Prophylactic intraoperative antithrombotics in open infrainguinal arterial bypass surgery: a systematic review

Unfractionated heparin (UFH) is used intraoperatively as antithrombotic by most vascular surgeons worldwide during infrainguinal bypass surgery (IABS) to reduce the risk of peroperative and early graft thrombosis. To reduce the harmful side effects of UFH (bleeding complications, HIT) and to reduce peroperative and early graft failure, other pharmaceuticals have been suggested for IABS. A systematic review was performed using MEDLINE, EMBASE and Cochrane databases. Only 9 studies on IABS and intraoperative antithrombotic use were eligible for review. Between studies heterogeneity was high and investigated study populations were often of small size. No study was retrieved comparing UFH to no-UFH. Dextran, human antithrombin and iloprost showed no beneficial effect compared to UFH alone for patency, mortality and morbidity. Low molecular weight heparin (LMWH) has potential benefits compared to UFH, but a statistically significant effect could not be demonstrated from the current review. The use of UFH during IABS to prevent intraoperative graft thrombosis has not been proven in randomized clinical trials. Dextran, human antithrombin and iloprost showed to be of no added beneficial effect for the patient compared to UFH alone. Data on the use of LMWH instead of UFH are promising, but no statistically significant benefit could be reproduced from literature. Results from a recent Cochrane review were favourable for LMWH, but it appeared that included data were not complete in that review. Randomized controlled trials are required for intra-operative use of antithrombotics and to improve peroperative and early patency after IABS.

Perioperative prophylactic antithrombotic strategies in vascular surgery: current practice in the Netherlands

AIM

The aim of this study was to evaluate the current practice of the use of perioperative antithrombotic drugs to prevent arterial thrombo-embolic complications during arterial vascular surgery by Dutch vascular surgeons. Aim was also to compare the results with the literature and to evaluate the effect of guidelines.

METHODS

A comprehensive questionnaire was sent to all Dutch vascular surgeons performing arterial reconstructive surgery.

RESULTS

The response rate was 84%. Acetylsalicylic acid (ASA) was continued perioperatively by most surgeons (91%). Clopidogrel was discontinued by the majority of respondents (65%). During operation 97% of surgeons administered unfractionated heparin (UFH) before arterial clamping. A minority (11%) measures peroperatively anticoagulant activity in patients' blood. After infrainguinal venous bypass most surgeons (81%) preferred monotherapy with vitamin K antagonists (VKA), in agreement with the Dutch guideline in this respect. Before the introduction of the guideline in 2005, a survey was performed in 2004. Results of our 2011 survey showed more respondents (6% to 11%) prescribed ASA or VKA according to these guidelines.

CONCLUSION

This survey showed a recognizable pattern of variation for perioperative arterial thrombosis prophylaxis amongst Dutch vascular surgeons, in agreement with reports from other countries over the past 20 years. Although a higher percentage of surgeons complied in 2011 with existing guidelines than in 2004, guidelines were not completely met. Possibly because current guidelines are not fully supported by evidence and do not cover all aspects of perioperative arterial thrombosis prophylaxis. Clearly there is need for (more) convincing data based on RCT's concerning the various aspects of perioperative arterial thrombosis prophylaxis.

Long term effects of epoetin alfa in patients with ST- elevation myocardial infarction

PURPOSE

The HEBE III trial showed that epoetin alfa administration in patients with a first ST-elevation myocardial infarction (STEMI) did not improve left ventricular function at 6 weeks after primary percutaneous coronary intervention (PCI). The long term effects of erythropoiesis- stimulating agents on cardiovascular morbidity and mortality are unknown, therefore we evaluated clinical events at 1 year after PCI.

METHODS

A total of 529 patients with a first STEMI and successful primary PCI were randomized to standard optimal medical treatment (N = 266) or an additional bolus of 60,000 IU epoetin alfa administered intravenously (N = 263) within 3 h after PCI. Analyses were performed by intention to treat.

RESULTS

At 1 year after STEMI, 485 patients had complete follow-up. The rate of the composite end point of all-cause mortality, re-infarction, target vessel revascularization, stroke and/or heart failure was 6.4 % (N = 15) in the epoetin alfa group and 9.6 % (N = 24) in the control group (p = 0.18). Thromboembolic events were present in 1.3 % (N = 3) of patients in the epoetin alfa group and 2.4 % (N = 6) in the control group. There was no evidence of benefit from epoetin alfa administration in subgroups of patients.

CONCLUSIONS

Administration of a single bolus of epoetin alfa in patients with STEMI does not result in a reduction of cardiovascular events at 1 year after primary PCI. There was a comparable incidence of thromboembolic complications in both treatment groups, suggesting that epoetin alfa administration is safe at long term.

Leaf photosynthesis and respiration of three bioenergy crops in relation to temperature and leaf nitrogen: how conserved are biochemical model parameters among crop species?

Given the need for parallel increases in food and energy production from crops in the context of global change, crop simulation models and data sets to feed these models with photosynthesis and respiration parameters are increasingly important. This study provides information on photosynthesis and respiration for three energy crops (sunflower, kenaf, and cynara), reviews relevant information for five other crops (wheat, barley, cotton, tobacco, and grape), and assesses how conserved photosynthesis parameters are among crops. Using large data sets and optimization techniques, the C(3) leaf photosynthesis model of Farquhar, von Caemmerer, and Berry (FvCB) and an empirical night respiration model for tested energy crops accounting for effects of temperature and leaf nitrogen were parameterized. Instead of the common approach of using information on net photosynthesis response to CO(2) at the stomatal cavity (A(n)-C(i)), the model was parameterized by analysing the photosynthesis response to incident light intensity (A(n)-I(inc)). Convincing evidence is provided that the maximum Rubisco carboxylation rate or the maximum electron transport rate was very similar whether derived from A(n)-C(i) or from A(n)-I(inc) data sets. Parameters characterizing Rubisco limitation, electron transport limitation, the degree to which light inhibits leaf respiration, night respiration, and the minimum leaf nitrogen required for photosynthesis were then determined. Model predictions were validated against independent sets. Only a few FvCB parameters were conserved among crop species, thus species-specific FvCB model parameters are needed for crop modelling. Therefore, information from readily available but underexplored A(n)-I(inc) data should be re-analysed, thereby expanding the potential of combining classical photosynthetic data and the biochemical model.

Ultrasound-accelerated thrombolysis for lower extremity ischemia: multicenter experience and literature review

AIM

This study evaluates the short-term outcome of ultrasound-accelerated thrombolysis in patients with lower extremity ischemia caused by thromboembolic occlusions.

METHODS

A retrospective cohort study was conducted from December 2008 to May 2011 of 57 patients (42 men; median age, 66 ± 11 years) undergoing 62 episodes of ultrasound-accelerated thrombolysis for thromboembolic arterial occlusions of the lower extremities. The EKOS EndoWave System (EKOS Corporation, Bothell, WA, USA) was combined with urokinase (100000 IU/hour). Thirty-day and 6-month follow-up consisted of clinical evaluation, and Duplex scan or magnetic resonance angiography of the treated extremity.

RESULTS

Initial technical success was 97%, radiologic success was 82%, and overall clinical success was 77%. Median thrombolysis time was 21 hours (IQR, 15-24). In 38 of 51 procedures with successful lysis (75%) complete lysis was achieved within 24 hours. Major hemorrhage occurred in 2 procedures (3%), and distal embolization in 2 procedures (3%). During the initial hospitalization, the major amputation rate was 8% (N.=5) and the mortality rate was 2% (N.=1). The 30-day patency rate was 81%, without additional mortality. During a median 6-month (range, 2-14) follow-up, 9 reinterventions were performed. Two patients underwent major amputation and 3 patients died; because of malignancy (N.=2) and stroke (N.=1).

CONCLUSION

Initial success rates of ultrasound-accelerated thrombolysis are high and complication rate is low. However, reintervention rate during short-term follow-up for recurrent ischemia is substantial. Results from a randomized controlled trial comparing ultrasound-accelerated thrombolysis with standard thrombolysis for lower extremity ischemia (DUET, Current Controlled Trials, ISRCTN72676102) are eagerly awaited.

A single dose of erythropoietin in ST-elevation myocardial infarction

AIMS

Cardioprotective effects of erythropoietin (EPO) have been shown in experimental and smaller clinical studies. We performed a prospective, multicentre, randomized trial to assess the effects of a single high dose of EPO after primary coronary intervention (PCI) for an ST-elevation myocardial infarction (STEMI). Methods and results Patients with a successful PCI for a first STEMI were randomized to receive either standard medical care alone, or in combination with a single bolus with 60,000 IU i.v. of epoetin alfa within 3 h after PCI. Primary endpoint was left ventricular ejection fraction (LVEF) after 6 weeks, assessed by planar radionuclide ventriculography. Pre-specified secondary endpoints included enzymatic infarct size and major adverse cardiovascular events. A total of 529 patients were enrolled (EPO n = 263, control n = 266). At baseline (before EPO administration), groups were well-matched for all relevant characteristics. After a mean of 6.5 (± 2.0) weeks, LVEF was 0.53 (± 0.10) in the EPO group and 0.52 (± 0.11) in the control group (P = 0.41). Median area under the curve (inter-quartile range) after 72 h for creatinine kinase was 50 136 (28 212-76 664)U/L per 72 h in the EPO group and 53 510 (33 973-90 486)U/L per 72 h in the control group (P = 0.058). More major adverse cardiac events occurred in the control than in the EPO group (19 vs. 8; P = 0.032). Conclusion A single high dose of EPO after a successful PCI for a STEMI did not improve LVEF after 6 weeks. However, the use of EPO was related to less major adverse cardiovascular events and a favourable clinical safety profile.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00449488; http://www.clinicaltrials.gov/ct2/show/NCT00449488?term=voors&rank=2.

Simulation of wheat growth and development based on organ-level photosynthesis and assimilate allocation

Intimate relationships exist between form and function of plants, determining many processes governing their growth and development. However, in most crop simulation models that have been created to simulate plant growth and, for example, predict biomass production, plant structure has been neglected. In this study, a detailed simulation model of growth and development of spring wheat (Triticum aestivum) is presented, which integrates degree of tillering and canopy architecture with organ-level light interception, photosynthesis, and dry-matter partitioning. An existing spatially explicit 3D architectural model of wheat development was extended with routines for organ-level microclimate, photosynthesis, assimilate distribution within the plant structure according to organ demands, and organ growth and development. Outgrowth of tiller buds was made dependent on the ratio between assimilate supply and demand of the plants. Organ-level photosynthesis, biomass production, and bud outgrowth were simulated satisfactorily. However, to improve crop simulation results more efforts are needed mechanistically to model other major plant physiological processes such as nitrogen uptake and distribution, tiller death, and leaf senescence. Nevertheless, the work presented here is a significant step forwards towards a mechanistic functional-structural plant model, which integrates plant architecture with key plant processes.

Analysing lodging of the panicle bearing cereal teff (Eragrostis tef)

Lodging, the permanent displacement of crop plants from their vertical because of root or shoot failure, is a major yield constraint of the gluten free, panicle bearing cereal teff. The objective of this paper was to analyse the causes of lodging of teff by using, modifying and validating conventional biomechanical models. The model parameters were obtained from a field trial with two contrasting teff cultivars, using novel in situ and laboratory measurements under wet and dry conditions. Cross-species model validation was done with rice (Oryza sativa). Teff is more susceptible to root lodging than to shoot lodging, although the data indicated that shoot strength is also insufficient. Hence, simultaneously breeding for both improved root anchorage and shoot strength is advocated. The study showed that the lodging model, derived for the spike-bearing cereal wheat, needed modifications in order to be able to deal with panicle-bearing plants such as teff and rice. Water adhering to plants owing to rain or dew increased calculated lodging susceptibility. To prevent underestimation of lodging susceptibility, future lodging research should be done under completely wet conditions (water saturated soil and wetted shoots).

Functional-structural plant modelling: a new versatile tool in crop science

Plants react to their environment and to management interventions by adjusting physiological functions and structure. Functional-structural plant models (FSPM), combine the representation of three-dimensional (3D) plant structure with selected physiological functions. An FSPM consists of an architectural part (plant structure) and a process part (plant functioning). The first deals with (i) the types of organs that are initiated and the way these are connected (topology), (ii) co-ordination in organ expansion dynamics, and (iii) geometrical variables (e.g. leaf angles, leaf curvature). The process part may include any physiological or physical process that affects plant growth and development (e.g. photosynthesis, carbon allocation). This paper addresses the following questions: (i) how are FSPM constructed, and (ii) for what purposes are they useful? Static, architectural models are distinguished from dynamic models. Static models are useful in order to study the significance of plant structure, such as light distribution in the canopy, gas exchange, remote sensing, pesticide spraying studies, and interactions between plants and biotic agents. Dynamic models serve quantitatively to integrate knowledge on plant functions and morphology as modulated by environment. Applications are in the domain of plant sciences, for example the study of plant plasticity as related to changes in the red:far red ratio of light in the canopy. With increasing availability of genetic information, FSPM will play a role in the assessment of the significance towards plant performance of variation in genetic traits across environments. In many crops, growers actively manipulate plant structure. FSPM is a promising tool to explore divergent management strategies.

Long-term effect of perindopril on coronary atherosclerosis progression (from the perindopril's prospective effect on coronary atherosclerosis by angiography and intravascular ultrasound evaluation [PERSPECTIVE] study)

The multicenter EUROPA trial of 12,218 patients showed that perindopril decreased adverse clinical events in patients with established coronary heart disease. The PERSPECTIVE study, a substudy of the EUROPA trial, evaluated the effect of perindopril on coronary plaque progression as assessed by quantitative coronary angiography and intravascular ultrasound (IVUS). In total 244 patients (mean age 57 years, 81% men) were included. Evaluable paired quantitative coronary angiograms were obtained from 96 patients randomized to perindopril and from 98 patients to placebo. Concomitant treatment at baseline consisted of aspirin (90%), lipid-lowering agents (70%), and beta blockers (60%). The primary and secondary end point was the difference of minimum and mean lumen diameters (quantitative coronary angiography) or mean plaque cross-sectional area (IVUS) measured at baseline and 3-year follow-up between the perindopril and placebo groups. After a median follow-up of 3.0 years (range 1.9 to 4.1), no differences in change in quantitative coronary angiographic or IVUS measurements were detected between the perindopril and placebo groups (minimum and mean luminal diameters -0.07 +/- 0.4 vs -0.02 +/- 0.4 mm, p = 0.34; mean luminal diameter -0.05 +/- 0.2 vs -0.05 +/- 0.3 mm, p = 0.89; mean plaque cross-sectional area -0.18 +/- 1.2 vs -0.02 +/- 1.2 mm(2), p = 0.48). In conclusion, we found no progression in coronary artery disease by quantitative coronary angiography and IVUS with long-term administration of perindopril or placebo, possibly because most patients were on concomitant treatment with a statin.

[High mortality in a herd with signs of jejunal hemorrhage syndrome]

Eleven cows from a herd of 80 dairy cows (14%) died over a 7-month period. Death occurred within 12-24 hours of the onset of the first clinical signs, namely, dullness and a decrease (mean 25%) in milk production. Within 12 hours the cows were unable to rise, felt cold, and were restless. Examined mucous membranes were pale. Two of three cows examined at necropsy had blood in the jejunum and high counts of Clostridium perfringens. Jejunal hemorrhage syndrome was diagnosed in these two cows on the basis of the clinical signs and postmortem findings.

Patient preferences for expectant management vs. surgical evacuation in first-trimester uncomplicated miscarriage

OBJECTIVE

Expectant and surgical management are widely accepted treatment options in case of a miscarriage. In the absence of differences in complications, the choice between both options can be based on patient preferences.

STUDY DESIGN AND SETTING

We studied treatment preferences for future miscarriages in women with a miscarriage randomized to expectant or surgical treatment or managed according to their own choice.

RESULTS

Data from 136 patients were analyzed. Women randomized either to expectant or surgical management opted for the allocated treatment in future in 55 and 74%, respectively. Of the women randomized to expectant management and with a successful spontaneous loss, 71% opted again for this treatment. Women who were managed according to their own treatment choice, held on to their initial treatment preference (expectant vs. surgical management; 84 and 88%, respectively). Preferences after treatment were strong.

CONCLUSION

A strong treatment preference should be taken into account in the counseling process. Women without a preference should be well informed on all medical aspects of the two options in order to facilitate informed-shared decision-making.

[Stillbirth/perinatal weak calf syndrome in dairy heifers: results of a pilot study]

A pilot study of 10 Dutch dairy herds was performed to investigate possible causes of stillbirth/perinatal weak calf syndrome in heifers. Possible causes and advice for further investigations on farms affected by this syndrome are discussed based on the results of investigations of blood and urine from pregnant young stock, postmortem examination of still-born calves, and a questionnaire held among farmers. Infections with Neospora caninum, Salmonella spp. or Leptospira hardjo, or a deficiency of iodine could be excluded.