascular treatment was associated with increased risk of unfavorable functional outcome.

Significant Slowed Cortical Venous Blood Flow in Patients with Acute Ischemic Stroke with Large Vessel Occlusion Suggests Poor Collateral Circulation and Prognosis

RATIONALE AND OBJECTIVES

To investigate the change of cortical venous flow in acute ischemic stroke patients with large vessel occlusion (LVO-AIS) and its clinical value.

MATERIALS AND METHODS

Baseline whole-brain 4D-CTA/CTP and clinical data of LVO-AIS and a control group were collected from June 2020 to October 2021. Venous inflow time (VIT), venous peak time (VPT), and venous outflow time (VOT) were analyzed on both sides of patients and normal controls. The VIT/VPT/VOT were statistically described and compared between the patient group and normal controls, then, in patients with different collateral circulation and prognoses. Next, the correlation between cortical venous drainage time and collateral circulation grading was analyzed. Finally, logistic regression analysis was used to explore the relationship between the three venous times and prognosis, and receiver operating characteristic (ROC) curves were plotted to assess the value of delayed cortical venous imaging in predicting prognosis.

RESULTS

149 LVO-AIS and 73 normal controls were collected. VIT, VPT, and VOT were significantly delayed on the affected side in the patient group compared with the healthy side (p<0.05) and the controls (p<0.05); VIT and VPT were also significantly delayed on the healthy side of patients compared with the controls (p<0.05). Delayed VIT and VPT on the affected side in the patient group were more significant in patients with poor collateral circulation (p<0.05), and VIT and VPT on the affected side in the patient group were negatively correlated with arterial collateral scores. VIT and VPT were significantly delayed in both sides of patients in the poor prognosis group compared with the good prognosis group (p<0.05). logistic regression showed that patients' affected VPT, arterial collateral scores, and NIHSS were independent predictors of poor prognosis, with an accuracy of 79.6% in predicting poor prognosis. The affected VPT and NIHSS were independent predictors of poor prognosis for patients presenting within 24 hours, with an accuracy of 79.6% in predicting poor prognosis.

CONCLUSION

Cortical venous flow was significantly slowed in both sides of LVO-AIS patients. delayed ipsilateral VPT in LVO-AIS patients can be used as an imaging indicator to determine poor collateral circulation and predict poor prognosis.

Predictors of deep-vein thrombosis in subarachnoid hemorrhage: a retrospective analysis

BACKGROUND

Subarachnoid hemorrhage is a severe subtype of hemorrhagic stroke, and deep-vein thrombosis is a frequent complication detected in these patients. In addition to other well-established risk factors, the early activation of coagulation systems present in patients with subarachnoid hemorrhage could potentially play a role in the incidence of deep-vein thrombosis. This study aims to identify possible predictors for deep-vein thrombosis related to subarachnoid hemorrhage.

METHODS

We conducted a retrospective cohort study on patients with a diagnosis of subarachnoid hemorrhage who presented to our institution between 1 January 2014 and 1 August 2018. We reviewed electronic medical records and analyzed several parameters such as Fisher scale, World Federation of Neurosurgical Surgeons scale, aneurysm site, surgical or endovascular treatment, decompressive craniectomy, vasospasm, infection (meningitis and pneumonia), presence of motor deficit, length of stay in the ICU, length of hospital stay, number of days under ventilator support, d-dimer at hospitalization, and the time to thromboprophylaxis (days).

RESULTS

The univariate analysis showed that intraparenchymal cerebral hemorrhage, d-dimer at hospitalization, the time to thromboprophylaxis, motor deficit, and aneurysm located at the internal carotid artery were statistically significant factors. Intraparenchymal cerebral hemorrhage (OR 2,78 95%CI 1.07-7.12), motor deficit (OR 3.46; 95%CI 1.37-9.31), and d-dimer at hospitalization (OR 1.002 95% CI 1.001-1.003) were demonstrated as independent risk factors for deep-vein thrombosis. Length of hospital stay was also found to be significantly longer in patients who developed deep-vein thrombosis (p value 0.018).

CONCLUSION

Elevated d-dimer level at the time of hospitalization, motor deficit, and the presence of an intraparenchymal hemorrhage are independent risk factors for deep-vein thrombosis. Patients with DVT also had a significantly longer hospital stay. Even though further studies are needed, patients with elevated d-dimer at hospitalization and intraparenchymal cerebral hemorrhage may benefit from a more aggressive screening strategy for deep-vein thrombosis.

Thromboelastography with Platelet Mapping Detects Platelet Dysfunction in Patients with Aneurysmal Subarachnoid Hemorrhage with Rebleeding

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) has high rates of disability and mortality, and aneurysm rebleeding is associated with poor functional outcomes. Thrombelastography with platelet mapping (TEG-PM) measures platelet function; however, it has not yet been researched in aSAH. We aimed to use TEG-PM to detect changes in platelet function in patients with aSAH and the difference in patients with and without rebleeding.

METHODS

We retrospectively included patients with aSAH who underwent a TEG-PM test on admission. Rebleeding was diagnosed according to clinical and imaging data. TEG-PM data of patients with unruptured intracranial aneurysms (UIA) were also obtained as controls. Univariate and multivariate logistic regression models were performed to investigate the relationship between the platelet function and rebleeding.

RESULTS

A total of 245 aSAH patients and 32 UIA patients were included in our study. Compared with controls, patients with aSAH demonstrated higher arachidonic acid (AA) and adenosine diphosphate (ADP) inhibition of platelet function (P<0.05). Among them, 27 patients with Hunt-Hess grade IV or V were classified as the severe SAH group. There was a significant correlation between the severe SAH group and the degree of pathway inhibition (P<0.05). Furthermore, AA (Spearman's r=0.264, P<0.001) and ADP (Spearman's r=0.183, P=0.004) inhibition were elevated in Hunt-Hess grade-dependent manners. The AA (Spearman's r=0.169, P=0.008) and ADP (Spearman's r=0.233, P<0.001) inhibition were also significantly correlated with Fisher grade. Thirty-five patients (14.3%) suffered rebleeding. Rebleeding was significantly correlated with systolic blood pressure (P=0.011), diastolic blood pressure (P=0.008), Hunt-Hess grade (P=0.034), Fisher grade (P=0.015), AA inhibition (P<0.001), and ADP inhibition (P<0.001). Multivariate logistic regression analysis model revealed that both AA (P=0.037) and ADP inhibition (P=0.008) were independent determinants for rebleeding.

CONCLUSION

TEG-PM may assess platelet dysfunction in patients with aSAH, and the diminished platelet response to ADP and AA may be associated with rebleeding. These findings deserve further investigation.

A Comparison of Diffusion-Weighted Imaging Abnormalities Following Balloon Remodeling for Aneurysm Coil Embolization in the Ruptured vs Unruptured Setting

BACKGROUND

The prothrombotic milieu seen in subarachnoid hemorrhage (SAH) poses a unique challenge to neurovascular surgeons with regard to device use and microcatheter practice.

OBJECTIVE

To determine how demographic factors and balloon practices impact diffusion-weighted imaging (DWI) abnormalities and outcomes in patients with SAH compared to those without (non-SAH).

METHODS

We retrospectively analyzed 77 patients with SAH treated by balloon-assisted coiling in a single institution compared with 81 consecutive patients with unruptured aneurysms treated by balloon-assisted coiling at the same institution. Data were collected with regard to demographic factors, procedural and anatomic considerations, and DWI abnormalities on postprocedural magnetic resonance imaging.

RESULTS

SAH patients were significantly more likely to have DWI abnormality (75% vs 21%, P < .0001) and had a higher number and volume of DWI (4.0 vs 3.0, P = .0421 and 1.3 vs 0.3 cc, P = .0041) despite similar balloon practices. SAH patients were not more likely to have DWI abnormality in vascular territory distal to the treated aneurysm but had a higher likelihood of DWI in a vascular territory unrelated to the aneurysm (81.5% vs 47.1%, P = .0235). Patients without DWI abnormality were significantly more likely to have a good outcome as defined by modified Rankin Score 0 to 2 (95.6% vs 81.6%, P = .0328). Patients with DWI abnormality more often underwent 4-vessel angiography (70.5% vs 48.0%, P = .0174), but this was not found to be significant on multivariate analysis.

CONCLUSION

Balloon-assisted coiling does not result in increased incidence of downstream ischemic events in SAH patients compared to non-SAH patients and is safe in this cohort of patients. Other factors, such as 4-vessel angiography of the SAH milieu itself, may predispose patients to a higher rate of ischemic events.

Thrombelastography Suggests Hypercoagulability in Patients with Renal Dysfunction and Intracerebral Hemorrhage

BACKGROUND

The objective of this study was to quantify coagulopathy using thrombelastography (TEG) in patients with renal dysfunction and intracerebral hemorrhage (ICH).

METHODS

We reviewed patients admitted with spontaneous ICH between November 2009 and May 2015. TEG was performed at the time of admission. Creatinine clearance (CCr) was calculated using the Cockroft-Gault equation. Patients were divided into 2 groups based on normal (CCr ≥ 90) or reduced renal function (CCr < 90). Multivariable regression models were conducted to compare the differences of TEG components.

RESULTS

A total of 120 patients were included in the analysis. The normal CCr group was younger (56.1 versus 62.3 years, P < .01), was more often male (73.6% versus 53.7%, P = .03), and had higher mean admission hemoglobin (14.2 versus 13.2 mEq/L, P < .01) than the reduced renal function group. The 2 groups were similar with respect to antiplatelet or anticoagulant use, coagulation studies, and baseline ICH volume. Following multivariate analysis, the reduced renal function group was found to have shorter K (1.5 versus 2.2 min, P = 004), increased angle (66 versus 62.2 degrees, P = .04), increased MA (67.3 versus 62.3, P = .02), and increased G (11.3 versus 9.9 dynes/cm², P = .04) compared with the normal group. Mortality, poor functional outcome (modified Rankin Scale score 4-6), hematoma enlargement, hospital length of stay, and surgical interventions were not different between the 2 groups.

CONCLUSIONS

Patients with ICH and reduced CCr display faster clotting rate and increased clot strength, suggesting that patients with renal dysfunction present with a relatively hypercoagulable state based on TEG parameters thought to reflect platelet activity.

Neurosurgical applications of viscoelastic hemostatic assays

Patients taking antithrombotic agents are very common in neurosurgical practice. The perioperative management of these patients can be extremely challenging especially as newer agents, with poorly defined laboratory monitoring and reversal strategies, become more prevalent. This is especially true with emergent cases in which rapid reversal of anticoagulation is required and the patient’s exact medical history is not available. With an aging patient population and the associated increase in diseases such as atrial fibrillation, it is expected that the use of these agents will continue to rise in coming years. Furthermore, thromboembolic complications such as deep venous thrombosis, pulmonary embolism, and myocardial infarction are common complications of major surgery. These trends, in conjunction with a growing understanding of the hemostatic process and its contribution to the pathophysiology of disease, stress the importance of the complete evaluation of a patient’s hemostatic profile in guiding management decisions. Viscoelastic hemostatic assays (VHAs), such as thromboelastography and rotational thromboelastometry, are global assessments of coagulation that account for the cellular and plasma components of coagulation. This FDA-approved technology has been available for decades and has been widely used in cardiac surgery and liver transplantation. Although VHAs were cumbersome in the past, advances in software and design have made them more accurate, reliable, and accessible to the neurosurgeon. VHAs have demonstrated utility in guiding intraoperative blood product transfusion, identifying coagulopathy in trauma, and managing postoperative thromboprophylaxis. The first half of this review aims to evaluate and assess VHAs, while the latter half seeks to appraise the evidence supporting their use in neurosurgical populations.

Elevated Red Cell Distribution Width is Associated with Cerebral Infarction in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Elevated red blood cell distribution width (RDW) has been associated with thrombotic disorders including myocardial infarction, venous thromboembolism, and ischemic stroke, independent of other inflammatory and coagulation biomarkers. The purpose of this study was to determine whether elevated RDW is associated with cerebral infarction and poor outcome after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

In this retrospective single-center cohort of aSAH patients (October 2009-September 2014), elevated RDW was defined as a mean RDW >14.5 % during the first 14 days after aSAH. Outcomes included cerebral infarction (CI) by any mechanism and poor functional outcome, defined as discharge modified Rankin Scale (mRS) >4, indicating severe disability or death.

RESULTS

Of 179 patients, 27 % had a high Hunt-Hess grade (IV-V), and 76 % were women. Twenty-four patients (13.4 %) underwent red blood cell (RBC) transfusion and compared to patients with normal RDW, patients with an elevated RDW were at greater odds of RBC transfusion (OR 2.56 [95 % CI, 1.07-6.11], p = 0.035). In univariate analysis, more patients with elevated RDW experienced CI (30.8 vs. 13.7 %, p = 0.017). In the multivariable model, elevated RDW was significantly associated with CI (OR 3.08 [95 % CI, 1.30-7.32], p = 0.011), independent of known confounders including but not limited to age, sex, race, high Hunt-Hess grade, and RBC transfusion. In multivariable analysis, RDW elevation was also associated with poor functional outcome (mRS > 4) at discharge (OR 2.59 [95 % CI, 1.04-629], p = 0.040).

CONCLUSIONS

RDW elevation is associated with cerebral infarction and poor outcome after aSAH. Further evaluation of this association is warranted as it may shed light on mechanistic relations between anemia, inflammation, and thrombosis after aSAH.

Thrombus remnant despite intra-arterial thrombolysis for thrombus formation during endovascular treatment of ruptured cerebral aneurysms: Does it harm?

BACKGROUND

The fate and safety of thrombus remnant despite intra-arterial thrombolysis for unexpected thrombus formation has rarely been reported.

METHODS

From January 2010 to May 2015, 131 consecutive patients with ruptured intracranial aneurysms were treated by endovascular methods at our institution. Among the 21 patients (16%) treated by intra-arterial thrombolysis for the thrombus formation during the procedure, nine patients (nine aneurysms) suffered from thrombus remnant. We reviewed the clinical and radiologic outcomes of patients with thrombus remnant as well as intraoperative and postoperative management of thrombus formation.

RESULTS

Thrombus formation occurred near the coiled aneurysm in eight patients, and distal embolic occlusion was observed in one patient. All nine patients were initially managed by intra-arterial thrombolysis with tirofiban. One patient with persistent distal embolic occlusion and two patients with distal migration of the thrombus after intra-arterial thrombolysis were additionally treated with stent retriever. One patient with occlusion of the parent artery near the coiled aneurysm despite intra-arterial thrombolysis was partially recanalized by permanent deployment of a stent retriever. Delayed cerebral angiography showed no increase in size of thrombus remnant in any patients. After the procedure, thrombus remnant was managed by intravenous tirofiban. Follow-up CT angiography on the first postoperative day showed patent arterial flow, and ischemic complication related with thromboembolism did not occur in any patients. One patient suffered from hemorrhagic complication.

CONCLUSION

If the patency of parent artery is maintained and the size of the thrombus remnant does not increase on delayed angiography after intra-arterial thrombolysis, postoperative thromboembolic events rarely occur.

Thromboelastography Parameter Predicts Outcome After Subarachnoid Hemorrhage: An Exploratory Analysis

OBJECTIVE

Hypercoagulability after subarachnoid hemorrhage (SAH) is well described and may be platelet mediated. Thromboelastography (TEG) provides a global assessment of coagulation. We sought to determine whether the maximum amplitude (MA) parameter of TEG, a measure of platelet strength and function, is associated with outcome after SAH.

METHODS

One hundred ten TEG analyses were performed for patients with moderate-to-severe SAH and compared with 6 healthy age- and sex-matched controls. TEG indices included MA, G value (G), alpha angle, and thrombus generation and were correlated to functional outcomes and laboratory tests including complete blood count, erythrocyte sedimentation rate, high sensitivity C-reactive protein, fibrinogen, and d-dimer, obtained on post-bleed days (PBDs) 1, 3, 5, 7, and 10.

RESULTS

MA was significantly elevated compared with controls on PBD 3 (70.0 mm ± 4.5 mm vs. 64.1 mm ± 6.5 mm; P = 0.02), PBD 5 (72.6 mm ± 5.3 mm vs. 64.1 mm ± 6.5 mm; P = 0.003), PBD 7 (73.0 mm ± 5.4 mm vs. 64.1 mm ± 6.5 mm; P = 0.003), and PBD 10 (73.4 mm ± 6.0 mm vs. 64.1 mm ± 6.5 mm; P = 0.005). G was significantly elevated compared with controls on PBD 3 (P = 0.03), PBD 5 (P = 0.01), PBD 7 (P = 0.01), and PBD 10 (P = 0.02). The only biomarker associated with poor outcome was CRP. Multivariate logistic regression demonstrated an association between elevated MA and outcome (odds ratio 39.1, P = 0.006) independent of CRP, age, Hunt Hess grade, and transfusion.

CONCLUSIONS

TEG indices are associated with poor outcome after SAH and may identify a platelet-mediated hypercoagulable state. The association between MA and outcome was stronger than that between traditional biomarkers and was independent of age and Hunt Hess grade.

The role of microclot formation in an acute subarachnoid hemorrhage model in the rabbit

Background. Microvascular dysfunction and microthrombi formation are believed to contribute to development of early brain injury (EBI) after aneurysmal subarachnoid hemorrhage (SAH). Objective. This study aimed to determine (i) extent of microthrombus formation and neuronal apoptosis in the brain parenchyma using a blood shunt SAH model in rabbits; (ii) correlation of structural changes in microvessels with EBI characteristics. Methods. Acute SAH was induced using a rabbit shunt cisterna magna model. Extent of microthrombosis was detected 24 h post-SAH (n = 8) by fibrinogen immunostaining, compared to controls (n = 4). We assessed apoptosis by terminal deoxynucleotidyl transferase nick end labeling (TUNEL) in cortex and hippocampus. Results. Our results showed significantly more TUNEL-positive cells (SAH: 115 ± 13; controls: 58 ± 10; P = 0.016) and fibrinogen-positive microthromboemboli (SAH: 9 ± 2; controls: 2 ± 1; P = 0.03) in the hippocampus after aneurysmal SAH. Conclusions. We found clear evidence of early microclot formation in a rabbit model of acute SAH. The extent of microthrombosis did not correlate with early apoptosis or CPP depletion after SAH; however, the total number of TUNEL positive cells in the cortex and the hippocampus significantly correlated with mean CPP reduction during the phase of maximum depletion after SAH induction. Both microthrombosis and neuronal apoptosis may contribute to EBI and subsequent DCI.

Effects of remote ischemic preconditioning on the coagulation profile of patients with aneurysmal subarachnoid hemorrhage: a case-control study

BACKGROUND

Animal studies suggest that ischemic preconditioning prolongs coagulation times.

OBJECTIVE

Because coagulation changes could hinder the translation of preconditioning into clinical settings where hemorrhage may be an issue, such as ischemic or hemorrhagic stroke, we evaluated the effects of remote ischemic preconditioning (RIPC) on coagulation in patients undergoing RIPC after aneurysmal subarachnoid hemorrhage (SAH).

METHODS

Twenty-one patients with SAH (mean age, 56.3 years) underwent 137 RIPC sessions 2 to 12 days after SAH, each consisting of 3 to 4 cycles of 5 to 10 minutes of lower limb ischemia followed by reperfusion. Partial thromboplastin time (PTT), prothrombin time (PT), and international normalized ratio (INR) were analyzed before and after sessions. Patients were followed for hemorrhagic complications.

RESULTS

No immediate effect was identified on PTT (mean pre-RIPC, 27.62 s; post-RIPC, 27.54 s; P = .82), PT (pre-RIPC, 10.77 s; post-RIPC, 10.81 s; P = .59), or INR (pre-RIPC, 1.030; post-RIPC, 1.034; P = .57) after each session. However, statistically significant increases in PT and INR were identified after exposure to at least 4 sessions (mean PT pre-RIPC, 11.33 s; post-RIPC, 12.1 s; P = .01; INR pre-RIPC, 1.02; post-RIPC, 1.09; P = .014, PTT pre-RIPC, 27.4 s; post-RIPC, 27.85 s; P = .092) with a direct correlation between the number of sessions and the degree of increase in PT (Pearson correlation coefficient = 0.59, P = .007) and INR (Pearson correlation coefficient = 0.57, P = .010). Prolonged coagulation times were not observed in controls. No hemorrhagic complications were associated with the procedure.

CONCLUSION

RIPC by limb ischemia appears to prolong the PT and INR in human subjects with SAH after at least 4 sessions, correlating with the number of sessions. However, values remained within normal range and there were no hemorrhagic complications.

Vascular neural network: the importance of vein drainage in stroke

This perspective commentary summarized the stroke pathophysiology evolution, especially the focus in the past on neuroprotection and neurovascular protection and highlighted the newer term for stroke pathophysiology: vascular neural network. Emphasis is on the role of venules and veins after an acute stroke and as potential treatment targets. Vein drainage may contribute to the acute phase of brain edema and the outcomes of stroke patients.

Delayed neurological deterioration after subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated by effects of transient cerebral ischaemia during bleeding plus effects of the subarachnoid blood. Secondary effects of SAH include increased intracranial pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift, and herniation, all of which contribute to pathology. Many patients survive these phenomena, but deteriorate days later from delayed cerebral ischaemia (DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI is thought to be caused by the combined effects of angiographic vasospasm, arteriolar constriction and thrombosis, cortical spreading ischaemia, and processes triggered by EBI. Treatment for DCI includes prophylactic administration of nimodipine, and current neurointensive care. Prompt recognition of DCI and immediate treatment by means of induced hypertension and balloon or pharmacological angioplasty are considered important by many physicians, although the evidence to support such approaches is limited. This Review summarizes the pathophysiology of DCI after SAH and discusses established treatments for this condition. Novel strategies--including drugs such as statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial delivery of nimodipine or magnesium--are also discussed.

Influence of chronic administration of anabolic androgenic steroids and taurine on haemostasis profile in rats: a thrombelastographic study

Anabolic androgenic steroids (AAS) are synthetic derivatives of testosterone with thrombogenic potential in high doses and long-term administration. Taurine, a widely distributed amino-sulfonic acid, is known for its beneficial effects in hypercoagulable states. In order to assess the impact of chronic administration of high doses of AAS and taurine upon haemostasis process in rats, 40 male Wistar rats were divided into four equal groups: control group (group C) - no treatment; androgen group (group A) - received 10 mg/kg per week of nandrolone decanoate (DECA); taurine (group T) - received oral supplementation of 2% taurine in drinking water; androgen and taurine group (group AT) - concomitant administration of DECA and taurine. After 12 weeks, blood samples were collected and haemostasis parameters were assessed with the thrombelastographic (TEG) analysis system: reaction time, clot kinetics (K, α), final clot strength, coagulation index and the clot lysis (Ly30). Nandrolone significantly decreased reaction time in group A compared with control (P<0.001), whereas taurine significantly increase reaction time (P=0.01), and this effect was maintained in group AT compared with group A (P=0.009). Similar differences between groups have been recorded for the clot kinetics parameters K, α. The final clot strength and coagulation index were significantly increased in group A versus group C (P=0.04, respectively P<0.001), but not in group AT versus group C (P>0.05). There were no differences in clot lysis, as shown by Ly30. Nandrolone produces an accelerated clot development and an increased clot firmness in Wistar rats. Taurine association ensures a protective effect against this hypercoagulable state, partially restoring the altered parameters of the coagulation profile.

Hypercoagulation following brain death cannot be reversed by the neutralization of systemic tissue factor

BACKGROUND

Cerebral injury and brain death is associated with apparent hypercoagulation and poor organ outcome. This experimental study challenges the hypotheses that i) brain death causes hypercoagulation and microvascular thrombosis and that ii) neutralizing systemic tissue factor (TF) by in vitro addition of a TF inhibitor (recombinant active site-inhibited factor VIIa (ASIS)) can reverse the hypercoagulable profile.

METHODS

Using a validated pig model of intracranial hemorrhage and brain death, 20 pigs were randomized to either control or brain death. The primary endpoints were coagulation parameters measured with whole blood thromboelastometry (ROTEM), thrombin generation and a porcine TF-sensitive plasma clotting time assay. In vitro spiking experiments with ASIS were performed in parallel with the latter two assessments. The kidneys were examined histologically for microvascular thromboses.

RESULTS

Brain death induced hypercoagulation, as demonstrated with ROTEM, thrombin generation, and reduced TF-sensitive plasma clotting time. In vitro inhibition of TF with ASIS did not reverse the hypercoagulation. No microvascular thromboses were found in the kidneys.

CONCLUSION

Brain death causes hypercoagulation; however, inhibition of TF does not reverse the coagulopathy. Thus, TF release does not seem to be the primary cause of this hypercoagulation. Minor changes in the levels of protein C suggest that the protein C pathway may be linked to the observed coagulopathy.

Association of hemodilution and blood pressure in uncontrolled bleeding

BACKGROUND

Hemodynamic status and coagulation capacity affect blood loss after injury. The most advantageous fluid and blood pressure to optimize resuscitation and minimize perturbation of coagulation are unclear. We investigated interactions of isovolumic hemodilution on hemodynamics, coagulation, and blood loss after injury.

METHODS

Twenty-five male rats were randomized into three groups (Whole Blood Uncontrolled Blood Pressure [WBU], n = 7; Lactated Ringers Uncontrolled Blood Pressure [LRU], n = 10; Whole Blood Controlled Blood Pressure [WBC], n = 8) with isovolumic hemodilution of 50% blood volume, with and without control of pre-injury blood pressure. All rats underwent uniform grade IV liver injury 30 min after serial exchanges. Post-injury blood loss and coagulation function were measured.

RESULTS

Dilution occurred, determined by hematocrit, with LRU having a greater reduction. Pre-injury mean arterial pressure (MAP) decreased compared with baseline (98 ± 7 mmHg) with LRU (62 ± 14 mmHg) and WBC (61 ± 10 mmHg), resulting in WBU (101 ± 13 mmHg) being significantly higher and not changed from baseline. Post-injury, MAP decreased from pre-injury, with LRU significantly lower than the other two groups. No differences were observed in prothrombin time/international normalized ratio or thromboelastography. Bleed volume was significantly different between groups: WBU < WBC < LRU and associated with the pre-injury MAP. Controlling baseline MAP, dilution with Lactated Ringers (LR) resulted in greater blood loss than whole blood (3.0 ± 0.4 versus 1.9 ± 0.3 mL).

CONCLUSIONS

In this rat model of liver injury, blood loss was associated with baseline MAP and type of fluid used for dilution. Hemodilution with LR did not produce coagulopathy based on laboratory values. When controlling baseline MAP, dilution with LR increased bleeding, confirming a functional coagulopathic state.

Acute microvascular changes after subarachnoid hemorrhage and transient global cerebral ischemia

Subarachnoid hemorrhage and transient global cerebral ischemia result in similar pathophysiological changes in the cerebral microcirculation. These changes include microvascular constriction, increased leukocyte-endothelial interactions, blood brain barrier disruption, and microthrombus formation. This paper will look at various animal and preclinical studies that investigate these various microvascular changes, perhaps providing insight in how these microvessels can be a therapeutic target in both subarachnoid hemorrhage and transient global cerebral ischemia.

Reconstruction of saccular and dissected intracranial aneurysms using Solitaire™ AB stents

Introduction

We aimed to evaluate the feasibility, safety, efficacy, and predictors for outcome of reconstructive treatment with Solitaire™ AB stent(s) based on 54 cases of saccular aneurysms and 14 of acute symptomatic dissecting aneurysms.

Methods

Fifty-eight consecutive patients (M/F = 28/30; median age, 53 years) harbouring 68 aneurysms (ruptured/unruptured = 12/56) underwent treatment with Solitaire™ AB stent(s) implantation between April 2010 and August 2011 in our institution. The data were retrospectively reviewed and analysed.

Results

The technical success rate of Solitaire™ AB stenting was 100%. The rates of the overall and the treatment-related adverse events were 9% (6/68) and 6% (4/68), respectively, and the recurrent rate was 1% (1/68). All of the adverse events (n = 6) occurred in tiny (n = 1, ≤3 mm) or small (n = 5, >3 to ≤10 mm) aneurysms. The majority (75%, 3/4) of thromboembolic events (thrombus, n = 2; infarction, n = 2) occurred in ruptured lesions, and 2 intraprocedural aneurysm ruptures occurred in the course of coiling when the stent(s) was/were applied within 6 months. Subarachnoid haemorrhages (SAH, p<0.05) and immediate occlusion grades (p<0.05) were predictors for overall adverse events by univariate analysis. Compared with the immediate post-treatment angiographic results, the follow-up angiographic imaging (mean, 13 months; range, 6–25 months) revealed that stent(s) implantation enhanced the rate of class I occlusion from 34% (23/68) to 93% (63/68). SAH was the only predictor for unfavourable outcomes (the modified Rankin Scale score [mRS], 2–6) during the mean 19-month (range, 12–27 months) of clinical follow-ups (p<0.05).

Conclusions

Although the complete obliteration of tiny and small aneurysms without complications remains a challenge, stent(s) implantation could lead to further occlusion of incompletely coiled aneurysms. SAH and the occlusion grade were the primary predictors for adverse events. SAH was the only predictor for unfavourable outcomes by univariate analysis.

A standardized technique for performing thromboelastography in rodents

Thromboelastography (TEG), used in liver transplant and cardiac surgery for nearly 50 years, has recently been applied to the trauma setting. Rodents are used widely for shock research, but are known to have differences in their coagulation system compared with humans. Consequently, the appropriate technique for performing TEG requires modification of the standard clinical protocol. Thromboelastography was performed with blood collected from the femoral artery of rodents, and technical modifications were tested to optimize results. Analysis of citrated whole blood using TEG revealed a more rapid onset of coagulation in rats compared with humans. The reference ranges of TEG parameters for Sprague-Dawley rats are detailed. Citrated native whole blood is the optimal TEG method in the assessment of coagulation in rodents. Investigators using TEG for research purposes should establish their own reference ranges to determine normal values for their target population.

Reduced clot-stability during the first 6 hours after aneurysmal subarachnoid haemorrhage--a prospective case-control study

INTRODUCTION

Early rebleeding is an important cause of death and disability following aneurysmal subarachnoid haemorrhage (SAH). Recent studies have shown that 50-90% of the rebleedings occurred within the first 6 hours after the primary bleeding. The mechanism leading to rebleeding remains to be established. In the present prospective case-control study we hypothesize that patients with SAH develop a coagulopathy characterized by reduced clot stability during the early period after the initial bleeding.

METHODS

Patients with aneurysmal SAH was studied with a dynamic clot lysis assay and markers of fibrinolysis and clot stabilizers in blood samples taken within and after 6 hours after onset of bleeding. Results were compared with blood samples from age and gender matched healthy controls.

RESULTS

36 patients were enrolled, 26 patients had blood samples collected within 6 hours after the initial bleeding whereas 10 patients had blood samples taken later than 6 hours after the initial bleeding. Patients demonstrated significantly reduced clot stability during the first 6 hours after initial bleeding. Fibrinolytic activity was increased during the first 6 hours along with the inhibitors of fibrinolysis whereas the modulators of fibrinolysis were reduced or inactivated.

CONCLUSION

During the first 6 hours after SAH patients exhibit reduced clot-stability. Probably a consequence of activated fibrinolysis in combination with reduced or inactivated factor XIII and thrombin-activable fibrinolysis inhibitor.

The prognostic value of thrombelastography in identifying neurosurgical patients with worse prognosis

Coagulopathy in patients with intracranial haemorrhage or traumatic brain injury (TBI) is associated with clinical deterioration and worse outcome. Whole blood viscoelastic haemostatic assays, like thrombelastography (TEG), might aid conventional coagulation assays in identification of patients with worse prognosis. We performed a review of patients (totalling 78 patients) with primary acute intracranial haemorrhage or isolated TBI admitted to a neurointensive care unit (NICU) for more than 24 h during a period of 9 months, who had TEG analysis performed at admission. Primary outcome was all-cause 30-day mortality, whereas decline in Glasgow Coma Scale (GCS) score at 24 h after admission or death due to cerebral incarceration were secondary outcomes. Patients were defined as hypocoaguable if TEG reaction time was more than 8 min, angle less than 55° and/or maximal amplitude less than 51 mm. Patients were defined hypocoaguable according to conventional coagulation assays if international normalized ratio was more than 1.3, platelet counts less than 100×10/l and/or activated partial thromboplastine time more than 35 s. Eight patients were hypocoaguable by TEG on admission to NICU and had higher 30-day mortality (63% vs. 16%, P=0.008), more often declined in GCS (57% vs. 16%, P=0.02) and expired due to cerebral incarceration (50% vs. 6%, P=0.02). Hypocoagulability by TEG, lower admission GCS and subarachnoid haemorrhage were independently associated with higher 30-day mortality [TEG: odds ratio (OR) 14.8 (2.2-100.1), P=0.006; GCS: OR 1.3 (1.1-1.5), P=0.006; subarachnoid haemorrhage: OR: 5.3 (1.3-22.3), P=0.02]. Only two patients were hypocoaguable by both conventional coagulation assays and TEG. The current data indicate that hypocoagulability by TEG at admission to NICU predicts worse prognosis. Low concordance with conventional coagulation assays indicates that TEG might be valuable in identifying patients with clinically relevant coagulopathy.