Percutaneous aortic valve replacement: new hope for inoperable and high-risk patients

Aortic stenosis is the most common valvular heart disease in the Western world and its prevalence is increasing with an aging population. Although medical therapy has little to offer in terms of prognosis or symptomatic relief, at least one-third of patients with severe aortic stenosis are denied valve surgery as a result of age and comorbidities. This review describes the development of the percutaneous aortic valve as an alternative therapy for such patients. The technique, initial results and the current limitations of the procedure are explained alongside the ongoing trials necessary in order that such therapy may eventually be made widely available.     

Effect of Armagnac fractions on human platelet aggregation in vitro and on rat arteriovenous shunt thrombosis in vivo probably not related only to polyphenols

Previous studies showed that alcohol-free extracts of Armagnac, an oak cask aged spirit rich in polyphenols, inhibit human platelet function in vitro and in vivo, in an experimental rat arteriovenous shunt thrombosis model and in human healthy volunteers. To identify active compounds, we fractionated a freeze-dried extract of a 10-year-old Armagnac using successively chloroform, diethyl ether and ethyl acetate. The 4 resulting fractions were tested on in vitro human platelet aggregation induced by ADP and in vivo on arteriovenous shunt thrombosis after 10 days oral treatment in rats. Active components were found mainly in fractions 1 and 3: at the highest concentration (2.4 10(-2) g/l), in vitro ADP-induced aggregation was inhibited by 62.7+/-2.1% and 51.2+/-3.8% for F1 and F3, respectively, vs 18.9+/-2.4% and 13.9+/-0.4% for fractions 2 and 4 and 33.6+/-1.5% for the crude extract. There was a significant decrease in thrombus weight with the crude extract and all fractions tested after 10 days treatment with 2.5 mg/kg/day orally, greatest with fraction 1. Characterisation of phenol content showed that fraction 1, the most biologically active, was essentially devoid of ellagic acid and ellagitannins, the polyphenols initially thought responsible for the effect, whereas fraction 2 which was mostly inactive, was the richest in polyphenols. CONCLUSION: The antiplatelet and antithrombotic activity of Armagnac seems mostly unrelated to polyphenols.     

A new plastic collection tube made of polyethylene terephtalate is suitable for monitoring traditional anticoagulant therapy (oral anticoagulant, unfractionated heparin, and low molecular weight heparin)

To improve the safety of blood collection, plastic tubes have been developed but various interactions with the coagulation system and/or antithrombotic drugs were reported with the first generation of such tubes. The aim of this multicentre study was to compare hemostasis test results measured in evacuated plastic tubes made of polyethylene terephtalate (VenoSafe, Terumo Europe) and in siliconized glass tubes containing the same citrate concentration (0.129 M). In addition, the impact of aging of the plastic tube was investigated by collecting blood samples in tubes at 8 months and at 1 month before expiry. Blood was drawn in 3 centres from untreated patients (n=269), patients on oral anticoagulant treatment (OAT, n=221), and patients treated with either unfractionated heparin (UFH, n=73) or a low molecular weight derivative (LMWH, n=48). Prothrombin time (PT) or INR, activated partial thromboplastin time (APTT) and anti-FXa activity were locally performed, when applicable. In untreated patients and in patients on OAT, PT and APTT values were found statistically shorter (p<0.05) when evaluated in plastic tubes than in glass tubes, except when PT was evaluated using a human thromboplastin. Surprisingly, significantly longer APTT and higher anti-FXa activities were obtained when blood from patients on UFH was drawn in plastic than in glass tubes. However, none of the differences had any clinical relevance (Bland-Altman analysis). In patients on anticoagulant treatment, there was no effect of aging of the plastic tubes. These results suggest that the plastic tube VenoSafe is suitable for coagulation testing both in untreated subjects and more interestingly in patients on traditional anticoagulant therapy during the whole shelf life indicated by the manufacturer.     

Transient hypolocomotion in rats repeatedly exposed to phencyclidine: an appraisal of motor function and motivation

Spontaneous locomotion in rats is reduced about 20 h following phencyclidine (PCP) exposure. Our primary purpose was to test if locomotor irregularities would outlast drug withdrawal and be modulated by a periodic auditory stimulation during or after repeated injections. To circumscribe plausible interpretations, motor coordination and motivation were assessed as well. 10 mg/kg of PCP decreased spontaneous locomotion during the injection period whether or not a sound was presented. Those effects did not persist after a 7-day washout. Motor coordination and motivation to perform a variety of goal-driven conducts in the presence or absence of reinforcement were all unaffected by PCP treatment. The generalized hypolocomotor effects induced by PCP likely resulted from an inability to self-generate behaviors. These deficiencies were apparent in contexts where response production was not clearly specified nor supported, regardless of reward contingency.     

Modulation of human corticomuscular beta-range coherence with low-level static forces

Although corticomuscular synchronization in the beta range (15-30 Hz) was shown to occur during weak steady-state contractions, an examination of low-level forces around 10% of the maximum voluntary contraction (MVC) is still missing. We addressed this question by investigating coherence between electroencephalogram (EEG) and electromyogram (EMG) as well as cortical spectral power during a visuomotor task. Eight healthy right-handed subjects compensated isometrically static forces at a level of 4% and 16% of MVC with their right index finger. While 4% MVC was accompanied by low coherence values in the middle to high beta frequency range (25-30 Hz), a significant increase of coherence mainly confined to low beta frequencies (19-20 Hz) was observed with force of 16% MVC. Furthermore, this increase was associated with better performance, as reflected in decreased relative error in force during 16% MVC. We additionally show that periods of good motor performance within each condition were associated with higher values of EEG-EMG coherence and spectral power. In conclusion, our results suggest a role for beta-range corticomuscular coherence in effective sensorimotor integration, thus stabilizing corticospinal communication.     

Crimean-Congo haemorrhagic fever cases in Turkey

Crimean-Congo haemorrhagic fever (CCHF) is an arbovirus infection, which is transmitted through ticks or via blood and secretions. Until recently, human cases of CCHF were unknown in Turkey; however, several acute disease cases were reported in 2002. We report on the investigation of a cluster of suspected CCHF cases in the middle part of the Black Sea from May 2002 to October 2003. The medical charts that we reviewed were obtained from all local physicians and our field investigations. 'Suspected case' was defined with regard to time, place, and both clinical and laboratory characteristics. A total of 108 patients were defined as suspected case. Among them 36 patients were reached and blood samples taken for examination for CCHF by using ELISA and RT-PCR. According to the laboratory analysis, 80.6% (29/36) were acute cases and 8.3% (3/36) were past CCHF infections. The overall mortality rate was 5.6%. There was no nosocomial infection; however, there were 2 family clusters. Tick exposure was the most prevalent risk factor (74.2%). A multidisciplinary collaboration should be developed in order to understand the magnitude of the disease and also to keep it under control.     

Are drug-eluting stents safe and effective in the long term?

The introduction of drug-eluting stents in 2002 revolutionized interventional cardiology by minimizing restenosis. Reports of increased late stent thrombosis with these stents compared with bare metal stents, probably due to delayed endothelialization, emerged late in 2006. These studies contained serious methodological flaws, however. Subsequent meta-analyses clearly showed only a small incremental risk of late stent thrombosis across all patient groups. Importantly, a significant and sustained benefit of drug-eluting stents due to reduced restenosis and thus repeat revascularization was also shown. Several 'real-world' registries have confirmed these results and suggested that the use of these stents in more complex situations is not associated with adverse outcomes. Stent thrombosis is a multifactorial problem, in which the stent is only one element. Further research is required to determine optimal procedural technique and antiplatelet regimens. Drug-eluting stents are safe and effective in the long-term, though intensive research continues into ways to reduce the risk of stent thrombosis in the next generation.     

Diagnostic accuracy, reproducibility and robustness of fibrosis blood tests in chronic hepatitis C: a meta-analysis with individual data

ObjectivesTo evaluate the diagnostic accuracy of liver fibrosis tests and its influencing factors in a meta-analysis with individual data.Design and methodsFour independent centers provided four blood tests and Metavir staging from 825 patients with chronic hepatitis C.ResultsFibroMeter AUROC (0.840) for significant fibrosis was superior to those of Fibrotest (0.803, p = 0.049), APRI (0.789, p = 0.001) and Hepascore (0.781, p < 0.001). The misclassification rate was lower for FibroMeter (23%) than for Fibrotest and Hepascore (both 28%, p < 0.001). The variation in the diagnostic cut-offs of tests among centers, reflecting the overall reproducibility, was: FibroMeter: 4.2%, APRI: 24.0%, Fibrotest: 24.2%, Hepascore: 35.0%. Accordingly, the proportion of patients diagnosed with significant fibrosis changed: FibroMeter: 0.8%, Hepascore: 2.4% (p = 0.02 vs FibroMeter), Fibrotest: 5.8% (p < 10^? 3), APRI: 18.2% (p < 10^? 3).ConclusionsThis study on clinical applicability shows significant differences in diagnostic accuracy, inter-center reproducibility, and robustness of biomarkers to changes in population characteristics between blood tests.