Defective fibrinolysis occurs after infrainguinal reconstruction

Renal transplant and hemostasis: early postoperative changes in recipients and donors

Background

The benefit of administering pharmacologic thromboprophylaxis following renal transplantation remains uncertain.

Objectives

To compare hemostatic parameters before and after renal transplant surgery in both recipients and their donors at predetermined time points.

Methods

Blood samples were collected at baseline (T1), immediately after surgery (T2), and at 24 hours after surgery (T3) in both recipients and donors and at 72 (T4) and 120 hours (T5) from recipients only. Assays included in vitro thrombin generation, factor VIII (FVIIIc) activity, von Willebrand factor (VWF) antigen, D-dimer, antithrombin activity, prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin complexes, and plasminogen activator inhibitor-1 (PAI-1) antigen.

Results

Fifty-two patients (28 recipients and 24 donors) were enrolled. Both donors and recipients had increased FVIIIc, VWF, F1 + 2, D-dimer, and PAI immediately after surgery but reduced antithrombin. Mixed-model analysis showed that the magnitude of change over time (between T1 and T3) for FVIIIc (mean estimated difference [MED], 72; 95% CI, 41-102; P < .0001), VWF (MED, 89; 95% CI, 35-142; P = .001), F1 + 2 (MED, 283; 95% CI, 144-422; P < .0001), thrombin-antithrombin complexes (MED, 3.5; 95% CI, 1.9-5.1; P < .0001), D-dimer (MED, 2.2; 95% CI, 1.0-3.3; P < .0001), PAI-1 (MED, 9.2; 95% CI, 3.4-14.9; P = .002), and time to peak thrombin generation (MED, 1.5; 95% CI, 0.35-2.7; P = .01) was more significant in recipients than in donors.

Conclusion

Persistence of a hypercoagulable state was more prominent in recipients after 24 hours despite recovery in renal function and initiation of thromboprophylaxis.

Fibrinolysis shutdown is associated with a fivefold increase in mortality in trauma patients lacking hypersensitivity to tissue plasminogen activator

BACKGROUND

Fibrinolysis shutdown (SD) is an independent risk factor for increased mortality in trauma. High levels of plasminogen activator inhibitor-1 (PAI-1) directly binding tissue plasminogen activator (t-PA) is a proposed mechanism for SD; however, patients with low PAI-1 levels present to the hospital with a rapid TEG (r-TEG) LY30 suggestive SD. We therefore hypothesized that two distinct phenotypes of SD exist, one, which is driven by t-PA inhibition, whereas another is due to an inadequate t-PA release in response to injury.

METHODS

Trauma activations from our Level I center between 2014 and 2016 with blood collected within an hour of injury were analyzed with r-TEG and a modified TEG assay to quantify fibrinolysis sensitivity using exogenous t-PA (t-TEG). Using the existing r-TEG thresholds for SD (<0.9%), physiologic (LY30 0.9-2.9%), and hyperfibrinolysis (LY30 > 2.9%) patients were stratified into phenotypes. A t-TEG LY30 greater than 95th percentile of healthy volunteers (n = 140) was classified as t-PA hypersensitive and used to subdivide phenotypes. A nested cohort had t-PA and PAI-1 activity levels measured in addition to proteomic analysis of additional fibrinolytic regulators.

RESULTS

This study included 398 patients (median New Injury Severity Score, 18), t-PA-Sen was present in 27% of patients. Shutdown had the highest mortality rate (20%) followed by hyperfibinolysis (16%) and physiologic (9% p = 0.020). In the non-t-PA hypersensitive cohort, SD had a fivefold increase in mortality (15%) compared with non-SD patients (3%; p = 0.003) which remained significant after adjusting for Injury Severity Score and age (p = 0.033). Overall t-PA activity (p = 0.002), PAI-1 (p < 0.001), and t-PA/PAI-1 complex levels (p = 0.006) differed between the six phenotypes, and 54% of fibrinolytic regulator proteins analyzed (n = 19) were significantly different.

CONCLUSION

In conclusion, acute fibrinolysis SD is not caused by a single etiology, and is clearly associated with PAI-1 activity. The differential phenotypes require an ongoing investigation to identify the optimal resuscitation strategy for these patients.

LEVEL OF EVIDENCE

Prognostic, level III.

Coagulation, Fibrinolysis, and Platelet Activation Following Open Surgical or Percutaneous Angioplasty Revascularization for Symptomatic Lower Limb Chronic Ischemia

Introduction:

Critical limb ischemia (CLI) is associated with a prothrombotic diathesis that involves a complex balance between the coagulation and fibrinolytic systems. Knowledge of this is essential when considering revascularization procedures but is often overlooked. The aim of this review is to summarize the available literature and provide an overview of the effects of lower limb angioplasty and open surgical revascularization on coagulation, fibrinolysis, and platelet activation.

Methods:

A MEDLINE and EMBASE search was conducted between 1973 and 2014 for articles relating to the effects of revascularization for patients with CLI on the fibrinolytic and coagulation pathways. Studies with a small cohort of patients (<5) were rejected.

Results:

Many of the studies included in this analysis had small cohorts. Multiple markers were assessed across the published literature including von Willebrand factor, tissue factor, prothrombin fragments 1 and 2, platelets, soluble platelet selectin, plasminogen activator inhibitor 1, tissue plasminogen activator, and thrombin–antithrombin complex. Percutaneous intervention causes an exaggerated prothrombotic and a disturbed fibrinolytic effect. Surgery seems to cause a similar prothrombotic derangement with reduced fibrinolysis and platelet hyperactivity, but this appears to be maintained for a considerable amount of time postoperatively.

Conclusion:

There is a sparse amount published on the effects of the coagulation and fibrinolytic systems in patients undergoing intervention for CLI. Much of these studies are small, historical, and completely heterogeneous, making it difficult to draw meaningful conclusions. The literature does identify a prothrombotic state in patients with CLI, which appears to be exacerbated by any form of intervention and prolonged in those having surgery. Understanding this may allow us to tailor the intervention offered to patients and prevent limb loss.

Perioperative myocardial infarction in non-cardiac surgery. Pathophysiology and clinical implications

Advances in surgical and anaesthetic techniques and an aging patient population have resulted in more complex procedures being performed in greater numbers of aged subjects and in patients with a high likelihood of significant cardiovascular disease. Nearly one fourth of non-cardiac surgical procedures (major intra-abdominal, thoracic, vascular, and orthopaedic procedures) performed in persons older than 65 years have been found to be associated with significant perioperative cardiovascular morbidity and mortality. During previous years the main attempt was to define strategies to accurately estimate perioperative cardiovascular risk based either on the characteristics of surgery and on patient characteristics. More recently preventive medical strategies have been proposed. Therefore, the physician has to be aware of the key elements useful to calculate the perioperative cardiovascular risk, and of the medical preventive treatment or further interventions to adopt in patients candidate to surgery.

Exercise training enhances endogenous fibrinolysis in peripheral arterial disease

PURPOSE

Acute clinical events resulting from atherosclerosis (myocardial infarction, stroke) are associated with impaired endogenous fibrinolysis, the system by which the body lyses inappropriately formed thrombus. Endurance exercise training improves fibrinolysis in normal subjects and those with coronary artery disease. The hypothesis of this study was that exercise training would improve fibrinolysis in subjects with peripheral arterial disease (PAD).

METHODS AND RESULTS

Twenty-one men with intermittent claudication (IC-EX) underwent treadmill exercise training for 6 months. Twenty age-matched male subjects with IC were followed for the same period (IC-NONEX). Fibrinolytic activity was measured prior to entry into exercise or "usual care," and at the completion of the study period. Fibrinolysis was quantified by measurement of the activity levels of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1), using an amidolytic method. Fibrinolysis, quantified as increased PAI-1 activity, was reduced in both claudicant groups relative to healthy controls at baseline. After 6 months of exercise, subjects in the IC-EX group experienced significant improvements in fibrinolytic activity, manifested as a 23% decrease in PAI-1 activity and a 28% increase in tPA activity. No changes occurred in the IC-NONEX group. In the IC-EX group, subjects with the highest initial PAI-1 values experienced the greatest decreases in PAI-1 activity and thus the greatest benefit from exercise.

CONCLUSIONS

Patients with PAD have impaired fibrinolytic activity, manifested primarily as increases in the inhibitor of fibrinolysis, PAI-1. Six months of exercise training reduced these impairments, and may serve as an intervention to reduce cardiovascular mortality and morbidity in these patients.

Activation of Coagulation and Fibrinolytic Systems in Patients with CLI is not Normalized after Surgical Revascularisation

OBJECTIVE

To study the activation of coagulation and fibrinolysis before, during and after surgical revascularisation in patients with critical limb ischemia (CLI).

DESIGN

Prospective clinical study.

MATERIALS AND METHODS

Forty patients with CLI underwent femoro-popliteal or femoro-distal reconstruction and were compared to a control-group. Measurements of prothrombin-fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) assessed activation of coagulation. Fibrinolysis was determined by tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and fibrin degradation product (D-dimer). The inflammatory mediators: Interleukin 2 receptor (IL-2-rec), Interleukin 6 (IL-6), Interleukin 10 (IL-10) and Monocyte chemoattractant protein 1 (MCP-1) was also analysed.

RESULTS

Patients (in 35 of the 40 reconstruction was possible) were operated upon using either vein (n=23) or ePTFE (n=12) grafts. Patients with CLI had a preoperative prothrombotic state as indicated by high TAT-levels and also ongoing fibrinolysis with high levels of t-PA and D-dimer. After reperfusion an ongoing prothrombotic state for the first week was demonstrated. A significant as well as defective fibrinolysis was also seen with increased levels of tPA and D-dimer unopposed by PAI-1 after one week and also after 30 days. Increased levels of inflammatory mediators IL-6, IL-10 and MCP-1 was observed after reperfusion and normalised after 30 days.

CONCLUSION

This study demonstrates significant disturbances of both the coagulation and fibrinolytic systems before, during and after revascularisation for CLI. This was accompanied by release of inflammatory mediators. A prothrombotic state and increased fibrinolysis were evident also 30 days after successful revascularisation.

Association between physical activity and endogenous fibrinolysis in peripheral arterial disease: a cross-sectional study

The purpose of this study was to determine whether daily physical activity was independently related to endogenous fibrinolysis in subjects with peripheral arterial disease (PAD). One hundred and six subjects with peripheral arterial disease (PAD) and intermittent claudication were characterized on the activity level of tissue plasminogen activator (tPA, the activator of fibrinolysis), the activity level of plasminogen activator inhibitor (PAI-1, the inhibitor of fibrinolysis), daily physical activity, ambulatory function, and demographic information. Subjects were separated into low (n = 36), moderate (n = 34), and high (n = 36) physical activity tertiles based on a 48-hour monitoring period with use of an accelerometer. The tPA activity of the low physical activity group (1.30 +/- 0.16 IU/mL) was 21% and 19% lower (p<0.05) than that of the moderate (1.65 +/- 0.18 IU/mL) and the high (1.61 +/- 0.15 IU/mL) physical activity groups, respectively. The PAI-1 activity of the low physical activity group (21.41 +/- 1.14 AU/mL) was 15% and 23% higher than that of the moderate (18.61 +/- 1.34 AU/mL) and the high (17.47 +/- 1.14 AU/mL) physical activity groups, respectively. Group differences in tPA activity and PAI-1 activity persisted after our controlling for group differences in measured and self-reported ambulatory measures. Daily physical activity is related to a more favorable endogenous fibrinolytic profile in PAD subjects with intermittent claudication. Subjects who expend fewer than 175 kcal/day in physical activities (approximately 35 minutes) are particularly susceptible to having a prothrombotic state. Subjects should be encouraged to participate in at least 35 minutes of physical activity each day to enhance fibrinolysis.

Etomidate and thiopental inhibit platelet function in patients undergoing infrainguinal vascular surgery

BACKGROUND

Postoperative platelet hyperaggregability following general anesthesia has been reported in patients undergoing major vascular surgery. In contrast, since anesthetic agents inhibited platelet function both in vitro and in vivo, an increased risk for postoperative bleedings due to prolonged platelet dysfunction has been discussed. Nevertheless, data describing platelet-affecting properties of induction agents such as etomidate and thiopental in patients undergoing major vascular surgery are lacking.

METHODS

Platelet function was determined at 0, 2, 20, and 200 microg/ml thiopental and at 0, 0.2, 2, 20 microg/ml etomidate in vitro in blood samples drawn from 16 patients suffering from severe occlusive arterial disease. In addition, 30 patients undergoing vascular surgery were investigated before (PRE) and after anesthesia induction (T0) either with etomidate (ETO group, n=16) or thiopental (THIO group, n=14), and 2 h after the beginning of surgery (T2). Platelet function was determined according to platelet aggregation, in vitro bleeding time, and flow cytometric measurements.

RESULTS

In vitro, P-selectin expression was inhibited by etomidate at 2 and 20 microg/ml (-28% and -38%, respectively) and also by thiopental at 200 microg/ml (-27%). In patients undergoing vascular surgery, anesthesia induction in the ETO group resulted in a 31% prolongation of the in vitro bleeding time and an inhibition of ADP- and collagen-induced platelet aggregation (-30% and -17%, respectively) and of P-selectin expression (-25%) at T0. In the THIO group, only ADP-induced platelet aggregation was affected (-16%). At T2, all parameters had reached PRE level again in both groups. Furthermore, in comparison with the THIO group, operation time was significantly prolonged and transfusion volume was significantly increased in the ETO group. In addition, platelet count and hematocrit significantly decreased at T2, whereas levels of tPA, PAI-1, fibrinogen and antithrombin III and partial thromboplastin time remained unchanged in both groups during the study period.

CONCLUSIONS

In the present study, etomidate and, to a minor extent, thiopental offered significant platelet inhibitory properties. Anesthetic-induced platelet inhibition may lead to higher transfusion rates and prolonged operation times. Therefore, anesthetic-related platelet inhibitory properties should be considered when searching for the anesthetic agent of choice, especially in patients with compromised hemostasis and co-existing bleeding disorders.

External pneumatic compression and fibrinolysis in abdominal surgery

INTRODUCTION

External pneumatic compression (EPC) devices prevent lower extremity deep venous thrombosis by increasing venous flow and thereby reducing stasis. Early studies suggested that they also enhance systemic fibrinolytic activity and thus prevent thrombus formation; more recent studies have been conflicting. The hypothesis of this study was that EPC devices enhance systemic fibrinolysis or reduce postoperative fibrinolytic impairment in patients undergoing abdominal surgical procedures.

METHODS

Each of 48 patients (98% male; mean age, 67 years) undergoing major intra-abdominal surgical procedures (36 bowel procedures, 12 aortic reconstructions) was prospectively randomized to one of three treatments for deep venous thrombosis prophylaxis: subcutaneous heparin injections (HEP group), use of a thigh-length sequential EPC device (EPC group), or both (HEP + EPC group). Antecubital venous samples were collected for measurement of systemic fibrinolytic activity on the day before surgery, after induction of anesthesia but before prophylaxis was initiated, and on postoperative days 1, 3, and 5. Fibrinolysis was assessed through measurement of the activities of the rate limiting fibrinolytic activator, tissue plasminogen activator, and its inhibitor plasminogen activator inhibitor-1 with amidolytic methods.

RESULTS

On the day before surgery, plasminogen activator inhibitor-1 activity was elevated in all groups in comparison with that in age-matched and sex-matched controls (20.3 +/- 0.6 AU/mL). In the HEP group, plasminogen activator inhibitor-1 activity was further elevated above the value for the day before surgery on postoperative day 1 (28.5 +/- 4.3 AU/mL; P =.04) and postoperative day 3 (25.1 +/- 1.9 AU/mL; P =.07). No significant decrease in plasminogen activator inhibitor-1 activity occurred in either group treated with EPC devices in comparison with the HEP group at any time. There were no changes in tissue plasminogen activator activity postoperatively in the HEP group and no significant increases in either EPC group at any point.

CONCLUSIONS

Reduced systemic fibrinolytic activity ("fibrinolytic shutdown") occurred in these patients after abdominal surgery; it was manifested as increased plasminogen activator inhibitor-1 activity. EPC devices did not enhance systemic fibrinolysis or prevent postoperative shutdown either by decreasing plasminogen activator inhibitor-1 activity or by increasing tissue plasminogen activator activity. These data suggest that EPC devices do not prevent deep venous thrombosis by fibrinolytic enhancement; effective prophylaxis is achieved only when the devices are used in a manner that reduces lower extremity venous stasis.

Endogenous fibrinolysis in patients with lower extremity ischemia

To explore the relationship between disorders of endogenous fibrinolysis and thrombosis in patients with lower extremity ischemia, we measured the activity of tissue plasminogen activator (tPAac) and plasminogen activator inhibitor (PAlac) and the antigens of tissue plasminogen activator (tPAa) and inhibitor (PAla) in plasma from 420 patients treated for lower extremity ischemia. Values and ratios observed were compared with those in healthy volunteers. Additionally, values and ratios in the patients were examined with respect to the severity of ischemia and site of atherosclerotic occlusion or stenosis (pelvic compared with femoropopliteal or crural). Patients with lower extremity ischemia had higher plasma concentrations of PAla (p<0.01) and PAlac (p<0.0001) than healthy volunteers. In patients with rest pain or gangrene, the ratio of tPAac to PAlac was higher than in patients with claudication (p<0.05). The elevation of tPAac in patients with the more severe form of lower extremity ischemia is probably the feedback protective reaction on prothrombotic mechanisms of the organism suffered from severe atherosclerosis. Results did not vary according to the site of occlusion or stenosis. Our study found defects in endogenous fibrinolysis in patients with lower extremity ischemia. A defect in fibrinolysis may contribute to the development of thrombosis in native arteries and bypasses.