Amputation-free survival in the long-term follow-up and gender-related characteristics in patients revascularized for critical limb ischemia

OBJECTIVE

Patients with Critical Limb Ischemia (CLI) present a high risk of cardiovascular events and death. Revascularization is the cornerstone of therapy to relieve ischemic pain and prevent limb loss. Literature data suggest that women tend to present with worse outcomes after revascularization. The aim of the present study is to determine amputation-free survival in a long-term follow-up in women and men following endovascular revascularization procedure for CLI.

METHODS

From November 2013 to December 2020, 357 consecutive patients were retrospectively included. Clinical and biological parameters were recorded at baseline before endovascular revascularization. During follow-up until February 2023, overall survival and amputation-free survival (freedom from major amputation) were analysed using the Kaplan-Meier method. Univariate and multivariate analyses were performed to study the parameters associated with amputation-free survival. A P<0.05 was considered as statistically significant.

RESULTS

A total of 357 consecutive patients were included, 189 men and 168 women with CLI, with a mean age of 78.6±12 years. Treated hypertension (79%), diabetes mellitus (48%), coronary artery disease (39%) and protein malnutrition (61%) were the most prevalent comorbidities. Women were older than men with a mean age of 82.4±11.4 years (versus 75.4±11 years in men) and presented more frequently with protein malnutrition (70% of women). Prevalence of diabetes, tobacco use and history of coronary heart disease were significantly higher in men. During the 10-year follow-up period, 241 patients had died (68%) and 38 (11%) underwent major amputation, of whom 22 patients were still alive on February 2023. Median survival was 35.5 months [IQR: 29.5; 43] in the overall population, 38.5 [32; 50.4] months in women and 33.5 months [24.7; 43.5] in men. No gender-related differences were noted according to peri-procedural complications, survival probability and amputation-free survival. In multivariate analysis for amputation-free survival, age, previous coronary heart disease, C-reactive protein level, left ventricular ejection fraction (LVEF)<60% and albumin level<35g/L were correlated with poor outcome. In particular, protein malnutrition, as a treatable risk factor, appears significantly correlated with poor outcome in both men and women (HR=2.50 [1.16;5.38], P=0.0196 in men; HR=1.77 [1.00;3.13], P=0.049 in women).

CONCLUSION

The present results highlight that mortality in patients after endovascular revascularization remains high with a mortality rate of 28% at 1 year, 40% at 2 years and 51% at 3 years. Women represented a distinct population, almost 10-year older than their male counterparts, with more prevalent protein malnutrition. However, no gender-related difference was noted according to amputation-free survival on the long-term follow-up. Associated risk factors are mainly age, a history of coronary heart disease, pre-procedural inflammatory syndrome and protein malnutrition. Correction of malnutrition could have the potential to improve functional and general long-term prognosis in patients with CLI together with optimal medical and interventional management.

Evaluation of the ankle brachial index and toe brachial index for peripheral arterial disease diagnosis in patients over 70 years with lower limb ulcers

OBJECTIVE

The aim of our study was to evaluate the diagnostic performance of the ankle brachial index using pulsed Doppler, and the toe brachial index using laser Doppler, in comparison with the arterial Doppler ultrasound of the lower limbs as a reference test, in a population of non-diabetic subjects over 70 years old with lower limb ulcers and without chronic renal failure.

METHODS

We included 50 patients, 100 lower limbs from the vascular medicine department of the Paris Saint-Joseph hospital from December 2019 to May 2021.

RESULTS

We found a sensitivity of 54.5% for the ankle brachial index and a specificity of 67.6%. Regarding the toe brachial index, the sensitivity was 80.3% and the specificity 44.1%. We could explain the low sensitivity of the ankle brachial index in our population by the mediacalcosis of elderly subjects, avoidable with the measurement of the toe blood pressure index, which had a better sensitivity.

CONCLUSION

In a population of subjects over 70 years of age with a lower limb ulcer, without diabetes and without chronic renal failure, it would seem judicious to use the ankle brachial index in association with the toe brachial index for the diagnosis of peripheral arterial disease, followed by an arterial Doppler ultrasound of the lower limbs in order to evaluate the lesion profile of patients with a result of less than 0.7 of toe brachial index.

Peri-procedural complications following endovascular revascularization for critical limb ischemia

OBJECTIVE

Revascularization procedures are considered the cornerstone of therapy in patients with critical limb ischemia (CLI) and multiple procedures are often required to attain limb salvage. The aim of the present study is to determine the prevalence of peri-procedural complications after endovascular procedure, and to determine the clinical and biological characteristics of patients associated to the risk of peri-procedural complications.

METHODS

From November 2013 to May 2021, 324 consecutive patients were retrospectively included, of whom 99 underwent more than one revascularization procedure for contralateral CLI or clinical recurrence of CLI. A total of 532 revascularizations were performed. Clinical and biological parameters were recorded at baseline before endovascular revascularization. The occurrence of a peri-procedural complication (local complications, fatal and non-fatal major bleeding or cardiovascular events) was recorded up to 30days after revascularization. Univariate and multivariate analyses were performed to study the parameters associated with per-procedural complications. A P<0.05 was considered as statistically significant.

RESULTS

A total of 324 consecutive patients were included, 177 men and 147 women with CLI, with a mean age of 77.6±11.9years. Most of these patients had cardiovascular comorbidities (41% with a history of coronary heart disease, 78% treated hypertensive patients, 49% diabetic patients). Peri-procedural mortality occurred in 13 patients (4%) and 9 patients (2.8%) experienced major amputation at one-month following revascularization. Among the 532 revascularization procedures, 99 major bleeding events (22.8% of the cohort population) and 31 cardiovascular events (8.6% of the cohort population), were recorded in the peri-procedural period. Cardiovascular events were associated with peri-procedural mortality. Complications at the puncture site occurred during 38 of the 532 procedures (10.2% of the cohort population). Compared with patients undergoing a single revascularization procedure, patients with multiple procedures presented a higher risk of major bleeding events (48.5% vs. 11.6%, P<0.0001) and access site complications (20.2% vs. 5.78%, P<0.0001). In multivariate analysis, pulse pressure <60mmHg and hemoglobin level <10g/dl were correlated with the occurrence of major bleeding events; left ventricular ejection fraction<60% and the absence of statin treatment were correlated with the occurrence of cardiovascular complications; a high chronological rank of revascularization was correlated with the occurrence of local complication. Finally, age and gender were not associated with the occurrence of peri-procedural complication.

CONCLUSION

The present results highlight that multiple revascularization procedures for limb salvage are required in almost one third of the population with critical limb ischemia and were associated with the risk of major bleeding events and access site complications. The most frequent complications of peripheral vascular interventions were major bleeding events. Adverse cardiovascular events were related with peri-procedural mortality. Anemia, blood pressure, left ventricular ejection fraction and statin treatment are important parameters to consider for peri-procedural outcomes, independently of age, gender and the chronological rank of revascularization procedure.

Incident cardiovascular events and early mortality in patients with revascularized critical limb ischemia

OBJECTIVES

Patients with critical limb ischemia (CLI) present a high risk of cardiovascular events and death. This study aimed to investigate the incidence of major adverse cardiovascular events (MACE) and one-year mortality in patients undergoing percutaneous revascularization procedure for CLI.

METHODS

This investigation is a retrospective analysis of an ongoing cohort study in patients with CLI undergoing endovascular revascularization, hospitalized in the vascular medicine department from November 2013 to December 2018. Major cardiovascular events were collected during the first year after revascularization procedure and were defined as heart failure, acute coronary syndrome, ischemic stroke and sudden death. Mortality and major limb amputations, defined as above-the-ankle amputation, were determined during the one-year follow-up period. Multivariate logistic regression analyses were performed to identify factors independently associated with the occurrence of MACE and one-year mortality after revascularization procedure. A P≤0.05 was considered as statistically significant.

RESULTS

The study included 285 consecutive patients, 157 men (55%) and 128 women (45%), with a mean age of 77.8±12 years. Treated hypertension was present in 222 (78%) patients; diabetes was present in 137 (48%) patients; 112 (39%) patients had known coronary heart disease and 20 (7%) patients were dialysis dependent. During the one-year follow-up after revascularization procedure, 75 (26.3%) patients presented an incident cardiovascular event, of whom 19 (6.7%) patients in the perioperative period. Cumulative mortality rate was 26.7% (76 patients) mostly from cardiovascular causes. Twenty-five patients (8.8%) experienced major amputation. In multivariate analysis, the occurrence of MACE was associated with an increased mortality risk (HR 6.96 (2.99-16.94), P<0.001). Other variables associated with an increased mortality were living in a nursing home and malnutrition. Decompensated heart failure and coronary heart disease were both associated with incident MACE in multivariate analysis, independently of confounders.

CONCLUSION

In the present study population, incident MACE were prevalent in the year following endovascular revascularization procedure in patients with CLI and were associated with an increased risk of mortality. Coronary heart disease and decompensated heart failure are important contributors for the occurrence of MACE. In this elderly patient population with CLI, these results should be taken into account during the multidisciplinary team meeting before consideration of revascularization procedure.

Characteristics and outcomes of octogenarians with revascularized critical limb ischemia: Impact of altered cardiac function for early mortality

OBJECTIVE

Patients with critical limb ischemia (CLI) present with advanced age and end-stage organ damage, in particular heart failure. The aim of the present study is to describe clinical and biological characteristics in octogenarian patients with CLI compared to their younger counterparts and to determine the peri-procedural risk and early mortality after endovascular procedure.

METHODS

From November 2013 to May 2019, 315 consecutive patients were retrospectively included. Clinical and biological parameters were recorded at baseline before endovascular revascularization. The main outcome was total 1-year mortality.

RESULTS

The study included 170 octogenarians and 145 non-octogenarians. The mean age of octogenarian patients was 86.9±4.8 years, almost 20 years higher than that registered in non-octagenarians patients (67.4±8.6 years). Octogenarian patients were mostly women (59.4%), presented with lower body mass index (23.8±4.4kg/m²), lower serum albumin level (31.5±5.4g/L) and lower creatinine clearance (66.1±24.5mL/mn) than younger counterparts. They were more likely to be institutionalized in a nursing home (27.1%). In the peri-procedural period, major bleeding occurred in 40 patients (12.7%), without statistical significance between the two age groups. Peri-procedural mortality occurred in 12 patients (3.8%), of whom 10 patients (83%) were octogenarians. Cumulative mortality rate was 25.4% (80 patients) during the one-year follow-up period: 58 octogenarians died (34.1%) compared to 22 non-octogenarian patients (15.2%), P<0.001. Cardiovascular events were highly prevalent, accounting for 40% of overall mortality. Twenty-five patients (8%) experienced major amputation, without significant difference between the two age groups. In octogenarian population, institutionalized status (P=0.004) and BNP level (P=0.001) were positively correlated with mortality whereas systolic blood pressure (P<0.001), left ventricular ejection fraction (P=0.003), serum albumin (P=0.020), C-Reactive protein (P=0.020) and renin-angiotensin system inhibitors at hospital discharge were negatively correlated with mortality. In multivariate analysis for mortality, only BNP level≥500pg/mL (HR 3.27; 95% CI 1.04-10.97; P=0.04), was correlated with mortality, independently of other confounders.

CONCLUSION

In the present study population, octogenarians represent a rather distinct CLI population, 20 years of age older as compared to non-octogenarians, with prevalent malnutrition and institutionalized status. The present results underline a substantial one-year mortality rate of 34.1% in this elderly population following revascularization procedure with a 6% peri-procedural mortality. Decompensated heart failure is an important contributor for mortality.

Prevalence and management of antivitamin K overdose in a hospital setting

INTRODUCTION

Vitamin K antagonist (VKA) related adverse events are the first cause for iatrogenic events in France, particularly due to the narrow therapeutic margin. The risk of bleeding increases significantly when the INR level is ≥5. The main objective of this study was to assess the prevalence of VKA overdose in a hospital setting (at D2 of hospital entry) and to evaluate physicians' adherence to clinical practice guidelines for the management of VKA overdose according to French National Authority for Health recommendations.

METHODS

This single-center retrospective observational study consisted in querying the computerized database of a Parisian hospital on 21275INR determinations (3995 patients, 6813 hospital stays) performed between 2013 and 2018.

RESULTS

An INR level ≥5 was noted during 350 (6%) of the hospital stays, in 331 patients (of whom 57% were women). The mean age of the patient population with an INR≥5 was 81.1 years. Infection, heart failure and renal failure were the most frequent acute medical conditions for hospital admission. Twenty-three patients (7%) had a bleeding complication, 11 of which were major bleeding complications. Older age was associated with the severity of bleeding complications. Fifteen in-hospital deaths (4%) were reported, not related to bleeding events. The management of VKA overdose did not comply with the recommendations in 43% of cases, in particular for the highest INRs (50% of noncompliance for an INR>6.4). Non-compliance with recommendations for VKA overdose was related to: the delay until the INR was checked (44% of cases); the indication for prescribing vitamin K (34% of cases); the dose or route of administration of vitamin K therapy (19% of cases); and the interruption or not of VKA therapy (12% of cases).

CONCLUSION

The management of VKA overdose in a hospital setting remains non-compliant with the recommendations in almost half of the cases, mainly due to the delayed INR control and inappropriate management of vitamin K therapy. Computerized alert system would be helpful for personalized patient management and improved pharmacovigilance to prevent iatrogenic VKA events.

Foot ischemia related to essential thrombocytemia and atherosclerosis

We report two cases of foot ischemia combining microvascular thrombosis related to essential thrombocytemia (ET) and a proximal ulcerating atherosclerotic plaque. This suggests that myeloproliferative neoplasms could also trigger distal embolism from an unstable atherosclerotic plaque by creating a prothrombotic status. These distal ischemic events were the first ET manifestation and therefore lead to myeloproliferative neoplasm diagnosis. In ET, thrombosis event can occur with a normal platelet count. Furthermore, hemogram should be regularly controlled among JAK2 muted patients considering the frequent evolution from isolated JAK2 mutation to ET.

Patients with atherosclerotic peripheral arterial disease have a high risk of lung cancer: Systematic review and meta-analysis of literature

PURPOSE

Lung cancer and atherosclerosis share common risk factors. Literature data suggest that the prevalence of lung malignancy in patients with peripheral arterial disease (PAD) is higher than in the general population. Our goal was to determine, through a systematic literature review, the prevalence of lung cancer in patients with PAD.

METHODS

We consulted available publications in the Cochrane library, MEDLINE, PUBMED, EMBASE, and ClinicalTrials.gov. We included all articles, written in English or French, published between 1990 and 2020 reporting the prevalence of lung cancer in patients with PAD (atherosclerotic aortic aneurysm or peripheral occlusive diseases). Patients with coronary artery disease, cardiac valvulopathy or carotid stenosis were not included. We did not include case reports. We performed a critical analysis of each article. Data were collected from two independent readers. A fixed effect model meta-analysis allowed to estimate a summary prevalence rate.

RESULTS

We identified 303 articles, and selected 19 articles according to selection criteria. A total of 16849 patients were included (mean age 68.3 years, 75.1% of males). Aortic aneurysms were found in 29% of patients and atherosclerotic occlusive disease in 66% of patients. Lung cancer was identified in 538 patients, representing a prevalence of 3%.

DISCUSSION

Lung cancer is found in 3% of patients with atherosclerotic PAD. This prevalence is higher than that found in lung cancer screening programs performed in the general population of smokers and former smokers. These patients should be screened for lung cancer. Their selection may dramatically increase the benefit of lung cancer screening.

Consistency of thrombophilia testing in a reference center according to the current guidelines

OBJECTIVE

The clinical relevance of hereditary thrombophilia (HT) testing in venous thromboembolic disease (VTE) is limited to specific guidelines. The present study aimed to evaluate the consistency of HT prescriptions in clinical practice according to the current French guidelines.

METHODS

This study was conducted from April 2017 to February 2018 in a specialized haemostasis centre and included 58 consecutive patients referred by their clinicians for thrombophilia screening (56 patients following a personal VTE event and 2 asymptomatic relatives of a first-degree patient who had had VTE). One experienced clinician met every patient and assessed a pre-test prediction for the presence or absence of HT based on the clinical characteristics of VTE which was compared to the HT biological results.

RESULTS

Among the 58 patients referred to our specialized haemostasis centre, 60% were outside the scope of recommendations for thrombophilia screening. Eight patients were diagnosed with HT. Six out of 8 (75%) patients with diagnosed HT had a history of unprovoked VTE event. Familial history with VTE was a poor predictor for positive HT testing among relatives. The positive and negative predictive values of the clinical prediction were respectively of 19% and 89%.

CONCLUSION

The present results underline that screening for HT remains too largely prescribed. Pre-test physician's feeling for the presence of HT was neither sensitive nor specific. Increasing physicians' awareness on this issue and current recommendations should limit prescriptions of HT tests while providing the best possible care for patients with VTE.

Ischemic stroke and non-valvular atrial fibrillation: When to introduce anticoagulant therapy?

About 20 to 30% of ischemic strokes are related to non-valvular atrial fibrillation. This type of situation is particularly at risk for both recurrence of the ischemic event and the hemorrhagic transformation of this stroke. The timing of the introduction or going back to the anticoagulant therapy in these patients remains a difficult issue, with a complex benefit-risk balance that needs to be assessed. Randomized controlled studies are lacking and current recommendations do not allow for clear decision making. The administration of a curative anticoagulant within 72 hours after the event is not recommended in the absence of demonstrated efficacy in preventing recurrence at this stage and because of the risk of intracerebral hemorrhage. This attitude can nevertheless be qualified by a transient accident or ischemic accident of very small size, and in the absence of any other risk factor for intra- or extra-cerebral hemorrhage. From the 4th day, after an appropriate case by case evaluation, the introduction of anticoagulant would be possible within a time which will remain at the appreciation of the medical teams. If the patient's risk of an intracerebral hemorrhage or general bleeding is transiently increased, it will be preferable to wait at least 2 weeks after the stroke. If this risk persists in the long term, the decision of the administration or not of an anticoagulant will have to be made with a multidisciplinary consultation. Vitamin K antagonists or direct oral anticoagulants may be prescribed as first-line therapy for the prevention of recurrence of ischemic stroke in a non-valvular atrial fibrillation patient. The choice will be based on the clinical and biological data of each patient. Direct oral anticoagulants have not shown superiority in the prevention of ischemic recurrence but open up new prospects for earlier treatment if their lesser risk of bleeding is confirmed after further studies.

Innovative endovascular approach for limb salvage in critical limb ischemia

In the absence of feasible revascularization, nearly one third of patients with critical limb ischemia experienced major amputation at 6 months. In patients with an independent living status, this decision is difficult to support without exhausting all chances to attain limb salvage and preserve functional autonomy. The present report describes a new procedure of revascularization by performing a full endovascular extra-anatomic femoropopliteal bypass for the treatment of limb-threatening ischemia. The patient presented with extensive tissue loss and a short-term risk of major amputation. She had experienced previous failure of conventional surgical and endovascular revascularization procedures and ligation of proximal femoral artery precluded any further revascularization attempt. Limb salvage was achieved with this endovascular revascularization procedure with complete wound closure. The patient still presents an independent living status and preserved functional autonomy without wound recurrence after a follow-up of more than 5 years.

Management of cancer-related thrombosis in the era of direct oral anticoagulants: A comprehensive review of the 2019 ITAC-CME clinical practice guidelines. On behalf of the Groupe Francophone Thrombose et Cancer (GFTC)

Venous thromboembolism (VTE) is a common disease complication in cancer patients and the second cause of death after cancer progression. VTE management and prophylaxis are critical in cancer patients, but effective therapy can be challenging because these patients are at higher risk of VTE recurrence and bleeding under anticoagulant treatment. Numerous published studies report inconsistent implementation of existing evidence-based clinical practice guidelines (CPG), including underutilization of thromboprophylaxis, and wide variability in clinical practice patterns across different countries and various practitioners. This review aims to summarize the 2019 ITAC-CME evidence-based CPGs for treatment and prophylaxis of cancer-related VTE, which include recommendations on the use of direct oral anticoagulants specifically in cancer patients. The guidelines underscore the gravity of developing VTE in cancer and recommend the best approaches for treating and preventing cancer-associated VTE, while minimizing unnecessary or over-treatment. Greater adherence to the 2019 ITAC guidelines could substantially decrease the burden of VTE and improve survival of cancer patients.

Molecular Basis of Antithrombin Type I Deficiency: The First Large In-frame Deletion and Two Novel Mutations in Exon 6

We report three novel mutations accounting for cases of inherited type I antithrombin (AT) deficiency. Using the polymerase chain reaction (PCR) and direct sequencing of the coding sequences of the AT gene, we found one mutation in exon 4 and two in exon 6. A deletion of 105 bp causing an in-frame deletion of 35 amino acids between Tyr 240 and Gly 276 was found in exon 4. In a second kindred, deletion of two adenines in codon 412-413 introduced a frameshift and a stop codon at position 431. The last mutation was an insertion of ACCG in codon 387, generating a frameshift with a stop codon located at the normal position.

The finding of a sequence repeat of nine residues located at the 5’and 3’ ends of the deleted fragment might explain the 105 bp deletion by slippage and mispairing at the replication fork during DNA synthesis. The second mutation is the fourth described within a region of six amino acids (between Phe 408 and Arg 413), which seems to be a cluster of mutations. In this case, the presence of a double repeat sequence - TTCCT and AACA - flanking this region could be particularly favorable for slipped mispairing.

These results confirm that human gene mutations are not random events but are strongly influenced by DNA flanking sequences.

[Posttraumatic nerve entrapment syndromes in the upper extremities]

Nerve entrapment syndromes in the upper extremities are common clinical disease patterns, less often as direct results of accidents. The most frequent compression syndrome is the carpal tunnel syndrome followed by the cubital tunnel syndrome. If the cause of the compression cannot be eliminated by conservative treatment options, an operative therapy is necessary. As the prognosis becomes worse with the duration of the nerve compression, it is important to initiate therapy at an early stage.

Lactic acidosis: relationship between metformin levels, lactate concentration and mortality

AIM

The role of metformin in lactic acidosis is regularly questioned. Arguments against a causal role for metformin in lactic acidosis occurrence are the lack of correlation between plasma metformin and lactate levels, as well as between metformin plasma levels and mortality. We aim to analyse these correlations in a large series of lactic acidosis cases recorded in the French nationwide pharmacovigilance database.

METHODS

All cases of lactic acidosis spontaneously reported between 1985 and October 2013 associated with metformin exposure were extracted from the pharmacovigilance database. We assessed the statistical correlations between prescribed daily doses of metformin, plasma concentrations of metformin and lactate, pH and plasma creatinine, as well as the relationship between mortality and these variables.

RESULTS

Seven hundred and twenty-seven cases of lactic acidosis were reported during the period. Metformin plasma concentration was documented for 260 patients, lactate plasma concentration for 556 patients, pH for 502 patients, creatinine for 397 patients and the vital outcome for 713 patients. Metformin plasma concentration, lactate concentration, pH and plasma creatinine were all correlated (P < 0.001). There were significant differences between surviving and deceased patients in terms of metformin plasma levels (25.2 vs. 37.4 mg/l, P = 0.002) and lactate concentrations (10.8 vs. 16.3 mmol/l, P < 0.001). Thirty per cent of patients died when metformin concentration was > 5 mg/l compared with 11% for patients with concentration < 5 mg/l (P = 0.003).

CONCLUSIONS

Our data suggest that metformin accumulation contributes to the pathogenesis and prognosis of lactic acidosis.

Contraceptive pills and thrombosis: effects of the French crisis on prescriptions and consequences for medicine agencies

The higher risk of venous thromboembolism with 3rd and 4th- generations combined oral contraceptives compared to 2nd generation triggered a media crisis in France. Exposure to 3rd or 4th-generation combined oral contraceptives led to an annual excess of around 100 premature deaths in Europe. In the absence of any demonstrated additional benefit of these combined oral contraceptives, measures were taken to decrease exposure of women to this illegitimate excess of risk. As a consequence, this crisis saw a 45% decrease in the prescription of 3rd and 4th-generations combined oral contraceptives, without adverse consequences.

No effect of isolated long-term supine immobilization or profound prolonged hypoxia on blood coagulation

BACKGROUND

Long-distance air travel is associated with an increased risk of venous thrombosis. The most obvious factor that can explain air travel-related thrombosis is prolonged seated immobilization. In addition, hypobaric hypoxia has been shown to affect coagulation, and the lowered atmospheric pressures present in the cabin during the flight may therefore play an etiologic role. Because immobilization and hypoxic conditions are usually present simultaneously in airplanes or hypobaric chambers, their separate effects on the coagulation system or on thrombosis risk have not been studied extensively.

OBJECTIVES

To investigate the separate effects of long-term immobilization and profound prolonged hypoxia on blood coagulation.

PATIENTS AND METHODS

We performed two studies in collaboration with European Space Agency/European Space Research and Technology Centre. In the first study, 24 healthy, non-smoking, adult women underwent 60 days of -6° head-down bed rest. In the second study, we took blood samples from 25 healthy men who participated during their stay in the Concordia station in Antarctica, where, due to the atmospheric conditions, continuous severe hypobaric hypoxia is present. In both studies, we measured markers of blood coagulation at baseline and at several time points during the exposures.

RESULTS AND CONCLUSIONS

We observed no increase in coagulation markers during immobilization or in the hypobaric environment, compared with baseline measurements. Our results indicate that neither immobilization nor hypoxia per se affects blood coagulation. These results implicate that a combination of risk factors is necessary to induce the coagulation system during air travel.

Fracture near press-on interlocking enhances callus mineralisation in a sheep midshaft tibia osteotomy model

INTRODUCTION

Factors which impair fracture healing after intramedullary (IM) nailing of long bone fractures range from surgical and biological factors to mechanical parameters. Mechanical parameters known to prolong bony consolidation are share forces at the site of the fracture. Fracture near press-on interlocking reduces share forces directly at the fracture site and is hypothesised to enhance callus mineralisation. A sheep model of midshaft tibia osteotomies evaluates the technique.

MATERIALS AND METHODS

Fracture near interlocking was achieved by surfacing a custom made nail with special hutches that enable firm screw seating on top of the nail ("golf ball" structure). Virtual (fine element analysis (FEA)) and biomechanical pilot tests were completed before in vivo application in 12 adult female German black sheep. Midshaft tibia osteotomy was performed creating a subcritical 7 mm gap for delay in union. One group (n=6) was treated with reamed IM nailing employing the custom made nail and in addition to proximal and distal standard interlocking a fracture near press on interlocking was employed. A second group of six sheep without additional press on interlocking served as control. 10 weeks after operation the quality of fracture healing was determined by micro-CT.

RESULTS

The FEA showed that axial loading up to 4000N did not lead to implant fatigue. Fracture near press on interlocking led to significantly more callus mineralisation compared to the conventional interlocking procedure (0.567 g/cm(3) ± 0.106 g/cm(3) versus 0.434 g/cm(3) ± 0.0836 g/cm(3), p=0.043).

CONCLUSIONS

Fracture near press on interlocking increases callus mineralisation in a subcritical osteotomy model in sheep. The results indicate that the reduction of share forces at the fracture site after nailing procedures may be effective in reducing the time until bony consolidation.

Therapeutic effect of fucoidan-stimulated endothelial colony-forming cells in peripheral ischemia

BACKGROUND

Fucoidan, an antithrombotic polysaccharide, can induce endothelial colony-forming cells (ECFC) to adopt an angiogenic phenotype in vitro.

OBJECTIVES

We evaluated the effect of fucoidan on vasculogenesis induced by ECFC in vivo.

METHODS

We used a murine hindlimb ischemia model to probe the synergic role of fucoidan-treatment and ECFC infusion during tissue repair.

RESULTS

We found that exposure of ECFC to fucoidan prior to their intravenous injection improved residual muscle blood flow and increased collateral vessel formation. Necrosis of ischemic tissue was significantly reduced on day 14, to 12.1% of the gastronecmius cross-sectional surface area compared with 40.1% in animals injected with untreated-ECFC. ECFC stimulation with fucoidan caused a rapid increase in cell adhesion to activated endothelium in flow conditions, and enhanced transendothelial extravasation. Fucoidan-stimulated ECFC were resistant to shear stresses of up to 21 dyn cm(-2). Direct binding assays showed strong interaction of fucoidan with displaceable binding sites on the ECFC membrane. Bolus intramuscular administration of fucoidan 1 day after surgery reduces rhabdomyolysis. Mice injected with fucoidan (15 mg kg(-1)) had significantly lower mean serum creatine phosphokinase (CPK) activity than control animals. This CPK reduction was correlated with muscle preservation against necrosis (P < 0.001).

CONCLUSIONS

Fucoidan greatly increases ECFC-mediated angiogenesis in vivo. Its angiogenic effect would be due in part to its transportation to the ischemic site and its release after displacement by proteoglycans present in the extracellular matrix. The use of ECFC and fucoidan together, will be an efficient angiogenesis strategy to provide therapeutic neovascularization.

[A special soft tissue procedure for treatment of hallux valgus]

OBJECTIVE

Maintaining the corrected position of the first metatasophalangeal axis. Reducing postoperative stiffness by forgoing a medial capsular shift.

INDICATIONS

Hallux valgus deformities or recurrent hallux valgus deformities.

CONTRAINDICATIONS

Existing osteoarthritis, joint stiffness, large bone defects, osteonecrosis. General medical contraindications to surgical interventions and anesthesiological procedures.

SURGICAL TECHNIQUE

Operation under regional anesthesia (foot block) or general anesthesia. Tourniquet. Longitudinal skin incision medial over the pseudexostosis of the first metatarsal bone. Preparing the tendon of the Musculus abductor hallucis. Detaching the tendon from the capsule. Incision of the joint capsule with protection of the extensor hallucis longus tendon and the dorsal neurovascular bundle in an L-wise manner. Osteotomy of the first metatarsal bone. Lax sutures of the capsule in correct position and reattachment of the Musculus abductor hallucis tendon shifted toward distal and dorsal, regarding the rotation of the hallux.

POSTOPERATIVE MANAGEMENT

Postoperative elevation of the operated foot. Analgesia with nonsteroidal antiinflammatory drugs. Postoperative weight-bearing according to the osteotomy. Passive mobilization of the metatarsophalangeal joint. Dressing for 4 weeks postoperatively in the corrected position. Radiologic control after 6 weeks. Hallux valgus orthosis at night and a toe spreader for a further 6 weeks.

RESULTS

A total of 30 isolated hallux valgus deformities with a mean preoperative intermetatarsal (IMA) angle of 12.9° (range 11-15°) were operated with a chevron osteotomy. The mean follow-up was 14.4 (range 8-17) months. The mean dorsiflexion at the last follow-up was 44° (range 20-60°). Only 2 patients had a dorsiflexion <40°. The mean reduction of the IM angle was 5.6° (range 3-7°). One patient required wound revision. There was no infection or avascular necrosis of the metatarsal head observed in the patients. At follow-up, 20 (67%) patients were completely satisfied, 9 (30%) satisfied, and 1 (3%) was not satisfied.

[Risk factors for recurrent venous thromboembolism]

Recurrent venous thromboembolism (VTE) is frequent and can be fatal. Long-term antithrombotic treatment reduces the risk of recurrent VTE but increases the risk of bleeding and, therefore, cannot be proposed for all patients. Predicting the probability of recurrence in an individual patient is of utmost importance for assessing the risk-benefit ratio of long-term anticoagulation. Multiple clinical risk factors for recurrent VTE have been identified which include: unprovoked first episode, anatomical proximal location, male gender, residual venous thrombosis, cancer and antiphospholipid syndrome. d-dimer level after discontinuation of oral anticoagulation can help to predict the risk of recurrence with a good negative predictive value. Finally, genetic polymorphisms and rare inherited deficiencies of natural anticoagulant proteins do not seem to be strongly associated to recurrence. New antithrombotic drugs may, in the near future, improve the safety and of long-term anticoagulation treatment.

Effects of eliminating tension by means of epineural stitches: a comparative electrophysiological and histomorphometrical study using different suture techniques in an animal model

Epineural stitches are a means to avoid tension in a nerve suture. We evaluate this technique, relative to interposed grafts and simple neurorraphy, in a rat model. METHOD: Twenty rats were allocated to four groups. For Group 1, sectioning of the sciatic nerve was performed, a segment 4 mm long discarded, and epineural suture with distal anchoring stitches were placed resulting in slight tension neurorraphy. For Group 2, a simple neurorraphy was performed. For Group 3, a 4 mm long graft was employed and Group 4 served as control. Ninety days after, reoperation, latency of motor action potentials recording and axonal counts were performed. Inter-group comparison was done by means of ANOVA and the non-parametric Kruskal-Wallis test. RESULTS: The mean motor latency for the simple suture (2.27±0.77 ms) was lower than for the other two surgical groups, but lower than among controls (1.69±0.56 ms). Similar values were founding in both group 1 (2.66±0.71 ms) and group 3 (2.64±0.6 ms). When fibers diameters were compared a significant difference was identified between groups 2 and 3 (p=0.048). CONCLUSION: Good results can be obtained when suturing a nerve employ with epineural anchoring stitches. However, more studies are needed before extrapolating results to human nerve sutures.

Protein S inherited qualitative deficiency: novel mutations and phenotypic influence

BACKGROUND

Only a few mutations associated with qualitative protein S deficiency have already been described. Sensitivity and specificity for type II PROS1 mutations of commercially available reagents for measuring Protein S (PS) activity are not well established. Whether these mutations are significant risk factors for thrombosis remains an unresolved question.

METHODS

In order to address the first point, we present and discuss the results of PROS1 analysis performed in the 30 probands with type II PS-inherited deficiency suspicion and 35 relatives, studied in our laboratory between 2000 and 2008. In order to investigate the influence of type II mutations on the coagulability level, thrombin generation tests were performed on plasma from 102 PROS1 type II, type I/III or PS Herleen mutation heterozygous carriers and controls.

RESULTS

Mutations (12 novel, six already described) which probably explain the qualitative phenotype, were found in 27 (90%) out of the 30 probands studied. In relatives, 78% of heterozygotes presented with a type II phenotype. An APC resistance phenotype was documented in type II and type I/III defects heterozygous carriers; however, the effect of type II was milder than the effect of type I/III PS mutations.

CONCLUSIONS

A PS functional assay (Staclot PS, Stago) was efficient in screening for PROS1 type II defects, particularly in probands. A significant positive influence of type II mutations on ex vivo thrombin generation was demonstrated. However, whether these mutations increase the risk of venous thromboembolism requires further investigation.

A multi-stage multi-design strategy provides strong evidence that the BAI3 locus is associated with early-onset venous thromboembolism

BACKGROUND

Factor VIII (FVIII) and von Willebrand factor (VWF) are two known quantitative risk factors for venous thromboembolism (VTE).

OBJECTIVES

To identify new loci that could contribute to VTE susceptibility and to modulating FVIII and/or VWF levels.

PATIENTS/METHODS

A pedigree linkage analysis was first performed in five extended French-Canadian families, including 253 individuals, to identify genomic regions linked to FVIII or VWF levels. Identified regions were further explored using 'in silico' genome-wide association studies (GWAS) data on VTE (419 patients and 1228 controls), and two independent case-control studies (MARTHA and FARIVE) for VTE, gathering 1166 early-onset patients and 1408 healthy individuals. Single nucleotide polymorphisms (SNPs) associated with VTE risk were further investigated in relation to plasma levels of FVIII and VWF in a cohort of 108 healthy nuclear families.

RESULTS

Four main linkage regions were identified, among which the well-characterized ABO locus, the recently identified STAB 2 gene, and a third one, on chromosome 6q13-14, harbouring four non-redundant SNPs, associated with VTE at P < 10(-4) in the GWAS dataset. The association of one of these SNPs, rs9363864, with VTE was further replicated in the MARTHA and FARIVE studies. The rs9363864-AA genotype was associated with a lower risk for VTE (OR = 0.58 [0.42-0.80], P = 0.0005) but mainly in non-carriers of the FV Leiden mutation. This genotype was further found to be associated with the lowest levels of FVIII (P = 0.006) and VWF (P = 0.001).

CONCLUSIONS

The BAI3 locus where the rs9363864 maps is a new candidate for VTE risk.

Maize- or potato-derived hydroxyethyl starches: is there any thromboelastometric difference?

BACKGROUND

Hydroxyethyl starches (HES) could differ with regard to the origin, and the influence on the coagulation of the raw material is unknown. This study compared the effects of a new potato-derived HES with a maize-derived HES and two crystalloid solutions.

METHODS

Whole blood from 10 healthy individuals was diluted by 20% and 40% using either non-balanced potato-derived HES 130/0.42/6:1, non-balanced maize-derived HES 130/0.4/9:1, isotonic saline or Ringer's lactate solution. Samples were analysed by thromboelastometry ROTEM(®) : Coagulation was initiated by acid ellagic [intrinsic thromboelastometry (INTEM)] or tissue factor (extrinsic thromboelastometry) with and without cytochalasin to determine the functional component of fibrinogen [cytochalasin-d-modified thromboelastometry (FIBTEM)]. Platelet count and fibrinogen activity were measured.

RESULTS

No effect of raw material was found as no difference was detected among the HES solutions. Whatever the solution, progressive haemodilution impaired haemostasis in a dose-dependant manner: For INTEM, the clot formation time was increased up to 308% and the maximum clot firmness (MCF) was decreased down to 49%. As dilution increased, initiation of coagulation was also impaired. Thromboelastometric alterations were more severe with HES than with crystalloids, especially regarding fibrin polymerization explorations: MCF of FIBTEM was considerably reduced from 12[10-14] to 2[2-3] mm (P<0.05). Fibrinogen activity and platelet count were reduced by dilution in a dose-dependant manner and decreased similarly in all groups.

CONCLUSION

Maize- and potato-derived HES have similar effects on coagulation. Both the starch preparations tested lead to more severe haemostatic defects than crystalloids, and impairment of fibrin polymerization appears to be a leading determinant of this coagulopathy.

The minor allele of GP6 T13254C is associated with decreased platelet activation and a reduced risk of recurrent cardiovascular events and mortality: results from the SMILE-Platelets project

BACKGROUND

Contradictory results have been published on the effects of T13254C (rs1613662), which distinguishes the two major isoforms of GP6, the gene encoding the platelet receptor glycoprotein VI, on platelet function and the risk of cardiovascular disease.

METHODS

We performed a population-based case-control study, the Study of Myocardial Infarctions in Leiden, among 547 male patients with a first myocardial infarction (MI) and 646 control subjects, as well as a prospective cohort study in which the same MI patients were followed for recurrent events (fatal and non-fatal MI and unstable angina) and mortality (median follow-up of 12 years). P-selectin expression by platelets induced by crosslinked collagen-related peptide (CRP-XL) was measured by whole blood flow cytometry in 274 MI patients.

RESULTS

T13254C was not associated with a first MI, but seemed to be associated with a reduced incidence of recurrent events [per-allele hazard ratio 0.77, 95% confidence interval (CI) 0.56-1.06] and mortality (hazard ratio 0.57, 95% CI 0.37-0.89). Pooling with the Heart and Estrogen/Progestin Replacement Study revealed hazard ratios of 0.81 (95% CI 0.66-0.99) and 0.73 (95% CI 0.55-0.96). The minor C-allele was also strongly associated with a reduced percentage of P-selectin-expressing platelets. The reduction per C-allele was 23% (95% CI 18-28%). In an independent study of 219 healthy volunteers, the per-allele reduction of CRP-XL-induced aggregation was 10% (95% CI 2-18%).

CONCLUSION

The minor allele of GP6 T13254C that reduced platelet activation and aggregation also seemed to be associated with a reduced incidence of recurrent cardiovascular events and mortality, but was not associated with first MI.