899 resultados para CEREBROVASCULAR TONE
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Evaluation of carotid artery intima-media thickness in patients affected by psoriasis Psoriasis is associated with an increased risk of atherosclerosis. This study compared subclinical atherosclerosis, evaluating intima-media thickness the of the carotid in psoriasis vulgaris patients and healthy controls using high-resolution ultrasonography and the correlation of this parameter with other cardiovascular risk factors, like insulin resistance and dyslipidemia, METHODS: We will study 40 psoriasis patients, asymptomatic for cardiovascular diseases, and 40 healthy controls matched for age and sex. Intima-media thickness of the common carotid arteries will be measured ultrasonographically. Diabetes mellitus, hypertension, renal failure, a history of cardiovascular or cerebrovascular disease will be exclusion criteria. Subjects who are receiving lipid-lowering therapy, antihypertensive or anti-aggregant drugs, nitrates or long-term systemic steroids will be also excluded. Objective of this study is the evaluation of carotid artery intima-media thickness and its correlation with other blood cardiovascular risk factors in patients affected by psoriasis but asinptomatic for coronary comparing this data with the healthy control subjects. Considering that the presence of psoriasis is an independent risk factor for subclinical atherosclerosis, we want to consider this method of evaluation of cardiovascular risk and to control this risk to prevent IMA.
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This thesis deal with the design of advanced OFDM systems. Both waveform and receiver design have been treated. The main scope of the Thesis is to study, create, and propose, ideas and novel design solutions able to cope with the weaknesses and crucial aspects of modern OFDM systems. Starting from the the transmitter side, the problem represented by low resilience to non-linear distortion has been assessed. A novel technique that considerably reduces the Peak-to-Average Power Ratio (PAPR) yielding a quasi constant signal envelope in the time domain (PAPR close to 1 dB) has been proposed.The proposed technique, named Rotation Invariant Subcarrier Mapping (RISM),is a novel scheme for subcarriers data mapping,where the symbols belonging to the modulation alphabet are not anchored, but maintain some degrees of freedom. In other words, a bit tuple is not mapped on a single point, rather it is mapped onto a geometrical locus, which is totally or partially rotation invariant. The final positions of the transmitted complex symbols are chosen by an iterative optimization process in order to minimize the PAPR of the resulting OFDM symbol. Numerical results confirm that RISM makes OFDM usable even in severe non-linear channels. Another well known problem which has been tackled is the vulnerability to synchronization errors. Indeed in OFDM system an accurate recovery of carrier frequency and symbol timing is crucial for the proper demodulation of the received packets. In general, timing and frequency synchronization is performed in two separate phases called PRE-FFT and POST-FFT synchronization. Regarding the PRE-FFT phase, a novel joint symbol timing and carrier frequency synchronization algorithm has been presented. The proposed algorithm is characterized by a very low hardware complexity, and, at the same time, it guarantees very good performance in in both AWGN and multipath channels. Regarding the POST-FFT phase, a novel approach for both pilot structure and receiver design has been presented. In particular, a novel pilot pattern has been introduced in order to minimize the occurrence of overlaps between two pattern shifted replicas. This allows to replace conventional pilots with nulls in the frequency domain, introducing the so called Silent Pilots. As a result, the optimal receiver turns out to be very robust against severe Rayleigh fading multipath and characterized by low complexity. Performance of this approach has been analytically and numerically evaluated. Comparing the proposed approach with state of the art alternatives, in both AWGN and multipath fading channels, considerable performance improvements have been obtained. The crucial problem of channel estimation has been thoroughly investigated, with particular emphasis on the decimation of the Channel Impulse Response (CIR) through the selection of the Most Significant Samples (MSSs). In this contest our contribution is twofold, from the theoretical side, we derived lower bounds on the estimation mean-square error (MSE) performance for any MSS selection strategy,from the receiver design we proposed novel MSS selection strategies which have been shown to approach these MSE lower bounds, and outperformed the state-of-the-art alternatives. Finally, the possibility of using of Single Carrier Frequency Division Multiple Access (SC-FDMA) in the Broadband Satellite Return Channel has been assessed. Notably, SC-FDMA is able to improve the physical layer spectral efficiency with respect to single carrier systems, which have been used so far in the Return Channel Satellite (RCS) standards. However, it requires a strict synchronization and it is also sensitive to phase noise of local radio frequency oscillators. For this reason, an effective pilot tone arrangement within the SC-FDMA frame, and a novel Joint Multi-User (JMU) estimation method for the SC-FDMA, has been proposed. As shown by numerical results, the proposed scheme manages to satisfy strict synchronization requirements and to guarantee a proper demodulation of the received signal.
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Zusammenfassung Nanokomposite aus Polymeren und Schichtsilikaten werden zumeist auf der Basis natürlicher Tone wie Montmorillonit hergestellt. Für NMR- und EPR-Untersuchungen der Tensidschicht, die das Silikat mit dem Polymer kompatibilisiert, ist der Eisengehalt natürlicher Tone jedoch abträglich, weil er zu einer Verkürzung der Relaxationszeiten und zu einer Linienverbreiterung in den Spektren führt. Dieses Problem konnte überwunden werden, indem als Silikatkomponente eisenfreies, strukturell wohldefiniertes Magadiit hydrothermal synthetisiert und für die Kompositbildung eingesetzt wurde. Die Morphologie des Magadiits wurde durch Rasterelektronenmikroskopie charakterisiert und der Interkalationsgrad von schmelzinterkalierten Polymer-Nanokompositen wurde durch Weitwinkelröntgenstreuung bestimmt. Polymere mit Carbonylgruppen scheinen leichter zu interkalieren als solche ohne Carbonylgruppen. Polycaprolacton interkalierte sowohl in Oragnomagadiite auf der Basis von Ammoniumtensiden als auch in solche auf der Basis von Phosphoniumtensiden. Die Dynamik auf einer Nanosekundenzeitskala und die Struktur der Tensidschicht wurden mittels ortsspezifisch spinmarkierter Tensidsonden unter Nutzung von Dauerstrich- (CW) und Puls-Methoden der elektronenparamagnetischen Resonanzspektroskopie (EPR) untersucht. Zusätzlich wurde die statische 2H-Kernmagnetresonanz (NMR) an spezifisch deuterierten Tensiden angewendet, um die Tensiddynamik auf einer komplementären Zeitskala zwischen Mikrosekunden und Millisekunden zu erfassen. Sowohl die CW-EPR- als auch die 2H-NMR-Ergebnisse zeigen eine Beschleunigung der Tensiddynamik durch Interkalation von Polycaprolacton auf, während sich in den nichtinterkalierten Mikrokompositen mit Polystyrol die Tensiddynamik verlangsamt. Die Rotationskorrelationszeiten und Aktivierungsenergien offenbaren verschiedene Regime der Tensiddynamik. In Polystyrol-Mikrokompositen entspricht die Übergangstemperatur zwischen den Regimen der Glasübergangstemperatur von Polystyrol, während sie in Polycaprolacton-Nanokompositen bei der Schmelztemperatur von Polycaprolacton liegt. Durch die erhebliche Verlängerung der Elektronenspin-Relaxationszeiten bei Verwendung von eisenfreiem Magadiit können Messdaten hoher Qualität mit Puls-EPR-Experimenten erhalten werden. Insebsondere wurden die Vier-Puls-Elektron-Elektron-Doppelresonanz (DEER), die Elektronenspinechoenveloppenmodulation (ESEEM) und die Elektronen-Kern-Doppelresonanz (ENDOR) an spinmarkierten sowie spezifisch deuterierten Tensiden angewandt. Die ENDOR-Ergebnisse legen ein Model der Tensidschicht nahe, in dem zusätzlich zu den Oberflächenlagen auf dem Silikat eine wohldefinierte mittlere Lage existiert. Dieses Modell erklärt auch Verdünnungseffekte durch das Polymer in Kompositen mit Polycaprolacton und Polystyrol. Die umfangreiche Information aus den Magnetresonanztechniken ergänzt die Information aus konventionellen Charakterisierungstechniken wie Röntgendiffraktion und Transmissionselektronenmikroskopie und führt so zu einem detaillierteren Bild der Struktur und Dynamik der Tensidschicht in Nanokompositen aus Polymeren und Schichtsilikaten.
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Oxidativer Stress in Form reaktiver Sauerstoffspezies (ROS) und Exzitotoxizität durch supraphysiologische Konzentrationen des Neurotransmitters Glutamat sind nicht nur beteiligt an der Pathogenese vielzähliger neurodegenerativer Erkrankungen wie Schlaganfall, Hirntrauma, Alzheimer Demenz oder Multipler Sklerose, sondern spielen zudem eine Schlüsselrolle im dort beobachteten Zusammenbruch der Blut-Hirn-Schranke. Glutamat führt durch Stimulation neuronaler und endothelialer NMDA-Rezeptoren zu einer Generierung von ROS. Nicht verfolgt worden war bisher, welche Auswirkungen ROS umgekehrt auch auf den NMDA-Rezeptor haben könnten. Im Rahmen der vorliegenden Arbeit wurde daher untersucht, ob und in welcher Weise die Exposition gegenüber reaktiven Sauerstoffspezies einen Einfluss auf die Expression und Aktivierbarkeit von NMDA-Rezeptoren auf zerebrovaskulären Endothelzellen ausübt.rnEs konnte zunächst die Expression der funktionell obligaten NR-1 Untereinheit des NMDA-Rezeptors auf der verwendeten Zelllinie b.End3 mittels Immunfluoreszenz-Mikroskopie gesichert werden. Ein Nachweis von mRNA für die Untereinheiten NR1 und NR2B, C und D erfolgte mittels RT-PCR. In der Analyse der replizierten RNA zeigten sich Hinweise für eine heterogene Komposition der exprimierten endothelialen NMDA-Rezeptoren.rnEs konnte weiter mit Hilfe der In-Cell-Western-Technik gezeigt werden, dass die Expression des NMDA-Rezeptors durch transiente Stimulation mit reaktiven Sauerstoffspezies im Sinne einer Heraufregulation moduliert werden kann. Die Stimulation der Zellen mit den reaktiven Sauerstoffspezies O2-, ONOO- und H2O2 führte dabei im Experiment zu einer deutlichen Zunahme der NR1-Expression, die spätestens nach 72 Stunden höchst signifikant war.rnUm zu überprüfen, welche Bedeutung diese Überexpression für die Integrität der Blut-Hirn-Schranke unter den exzitotoxischen Bedingungen hoher Glutamatkonzentrationen haben könnte, wurde mit Hilfe des ECIS-Systems („Electrical Cell-Substrate Impedance Sensing“) die Impedanz ROS-präexponierter Endothelmonolayer gemessen. Auf Rezeptorstimulation mit dem spezifischen Agonisten NMDA reagierten die vorbehandelten Gruppen mit einem Abfall der Impedanz gegenüber der nicht vorbehandelten Kontrolle.rnrnDie vorliegenden Ergebnisse zeigen, dass ROS in der Lage sind, funktionelle endotheliale NMDA-Rezeptoren zu induzieren und auf diesem Weg zu einem verstärkten Abfall der BHS-Integrität unter den Bedingungen exzitotoxischen und oxidativen Stresses führen. Dies stellt einen neuen Mechanismus zur Erklärung der Pathogenese des Blut-Hirn-Schrankenversagens dar.
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Background. A sizable group of patients with symptomatic aortic stenosis (AS) can undergo neither surgical aortic valve replacement (AVR) nor transcatheter aortic valve implantation (TAVI) because of clinical contraindications. The aim of this study was to assess the potential role of balloon aortic valvuloplasty (BAV) as a “bridge-to-decision” in selected patients with severe AS and potentially reversible contraindications to definitive treatment. Methods. We retrospectively enrolled 645 patients who underwent first BAV at our Institution between July 2007 and December 2012. Of these, the 202 patients (31.2%) who underwent BAV as bridge-to-decision (BTD) requiring clinical re-evaluation represented our study population. BTD patients were further subdivided in 5 groups: low left ventricular ejection fraction; mitral regurgitation grade ≥3; frailty; hemodynamic instability; comorbidity. The main objective of the study was to evaluate how BAV influenced the final treatment strategy in the whole BTD group and in its single specific subgroups. Results. Mean logistic EuroSCORE was 23.5±15.3%, mean age was 81±7 years. Mean transaortic gradient decreased from 47±17 mmHg to 33±14 mmHg. Of the 193 patients with BTD-BAV who received a second heart team evaluation, 72.5% were finally deemed eligible for definitive treatment (25.4%for AVR; 47.2% for TAVI): respectively, 96.7% of patients with left ventricular ejection fraction recovery; 70.5% of patients with mitral regurgitation reduction; 75.7% of patients who underwent BAV in clinical hemodynamic instability; 69.2% of frail patients and 68% of patients who presented relevant comorbidities. 27.5% of the study population was deemed ineligible for definitive treatment and treated with standard therapy/repeated BAV. In-hospital mortality was 4.5%, cerebrovascular accident occurred in 1% and overall vascular complications were 4% (0.5% major; 3.5% minor). Conclusions. Balloon aortic valvuloplasty should be considered as bridge-to-decision in high-risk patients with severe aortic stenosis who cannot be immediate candidates for definitive percutaneous or surgical treatment.
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Disruption of the blood-brain barrier (BBB) results in cerebral edema formation, which is a major cause for high mortalityrnafter traumatic brain injury (TBI). As anesthetic care is mandatory in patients suffering from severe TBI it may be importantrnto elucidate the effect of different anesthetics on cerebral edema formation. Tight junction proteins (TJ) such as zonularnoccludens-1 (ZO-1) and claudin-5 (cl5) play a central role for BBB stability. First, the influence of the volatile anestheticsrnsevoflurane and isoflurane on in-vitro BBB integrity was investigated by quantification of the electrical resistance (TEER) inrnmurine brain endothelial monolayers and neurovascular co-cultures of the BBB. Secondly brain edema and TJ expression ofrnZO-1 and cl5 were measured in-vivo after exposure towards volatile anesthetics in native mice and after controlled corticalrnimpact (CCI). In in-vitro endothelial monocultures, both anesthetics significantly reduced TEER within 24 hours afterrnexposure. In BBB co-cultures mimicking the neurovascular unit (NVU) volatile anesthetics had no impact on TEER. In healthyrnmice, anesthesia did not influence brain water content and TJ expression, while 24 hours after CCI brain water contentrnincreased significantly stronger with isoflurane compared to sevoflurane. In line with the brain edema data, ZO-1 expressionrnwas significantly higher in sevoflurane compared to isoflurane exposed CCI animals. Immunohistochemical analysesrnrevealed disruption of ZO-1 at the cerebrovascular level, while cl5 was less affected in the pericontusional area. The studyrndemonstrates that anesthetics influence brain edema formation after experimental TBI. This effect may be attributed tornmodulation of BBB permeability by differential TJ protein expression. Therefore, selection of anesthetics may influence thernbarrier function and introduce a strong bias in experimental research on pathophysiology of BBB dysfunction. Futurernresearch is required to investigate adverse or beneficial effects of volatile anesthetics on patients at risk for cerebral edema.
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This thesis focuses on the translation of six picture books that challenge and subvert – each one in its peculiar way – typical stereotypes found in Children’s Literature. I think that stereotyping is an all-important theme in picture books because these books are the ones that will introduce children to literature and young readers have the right to find in it every kind of model. Showing children a variety of characters that reflects the multiple forms of reality will allow them to choose which kind of person to be. In my opinion, this freedom is much needed especially here, in Italy, in this moment of history. This work also studies the stereotypes that have appeared – and are still present, to some extent – in Children’s Literature, the ways in which they are dangerous for young readers, and how they have changed over time. I centered my research on three major themes that have been subject to stereotyping: race, disability and gender. I searched for the right books to translate paying attention not only to the themes they focused on but also to how they dealt with such themes, the tone of each picture book and, obviously, its quality. The selection resulting from my research reflects a diverse world and a celebration of difference. Before actually translating them, I engaged in a deep analysis of their structures, themes and meanings, so that I would be able to enter the ‘world’ of the book and to understand its ‘secrets’ better. This analysis proved to be fundamental during the translation phase and allowed me to make conscious translation choices that I have explored in the part dedicated to the commentary of the translation.
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Early classification of ischemic stroke subtype is important for secondary stroke prevention and may guide further investigations.
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During short-term postural changes, the factors determining the amplitude of intracranial pulse pressure (ICPPA) remain constant, except for cerebrovascular resistance (CVR). Therefore, it may be possible to draw conclusions from the ICPPA onto the cerebrovascular resistance (CVR) and thus the relative change in cerebral perfusion pressure (CPP).
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BACKGROUND: Atrial fibrillation (AF) is a significant risk factor for cardiovascular (CV) mortality. This study aims to evaluate the prognostic implication of AF in patients with peripheral arterial disease (PAD). METHODS: The International Reduction of Atherothrombosis for Continued Health (REACH) Registry included 23,542 outpatients in Europe with established coronary artery disease, cerebrovascular disease (CVD), PAD and/or >/=3 risk factors. Of these, 3753 patients had symptomatic PAD. CV risk factors were determined at baseline. Study end point was a combination of cardiac death, non-fatal myocardial infarction (MI) and stroke (CV events) during 2 years of follow-up. Cox regression analysis adjusted for age, gender and other risk factors (i.e., congestive heart failure, coronary artery re-vascularisation, coronary artery bypass grafting (CABG), MI, hypertension, stroke, current smoking and diabetes) was used. RESULTS: Of 3753 PAD patients, 392 (10%) were known to have AF. Patients with AF were older and had a higher prevalence of CVD, diabetes and hypertension. Long-term CV mortality occurred in 5.6% of patients with AF and in 1.6% of those without AF (p<0.001). Multivariable analyses showed that AF was an independent predictor of late CV events (hazard ratio (HR): 1.5; 95% confidence interval (CI): 1.09-2.0). CONCLUSION: AF is common in European patients with symptomatic PAD and is independently associated with a worse 2-year CV outcome.
Prevalence of findings compatible with carotid artery calcifications on dental panoramic radiographs
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Cerebrovascular accidents are responsible for killing or disabling more than half a million Americans every year. They are the third leading cause of death in this country. In Germany, the annual stroke incidence reaches 182 cases per 100,000 inhabitants. Stroke there is the fourth leading cause of death. There is a need of finding cost-effective means of decreasing stroke mortality and morbidity. Instruments for early diagnosis are of great humanitarian and economic importance. All possible clinical findings should be taken into account. It is not the demand of this study to present the panoramic radiograph as a screening test method for early diagnosis of atherosclerosis. The aim is to show the potential of this radiograph used in everyday clinical dental practice by the prevalence of radiopaque findings in the carotid region. This study included panoramic dental radiographs of 2,557 patients older than 30 years of age. Fifty-nine percent of the patients were women and 41% were men. The radiographs were adjudged for signs compatible with carotid arterial calcifications appearing as a radiopaque nodular mass adjacent to the cervical vertebrae at or below the intervertebral space C3-4. Of all these radiographs, 4.8% showed radiopaque findings compatible with atherosclerotic lesions. The proportion of women reached 64.8% and that of men reached 35.2%. In accordance to recent literature, the results of this study show that about 5% of the patients show radiological findings compatible with carotid arterial calcifications. Some of these patients at risk for a cerebrovascular accident may be identified in the dentist's office by appropriate review of the panoramic dental radiograph. The suspicion of carotid artery calcifications demands an impetuous referral to an appropriate practitioner who can assist in the control of risk factors and if necessary arrange surgical removal of the carotid arterial plaque. So, the dentist should be aware of this problem and able to make a contribution to stroke prevention.
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Cardiovascular event rates have been shown to increase substantially with the number of symptomatic disease locations. We sought to assess the risk profile, management and subsequent event rates of polyvascular disease patients. Consecutive outpatients were assessed for atherosclerotic risk factors and medications in the REACH Registry. A total of 19,117 symptomatic patients in Europe completed a 2-year follow-up: 77.2% with single arterial bed disease (coronary artery or cerebrovascular or peripheral arterial disease) and 22.8% with polyvascular disease (>/= 1 disease location). Polyvascular disease patients were older (68.5 +/- 9.4 vs 66.3 +/- 9.9 years, p < 0.0001), more often current or former smokers (64.9% vs 58.7%, p < 0.0001), and more often suffered from hypertension (59.5% vs 46.6%, p < 0.0001) and diabetes (34.5% vs 25.9%, p < 0.0001) than single arterial bed disease patients. Despite more intense medical therapy, risk factors (smoking, hypertension, low fasting glucose, and low fasting total cholesterol) were less often controlled in polyvascular disease patients. This was associated with substantially more events over 2 years compared with single arterial bed disease patients (cMACCE [cardiovascular death/non-fatal stroke/non-fatal MI] odds ratio, 1.63 [95% CI, 1.45-1.83], p < 0.0001). In conclusion, polyvascular disease patients have more cardiovascular risk factors, and the prognosis for these patients is significantly worse than for patients with single arterial bed disease. This suggests a need to improve detection and consequent medical treatment of polyvascular disease.
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Objective: Myocardial infarction has been associated with both transportation noise and air pollution. We examined residential exposure to aircraft noise and mortality from myocardial infarction, taking air pollution into account. Methods: We analyzed the Swiss National Cohort, which includes geocoded information on residence. Exposure to aircraft noise and air pollution was determined based on geospatial noise and air-pollution (PM10) models and distance to major roads. We used Cox proportional hazard models, with age as the timescale. We compared the risk of death across categories of A-weighted sound pressure levels (dB(A)) and by duration of living in exposed corridors, adjusting for PM10 levels, distance to major roads, sex, education, and socioeconomic position of the municipality. Results: We analyzed 4.6 million persons older than 30 years who were followed from near the end of 2000 through December 2005, including 15,532 deaths from myocardial infarction (ICD-10 codes I 21, I 22). Mortality increased with increasing level and duration of aircraft noise. The adjusted hazard ratio comparing ≥60 dB(A) with <45 dB(A) was 1.3 (95% confidence interval = 0.96-1.7) overall, and 1.5 (1.0-2.2) in persons who had lived at the same place for at least 15 years. None of the other endpoints (mortality from all causes, all circulatory disease, cerebrovascular disease, stroke, and lung cancer) was associated with aircraft noise. Conclusion: Aircraft noise was associated with mortality from myocardial infarction, with a dose-response relationship for level and duration of exposure. The association does not appear to be explained by exposure to particulate matter air pollution, education, or socioeconomic status of the municipality.
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Although non-organic hearing losses are relatively rare, it is important to identify suspicious findings early to be able to administer specific tests, such as objective measurements and specific counseling. In this retrospective study, we searched for findings that were specific ti or typical for non-organic hearing losses. Patient records from a 6 year period (2003-2008) from the University ENT Department of Bern, Switzerland, were reviewed. In this period, 40 subjects were diagnosed with a non-organic hearing loss (22 children, ages 7-16, mean 10.6 years; 18 adults, ages 19-57, mean 39.7 years; 25 females and 15 males). Pure tone audiograms in children and adults showed predominantly sensorineural and frequency-independent hearing losses, mostly in the range of 40-60 dB. In all cases, objective measurements (otoacoustic emissions and/or auditory-evoked potentials) indicated normal or substantially better hearing thresholds than those found in pure tone audiometry. In nine subjects (22.5%; 2 children, 7 adults), hearing aids had been fitted before the first presentation at our center. Six children (27%) had a history of middle ear problems with a transient hearing loss and 11 (50%) knew a person with a hearing loss. Two new and hitherto unreported findings emerged from the analysis: it was observed that a small air-bone gap of 5-20 dB was typical for non-organic hearing losses and that speech audiometry might show considerably poorer results than expected from pure tone audiometry.
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Patients with an implantable cardioverter defibrillator (ICD) have an ongoing risk of sudden incapacitation that might cause harm to others while driving a car. Driving restrictions vary across different countries in Europe. The most recent recommendations for driving of ICD patients in Europe were published in 1997 and focused mainly on patients implanted for secondary prevention. In recent years there has been a vast increase in the number of patients with an ICD and in the percentage of patients implanted for primary prevention. The EHRA task force on ICD and driving was formed to reassess the risk of driving for ICD patients based on the literature available. The recommendations are summarized in the following table and are further explained in the document, (Table see text). Driving restrictions are perceived as difficult for patients and their families, and have an immediate consequence for their lifestyle. To increase the adherence to the driving restrictions, adequate discharge of education and follow-up of patients and family are pivotal. The task force members hope this document may serve as an instrument for European and national regulatory authorities to formulate uniform driving regulations.