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Biomedical subjects

Wilfried Lang

Publications and source records attributed to Wilfried Lang.

32 records · Page 2Linked to original sources
PubMed2003

Hemostatic markers with bolus versus prolonged heparin after carotid artery stenting.

BACKGROUND: The evolving technique of carotid stenting (CS) requires optimal antithrombotic strategies to reduce periinterventional thromboembolic risk. In animal models of balloon injury, tissue factor (TF) was shown to be the major procoagulant of the atherosclerotic plaque mediating prolonged procoagulant activity. METHODS: We analyzed TF and TF-dependent hemostatic markers before and 2, 6 and 24 h after CS with two antithrombotic drug regimens. Group A (n=20) received prolonged unfractionated heparin (UFH) for 18-20 h starting at intervention next to aspirin and thienopyridine. In group B (n=16), single bolus UFH was administered next to combined antiplatelet therapy. Natural anticoagulants were determined at baseline. RESULTS: Patients with symptomatic and asymptomatic cerebrovascular disease did not differ in plasma TF levels. Furthermore, no statistically significant difference for TF, TFPI/Xa-complex and prothrombin fragment F1.2 was observed between bolus and prolonged heparin treatment. No significant change was found in time course for these parameters. Two patients (5.5%; one in each treatment group) suffered periinterventional minor stroke associated with increased levels of F1.2 and TFPI/Xa-complex. Both were resistant to activated protein C (APC ratio<1.9) due to heterozygous factor V Leiden mutation. CONCLUSIONS: No significant activation of the TF pathway was seen with both antithrombotic regimens suggesting that single bolus UFH combined with antiplatelet therapy is generally sufficient to control TF-dependent procoagulant activity after CS. However, patients with resistance to activated protein C may be at increased periinterventional stroke risk.

Aged↗
PubMed2003

Olfaction and depth of word processing: a magnetoencephalographic study.

Using a whole-cortex magnetoencephalograph, magnetic field changes were recorded to describe brain activities related to simultaneous visual and olfactory processing and to detect odor-related influences on verbal information processing. Words had to be either shallowly (nonsemantic) or deeply (semantic) encoded by healthy young subjects, each of these tasks under two different kinds of olfactory stimulation. After each encoding phase, word recognition performance was tested. First, the odor was randomly associated with some of the study words (simultaneous stimulation; same duration as for words) for both depths of word processing conditions, and second, continuous olfactory stimulation (permanent stimulation) was provided during the whole study phases of both depths of word processing conditions. The statistical analysis of the physiological data revealed evidence of a specific odor-induced effect depending on depth of word processing and kind of olfactory stimulation. Brain activity between about 250 and 450 ms as well as between about 650 and 1000 ms after stimulus onset was found to vary as a function of odor delivery and depth of word processing. In addition, a significant effect of odor stimulation on subsequent word recognition performance occurred in case of simultaneous odor stimulation and semantic word encoding. It is interpreted that in this case, word recognition performance significantly decreased because of the presence of the odor during prior word encoding. Such a behavioral effect was missing in all other conditions. The present psychological and physiological findings support the idea that semantic word encoding is specifically affected by simultaneous olfactory information processing. It is concluded that this phenomenon is due to a competition with cortical regions related to language and olfactory information processing, as suggested by T. S. Lorig (1999, Neurosci. Biobehav. Rev. 23, 391-398).

Adult↗
PubMed2003

Association between course of blood pressure within the first 24 hours and functional recovery after acute ischemic stroke.

STUDY OBJECTIVE: The relation between course of blood pressure within the first 24 hours after acute stroke and early neurologic outcome remains a matter of dispute. We investigate this relation with adjustment for other influencing variables. METHODS: Three hundred seventy-two patients with the diagnosis of ischemic stroke were included to evaluate the relation between blood pressure course and early neurologic outcome. The following data were collected: age; sex; history of hypertension, diabetes mellitus, hyperlipidemia, coronary heart disease, peripheral vascular disease, and stroke; smoking habits; preadmission blood pressure, blood pressure on admission, and blood pressure 24 hours later; antihypertensive treatment; and stroke localization. We assessed outcome at day 5 after admission as dependent or independent (Rankin Scale score <or=2) and applied multivariate logistic regression analysis to investigate the effect of blood pressure changes on outcome, with adjustment for other baseline variables. RESULTS: Relative changes of systolic and diastolic blood pressure within hospital admission to 24 hours after admission revealed significant differences of patients' neurologic outcome only for diastolic blood pressure changes from admission to 24 hours. A diastolic blood pressure decrease more than 25% from admission until 24 hours after admission was associated with a 3.8-fold increased adjusted odds (95% confidence interval 1.2 to 12.1) for poor neurologic outcome on day 5 (Rankin Scale score 3 to 5). CONCLUSION: Excessive diastolic blood pressure reduction was associated with an increased risk for an impaired neurologic outcome in patients with ischemic stroke. The association between both characteristics was independent from concomitant risk factors, stroke localization, and possible antihypertensive treatment.

Activities of Daily Living↗
PubMed2003

Effect of carotid artery stenting on the external carotid artery.

OBJECTIVE: We studied the fate of the ipsilateral external carotid artery (ECA) after stenting of the internal carotid artery (ICA) compared with the contralateral ECA. SUBJECTS AND METHODS: One hundred twenty-one ipsilateral ECAs in 112 consecutive patients who underwent carotid artery Wallstent placement were prospectively studied with color-coded duplex sonographic scanning (CCDS) and compared with 83 contralateral ECAs over 2 years. CCDS was scheduled for the day before (day 0), the day after (day 1) and 3, 6, 12, and 24 months after stenting. Development of ECA occlusive disease was evaluated with ECA-common carotid artery flow ratio (peak systolic velocity). For estimation of ECA stenosis 70% or greater, flow ratio 4.1 was used as the cutoff point. RESULTS: Before and after stenting, two and three (one additional) ECA occlusions were seen. Median grade of ECA stenosis on day 1 did not significantly change at angiography (P = 1.0; tendency of increase) or CCDS (P =.27; tendency of decrease).At follow-up (day 1-24 months, CCDS only), frequency of stenosis 70% or greater in the ipsilateral ECA was 21 of 120 (17.5%) on day 1 and 41 of 107 (38.32%) at 24 months, and 3 of 107 (2.5%) and 5 of 107 (4.67%) ECA occlusions were registered at the two time points. Progression of disease, as demonstrated by increase in flow ratio over time, was much more pronounced in the ipsilateral ECAs compared with the contralateral ECAs (P =.0002). In stented ICA, 2 (1.85%) asymptomatic recurrent stenoses 70% or greater were found at CCDS. One of three patients with new ECA occlusions reported jaw claudication for 10 days. Perioperative stroke (one major, four minor) occurred in 5 of 121 patients (4.46%). Two minor strokes caused by embolization occurred during the first year. CONCLUSION: The more pronounced progression of arteriosclerotic disease at the orifice of the ipsilateral ECAs during the first year after carotid stenting might be due to local factors of the ICA stent. Its clinical significance in respect to the effect of the ECA as collateral supply to the brain might depend on the incidence of carotid stent rerecurrent stenosis, which was low in the present study.

Aged↗
PubMed2003

Olfaction and face encoding in humans: a magnetoencephalographic study.

Magnetic field changes were recorded while 20 healthy young participants performed a deep face encoding task. Some of the faces were randomly associated with a simultaneously presented odor. A recognition test, during which all faces were presented again together with the same number of new faces, followed. The task was to discriminate between repeated and new faces. During the recognition test no odor was presented. The recognition performance was significantly influenced by the simultaneously associated odor during the encoding phase. Faces associated with odor were less accurately recognized. In addition, we found significant physiological differences between 'encoded faces without odor' and 'encoded faces with odor'. In particular, two effects occurred. Between about 200 and 300 ms after stimulus onset 'encoded faces without odor' evoked higher brain activity than 'encoded faces with odor'. Between about 600 and 900 ms after stimulus onset 'encoded faces with odor' evoked higher brain activity than 'encoded faces without odor'. Whereas the latter effect is interpreted as reflecting conscious olfactory information processing, the earlier effect is suggested to reflect an odor influence on face encoding. We suggest that the simultaneous odor association distracted face encoding resulting in a significantly reduced recognition performance. These findings are suggested to represent evidence of multimodal sensoric interactions between visual face processing and olfactory information.

Adult↗
PubMed2003

Is the factor XIII 34Val/Leu polymorphism a protective factor for cerebrovascular disease?

A frequent polymorphism in the factor XIII (FXIII) A-subunit gene, leading to a Val to Leu amino acid exchange at position 34, suggested to affect clot stability, has been associated with a decreased risk for venous thromboembolism and myocardial infarction. Its role in the development of stroke is still under investigation. Ninety-four patients with primary arterial intracerebral haemorrhage (mean age +/- standard deviation: 69 +/- 14 years; 48 men, 46 women), 718 patients with ischaemic stroke (63 +/- 14 years; 395 men, 323 women) and 369 healthy control subjects (59 +/- 14 years; 299 men, 170 women) were analysed for FXIII Val34Leu. No differences in genotype distribution between all three groups were observed. Also, no significant differences in the genotype distribution were found between subgroups of patients stratified according to age, sex, aetiology, history of hypertension, antiplatelet or anticoagulant medication and other vascular risk factors. In contrast to previously reported findings in smaller collectives, our data suggest that an association of the FXIII Val34Leu polymorphism with a decreased risk of ischaemic stroke or an increased risk of intracerebral haemorrhage is highly unlikely. Thus, screening for the FXIII Val34Leu polymorphism will not contribute significantly to the risk prediction of cerebrovascular disease.

Adult↗
PubMed2003

[Acute therapy of ischemic stroke].

Thrombolysis was used in 3.7% of stroke patients who were admitted to the Neurological Departments of Vienna. High doses of heparin were associated with an increased risk of secondary symptomatic hemorrhage (OR 10.3; 95% CI 2.4-43.2). But none of the patients with TIA or minor stroke who received high dosages of heparin suffered from secondary symptomatic hemorrhage. Spontaneous or therapeutically induced decrease of the diastolic blood pressure by more than 20 mmHg was associated with a three-fold risk of an unfortunate functional outcome. Complications following stroke are frequent and most likely to occur within the first 5 days. Pneumonia was found to be an independent risk factor for an unfortunate functional outcome after three months. A main field of activity of stroke units should be to prevent or to early recognize and treat complications.

Acute Disease↗
PubMed2003

Determination of lipid profiles and use of statins in patients with ischemic stroke or transient ischemic attack.

BACKGROUND AND PURPOSE: Statins reduce the risk of myocardial infarction and stroke in patients with vascular disease. Inappropriate serum lipid determination and underuse of statins have been documented in patients with coronary artery disease. Evaluation of hyperlipidemia and treatment with statins in patients with recent ischemic cerebrovascular events have not yet been investigated. METHODS: We determined the frequency of total cholesterol (TC) and low-density lipoprotein cholesterol measurements and the use of statins in a multicenter prospective cohort study of 1743 patients with acute ischemic stroke or transient ischemic attack (TIA). Using multivariate logistic regression analysis, we determined the influence of several clinical variables on lipid measurements and the prescription of statins at hospital discharge. RESULTS: TC was measured in 90% and low-density lipoprotein cholesterol was measured in 48% of the patients. Differences between the centers accounted for most of the observed variability in a multivariate model. Statin prescription also varied widely between the centers. The prescription of a statin at discharge was most strongly associated with statin intake before the event and with increasing TC levels; elderly patients received statins less often. Coronary artery disease, peripheral artery disease, and other manifestations of atherosclerosis were not independently associated with the use of statins; 68% of the patients with manifest atherosclerosis and TC levels >200 mg/dL were discharged without a statin. CONCLUSIONS: The determination of serum lipid profiles varies widely between different centers. Statins are highly underused in patients with recent ischemic stroke or TIA, particularly in those in whom statins are indicated according to existing recommendations (eg, patients with additional coronary artery disease and hypercholesterolemia). Currently, international guidelines concerning the use of statins are not adequately implemented in clinical practice in patients with stroke or TIA.

Aged↗
PubMed2003

Healing of carotid stents: a prospective duplex ultrasound study.

PURPOSE: To study the dynamics of carotid stent healing over a 2-year period using duplex ultrasound imaging. METHODS: One hundred twelve patients with 121 successfully stented carotid arteries were examined with color-coded duplex ultrasound the day after the stent procedure and at 1, 3, 6, 12, and 24 months in follow-up. The maximal thickness and echogenicity of the layer between the stent and the perfused lumen (SPL) were evaluated. Echogenicity was classified as echogenic if the SPL layer was clearly detected in B mode and echolucent if the SPL layer was barely visible in B mode, its border defined by assistance of color-coded flow. RESULTS: At day 1, an echolucent SPL layer with a median thickness of 0.7 mm was interpreted as a thrombotic layer, which decreased at 1 month to practically zero (i.e., not detectable). In follow-up, increases in thickness (mainly up to 6 months) and echogenicity (up to 12 months) of the SPL layer were interpreted as neointimal ingrowth. At 3, 6, and 12 months, the median maximal thickness of the SPL layer was 0.5 mm, 0.9 mm, and 1.0 mm, respectively, whereas the percentage of patients with an echogenic SPL layer was 27% (32/119), 56% (66/117), and 95% (105/110), respectively, at the same time intervals. No further change was observed at the 24-month examination. CONCLUSIONS: Three phases of carotid stent incorporation are defined: (1) an early unstable period soon after stent placement with an echolucent (thrombotic) SPL layer, (2) a moderately unstable phase with ingrowing neointima (1-12 months), and (3) a stable phase from the second year on. These data may indicate the need for different intensities of therapy and surveillance intervals.

Aged↗
PubMed2003

Hypotension and bradycardia after elective carotid stenting: frequency and risk factors.

PURPOSE: To investigate the frequency of and risk factors for hypotension and bradycardia in response to elective carotid stenting and their association with neurological complications. METHODS: A retrospective analysis was conducted of 471 patients (321 men; median age 72 years, interquartile range 64-77) who underwent elective carotid artery stenting without cerebral protection for high-grade (>70%) symptomatic (n=147) or asymptomatic (n=324) internal carotid artery stenosis at a single center. Frequency and potential risk factors for severe hypotension (systolic blood pressure <80 mmHg) or bradycardia (heart rate <50 bpm) were studied. RESULTS: Thirty-four (7%) patients had severe hypotension (n=23), bradycardia (n=2), or both (n=9) despite routine premedication with atropine and adequate fluid balance. Intravenous catecholamines (dopamine) were necessary in 8 patients with prolonged hypotension; none of the patients with bradycardia needed pacemaker support. Neurological complications (transient ischemic attack, minor stroke, major stroke, death) occurring in 33 (7%) patients were not significantly associated with hemodynamic instability (4/34 [12%] versus 29/437 [7%], p=0.26). Age >77 years (fourth quartile; OR 6.40, 95% CI 1.80 to 22.78, p=0.004) and coronary artery disease (OR 2.81, 95% CI 1.29 to 6.14, p=0.010) were associated with an increased adjusted risk for hypotension or bradycardia. CONCLUSIONS: Hemodynamic instability due to hypotension and bradycardia in response to carotid artery stenting occurs in a relatively low proportion of patients. Elderly patients and those with coronary artery disease are at highest risk. Although the rate of neurological complications was not significantly increased in patients with hemodynamic instability, the higher frequencies of neurological complications in these patients admonish us to be careful.

Aged↗
PubMed2002

Evidence of conscious and subconscious olfactory information processing during word encoding: a magnetoencephalographic (MEG) study.

The present study was meant to distinguish between unconscious and conscious olfactory information processing and to investigate the influence of olfaction on word information processing. Magnetic field changes were recorded in healthy young participants during deep encoding of visually presented words whereby some of the words were randomly associated with an odor. All recorded data were then split into two groups. One group consisted of participants who did not consciously perceive the odor during the whole experiment whereas the other group did report continuous conscious odor perception. The magnetic field changes related to the condition 'words without odor' were subtracted from the magnetic field changes related to the condition 'words with odor' for both groups. First, an odor-induced effect occurred between about 200 and 500 ms after stimulus onset which was similar in both groups. It is interpreted to reflect an activity reduction during word encoding related to the additional olfactory stimulation. Second, a later effect occurred between about 600 and 900 ms after stimulus onset which differed between the two groups. This effect was due to higher brain activity related to the additional olfactory stimulation. It was more pronounced in the group consisting of participants who consciously perceived the odor during the whole experiment as compared to the other group. These results are interpreted as evidence that the later effect is related to conscious odor perception whereas the earlier effect reflects unconscious olfactory information processing. Furthermore, our study provides evidence that only the conscious perception of an odor which is simultaneously presented to the visual presentation of a word reduces its chance to be subsequently recognized.

Adult↗
PubMed2002

Single-center experience with carotid stent restenosis.

PURPOSE: To report the angiographic morphology of carotid stent restenosis and the possible therapies based on data from a single-center experience. METHODS: In a 45-month period, 279 patients (196 men; mean age 70 +/- 9 years, range 50-89) underwent successful Wallstent placement in 303 stenotic internal carotid arteries (ICA). Patients were followed with duplex sonography; angiography was used to confirm any significant (> or =70%) recurrent lesions detected on the ultrasound scan. Further balloon dilation with or without stent placement was undertaken. RESULTS; Over a median 12-month follow-up (interquartile range 6-24), there were 9 (3.0%) carotid stent restenoses found, all within 12 months after stent placement. Two types of restenosis were differentiated. In the more common form, "in-stent" stenoses (n = 6) were detected and treated with stent placement; lasting success (patency >12 months after retreatment) was achieved in 4. Early second and third recurrences arose in the other 2 stents within 3 months of the first retreatment; additional stents were placed at each recurrence. Both patients suffered a major cerebral event after 17 months. Less often, an "end of stent" stenosis (n = 3) developed at a kink in the ICA adjacent to the cephalad end of the stent. Lasting success was achieved by balloon dilation without additional stent placement in all 3 cases. No procedure-related complications were observed within 30 days after any treatment for restenosis. CONCLUSIONS: Carotid stent restenosis, which occurs rarely after 1 year, can be treated safely by further percutaneous interventions.

Aged↗
PubMed2002

Carotid artery stenting in older patients: is age a risk factor for poor outcome?

PURPOSE: To assess the impact of age on technical success and complications of carotid stenting in a prospective single-center cohort study. METHODS: One hundred eleven consecutive patients (74 men; median age 70 years) with >or=70% symptomatic (n=33) or >or=90% asymptomatic (n=78) internal carotid artery (ICA) stenosis underwent carotid artery stent implantation. Primary technical success and periprocedural complications were compared in patients aged >75 years (n=28) to patients <75 years (n=83). RESULTS: Patient groups below and above 75 years compared well with respect to baseline demographic and clinical data. Successful stenting was achieved in 108 (97%) patients. The combined neurological complication rate was 7% (n=8), with 1 (1%) major stroke, 1 (1%) minor stroke, and no 30-day mortality. Technical angiographic complications occurred in 8 (7%) patients. No significant differences between patients >75 years and those <75 years were observed for primary success rates (100% [28/28] versus 96% [80/83]; p=0.8), overall complications (14% [4/28] versus 16% [13/83]; p=1.0), neurological complications (7% [2/28] versus 7% [6/83]; p=1.0), or technical complications (7% [2/28] versus 4% [3/83]; p=0.6). CONCLUSIONS: Elective carotid stenting can be performed safely in older patients with several comorbidities. Patient age does not seem to be an independent risk factor for poor outcome after endovascular treatment of internal carotid artery stenosis.

Age Factors↗