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Biomedical subjects

M Heller

Publications and source records attributed to M Heller.

At least 163 records · Page 9Linked to original sources
PubMed1998

[Percutaneous therapy of occlusions of calf arteries with newly developed hydrodynamic thrombectomy catheter, Angiojet LF140].

PURPOSE: To evaluate the rheolytic thrombectomy catheter Angiojet LF140 (RTC) for treatment of calf artery occlusions. PATIENT AND METHOD: A 47-year-old male patient with an 8 cm measuring occlusion of the femoropopliteal and all calf vessels, suffering from limb threatening ischemia for 21 days, was treated with hydrodynamic thrombectomy (RT) using the modified RTC LF140. RESULTS: Most of the occluded segments could be successfully recanalized with the RTC. 450 ml of heparinized saline were injected. Parts of the tibial posterior artery and the fibular artery remained occluded. Additional long-term fibrinolysis therapy was administered (24 h), until all lower limb arteries were completely recanalized (+3 according to Rutherford). CONCLUSION: The modified RTK LF140 allows the treatment of acute thrombotic occlusions, even small caliber vessels. The device fails to remove organized and walladherent thrombus.

Catheterization↗
PubMed1998

[The assessment of the morphological changes after ventral diskectomy by thin-section computed tomography].

PURPOSE: We examined the changes of the intervertebral body space, the morphology of bone cement interponates and vertebrae after cervical discectomy and ventral fusion with high resolution CT. MATERIALS AND METHODS: CT scans were performed on 25 patients preoperatively, one week and six months after cervical discectomy and ventral fusion. RESULTS: There was no change in the size of the interponates. During follow-up new ossifications were found in 18 of the patients, two of them with neurological deficits. While directly after surgery the sagittal spinal canal diameter was enlarged, six months later particularly the lateral width was found to be reduced. After surgery soft tissue already narrowed the spinal canal in similar shape as the former prolapse. CONCLUSION: We conclude that postoperative neurologic deficits can only be partially explained by the described structural changes, because similar findings were made in uncomplicated postoperative courses as well as in patients with deficits.

Adult↗
PubMed1998

[Suction pump-supported aspiration thrombectomy: an in-vitro comparison with a thrombus fragmentation procedure].

PURPOSE: To compare the efficacy of vacuum pump controlled aspiration thrombectomy (VPCAT) with the Amplatz thrombectomy device (ATD) for treatment of thrombotic occlusions. MATERIALS AND METHODS: In a flow-model a superficial femoral artery is simulated. VPCAT provides the connection either of an aspiration catheter (AC, 8 F) or a multipurpose catheter (MPC, 8 F) with a vacuum pump (-110 mbar underpressure). 7 day old porcine blood (n = 30; 7.4 g +/- 0.1g) was treated with AC and MPC (VPCAT technique) and with the ATD. RESULTS: Complete thrombectomy was achieved with all techniques. Thrombectomy time was short for ATD (8.8 +/- 0.94 s; p < 0.01). MPC caused the least overall weight of emboli related to thrombus weight (5.14 0/100; p < 0.01). ATD caused the least embolisms at 1000 microns (3.27 mg; p < 0.05), and the most embolisms at 100 microns and at 10 microns (26.5 mg and 26.9 mg; p < 0.01). The aspirated volume of the MPC (33 +/- 17 ml) was half the volume of the AC (65 +/- 25 ml). CONCLUSIONS: In-vitro, VPCAT proves to be an alternative procedure to ATD. The use of a wide lumen multipurpose catheter is advantageous. In vitro, embolism rates of all methods are sufficiently low.

Analysis of Variance↗
PubMed1998

[Treatment of arterial femoropopliteal obstructions with Palmaz midsize stents].

PURPOSE: To evaluate effectiveness, success and patency rates after endovascular treatment with mid-size Palmaz stents in high-grade stenoses or short-distance occlusions of femoral arteries. MATERIALS AND METHODS: 27 patients with 10 occlusions (average length 3.2 +/- 1.4 cm) and 17 severe stenoses of the superficial femoral artery were treated with 33 mid-size Palmaz stents. The follow-up included Doppler ultrasound at one, three, 6 and 12 months and an angiography at 6 months. Mean follow-up was 6.5 months. RESULTS: Technical success was 100%. The ankle-brachial index improved from 0.57 +/- 0.28 pretreatment to 0.87 +/- 0.13 within 24 hours. Acute stent thrombosis occurred in two patients (< 3 weeks). Angiography at 6 months revealed restenosis rates of 7.4% (> 50%, n = 2). Life-table analysis according to Kaplan-Meier revealed 6-month primary and secondary patency rates of 84% and 91%. CONCLUSION: With regard to our limited data, the implantation of mid-size Palmaz stents in femoral arteries seems promising in treatment of short-distance occlusions and stenoses of the femoral artery.

Aged↗
PubMed1998

[Percutaneous thrombectomy and mechanical thrombolysis].

Treatment of acute embolic and thrombotic occlusions of arteries has to be initiated immediately to save the limb at risk. Surgery has been the treatment of choice for the last decades. Percutaneous mechanical methods for thrombectomy and thrombolysis have evolved and offer alternative treatment options, reducing the peri-operative risk. Percutaneous aspiration thrombembolectomy (PAT), recirculation thrombectomy with the Amplatz device, and different systems for hydrodynamic thrombectomy and thrombolysis (Angiojet, Hydrolyer, S.E.T. catheter) are routinely used for percutaneous thrombectomy and mechanical thrombolysis. These 3.5-10 F systems allow for the rapid removal of a fresh clot from different vascular regions. Complete removal of the clot can be achieved in 19-49%; adjunctive use of other percutaneous methods (thrombolysis and thrombectomy: 60-80%; PTA and atherectomy: 81-100%) results in primary success rates of 67-100% for recanalization of acutely occluded vessels. Primary indications for percutaneous thrombectomy and mechanical thrombolysis are acute occlusions of peripheral arteries and dialysis fistulas; limited experience exists for the treatment of occlusions of the visceral and pelvic vessels. Percutaneous methods seem promising for treatment of acute pulmonary embolism.

Acute Disease↗
PubMed1998

Exacerbated pain in cervical radiculopathy at axial rotation, flexion, extension, and coupled motions of the cervical spine: evaluation by kinematic magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors evaluate the functional changes in patients with cervical radiculopathy and increasing symptoms after provocative maneuvers at flexion, extension, axial rotation, and coupled motions of the cervical spine. METHODS: Twenty-one patients with cervical disc herniation (n = 17) or cervical spondylosis (n = 4) in whom symptoms were elicited at flexion, extension, axial rotation, and coupled motions of the cervical spine were studied. The patients were examined inside a positioning device by using a circular surface coil for signal reception. At neutral position (0 degrees) and at provocative positions sagittal T2-weighted turbo spin-echo, axial T2-weighted two-dimensional flash sequence, sagittal three-dimensional (3D) fast imaging with steady state precision sequence and coronal 3D double-echo-in-the-steady-state sequences were obtained. The 3D sequences were reformatted in the axial and oblique coronal planes perpendicular to the exiting nerve roots. The images were evaluated for the size of disc herniations, the foraminal size and cervical cord rotation or displacement at provocative position compared with neutral position (0 degrees). RESULTS: Compared with neutral position (0 degrees), change in size of disc herniation was not found in any (0%) of the provocative positions. In five (24%) patients cervical cord rotation or displacement was noted at axial rotation. The foraminal size increased at flexion, axial rotation to the opposite side of pain and flexion combined with axial rotation to the opposite side of the pain. The foraminal size decreased at extension combined with axial rotation to the side of the pain. A decrease or no change in foraminal size was observed at either extension or axial rotation to the side of the pain. CONCLUSIONS: In patients with cervical disc herniation or cervical spondylosis, exacerbated pain at defined provocative maneuvers is related more to changes in the foraminal size and to nerve root motion with, in some cases, cervical cord rotation or displacement than to changes in the size of herniated discs.

Adult↗
PubMed1998

Dynamic changes of the spinal canal in patients with cervical spondylosis at flexion and extension using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors determine the dynamic changes of the spinal canal during flexion and extension in patients with cervical spondylosis. METHODS: Forty-six patients were studied inside a whole-body magnetic resonance (MR) scanner with between 50 degrees of flexion and 30 degrees of extension, using a positioning device. At neutral position (0 degree) and maximum flexion and extension sagittal T2-weighted turbo spin echo sequences were acquired. RESULTS: A significant (P < or = 0.05) increase of spinal stenosis was found at extension (48%, 22 of 46 patients) when compared with flexion (24%, 11 of 46). Cervical cord compression was diagnosed at flexion in 5 patients (11%) and at extension in 9 patients (20%). Concerning the number of patients with cervical cord compression at flexion and extension, significant differences (P < or = 0.05) were found in patients with degenerative changes at four segments compared with patients with one segment involvement. CONCLUSIONS: Magnetic resonance imaging identified a significant percentage of increased spinal stenosis at flexion and, especially, at extension, which was not observed at neutral position (0 degree). Flexion and extension MR imaging demonstrates additional information using a noninvasive technique concerning the dynamic factors in the pathogenesis of cervical spondylotic myelopathy.

Adult↗
PubMed1998

Visualization of flow patterns from stents and stent-grafts in an in vitro flow-model.

RATIONALE AND OBJECTIVES: The authors determine flow characteristics and pressure gradients of different stents and stent grafts in an in vitro flow-model. METHODS: Five vascular stents (Memotherm, Cragg, two Palmaz P308, Strecker, and Wall) and one stent graft (Cragg EndoPro System 1), equal in length (60 mm) and diameter (10 mm), were deployed in a closed flow-model. The inner diameter of the tube measured 9 mm. Flow at 1.5 L/min, 6 L/min, and 10 L/min was simulated. Flow patterns were visualized by anionic particles illuminated with two Helium-Neon lasers. Laminary flow characteristics and pre-/poststent pressure gradients were determined in either expanded stent, 25% stenosis, or 50% stenosis. RESULTS: Stent implantation induced a decrease of laminary flow compared with an unstented tube with and without concentric 25% stenosis (P < 0.01) at all flow rates and an increase of pressure gradients compared with an unstented tube for flow rates greater than 1.5 L/min (P < 0.01) (except for Cragg EndoPro System 1 stent, which revealed an increase of the pressure gradient at a flow rate of 1.5 L/min [P < 0.01]). Memotherm stent permitted maximum of laminary flow at all flow rates and stenoses (expanded: 79.50% at 1.5 L/min to 69.90% at 10 L/min; P < 0.01). Memotherm and Palmaz permitted lowest pressure gradients (P < 0.01). All of the endoprostheses demonstrated laminary flow at 50% stenosis. CONCLUSIONS: The investigated stents and stent grafts showed different severity of flow disturbances and pressure gradients at different graded stenoses. Inadequate stent depolyment bears the risk of creating less laminary flow and pathologic pressure gradients. Because flow disturbances and pressure gradients may influence neointimal hyperplasia, stent design and completeness of stent unfolding are important regarding the appearance of postinterventional restenoses.

Analysis of Variance↗
PubMed1998

Streptococcal peritonitis in a young dromedary camel.

A male dromedary camel was presented for a primary Streptococcal zooepidemicus septic peritonitis. An underlying gross lesion was not identified during abdominal exploratory surgery. The camel responded to peritoneal lavage, peritoneal drainage and systemic antibiotic therapy. Thrombophlebitis of the left jugular vein was diagnosed 14 days after surgery. The camel died of an unknown cause 24 days after surgery.

Animals↗
PubMed1998

Percutaneous placement of a self-expandable stent for treatment of a malignant pulmonary artery stenosis.

Venous stent placement is widely accepted as the treatment of stenoses caused by external tumour compression to reduced clinical sequelae. We report percutaneous stent placement into a severely obstructed right pulmonary artery in a 73-year-old female patient. The underlying disease was a medistinal tumour mass of unknown aetiology. Pulmonary perfusion was successfully but temporarily restored by the intervention.

Aged↗
PubMed1998

Pulmonary Wegener's granulomatosis: correlation between high-resolution CT findings and clinical scoring of disease activity.

STUDY OBJECTIVE: To evaluate the usefulness of high-resolution CT (HRCT) for monitoring pulmonary disease activity in Wegener's granulomatosis (WG). DESIGN: Prospective study of CT and clinical data. SETTING: Main referral hospital for rheumatic diseases and department of diagnostic radiology of collaborating university hospital. PATIENTS: Seventy-three patients with WG underwent 98 staging examinations using HRCT. The status of pulmonary disease activity at the time of examination was scored according to clinical, bronchoscopic, BAL, and radiographic findings as follows: activity (n=25, group 1), past activity (n=45, group 2) and lack of any pulmonary disease (n=28, group 3). HRCT findings were correlated with the clinical scoring of pulmonary disease activity. RESULTS: Of 98 staging examinations 78 (79.6%) revealed abnormal CT scans showing the following main abnormalities: (a) nodules or masses (group 1: 16 [60.4%], group 2: 9 [20%]); (b) parenchymal bands (group 1: 12 [48%], group 2: 27 [60%], group 3: 6 [21.5%]); (c) septal thickening (group 1: 8 [32%], group 2: 6 [13.3%]); (d) parenchymal opacification (group 1: 7 [28%], group 2: 4 [8.9%]); and (e) pleural irregularity (group 1: 14 [56%], group 2: 22 [49%], group 3: 9 [32%]). Nodules/masses and areas of parenchymal opacification were significantly associated with florid disease activity of the lungs. Parenchymal bands and septal thickening were observed in both groups with pulmonary involvement, but statistical analysis revealed no significant difference. Pleural irregularities were nonspecific. CONCLUSION: HRCT may be a useful adjunct to clinical scoring of pulmonary disease activity in patients with WG and suspected lung involvement.

Adult↗
PubMed1998

Restenosis of peripheral stents and stent grafts as revealed by intravascular sonography: in vivo comparison with angiography.

OBJECTIVE: Our objective was to compare intravascular sonography with digital subtraction angiography (DSA) in the assessment of luminal dimension and morphologic features of endovascular stents and stent grafts. MATERIALS AND METHODS: Thirty-seven pelvic and 24 femoral stents (12 Wall-stents; 27 covered and 22 uncovered nitinol stents) in 50 patients were evaluated 15 +/- 10 months after implantation by DSA and intravascular sonography. The degree of maximum instent restenosis as revealed by DSA and intravascular sonography was compared for each location. Morphologic features of the stents and stenoses were also assessed. RESULTS: Intravascular sonography and DSA correlated well (R2 = .96) in determining in-stent restenosis. In-stent restenosis was underestimated by 13% +/- 6% by DSA compared with intravascular sonography. Differences in determining in-stent restenosis with intravascular sonography and DSA were not associated with severity of stenosis or type of stent. Intravascular sonography revealed incomplete expansion of stents in 21 cases, whereas DSA revealed incomplete expansion of stents in seven cases. The intra- and interobserver variabilities in our study were 4% and 5%, respectively. CONCLUSION: In-stent restenoses are underestimated with DSA. Intravascular sonography is superior to DSA for detection of incomplete stent expansion.

Alloys↗
PubMed1998

Evaluation of maximum neointima proliferation and plaque morphology in iliac self-expanding nitinol stents with intravascular sonography.

OBJECTIVE: The purpose of this study was to use intravascular sonography to evaluate neointima formation, plaque location, and the performance of self-expanding nitinol (Memotherm) stents in iliac arteries. SUBJECTS AND METHODS: Seventeen patients (mean age, 64+/-9.4 years) with stenoses or occlusions of the common (n = 12) or external (n = 5) iliac artery were treated with 21 Memotherm stents (mean diameter +/- SD, 8.9+/-1.3 mm; mean length, 53+/-20.9 mm). Four patients had two stents each. Intravascular sonography was performed 13+/-6 months after stent implantation. Maximum thickness of neointima and maximum cross-sectional plaque area were measured. Qualitative analysis of plaque composition and lesion topography were also assessed. RESULTS: Intravascular sonography revealed 22.1%+/-17.3% maximum percentage of restenosis, and maximum plaque area was found to be 11.2+/-10 mm2. Only hypoechogenic in-stent lesions (soft plaques) were found. Seven (33%) incomplete stent expansions and two (10%) incomplete appositions of the stent to the vessel wall were revealed by intravascular sonography. CONCLUSION: Iliac artery Memotherm stents generally showed moderate in-stent restenosis with uniform neointima distribution. Incomplete stent expansion was detected in one third of all implanted stents.

Alloys↗
PubMed1998

[PTA of the brachiocephalic arteries].

PURPOSE: Assessment of the technical success and mid-term success of PTA of brachiocephalic occlusive disease. MATERIAL AND METHODS: 24 patients, who were treated interventionally because of stenoses of the brachiocephalic arteries were enrolled into this prospective study. In total there were 27 lesions (26 arteriosclerotic lesions and one dissection with pseudoaneurysma). 18 lesions were located in the subclavian artery (extending into the axillar artery in one case), 4 in the brachiocephalic trunk, three in the common carotid artery and two in the vertebral artery. As adjunctive to balloon dilatation 8 stents were implanted. RESULTS: Technical success was achieved in 24/27 lesions. There was an embolic complication in one of 27 interventions. 15/24 patients with 17 treated lesions underwent control angiography with a mean follow-up of 14 months. Follow-up angiography revealed one occlusion and three significant restenoses. 5/24 patients agreed only to clinical follow-up and Doppler examinations, three were lost and one patient died. CONCLUSION: PTA of brachiocephalic occlusive disease showed good technical success. Additional implantation of stents may be useful. Midterm success is satisfactory.

Aged↗
PubMed1998

Classification system based on kinematic MR imaging in cervical spondylitic myelopathy.

BACKGROUND AND PURPOSE: Functional myelographic studies are often used to evaluate the dynamic changes of the cervical spinal canal during flexion and extension. The purposes of this study were to use kinematic MR imaging to assess the dynamic changes of the cervical spine in patients at different stages of degenerative disease and to describe a classification system based on static and dynamic factors in the pathogenesis of cervical spondylitic myelopathy. METHODS: Eighty-one patients with different stages (I-IV) of degenerative disease of the cervical spine were examined with MR imaging. In the neutral position (0 degrees) and at maximum flexion and extension, spinal stenosis was classified for each segment according to the following grading system: 0 = normal, 1 = partial obliteration of the anterior or posterior subarachnoid space, 2 = complete obliteration of the anterior or posterior subarachnoid space, and 3 = cervical cord compression or displacement. RESULTS: At flexion and extension, the prevalence of spinal stenosis and cervical cord impingement increased as the stage of degenerative disease progressed. With regard to a pincer effect (anterior and posterior cord impingement) and cord encroachment at multiple segments, statistically significant differences were observed at stages III and IV as compared with stages I and II. Significant increase in cord impingement was seen in 22 (27%) of 81 patients at extension, as compared with four (5%) of 81 patients at flexion. CONCLUSION: Regardless of the stage of degenerative disease and grade of spinal stenosis at the neutral position (0 degrees), cervical spinal motion may contribute to the development of cervical spondylitic myelopathy.

Adult↗
PubMed1998

[Ultrasound--already clinically relevant?].

The rapid development of Quantitative Ultrasound (QUS) methods in recent years allows to use these devices in a clinical setting. Their primary role is the assessment of fracture risk due to osteoporosis. Further investigations are required for use of QUS for monitoring and diagnostic purposes. Differences between the QUS parameters, Speed of Sound (SOS) and Broadband Ultrasound Attenuation (BUA), between different measurement sites and measurement technology need to be appreciated. Consequently, QUS devices need to be validated individually. In addition, adequate quality assurance measures need to be implemented. QUS and bone densitometry have different complementing features and both should find their place in the clinical arena. These recent developments open up the opportunity to reduce the number of fractures by targeted diagnostic assessments which should lead to medical progress and should also bring along socio-economical advantages.

Bone Density↗
PubMed1997

Structure and chromosomal assignment of the human cathepsin K gene.

Cathepsin K is a recently identified lysosomal cysteine proteinase that is the major protease responsible for bone resorption and remodeling. Mutations in this gene cause the sclerosing osteochondrodysplasia pycnodysostosis. To assess its evolutionary relatedness to other cysteine proteases and to facilitate mutation identification in patients with pycnodysostosis, a genomic clone, 74e16, containing the cathepsin K gene was isolated from a human PAC library, and the cathepsin K genomic structure was determined. The cathepsin K gene contained eight exons and spanned approximately 9 kb. The transcription initiation site, determined by primer extension analysis, was 169 nucleotides upstream from the translation initiation site. The 5'-flanking region lacked a TATA box but contained two AP1 sites. Comparison of genomic and cDNA sequences suggested that this flanking sequence may be the major promoter in osteoclasts and macrophages. Cathepsin K was mapped to chromosome 1q21 by fluorescence in situ hybridization and found to reside within 150 kb of an evolutionarily related cysteine protease, cathepsin S. These findings expand our understanding of the papain family lysosomal cysteine proteases and should facilitate mutation analysis in pycnodysostosis.

Base Sequence↗