Biomedical subjects

Jan Grimm

Publications and source records attributed to Jan Grimm.

25 records · Page 2Linked to original sources

PubMed2002

Endovascular placement of self-expanding nitinol coil stents for the treatment of femoropopliteal obstructive disease.

PURPOSE: To report on a prospective two-center study to evaluate safety and effectiveness of a self-expanding nitinol coil stent in patients with femoropopliteal obstructive disease. MATERIALS AND METHODS: The IntraCoil nitinol stent was used in 37 patients (28 men and nine women; mean age, 62.4 y plus minus 10.7; range, 43-81 y) presenting with high-grade stenoses (n = 23) or short (<3 cm) occlusions (n = 17) of the superficial femoral artery (SFA; n = 33) or popliteal artery (n = 4). Indications for stent placement were significant residual stenosis (>30%) or dissection after angioplasty. Follow-up evaluations with measurement of the Doppler ankle-brachial index (ABI), assessment of Rutherford clinical stage, and color-coded duplex sonography were performed at discharge and 1, 3, 6, 12, and 18 months thereafter. Primary endpoints of the study were immediate technical and clinical success and 1-year patency. RESULTS: Initial technical success was achieved in all patients. In 10 patients (27%), more than one 40-mm-long device had to be implanted for total lesion coverage; in three patients (8.1%), stents were placed in two separate segments of the SFA simultaneously. The total number of stents deployed was 50. Stent placement induced an initial improvement of the ABI from 0.54 plus minus 0.2 to 0.92 plus minus 0.11 (P <.01). Follow-up data for 12 months after treatment are available for 29 of 37 patients (78.4%); mean follow-up is 15.6 months (range, 1-26 mo). Primary patency rates at 6 and 12 months were 97.1% (SE = 2.9) and 86.2% (SE = 6.5). The primary assisted patency rate was 100% at 12 months. CONCLUSION: Endovascular placement of the IntraCoil self-expanding nitinol coil stent for salvage of failed angioplasty in patients with femoropopliteal obstructive disease is an effective and safe procedure with promising mid-term results.

Adult↗

PubMed2002

In vitro effectiveness of mechanical thrombectomy devices for large vessel diameter and low-pressure fluid dynamic applications.

PURPOSE: To determine in vitro the efficacy of clot removal of the AngioJet (AJ; new 6-F generation), Hydrolyser (HL; 6-F), and Oasis (OS; 6-F) hydrodynamic thrombectomy devices and the Amplatz Thrombectomy Device fragmentation catheter (ATD; 8-F and new-generation 7-F) in large-diameter vessels and low-pressure fluid dynamic applications (ie, pulmonary embolism). MATERIALS AND METHODS: Thrombectomy of clots (N = 60; n = 12 for each tested device) created from 5-day-old porcine blood (16 g) was performed with the AJ (with coaxial 0.035-inch guide wire), HL, OS, and ATD in a bench-top model simulating low-pressure fluid dynamics (pulsed flow, 1,250 L/min). Tubes made of silicone (20-mm inner diameter) containing thrombus simulated a large-diameter vessel. The effluent was passed through a three-step filter system (10-1,000 micro m; pressure drop, 15 mm Hg). RESULTS: Mean thrombectomy time ranged from 83 seconds (7-F ATD) to 185 seconds (OS; P <.0001 compared to all). Remaining thrombus ranged from 5.4 g/32.7% (AJ) to 11.1 g/68.1% (HL; P <.001 compared to all). The AJ's fluid balance was 0.92, whereas the mean ratio of applied saline solution to aspirated fluid for the other devices were significantly different than isovolumetric conditions (HL, 0.64; OS, 0.59; P <.0001 compared to AJ). The AJ (0.36%), HL (0.43%), and OS (0.38%) caused the least overall emboli larger than 10 micro m; the ATD (7-F, 0.82%; 8-F, 0.74%) caused the most (P <.001 for both). CONCLUSIONS: The tested mechanical thrombectomy devices showed performance differences in thrombectomy time, efficacy of thrombus removal, and peripheral embolization rates. Based on low embolization rates for all devices tested, the experimental data indicate that the 7-F ATD and the 0.035-inch guide-wire-compatible AJ showed feasibility advantages for thrombectomy in large vessel diameter and low-pressure fluid dynamic applications.

Animals↗

PubMed2002

Experience on endothelial cell adhesion on vascular stents and stent-grafts: first in vitro results.

RATIONALE AND OBJECTIVES: To evaluate endothelial cell (EC) attachment on different stents and stent-grafts combined with different coating materials. MATERIALS AND METHODS: Three segments (approximately 1cm(2) each) of Cragg-, Memotherm-, Palmaz-, Strecker-, and Wall-stents, uncovered or covered with polytetrafluoroethylene (PTFE), polyurethane (PU) or polyester (Dacron) were precoated with fibronectin and seeded in vitro under steady conditions with 2 x 10(5) human venous EC/cm(2) for 2 days. EC attachment and morphology was assessed by scanning electron microscopy. RESULTS: Superior EC attachment on uncovered stents was seen on Memotherm-, Palmaz-, and Wall-stent. On uncovered Cragg- and Strecker-stent only a few single and rounded EC could be detected. PTFE-covering lead to an equal or decreased EC coverage in comparison with the uncovered prostheses. An increase in EC coverage on PU-covered stents was seen and on polyester covered stents as compared with uncovered stents. CONCLUSION: In vitro, EC attachment is clearly different on vascular stents and stent-grafts, probably depending on the material of the stents stent and unknown manufacturing related components. When EC adhesion is desired and stent covering is used, the choice of covering material may influence EC adhesion.

Cell Adhesion↗

PubMed2002

Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging: multicenter study comparing MR and dual-phase spiral CT.

PURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were suspected of having focal liver lesions were included in a multicenter study and underwent dual-phase spiral CT and enhanced MR imaging. Image interpretations performed by independent experienced radiologists were compared with the final diagnosis that was based on all available clinical information (including histopathologic findings in 77 patients) and that was determined with consensus. Differences in classifications by using either enhanced MR imaging or dual-phase spiral CT were analyzed with the McNemar test, and receiver operating characteristic (ROC) curves were used to compare the diagnostic performance of enhanced MR imaging and dual-phase spiral CT. RESULTS: Lesion classification was correct in 108 (74%) patients with enhanced MR imaging and in 83 (57%) with dual-phase spiral CT (P =.001). Lesions were correctly classified as either malignant or benign in 123 (85%) patients with enhanced MR imaging and in 98 (68%) with dual-phase spiral CT (P =.001). Classification of lesions as either hepatocellular or nonhepatocellular was correct in 130 (90%) patients with enhanced MR imaging and in 93 (64%) with dual-phase spiral CT (P =.001). These differences remained when analyses were restricted to histopathologically confirmed diagnoses. Comparison of the ROC curves illustrated that enhanced MR imaging performance surpassed that of dual-phase spiral CT. CONCLUSION: Mn-DPDP-enhanced MR imaging is superior to dual-phase spiral CT in classification of focal liver lesions.

Adult↗

PubMed2002

Comparison and modification of two cerebral protection devices used for carotid angioplasty: in vitro experiment.

The effectiveness of two basic cerebral protection devices designed for carotid angioplasty with and without additional aspiration techniques was compared in an in vitro model. During carotid angioplasty, embolization was simulated by injecting polyvinyl alcohol particles of different sizes into the model system. None of the tested devices, all of which were positioned in the internal carotid artery, was able to completely prevent embolization. In the internal carotid artery, the rate of particle capture did not vary among protection devices. However, embolization into the external carotid artery was more frequent with use of the GuideWire, as compared with that with use of the Angioguard.

Angioplasty, Balloon↗

PubMed2002

In vitro comparison of four cerebral protection filters for preventing human plaque embolization during carotid interventions.

PURPOSE: To evaluate in an in vitro bench-top model the efficacy of 4 filtration devices designed for cerebral protection during carotid angioplasty. METHODS: Embolization during carotid angioplasty was simulated with human plaque material (8 to 12 particles weighing 6.02 +/- 0.10 mg) in an open flow model with the aortic arch and carotid bifurcation made from elastic silicone tubes and saline used as the fluid medium. The 500 to 1500-microm particles were injected into the internal carotid artery (ICA) in front of the test protection device, which was deployed 5 cm distal to the bifurcation. Particles getting past the protection device or flowing into the external carotid artery (ECA) were caught in 100-microm filters and weighed. Ten trials were made on each of 4 devices: Angioguard, FilterWire EX, TRAP, and NeuroShield. All were deployed according to the manufacturers' directions except the FilterWire, which was manually repositioned in all tests to eliminate a gap between the filter and the tube wall. RESULTS: The lowest weight of missed particles in the effluent was obtained with the NeuroShield (0.05 +/- 0.04 mg, 0.8% of injected particle weight) and FilterWire (0.08 +/- 0.05 mg, 1.3%; p=0.254 compared to NeuroShield, p=0.006 versus TRAP). The weight of particles missed by the TRAP device (0.16 +/- 0.06 mg, 2.6%; p<0.001 versus NeuroShield and Angioguard, p<0.05 compared to FilterWire) was higher, and the largest amount of missed particles was observed with the Angioguard filter (0.27 +/- 0.06 mg, 4.4%; p<0.001 compared to all). NeuroShield and FilterWire were significantly different (p<0.001) compared to Angioguard and TRAP in a pairwise analysis. No embolization into the ECA occurred. CONCLUSIONS: In vitro, none of the tested devices had the ability to completely prevent embolization into the ICA. Comparing current designs, the NeuroShield filter and the FilterWire EX captured the highest percentage of human particles in this in vitro model, probably due to their larger filter volume.

Balloon Occlusion↗

PubMedDate not supplied

Influence of thrombus age on the mechanical thrombectomy efficacy of the amplatz thrombectomy device in vitro.

PURPOSE: To determine the efficacy of thrombectomy for the Amplatz Thrombectomy Device (ATD) according to the age of the thrombus. METHODS: Thrombectomy was performed with the 7 Fr or 8 Fr ATD. Five-day-old or 8-day-old thrombi were made from porcine blood by clotting within silicone tubes to be used in a flow model. Emboli sizes, weight, remaining thrombus and activation time were evaluated. RESULTS: The age of the thrombus had no influence on the activation time necessary for complete thrombolysis. A significant difference was found in the overall amount of embolization only with the 7 Fr device although a similar trend was shown with the 8 Fr device. The amount of embolized thrombotic material was higher for both devices if older thrombi (i.e., 8 days old) were processed. The overall impression was that the 8 Fr device showed slightly better results (less remaining thrombus and embolization). CONCLUSION: A tendency toward higher amounts of embolization was observed if older thrombi were used in the model. Therefore the interventional radiologist should be aware of the potentially higher risk of peripheral embolization when performing mechanical thrombectomy (with the ATD) in older thrombotic occlusions, especially since the higher rate of embolization was mainly due to an increased proportion of larger embolic particles (1 mm), which are clinically more significant.

Animals↗