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Biomedical subjects

I Baumgartner

Publications and source records attributed to I Baumgartner.

At least 37 records · Page 2Linked to original sources
PubMed2001

Rapid D-dimer testing and pre-test clinical probability in the exclusion of deep venous thrombosis in symptomatic outpatients.

We assessed the performance of three rapid D-dimer tests (Auto Dimertest, VIDAS and Tinaquant) in combination with a pretest clinical probability model for deep venous thrombosis (DVT) in 106 consecutive outpatients with suspected DVT. Contrast venography or colour-coded duplex ultrasonography demonstrated the presence of DVT in 47 patients (14 distal DVT and 33 proximal DVT). First, we assessed the accuracy indices for different cut-off levels of the rapid D-dimer tests. Sensitivity was found to be 97.9-100%, negative predictive value (NPV) was 96.3-100%, and the exclusion rate was 24.5-31.1%. Next, the patients were grouped according to the pre-test clinical probability model in categories with low, moderate or high probability. In patients with a low pre-test probability, DVT would have been directly ruled out and the patients would not have undergone further investigations. In patients with a moderate probability, D-dimer testing and, in the case of a positive result, objective testing would have been performed and, in the case of a negative result, they would have been ruled out of having DVT. Patients with high probability would directly have undergone objective tests for DVT. The combination with the pre-test clinical probability model improved the exclusion rate (43.5-44.6%), whereas sensitivity (97.5-100%) and NPV (97.6-100%) remained roughly unchanged. The combination of rapid D-dimer tests with a pre-test clinical probability model may help to reduce unnecessary work-up in patients with suspected DVT.

Adolescent↗
PubMed2001

Somatic gene therapy in the cardiovascular system.

This review surveys a range of approaches using plasmid DNA encoding the 165-amino-acid isoform of vascular endothelial growth factor (phVEGF165) to therapeutically modulate micro- or macrovascular endothelial cells, focusing on strategies to augment postnatal collateral circulation in arterial insufficiency or to accelerate re-endothelialization after balloon angioplasty to prevent restenosis. We focus on intra-arterial and intramuscular/intramyocardial gene transfer of the VEGF165 gene, the options that have been most thoroughly studied to date in patients. We review developmental and postnatal significance of the endothelial-cell-specific mitogen VEGF that has stimulated these studies and present limitations of current knowledge as well as challenges for the future.

Animals↗
PubMed2000

Lower-extremity edema associated with gene transfer of naked DNA encoding vascular endothelial growth factor.

BACKGROUND: Vascular endothelial growth factor (VEGF) promotes angiogenesis and vascular permeability. The extent to which VEGF may cause tissue edema in humans has not been established. OBJECTIVE: To evaluate patients undergoing VEGF gene transfer for evidence of lower-extremity edema. DESIGN: Prospective consecutive case series. SETTING: Hospital outpatient clinic. PATIENTS: 62 patients with critical limb ischemia and 28 patients with claudication. INTERVENTION: Gene transfer of VEGF DNA. MEASUREMENTS: Semiquantitative analysis of lower-extremity edema. RESULTS: Lower-extremity edema was observed in 31 of 90 (34%) patients. Edema was less common in patients with claudication than in those with pain at rest (P = 0.016) or ischemic ulcers (P < 0.001), and it was less common in patients with pain at rest than in those with ischemic ulcers (P= 0.017). Treatment was typically limited to a brief course of oral diuretics. CONCLUSIONS: Vascular endothelial growth factor may enhance vascular permeability in humans. At the doses of plasmid DNA used in this study, lower-extremity edema responded to oral diuretic therapy and did not seem to be associated with serious sequelae.

Administration, Oral↗
PubMed2000

Therapeutic angiogenesis: theoretic problems using vascular endothelial growth factor.

Angiogenic growth factors constitute a potentially novel form of therapy for patients with ischemic vascular disease. In case of vascular endothelial growth factor (VEGF), a cytokine secreted from intact cells, bioavailability and meaningful angiogenic bioactivity was shown to be achievable by intramuscular gene transfer in patients with chronic critical limb ischemia. Angiogenesis, however, is a two-sided coin with detrimental consequences in non-target tissues. In particular, the theoretic risk of tumor or plaque angiogenesis must not be ignored, though based on experimental and clinical data there is every reason to believe that a short-term increase of circulating VEGF is safe. More sophisticated remains the controversy concerning mechanisms involved in apparent clinical benefits of growth factors (or growth factor genes). This article argues some theoretic problems using naked plasmid DNA encoding VEGF for the purpose of therapeutic angiogenesis.

Angioplasty, Balloon↗
PubMed2000

Renal artery stenting following acute aortic dissection: implantation and follow-up.

Two patients with renal artery involvement in type B dissection of the aorta were treated by percutaneous stent implantation. Both of them were hypertensive and showed increasing serum creatinine levels. After stent implantation in the renal arteries blood pressure and renal function improved, and the renal arteries were patent in duplex ultrasound 15 and 30 months after treatment respectively.

Aged↗
PubMed2000

Percutaneous catheter thrombus aspiration for acute or subacute arterial occlusion of the legs: how much thrombolysis is needed?

OBJECTIVE: To evaluate the role of a combined percutaneous endovascular approach including thrombus aspiration, catheter thrombolysis, and percutaneous transluminal angioplasty (PTA) to treat acute and subacute occlusions of native leg arteries. MATERIALS AND METHODS: Retrospective evaluation of the effectiveness and safety of this catheter therapy in 89 consecutive patients (93 legs) in a single centre. RESULTS: Treatment was initially successful in 90% of legs. Mortality at 30 days was 8%, and at 12 months 19%. Amputation-free survival at 12 months was 78%. Aspiration alone was sufficient in 31% of cases, urokinase (mean dose 112 500+/-55 900 IU) was used in 22%, PTA was added in 69%. There was no major bleeding except for one false aneurysm treated by ultrasound-guided compression. Secondary interventions within 12 months were required in 30% of cases (14 endovascular, 16 open surgical procedures). CONCLUSIONS: Catheter thrombus aspiration in combination with thrombolysis and/or PTA is highly effective. Only in a minority of patients are thrombolytics in modest doses necessary, and serious bleeding complications are rare. We recommend this procedure as first-line treatment for acute or subacute infrainguinal arterial occlusions.

Acute Disease↗
PubMed2000

Stent placement in ostial and nonostial atherosclerotic renal arterial stenoses: a prospective follow-up study.

PURPOSE: To compare the results of balloon percutaneous transluminal renal angioplasty (PTRA) and stent placement in atherosclerotic ostial, proximal, and isolated truncal stenoses. MATERIALS AND METHODS: Between January 1994 and April 1998 the authors prospectively followed up 163 consecutive patients with 200 atherosclerotic renal arterial lesions after primary PTRA or primary stent placement. Duplex ultrasonography was performed 1 day and 3, 6, and 12 months later. RESULTS: The primary 12-month PTRA patency rates were 34% (21 of 33 atherosclerotic lesions) for ostial stenoses, 65% (20 of 60) for proximal stenoses, and 83% (five of 30) for truncal stenoses (chi(2) value, 15.63; P <.001). The corresponding stent patency rates were 80% (four of 21), 72% (nine of 34), and 66% (five of nine), respectively (chi(2) value, 4.11; not significant). Significant stent-related reduction in risk of restenosis was limited to the ostial stenoses (P =.002). CONCLUSION: Renal arterial stent placement considerably improves patency in ostial stenoses, but compared with the technically successful PTRA, it does not significantly improve primary patency in proximal and isolated truncal renal arterial stenoses.

Adult↗
PubMed2000

Innervated myotendinous cylinders in human extraocular muscles.

PURPOSE: To analyze palisade endings and their end organs, the so-called innervated myotendinous cylinders (IMCs), of human extraocular muscle (EOM) in more detail and to clarify with the help of double-fluorescent labeling and electron microscopy whether terminals in IMCs are sensory, serving proprioception. METHODS: EOMs obtained from a donated cadaver (66 years) and distal parts of EOMs from multiorgan donors (35, 53 years) were processed for double-fluorescent labeling. Antibodies against the protein gene product 9.5 and alpha-bungarotoxin labeling were used on cryostat sections of distal myotendons. EOMs from multiorgan donors (2, 17 years) were prepared for electron microscopy. RESULTS: Palisade endings investing muscle fiber tips established contacts with tendon fibrils and the muscle fiber attached. Alpha-bungarotoxin bound to myoneural contacts but not to axonal varicosities in the tendon compartment. Ultrastructural analysis revealed that palisade endings form IMCs, which were associated exclusively with multiply innervated global layer muscle fibers. IMCs consisted of a muscle fiber tendon junction, tightly enclosed by fibrocytes, and a supplying axon with preterminals and terminals. Terminals contained mitochondria, few neurotubuli, few neurofilaments, and accumulations of clear vesicles of uniform size. A basal lamina always intervened between axolemma and tendon fibrils as well as between axolemma and muscle fiber cell membrane. CONCLUSIONS: Palisade endings of human EOM form IMCs as in cat, monkey, and sheep. In contrast to animals, myoneural contacts in human IMCs are almost certainly motor, whereas terminals contacting tendon fibrils are arguably sensory. Thus, IMCs might be best described as "propriocept-effectors."

Adolescent↗
PubMed1999

Stenting of the peripheral, renal and supraaortic arteries and the aorta.

In spite of the limited experience with the newer types of stents (covered stents, stent grafts) and the resultant reservations, this development is one of the most fascinating features of the last decade and opens new perspectives for vascular medicine and endovascular surgery in the near future. At present stents in the aortoiliac region, including the origin of renal arteries, appear to fulfil their promise. In the femoropopliteal and crural region there are still unresolved problems (relapse rate around 50%), and stents should be implanted only in salvage situations. However, primary application of stents cannot be recommended even in the unproblematic regions, due to the possibility of stent-induced intimal hyperplasia and the high cost of the devices. In other more controversial regions such as the carotid arteries, the application is still experimental and should be performed under controlled study circumstances.

Aged↗
PubMed1999

A validation study on the intraobserver and interobserver reproducibility of renal artery duplex ultrasound.

Aim of the present study was to evaluate intraobserver and interobserver reproducibility of direct renal artery Doppler velocimetry. Healthy volunteers were evaluated by one examiner on three separate occasions and by three different examiners in a single day. Peak systolic velocities of the aorta (PSV.Ao) and proximal renal arteries (PSV.RA) were taken at an optimal angle below 60 degrees. The renal-to-aortic ratio (RAR) was calculated dividing PSV.RA by PSV.Ao. Mean values +/- 2 SD were 85 +/- 34 (49-150) cm/s for the PSV.RA, 38 +/- 20 (0-60 degrees) for the Doppler angle of insonation, 102 +/- 37 (63-153) cm/s for the PSV.Ao, and 0.85 +/- 0.41 (0.49-1.58) for the RAR. Correlation coefficients and coefficient of variation were 0.64-0.82/7.8%-10.1% (PSV.RA), 0.75-0.82/9.9%-13.8% (RAR) for intraobserver evaluations; and 0.79-0.80/7.7%-12.5% (PSV-RA), 0.65-0.78/9.5%-12.3% (RAR) for interobserver evaluations. Reliable results of direct renal artery Doppler velocimetry confirm clinical applicability and suitability for repeated measurements after catheter-based interventions or surveillance of low-grade stenoses.

Adult↗
PubMed1999

PTA of the subclavian and innominate arteries: long-term results.

BACKGROUND: To investigate the long-term clinical and duplex sonographic results of percutaneous transluminal angioplasty (PTA) of the subclavian and innominate arteries, and the potential of a new double balloon technique to avoid cerebrovascular thromboembolism. PATIENTS AND METHODS: Forty-three PTAs were performed on 38 subclavian, four innominate arteries and one subclavian-subclavian bypass in 37 patients. In three instances a protective double balloon technique was used. Indication for the intervention was: subclavian steal syndrome (n = 14 [38%]), upper extremity arterial insufficiency (n = 26 [70%]), peripheral thromboembolism (n = 8 [22%]) and PRIND/stroke (n = 3 [8%]). Analysis of long-term follow-up (median 15, range 2 to 100 months) was possible of 28 patients including duplex sonographic assessment in 23 patients. The cumulative patency rate was calculated by means of life-table analysis. RESULTS: Technical success was achieved in 36 endovascular procedures (84%). Minor peripheral catheter complications occurred in three interventions (7%), cerebrovascular thromboembolism in four (9%). No cerebrovascular complications were seen using the double balloon technique. On final check-up 4 patients (14%) suffered from subclavian steal syndrome, 3 (11%) from mild upper extremity arterial insufficiency and one (4%) from rest pain. Duplex sonography showed no stenosis in 12 of 23 patients (52%) and a stenosis of less than 50% in 8 (35%). The life-table analysis showed a secondary cumulative patency rate of 72% after 100 months with all restenoses occurring within 24 months. CONCLUSIONS: PTA of the subclavian and innominate arteries appears to be a useful alternative to surgery with a low complication rate. The long-term patency rate of 72% is comparable to results of other series. In high risk situations cerebrovascular complications may be reduced using the new double balloon technique.

Adult↗
PubMed1999

Fine structural analysis of extraocular muscle spindles of a two-year-old human infant.

PURPOSE: To clarify whether structural peculiarities formerly described in extraocular muscle (EOM) spindles of aged persons are already present in EOM spindles of a 2-year-old infant. METHODS: Distal halves of two EOMs obtained from a 2-year-old multiorgan donor were immersion-fixed and prepared for electron microscopy. The fine structure of 10 muscle spindles and of 1 "false spindle" was investigated. RESULTS: Extraocular muscle spindles of an infant 2 years of age had 2- to 4-layered outer capsules, 376 microm (range, 217-606 microm) long and 97 microm (range, 55-140 microm) wide. In 10 EOM spindles, 4 to 16 intrafusal muscle fibers (mean, 7.9) were present. From a total of 79 intrafusal fibers, 43 (54%) were nuclear chain fibers, and 8 of the 43 exhibited posttraumatic degenerative changes. Thirty-six (46%) intrafusal fibers indistinguishable from extrafusal fibers were called anomalous fibers. No nuclear bag fibers were found. Each muscle spindle contained a variable number of chain fibers and at least one anomalous fiber. Sensory nerve terminals were restricted to the 35 normal chain fibers but were absent from damaged chain fibers and from anomalous fibers. One "false spindle" without a periaxial space was composed of three anomalous fibers and one chain fiber, all of them devoid of sensory terminals. CONCLUSIONS: Most structural particularities of human EOM spindles described in aged persons are already found in the infant. They cannot be interpreted as age-related changes, but rather they represent specific features of human EOM spindles.

Aged↗